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Plants and their Interaction to Environmental Pollution: Damage Detection, Adaptation, Tolerance, Physiological and Molecular Responses Azamal Husen

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PLANTS AND THEIR INTERACTION TO ENVIRONMENTAL POLLUTION

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PLANTS

AND

THEIR INTERACTION

TO

ENVIRONMENTAL POLLUTION Damage Detection, Adaptation, Tolerance, Physiological and Molecular Responses

Edited by Azamal Husen Wolaita Sodo University, Wolaita, Ethiopia

Elsevier

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Dedication

To my Nana, Mohammad Habib (July 12, 1899–August 03, 1991)

A philanthropist, untold freedom fighter and retired as Treasury Officer from Azamgarh, in 1954. A Founder Member and Treasurer of Sukhpura Inter College, Ballia, India

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Contributors xi

About the editor xv Preface xvii

1. Plants and their unexpected response to environmental pollution: An overview

Shakeelur Rahman, Sahil Mehta, and Azamal Husen 1. Introduction 1

3. Effect of elevated CO2 on plant growth, active constituents, and production

Harmanjot Kaur, Antul Kumar, Anuj Choudhary, Shivam Sharma, D.R. Choudhary, and Sahil Mehta

1. Introduction 61

2. Current status of CO2 and historical perspectives 62

3. Effect of high CO2 on plant growth 64

4. Effect on the production of active constituents 69

5. Deleterious effect of alleviated CO2 on the plant architecture

6. Conclusion 73 References

4. Effect of elevated O3 on plants growth, active constituents, and production

Priti Chauhan and Neeti Sharma

1. Introduction 79

2. Chemistry of tropospheric O3 formation 80

2. Effect of UV-B radiation on plants growth, active constituents, and productivity

Irina F. Golovatskaya and Nikolay I. Laptev

1. Introduction 26

2. Physiological reactions of plants in response to UV-B-radiation 28

3. UV-B signaling in the plant 35

4. Plants protection mechanisms from the negative effects of UV-B 45

5. Applications of UV-B radiation in practice

3. Mechanisms by which O3 damages plant tissue 81

4. Volatile organic compounds (VOCs) 82

5. Toxicology of plants 83

6. The effects of ozone on plants 83

7. Measurements of ozone-induced changes 85

8. Visible injury and physiological effects 85

9. Effects on plant growth

10. Biochemical effects of O3 87

2. Plant

air pollution 4 3. Plant response to photochemical oxidants 6 4. Plant response to light pollution 8 5. Plant response to soil pollution 10 6. Plant response to water pollution 11 7. Plant response to noise pollution 12 8 Plant response to nanoparticles 14 9. Conclusion 15 References 16

response to

6. Conclusion 54 References 54 Further reading 60

11. Productivity measurements 88

12. The impact on crops and trees

13. Ozone and reactive oxygen species

for the surface 89

14. Ozone as a disinfectant

15. ROS and plant cell metabolism

90 References 91

vii

16. Conclusion

Contents

5. Plants response to SO2 or acid deposition

Suchisree Jha and Ashok Yadav

1. Introduction 99

2. Plant and SO2 or acid rain 100

3. Plants response to SO2 or acid deposition 100

4. Plants develops their defense system 105

5. Conclusion 106 References 106

6. Fly ash toxicity, concerned issues and possible impacts on plant health and production

Saurabh Sonwani, Anshu Gupta, Pallavi Saxena, and Anita Rani

1. Introduction 109

2. Fly ash composition 111

3. Causes of fly ash toxicity 112

4. Impact of fly ash on crop health and productivity 113

5. Effects of heavy metals on plant metabolism and physiology 117

6. Conclusion 119 References 120

7. Effect of coal-smoke pollution on plants growth, metabolism and production

Saumya Srivastava, Rajlaxmi Singh, and Prahlad Arya (Kumar)

1. Introduction 125

2. Principal phytotoxic gases of coal burning and their impact on flora 126

3. Other gases/release of coal burning and their impact on vegetation of the world 129

4. Conclusion 134

References 134

8. Effect of heavy metals on growth, physiological and biochemical responses of plants

Arslan Hafeez, Rizwan Rasheed, Muhammad Arslan Ashraf, Freeha Fatima Qureshi, Iqbal Hussain, and Muhammad Iqbal

1. Introduction 139

2. Effect of heavy metal pollution on plants 140

3. Cadmium (Cd) 142

4. Lead (Pb) 145

5. Arsenic (As) 147

6. Mercury (Hg) 149

7. Metal stress tolerance mechanisms in plants 150

8. Conclusion 151 References 151

9. Interaction of nanoparticles and nanocomposite with plant and environment

Chandrabose Selvaraj, Chandrabose Yogeswari, and Sanjeev Kumar Singh

1. Introduction 162

2. Sources of nanomaterials 162

3. Classification of nanoparticles 163

4. Organization of nanomaterials based on their sizes 165

5. Types of nanomaterials based on their source 165

6. Types of nanoparticles related to plants 166

7. Cerium NPs (CeO NPs) 168

8. Silicon NPs (SiNPs) 168

9. Titanium dioxide NPs (TiO2 NPs) 169

10. Nano pesticides 170

12. Interaction of NMs with soil and rhizosphere

19. Impact of natural organic material on NP-induced effects 182

20. Concluding remarks 183

Acknowledgment 183

References 183

10. Toxic effects of essential metals on plants: From damage to adaptation responses

Shivam Sharma, D.R. Choudhary, Viveka Katoch, Antul Kumar, Anuj Choudhary, B.M. Harish, Harmanjot Kaur, and Sahil Mehta

1. Introduction 195

2. Metal toxicity in plants 197

viii Contents

11. Nanoemulsion 173

173

13. Interaction of NMs with overall environment 174

178

14. Factors influencing the uptake and translocation of NPs 175 15. NPs for plant pathogen detection

16. Transport and interaction 179 17. Nanoparticle-plant interaction pathways 180 18. Effects of ion-releasing NP 181

11. Phytoremediation strategies of plants: Challenges and opportunities

Poonam Sharma, Smita Rai, Krishna Gautam, and Swati Sharma

12. Pesticide toxicity and their impact on plant growth, active constituents and productivity

Himani Gautam, Shubhra Singh, Hema Prashad, Antul Kumar, Anuj Choudhary, Harmanjot Kaur, Om Prakash Narayan, Shambhu Krishan Lal, and Sahil Mehta

1. Introduction 232

2. Phytotoxicity effects on plants 233

3. Pesticides phytotoxicity symptoms on plants 236

4. Impact of pesticide toxicity on soil health and plant 237

5. Other measures for the prevention of pesticides phytotoxicity 246

6. Conclusion 246 References 247

13. Plant responses to water pollution

Nirmal Singh, Sourabh, Pramod Kumar, Preeti, and Sahil Mehta

1. Introduction 253

2. Water pollution: Definition, types, and extent of the problem 254

3. Plant and water pollution 257

4. Concluding remarks 261

References 261

Contributors

K.F. Abdelmotelb Department of Genetics, Faculty of Agriculture, Zagazig University, Zagazig, Egypt

Qasim Ali Department of Soil Sciences, Faculty of Agriculture and Environment, The Islamia University of Bahawalpur, Bahawalpur, Pakistan

Phaniendra Alugoju Natural Products for Neuroprotection and Anti-Ageing Research Unit; Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand

Ayesha Anwar Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, Pakistan

Prahlad Arya (Kumar) Department of Geology, Patna Science College, Patna University, Patna, Bihar, India

Muhammad Arslan Ashraf Department of Botany, Government College University Faisalabad, Faisalabad, Pakistan

Sana Ashraf College of Earth and Environmental Sciences, Quaid-e-Azam Campus, University of the Punjab, Lahore, Pakistan

Geeta Boken Department of Genetics and Plant Breeding, CCS Haryana Agricultural University, Hisar, Haryana, India

D.R. Choudhary Department of Vegetable Science and Floriculture, CSK HPKV, Palampur, Himachal Pradesh, India

Priti Chauhan Department of Biosciences and Biotechnology, Banasthali Vidyapith, Jaipur, Rajasthan, India

Akash Ravindra Chichaghare Department of Silviculture and Agroforestry, Kerala Agricultural University, Thrissur, Kerala, India

Anuj Choudhary Department of Botany, Punjab Agricultural University, Ludhiana, Punjab, India

Sami El Khatib LIU, Lebanese International University, Al Khyara-West Bekaa, Lebanon

Himani Gautam Department of Entomology, Dr. YS Parmar University of Horticulture and Forestry, Nauni Solan, Himachal Pradesh, India

Krishna Gautam Centre for Energy and Environmental Sustainability, Lucknow, Uttar Pradesh, India

Irina F. Golovatskaya Department of Plant Physiology, Biotechnology and Bioinformatics, National Research Tomsk State University, Tomsk, Russia

Anshu Gupta Department of Environmental Science, Government Degree College, Jammu, India

Arslan Hafeez Department of Botany, Government College University Faisalabad, Faisalabad, Pakistan

B.M. Harish Department of Vegetable Science and Floriculture, CSK HPKV, Palampur, Himachal Pradesh, India

Azamal Husen Wolaita Sodo University, Wolaita, Ethiopia

Iqbal Hussain Department of Botany, Government College University Faisalabad, Faisalabad, Pakistan

Muhammad Iqbal Department of Botany, Government College University Faisalabad, Faisalabad, Pakistan

Suchisree Jha Plant Nutrition Department, Indofil Industries Limited, Thane, Maharashtra, India

Contributors

Viveka Katoch Department of Seed Science and Technology, CSK HPKV Palampur, Himachal Pradesh, India

Harmanjot Kaur Department of Botany, Punjab Agricultural University, Ludhiana, Punjab, India

Kehkashan Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, Pakistan

Wajahat Ali Khan International Centre for Genetic Engineering and Biotechnology, New Delhi, Delhi, India

Maha Krayem LIU, Lebanese International University, Al Khyara-West Bekaa, Lebanon

Antul Kumar Department of Botany, Punjab Agricultural University, Ludhiana, Punjab, India

Pramod Kumar Department of Agronomy, CCS Haryana Agricultural University, Hisar, Haryana, India

Pascal Labrousse Université de Limoges, PEIRENE EA 7500, Limoges, France

Manisha Lakhanpal Department of Forest Products (Medicinal and Aromatic Plants), Dr YS Parmar university of Horticulture and Forestry, Nauni, Himachal Pradesh, India

Shambhu Krishan Lal School of Genetic Engineering, ICAR–Indian Institute of Agricultural Biotechnology, Ranchi, Jharkhand; International Centre for Genetic Engineering and Biotechnology, New Delhi, India

Nikolay I. Laptev Department of Ecology, Nature Management and Environmental Engineering, National Research Tomsk State University, Tomsk, Russia

Shivaji Ajinath Lavale Centre for Plant Biotechnology and Molecular Biology, Kerala Agricultural University, Thrissur, Kerala, India

Paul V. Manley Department of Civil, Architectural and Environmental Engineering, College of Engineering and Computing, Missouri University of Science and Technology, Rolla, MO, United States

Sahil Mehta Department of Botany, Hansraj College, University of Delhi, New Delhi, India

Om Prakash Narayan BME Department, Tufts University, Medford, MA, United States

Shri Hari Prasad Centre for Plant Biotechnology and Molecular Biology, Kerala Agricultural University, Thrissur, Kerala, India

Hema Prashad Department of Entomology, Dr. YS Parmar University of Horticulture and Forestry, Nauni Solan, Himachal Pradesh, India

Preeti ICAR-National Bureau of Plant Genetic Resources, New Delhi, India

Freeha Fatima Qureshi Department of Botany, Government College University Faisalabad, Faisalabad, Pakistan

Shakeelur Rahman Prakriti Bachao Foundation, Ranchi, Jharkhand, India

Smita Rai Department of Biosciences, Integral University, Lucknow, Uttar Pradesh, India

Anita Rani Department of Botany, Dyal Singh College, University of Delhi, Delhi, India

Rizwan Rasheed Department of Botany, Government College University Faisalabad, Faisalabad, Pakistan

Azna Safdar Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, Pakistan

Pallavi Saxena Department of Environmental Sciences, Hindu College, University of Delhi, Delhi, India

Chandrabose Selvaraj Computer-Aided Drug Design and Molecular Modeling Lab, Department of Bioinformatics, Science Block, Alagappa University, Karaikudi, Tamil Nadu, India

Neeti Sharma Department of Biosciences and Biotechnology, Banasthali Vidyapith, Jaipur, Rajasthan, India

Poonam Sharma Department of Bioengineering, Integral University, Lucknow, Uttar Pradesh, India

Shivam Sharma Department of Vegetable Science and Floriculture, CSK HPKV, Palampur, Himachal Pradesh, India

Swati Sharma Department of Biosciences, Integral University, Lucknow, Uttar Pradesh, India

Khushboo Singh School of Agricultural Sciences, K.R. Mangalam University, Gurugram, Haryana, India

xii

Nirmal Singh Department of Seed Science and Technology, CCS Haryana Agricultural University, Hisar, Haryana, India

Rajlaxmi Singh Department of Botany, Patna University, Patna, Bihar, India

Sanjeev Kumar Singh Computer-Aided Drug Design and Molecular Modeling Lab, Department of Bioinformatics, Science Block, Alagappa University, Karaikudi, Tamil Nadu, India

Shubhra Singh Department of Entomology, Dr. YS Parmar University of Horticulture and Forestry, Nauni Solan, Himachal Pradesh, India

Saurabh Sonwani Department of Environmental Studies, Zakir Husain Delhi College, University of Delhi, Delhi, India

Sourabh ICAR – Central Arid Zone Research Institute, Jodhpur, Rajasthan, India

Saumya Srivastava Department of Botany, Patna University, Patna, Bihar, India

Tewin Tencomnao Natural Products for Neuroprotection and Anti-Ageing Research Unit; Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand; Department of Physiology, University of Kentucky, Lexington, KY, United States

Stephen M. Via Department of Biology, College of Science, Engineering, and Technology, Norfolk State University, Norfolk, VA, United States

Ashok Yadav ICAR-Central Agroforestry Research Institute, Jhansi, Uttar Pradesh, India

Chandrabose Yogeswari Ezhilnala Siddha Varma Hospital and Research Centre, Madurai, Tamil Nadu, India

xiii

Contributors

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About the editor

Professor Azamal Husen holds a BSc from Shri Murli Manohar Town Post Graduate College, Ballia, UP; an MSc from Hamdard University, New Delhi; and a PhD from Forest Research Institute, Dehra Dun, India.. He is Foreign Delegate at Wolaita Sodo University, Wolaita, Ethiopia. He has served the University of Gondar, Ethiopia, as Full Professor of Biology, and worked there as the coordinator of MSc Program and as the Head of the Department of Biology. He was Visiting Faculty of the Forest Research Institute, and the Doon College of Agriculture and Forest at Dehra Dun, India. Dr. Husen’s research and teaching experience of 20 years includes biogenic nanomaterial fabrication and application, plant responses to nanomaterials, plant adaptation to harsh environments at the physiological, biochemical and molecular levels, herbal medicine, and clonal propagation for improvement of tree species.

Dr. Husen has conducted several research projects sponsored by various funding agencies, including the World Bank (FREEP), the National Agricultural Technology Project (NATP), the Indian Council of Agriculture Research (ICAR), the Indian Council of Forest Research Education (ICFRE), and the Japan Bank for International Cooperation (JBIC). He received four fellowships from India and a recognition award from the University of Gondar, Ethiopia, for his excellent teaching, research, and community service. An efficient evaluator of research projects, book proposals, etc., Dr. Husen has been on the editorial board and the panel of reviewers of several reputed journals published by Elsevier, Frontiers Media SA, Taylor & Francis, Springer Nature, RSC, Oxford University Press, Sciendo, The Royal Society, CSIRO, PLOS, MDPI, and John Wiley & Sons. He is on the advisory board of Cambridge Scholars Publishing, UK. He is Fellow of the Plantae group of the American Society of Plant Biologists, and Member of the International Society of Root Research, Asian Council of Science Editors, and INPST. He has more than 200 publications to this credit; he is also Editor-in-Chief of the American Journal of Plant Physiology. He is also working as Series Editor of Exploring Medicinal Plants, published by Taylor & Francis Group, USA; Plant Biology, Sustainability, and Climate Change, published by Elsevier, USA; and Smart Nanomaterials Technology, published by Springer Nature Singapore Pte Ltd. Singapore.

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Preface

Environmental pollution as a consequence of diverse human activities has become a global concern. Urbanization, mining, industrial revolution, burning of fossil fuels/firewood, and poor agricultural practices as well as improper dumping of waste products are largely responsible for the undesirable change in the environment composition. The sources of pollution may be the point sources, which are easily identified; and/or nonpoint sources, where the pollution comes from diffuse sources that are not easy to pinpoint. In our society, the environmental pollution is mainly classified as air pollution, water pollution, land pollution, noise pollution, thermal pollution, light pollution, and plastic pollution. Nowadays, it has been realized that with the increasing environmental pollution, impurities may accumulate in plants, which are required for basic human uses such as food, clothing, and medicine. Environmental pollution has tremendous impacts on phenological events, structural patterns, physiological phenomena, biochemical status, and the cellular and molecular features of plants. Exposure to environmental pollution induces acute or chronic injury depending on the pollutant concentration, exposure duration, season, and plant species. Moreover, the global rise of greenhouse gases such as carbon monoxide, carbon dioxide, nitrous oxides, methane, chlorofluorocarbons, and ozone in the atmosphere is among the major threats to the biodiversity. They have also shown visible impacts on life cycles and distribution of various plant species. Anthropogenic activities, including the

fossil-fuel combustion in particular, are responsible for steady increases in the atmospheric greenhouse gas concentrations. This phenomenon accelerates the global warming. Studies have suggested that the changes in carbon dioxide concentrations, rainfall, and temperature have greatly influenced the plant physiological and metabolic activities including the formation of biologically active ingredients. Taken together, plants interact negatively with pollutants and cause adverse ecological and economic outcomes. Therefore, plant response to pollutants requires more investigation in terms of damage detection, adaptation, tolerance, and the physiological and molecular responses. The complex interplay among other emerging pollutants, namely, radioisotopes, cell phone radiation, nanoparticles, nanocomposites, heavy metals, etc. and their impact on plant adaptation strategies, and possibility to recover, mitigation, phytoremediation, etc., also needs to be explored. Further, it is necessary to elucidate better the process of the pollutant’s uptake by plant and accumulation in the food chain, and the plant resistance capability against the various kinds of environmental pollutants. In this context, the identification of tolerance mechanisms in plants against pollutants can help in developing eco-friendly technologies, which requires molecular approaches to increase plant tolerance to pollutants, such as plant transformation and genetic modifications. Pollutant-induced overproduction of reactive oxygen species that cause DNA damage and apoptosis-related alterations has also been examined. They also trigger changes at

xvii

the levels of transcriptome, proteome, and metabolome, which has been discussed in this book.

The book in hand covers a wide range of topics as mentioned above. It incorporates chapters that the authors have skillfully crafted with clarity and precision, reviewing up-to-date literature with lucid illustrations. The book caters to the need of graduate students and is also useful for both novices and experienced scientists/researchers. It should also inspire industrialists and policy makers associated with plant products and the

environmental health and planning. I extend my sincere thanks to all the contributors for their timely response and excellent contributions. Finally, my special thanks go to Shagufta, Zaara, Mehwish, and Huzaifa for providing their time, encouragement, and extended support to put everything together. I would be happy to receive comments and criticism, if any, from subject experts and general readers of this book.

Azamal Husen

xviii Preface

CHAPTER 1

Plants and their unexpected response to environmental pollution: An overview

Shakeelur Rahmana, Sahil Mehtab, and Azamal Husenc

aPrakriti Bachao Foundation, Ranchi, Jharkhand, India, bDepartment of Botany, Hansraj College, University of Delhi, New Delhi, India, cWolaita Sodo University, Wolaita, Ethiopia

Abbreviations

ATP adenosine tri-phosphate

CFCs chloro fluoro carbons

dB decibel

FR far-red

H2S hydrogen sulfide

HCl hydrogen chloride

HF hydrogen fluoride

NO2 nitrogen dioxide

NPs nanoparticles

NMs nanomaterials

PAN peroxy acetyl nitrate

PAR photosynthetically active radiation

R red

ROS reactive oxygen species

SPL sound pressure level

SOD superoxide dismutases

UV ultraviolet radiation

1. Introduction

Environmental pollution is one of the most complex problems in the modern world. Combustion of fossil fuels, urbanization, chemicals used in agriculture, traffic load, war weapons, airplanes, and industrialization results in increased emission of toxic gases. These

1. Plants and their unexpected response

are the major sources of pollution responsible for numerous impacts on the flora and fauna (Husen, 2021a,b,c, 2022). As a result, the chemical composition of the atmosphere has been distorted. In the present scenario, the increase in the concentration of greenhouse gases such as carbon monoxide (CO), carbon dioxide (CO2), nitrous oxides (NOx), methane (CH4), chlorofluorocarbons (CFCs), and ozone (O3) in the atmosphere is among the most major threats to the biodiversity. Overall, environmental pollution has tremendous impacts on plant growth, development, and physiological performance at the cellular and molecular levels (Husen, 2022; Deepti et al., 2022a,b; Rahman and Husen, 2022) (Fig. 1). The global rise of environmental pollution also leads to climate change causing visible impacts on life cycles and distribution of various plant species. The raised level of CO2 and sulfur dioxide (SO2) in the atmosphere is also affecting the productivity and quality of plants species, showing major changes in their chemical composition (Husen, 1997, 2022; Husen et al., 1999; Idso et al., 2000; Iqbal et al., 2018).

Plants absorb pollutants on the surface of leaves, and onto the plant root-soil system to mitigate global warming and minimize the pollution load in a particular area. Moreover, forests act as a purification system of the planet earth by absorbing airborne chemicals and releasing oxygen. However, another aspect is that water pollution gives sufficient space for other plants to grow well because the nutrients they need for existence are collected in the polluted water. Water pollution also modifies the growing environment of plants, such as the removal of essential nutrients and bringing in new and hazardous ones. Acid rain (mainly NO2 and SO2 deposition), also harm by burning or killing plants in a specific location. Soils and freshwaters are naturally acidic (pH < 7) owing to the oxidation and respiration reactions in biotic and abiotic systems. During the twentieth century, the acidity of many regions of the world continuously increased as a consequence of energy and food production.

to environmental

pollution

FIG. 1 Plant response to various types of environmental pollution.

The phenomena and impacts of acid rain on vegetation create a complex situation for plants which ends up with the plants being unable to flourish. Acidic conditions accumulate a lot of aluminum ions in the soil, which destroys roots systems and prevents the uptake of important nutrients and ions (Lal, 2016).

Some plants, such as species of cactus bloom only in the dark at night. They are pollinated by bats and moths and other nocturnal animals or insects. Increasing the duration of light in such areas will disrupt the pollination and this affects plant's ability to flower and reproduce and this will ultimately disrupt our food sources. It is amazing to know that plants, like animals, are sensitive to light, intensity, color, and duration of exposure. Photosynthesis, therefore, requires blue and red lights of high intensity. Low-intensity red and infrared lights are good for regulating biological rhythms and controlling processes like seed germination, flower development, leaf expansion, stem elongation, etc. thus, light pollution perhaps, therefore affects all these biological phenomena.

Air pollution can affect plants directly through the leaves, as well as indirectly by the acidification of the soil environment (Iqbal et al., 1987, 2010a,b, 2011; Husen and Iqbal, 2004; Kumar and Nandini, 2013). The impacts of atmospheric pollution are generally observed on leaves because they are the first receptors (Randhi and Reddy, 2012). It has also been observed in different studies that the majority of plants exposed to a polluted atmosphere start many physiological changes before visible injuries to the leaves (Abida and Harikrishna, 2010). The study on environmental pollution in relation to anatomical, morphological, physiological, and biochemical parameters of plants has been conducted by several researchers (Husen, 2021a,b,c). Some of the biochemical mechanisms assist to acclimatize plants to atmospheric pollutants. It can be assessed by several parameters or air pollution tolerance indexes such as total chlorophyll, relative water content, ascorbic acid, and pH. Similarly, the tolerance of plants to heavy metal toxicity has to be established to judge their possible application in soil phyto stabilization and plantation in mining areas contaminated with heavy metals (Nadgorska-Socha et al., 2013a,b; Iqbal et al., 2015). A plant in stress delays flowering as it uses all its resources to face the threat. For example, most of the plants exposed to vehicular pollution, delay in flowering as they are fighting the emissions.

Another important concern is the depletion in the stratospheric O3 layer causes ultraviolet radiation (UV-B) radiation which is harmful not only to human health but also to plants and sea biota. It physically injures the plant leaves, causing abnormal yellowing of leaves or chlorosis. These results in a deficiency in chlorophyll, meaning the plant will not be able to make its own food or energy. With a higher concentration of O3, plant leaves will simply die due to too much exposure. Destruction by the O3 in the lower atmosphere restricts respiration, obstructs stomata, prevents photosynthesis, and stunts plant growth (Deepti et al., 2022a).

Plants have shown immediate (acute) and long (chronic) impacts of environmental pollution on plant growth and developmental processes (Husen, 1997, 2021c, 2022), which may depend on the types of plant species, exposure duration, concentration, and types of pollutants. It has been suggested that the anthropogenic or naturally produced pollutants interact with various plant species, and alter plant growth, development, biochemical physiological, and molecular performance. Moreover, their impact may vary according to the pollution source, pollutant types, season, exposure duration, plant species, leaf types, leaf thickness, presence of leaf hair or trichomes, epicuticular wax, etc. (Husen, 2021c, 2022). Taken together,

1. Introduction 3

1. Plants and their unexpected response to environmental pollution

this chapter reports the effect of various environmental pollution on plant growth and development, cytological, biochemical, physiological, and molecular responses.

2. Plant response to air pollution

The most significant anthropogenic phytotoxic gaseous air pollutants include nitrogen dioxide (NO2), O3, CO2, SO2, hydrogen sulfide (H2S), hydrogen chloride (HCl), hydrogen fluoride (HF), chlorine (Cl2), ethylene (C2H4), peroxyacetyl nitrate (PAN), and ammonia (NH3). These gases can be categorized according to their biochemical and physiological activity in plant cells as given in Table 1 (De Kok and Stulen, 1998).

The air pollutants that cause plant injury are most common near large cities, refineries, smelters, electric power plants, incinerators, refuse dumps, pulp and paper mills, and coal, gas, petroleum burning furnaces, other industries, airports, and highways. Several factors administer the level of injury and the area where air pollution is a problem, these are type and concentration of pollutants, length of exposure, distance from the source, meteorological conditions, and maturity of plant tissues, species, and variety of plants (Husen, 2021c, 2022). The extreme temperature, light, soil moisture deficit, and humidity recurrently modify the response of the plant to air pollutants. The impacts of pollutants on plants include burning at leaf tips or margins, blotchy foliage, twig dieback, premature leaf drop, delayed maturity, early drop of blossoms, stunted growth, and reduced yield. Generally, the visible injury to plants is of three types collapse of leaf tissue with the development of necrotic patterns, alterations in growth or premature loss of foliage, and yellowing or other color changes.

Air pollution injuries can create confusion with the symptoms caused by bacteria, fungi, nematodes, insects, viruses, toxicities, nutritional deficiencies as well as the adverse effects of water, temperature, and wind. SO2 is one of the key air pollutants which can get enter in the plant parts through roots as well as stomatal opening during photosynthesis and respiration. Young plants and matured leaves are most susceptible to SO2. SO2 injury can be severe 30 miles or more from its source. Injury, however, is generally highest in the surrounding area of the source. The degree of injury increases as both the concentration of sulfur dioxide and the length of exposure increase. Different responses of the plants against SO2 exposure have been reported (Rahman and Husen, 2022). It also depends on the plant species and different environmental factors (Rahman and Husen, 2022).

TABLE 1

Air pollutant

The main metabolic activities of phytotoxic air pollutants in plants.

Metabolic activity

O3, PAN

SO2, NO2, HF, HCl

SO2

Oxidizing

Acidifying

Mutagenic

SO2, NO2, H2S Reducing

NH3, NH4 +, NO2, NO

O3, PAN, SO2, HF, C2H4

N-eutrophying

Disturbing hormonal balance

Plants are most sensitive to SO2 during periods of high relative humidity, bright sun, and adequate plant moisture during the late spring and early summer. Some of the responses are damaging photosystem, changes in the stomatal density, and deviations in the efficiency of carbon fixation (Swanepoel et al., 2007; Haworth et al., 2012; Husen, 2022). The exposure of succulent, broad-leaved plants to SO2 and its by-product sulfuric acid generally results in dry, white, or straw papery spots. Chronic injury causes brown to reddish-brown or black blotches on both surfaces of the leaf of some plant species. A tan to reddish-brown banding or dieback occurs on conifer leaves with adjoining areas. SO2 from the atmosphere along with H2S works as a sulfur source that can be up-taken through stomata of the plants other than the sulfate uptake from the roots. This stomatal uptake affects the metabolic profile of the plant.

Glucosinolates are sulfur-containing secondary metabolites that play an important function in sulfur storage which helps in the redistribution of sulfur during the sulfur-deprived condition (Falk et al., 2007). Two members from the genus Brassica were exposed to the 0.25 μL 1 of SO2 for seven days to examine the deviations in the glucosinolate content (Aghajanzadeh et al., 2015). The glucosinolate content was observed negligible change in the shoot under sulfur deprived as well as sufficient conditions. It has been reported that the high concentration of hydrogen sulfide (H2S) is responsible for leaf lesions, defoliation, tissue death and decreased growth rate in some plant species. H2S is also a signaling molecule that is proven to endorse the antioxidant activities in many plants against abiotic stresses. The application of H2S increased the antioxidant potential and quality in plants. Brassica oleracea was applied with the incrementing levels of sodium hydrosulfide (as an H2S donor) to check the physiological and antioxidative changes. It was observed that the lower levels of treatment showed increased contents of anthocyanins, flavonols, total phenolics, sinigrin, and carotenoids (Montesinos-Pereira et al., 2016). H2S has been also noted to mediate nicotine biosynthesis in Nicotiana tabacum when the growth of plants is induced under high temperatures. The element fluorine is found in fluorides compounds. Injury by particulate or gaseous fluorides is either a reddish brown or tan or yellowish mottle blistering at the tips and margin of broadleaved plants. A narrow, chlorotic to the dark brown band is mostly found between living and dead tissues (Chen et al., 2016). Many explanations related to plant response to SO2 pollution have been discussed in detail in the chapters to follow.

Further, greenhouse gases are major environmental challenge for a range of plant species (Husen, 2022; Choudhary et al., 2022). In this connection, CO2 is one of the key causes of a terrific rise since industrialization took place. Overall, the performance of plants to elevated CO2have shown both positive and negative responses. In terms of positive response, elevated CO2increased photosynthesis and subsequently higher growth, biomass, and plant yield (Ainsworth and Long, 2005; De Souza et al., 2008; van der Kooi et al., 2016). Though, in terms of negative response, elevated CO2has decreased a variety of nutrients including protein concentrations, vitamins, and macro- and microelements in plants (Myers et al., 2014; Fernando et al., 2015; Broberg et al., 2017; Thompson et al., 2019). Therefore, it is essential to understand the effect of elevated CO2 on plant growth and production. The elevated CO2 significantly affects photosynthetic features, metabolism, and plant development (Nowak et al., 2004; Ainsworth and Long, 2005).

It is assumed that C4 photosynthesis was saturated at ambient CO2 and that C4 plants might be less and/or not at all affected by the increased level of CO2 in comparison to C3 plant species (Pearcy and Ehleringer, 1984; Bowes, 1993). Possibly, this assumption appeared

2. Plant response to air pollution 5

1. Plants and their unexpected response

in the anatomical and functional variation of C3 and C4 plant species and higher CO2 levels in bundle sheath cells of C4 leaves. However, it has been also observed that the variation between C3 and C4 is not as important as anticipated and that C4 plants can also accelerate photosynthesis under elevated CO2. For example, Ziska and Bunce (1997) reported an increase in growth (3%–25%) and photosynthesis (4%–30%) in six different weed species namely, Amaranthus retrofexus, Echinochloa crus-galli, Panicum dichotomiforum, Setariafaberi, Setariaviridis, and Sorghum halapense; and also, inf our crop species namely, Amaranthus hypochondriacus, Saccharum offcinarum, Sorghum bicolor, and Zea mays under elevated CO2.

In some investigations, under abiotic stress (high temperature and drought) conditions it has been noticed that the elevated CO2 reduces the negative effects of stress by mitigating oxidative stress and improving water status in Arabidopsis thaliana (Abo Gamar et al., 2019). Balasooriya et al. (2020) has demonstrated that elevated CO2 (950 ppm) and higher temperature (30°C) increased the amounts of accessible bioactive compounds in strawberries plants. It has been also reported that the rice seed priming with salicylic acid (25 mg L 1) and ascorbic acid (100 mg L 1) increased germination rate, other seed quality features, α-amylase activity, and antioxidant enzyme activities under stress due to elevated CO2 and temperatures (Nedunchezhiyan et al., 2020).

Medicinal plants are good sources for plant secondary metabolites; they hold significant plasticity to acclimatize to the changing environments (Husen, 2021a,b, 2022). Digitalis lanata is known for its use in heart failures (Rahimtoola, 2004), when treated with elevated CO2, there was a 3.5-folds increase in digoxin, a cardenolide glycoside. The digoxin also enhances other three glycosides viz. digoxin-mono-digitoxoside, digitoxin, and digitoxigenin showing a decline in their concentration (Stuhlfauth et al., 1987). It was observed in an experiment on Hymenocallis littoralis whose bulbs are known for their antineoplastic and antiviral properties, the elevated CO2 resulted in an increase in three types of alkaloids (Pancratistatin, 7-deoxynarciclasine, and 7-deoxy-trans dihydronarciclasin) in the first year and decrease in their concentration for the subsequent year (Idso et al., 2000). Similarly, in Ginkgo biloba a traditional Chinese medicinal plant used in Alzheimer’s disease, vascular or mixed dementia (Weinmann et al., 2010) elevated CO2 and O3 together resulted in altered terpenoid content, increase in quercetin aglycon, and decrease in keampferol aglycon (Huang et al., 2010). In Zingiber officinale, elevated CO2 increased flavonoid and phenolic content (Ghasemzadeh et al., 2010). Many explanations and findings related to the aforementioned subject are discussed in Chapter 3.

3. Plant response to photochemical oxidants

The most important photochemical oxidants in the atmosphere include NO2, O3, and PAN. These oxidants are secondary pollutants that develop as a result of sunlight reacting with the products of fuel combustion. O3 is come down from the stratosphere by vertical winds or formed during electrical storms; more importantly, it is produced when sunlight reacts with nitrogen oxides and hydrocarbons formed by refuse burning and combustion of coal or petroleum fuels, especially the exhaust gases from internal-combustion engines. O3 is well known for its life-protective layer against ultra violet radiations. However, the ground level of O3 is increasing because of the rise in O3 precursor emissions in polluted areas. Plant performance

to environmental

pollution

under elevated O3 has been reported by many investigators (Rai and Agrawal, 2012; Fuhrer et al., 2016; Jolivet et al., 2016; Li et al., 2017; Yendrek et al., 2017; Mills et al., 2018; Shang et al., 2019; Peng et al., 2019; Ghosh et al., 2020; Mohamed et al., 2021; Deepti et al., 2022a; Yin et al., 2022). They have shown that the young plants are generally the most sensitive to O3 whereas mature plants are relatively resistant.

O3 is most likely an important plant-toxic air pollutant and a very active form of oxygen that causes different types of symptoms on broad-leaved plants such as interveinal chlorosis, necrosis, scar on the upper surface of leaves, tissue collapse, flecking, bleaching, and mottling. O3 reduced the plant growth and slow down bud formation and flowering. Affected leaves of certain plants, such as tobacco, citrus, and grape shrink and drop early. Conifers recurrently express a yellow to brown mottling and tip burn, or flecking and banding of the needles (Stolte, 1996). The flecks may later combine to form larger, bleached white to yellowish dead areas. O3 usually attacks nearly mature leaves first, moving to younger and older leaves. The leaves tissues damaged by O3 are infected by certain fungi like Botrytis. O3 has several biochemical and physiological effects on plants.

At the biochemical level, O3 oxidizes sulfhydryl and fatty acid double bonds, increases membrane permeability, disrupts membrane-bound photosynthetic systems, and reduces foliar sugar and polysaccharide levels. At the physiological level, stomatal conductance, net photosynthesis, and water use efficiency are reduced, dark respiration is affected, carbon allocation is changed, leaf senescence is accelerated, foliar visible injuries and leaching are increased, floral yield is decreased, and fruit set is delayed. O3-induced reduction in growth rates and yield happens through impaired net photosynthesis and regeneration (Rai and Agrawal, 2012; Deepti et al., 2022a). O3 impacts changes in wood quality reduced wood density and tracheid length, resulting in reductions in wood strength, pulp yield, and quality. The oxidation products of atmospheric nitrogen (NOx) are chemically reactive gaseous pollutants with harmful effects on biological systems. NO2 is a precursor molecule for other NOx components and O3 (Chappelka and Samuelson, 1998). A reduction in the level of RNA transcript for the small subunit of RuBisCO, photosynthetic gene expression under ozone stress has been reported in rice plants (Agrawal et al., 2002).

In another report, Sarkar and Agrawal (2010) also reported reduced levels of mRNA (both small and large subunits of RuBisCO) in the same plant under ozone exposure. In an experiment, Ghosh et al. (2020) used two sowing dates (timely sown and late sown) to explore the effect of elevated O3 on Triticum aestivum cv. HD 2967 growth including biomass, leaf gas exchange rate and other yield features such as the length of the ear plant, weight of ears plant, number of grains plant, weight of grains plant, husk weight plant, straw weight plant, harvest index, test weight of the grains, and straw grain ratio. Ghosh et al. (2020) concluded that O3 stress affected growth and productivity and late sowing practice is not worthwhile for wheat cultivation. Many other investigations have exhibited that O3 stress adversely influences photosynthesis and other related physiological performance in wheat (Feng et al., 2008; Ghosh et al., 2020), soybean (Morgan et al., 2003), rice (Ainsworth, 2008), radish, and brinjal (Tiwari and Agrawal, 2011). The reduced rate of assimilation was attributed to decreased carboxylation efficiency and was associated with reduced RuBisCO activity (Leitao et al., 2007). Sarkar and Agrawal (2010) reported that the degree of O3-induced foliar injury depends on the exposure duration and concentration. Reduced photosynthesis may also be noticed because of damage to thylakoids, which influenced photosynthetic transport of electrons and is

3. Plant response to photochemical oxidants 7

shown by a decrease in the Fv/Fm ratio. Quite often, the Fv/Fm ratio is associated with plant stress condition evaluation (Husen, 2009, 2010, 2013; Husen et al., 2017, 2019).

Next to O3, the most plant-toxic oxidant is PAN. Similar to O3, PAN is produced when sunlight reacts with different exhaust gases. PAN is formed by oxides of nitrogen reacting with unsaturated hydrocarbons in presence of light. PAN causes a collapse of tissue on the lower leaf surface of many plant species. The distinctive leaf marking is a bronzing, glazing, or silvering that commonly develops in blotches. On some plants, such as tobacco, petunia, bean, and tomato the wrinkle may be through the entire thickness of the leaf blade. In grasses, the collapsed tissue has a bleached appearance, with tan to yellow, transverse bands. Conifer needles change into yellow. Senescence, chlorosis, moderate to severe stunting, and premature leaf drop can occur. PAN is most toxic to lower plants and young leaves.

Damage caused by ethylene (H2C-CH2) is often associated with PAN and O3 in urban areas. Ethylene modifies the activities of plant hormones and growth regulators, which affect developing tissues and normal organ development, without causing leaf-tissue collapse and necrosis. Broad-leaved plants injury occurs as downward curling of the leaves and shoots, followed by a stunting of growth. O3 and PAN-compounds are the main photochemical oxidants, having severe adverse effects on plants. A large number of experiments have been carried out to explain the physiological and biochemical mechanisms of toxicity of O3 in crop plants, medicinal plants, and various forest trees species (Stolte, 1996; Deepti et al., 2022a). In several herbaceous crop plants, there was a positive correlation between O3 exposure and the induction of arginine decarboxylase activity, resulting in increased spermidine content in barley and increased putrescine content in O3-resistant tobacco and potato. These depositions in polyamine compounds were correlated with improved protection against O3 damage in leaves (Grunhage et al., 2001). It was observed in a study on Melissa officinalis, an important medicinal plant used for the treatment of the central nervous system (CNS) related disorders, dementia, and anxiety with elevated O3 concentrations showed that the total anthocyanins increased to a significant extent along with phenolics and tannins (Pellegrini et al., 2011). It was found that pericarp of Capsicum baccatum when exposed to O3 shows a decrease in capsaicin and dihydrocapsaicin (Bortolin and Caregnato, 2016). The effect of O3 as an indicator of secondary metabolites alterations under in vitro conditions has also been studied. An experiment on Pueraria thomsnii suspension cultures showed an increase in puerarin production by cells treated with O3 (Sun et al., 2012). Many explanations related to plant response to O3 exposure have been discussed in detail in the chapters to follow.

4. Plant response to light pollution

Light pollution refers to the large amount of light produced by most urban and other heavily populated areas. Light pollution has been shown to hinder the migration patterns of birds and the activities of nocturnal animals which are helpful in pollination. Photosynthetically active radiation (PAR, 400–700 nm) is part of the visible light (380–760 nm). The major wavelengths sensed by plant photoreceptors and pigments correspond to blue (400–500 nm) and red (R, 600–700 nm), and, to a lesser extent, green (500–600 nm) light. Plants perceive a small fraction of near-infrared radiation or far-red (FR) light due to phytochromes with a sensitivity peak at 730 nm, which is important for plant development (Huche-Thelier et al., 2016).

to environmental pollution

1. Plants and their unexpected response

Generally, plants developed two opposite strategies in response to competition for light, i.e., shade avoidance and shade tolerance (Ruberti et al., 2012). Plants shaded within a canopy will have reduced R/FR and blue/green ratios, sensed by phytochromes and cryptochromes, respectively. FR photons are not effective to induce photosynthesis, so a low R/FR ratio may quickly provoke changes in gene expression and physiological responses, controlling phenotypic plasticity and allowing plants to compete better with surrounding plants (Keuskamp et al., 2010). Flowering plants respond to the reduction in R/FR ratio due to phytochrome photoreceptors which is an early signal of neighbor proximity and activate complex developmental responses like elongated stems, petioles, hypocotyls and internodes, smaller leaves/ reduction in leaf development, apical dominance, suppression of branching and early flowering (Keuskamp et al., 2010; Ruberti et al., 2012). Stimulation of height growth is a remarkable shade avoidance response. The response is fast and reversible when returning plants to light with a high R/FR ratio. In contrast to shade avoidance, shade-tolerance response inhibits shade avoidance characteristics and increases leaf expansion causing interception of more radiation and simultaneous chlorophyll reorganization to improve photosynthetic efficiency (Gommers et al., 2013; Park and Runkle, 2017).

Light is also used as elicitor treatment to improve the biosynthesis of bioactive compounds in plants. In addition, UV and PAR depending on their quality and intensity may induce ROS and oxidative stress, affecting the biosynthesis of primary and secondary metabolites, plant growth and biomass as well as phytohormones (Wani et al., 2016; Deepti et al., 2022b). Further, the effect of UV-B radiation on plants growth, active constituents, and production has been discussed in detail in the chapters to follow. Other types of light or shade also stimulate very complex metabolic acclimation responses, including the synthesis of new secondary metabolites, which were not found under control conditions. Biosynthesis of both plant secondary metabolites and phytohormones depends on environmental factors, genotype, and genetic regulation. Different plant species have their own optimal light set, i.e., quality and quantity which administer to elicit maximal yield of secondary metabolites (Zhou et al., 2016). Specific light irradiation with narrow-bandwidth light could influence important herbal traits like aroma in sweet basil. It was reported that the quick adjustment of plants to the new light environment to obtain healthier food products reduces the toxic compounds such as methyl eugenol in basil.

The effect of light quality including white, yellow, blue, and red onquinoline alkaloid production was observed in Camptotheca acuminate seedlings. It was found that compared with white light, redlight provoked the highest leaf biomass and camptothecin yield, whereas blue light led to the highest camptothecin content, higher activities of camptothecin biosynthesisrelated enzymes (TSB, b-subunit of tryptophan synthase and TDC, tryptophan decarboxylase) and parallel transcript levels of TSB, TDC1, and TDC2 genes, but lowest leaf biomass. It was concluded that red light had the best effect on increasing the production of camptothecin in leaves of C. acuminata seedlings and suggested that light quality manipulation could be an effective approach to getting high camptothecin yield (Liu et al., 2015). Concentrations of calycosin 7-O-b-glucoside, hesperidin, and pseudobaptigenin were significantly increased by blue light when compared with white light but growth was not affected by different wavebands, i.e., white, red, blue, yellow, complete darkness treatment observed in Cyclopia subternata callus (Kokotkiewicz et al., 2014). It was studied that blue light increased total phenolic and total flavonoid contents for callus cultures of Stevia rebaudiana (Ahmad et al., 2016).

4. Plant response to light pollution 9

1. Plants and their unexpected response to environmental pollution

Blue LED spectrum or cool fluorescent lamp with 27 L mol m 2 s 1 was the best for the most favorable in vitro growth of Achillea millefolium but there was variation in amount, number, and profile of volatile compounds under the influence of quality and light intensity (Alvarenga et al., 2015). The effects of shade were observed in Paeonia lactiflora, which is a high-light demanding plant containing many bioactive compounds with pharmaceutical importance as paeoniflorin, oleanolic acid, and ursolic acid (Zhao et al., 2012). The report indicated that different morphological parameters were higher in sun-exposed compared to shade-grown peony. Shade reduced soluble protein, soluble sugar, and malondialdehyde contents that caused delayed initial flowering date, lengthened flowering time, faded flower color, and reduced flower fresh weight. It was observed that reduced anthocyanin content was the reason for fading flower color under shade. In comparison with shaded leaves, sun-exposed leaves had better-developed photoprotection mechanisms, including augmentation of zeaxanthin pools and de-epoxidation state of the xanthophylls cycle. Enhancement in spermine concentration was found in turmeric rhizome grown under-screen shading (Ferreira et al., 2016).

5. Plant response to soil pollution

Soil is a key factor as it manages the biological, geochemical, and hydrological cycles (Berendse et al., 2015). Toxic heavy metals such as cadmium (Cd), chromium (Cr), nickel (Ni), arsenic (Ar), etc. have been harshly included in the environment through variable sources including industrial effluent, fertilizers, pesticides, and metal smelters. Heavy metals are present in the soil as free metal ions, metal complexes in soluble form, exchangeable metal ions, and insoluble or precipitated oxides, carbonates, hydroxides or they may also form a part of structural silicates (Rai et al., 2004). Soil pollution is now considered a challenge of a global dimension and is incorporated into environmental policy frameworks. Soils have been used to detect the accumulation, deposition, and distribution of heavy metals (Alirzayeva et al., 2006). Plants exposed to a heavy metal contaminated environment tend to change the secondary metabolite profile. This interaction may lead to either inhibition or stimulation of the secondary bioactive compounds. Heavy metal exposure is a cause of induction of oxidative stress triggering the formation of highly active signaling molecules which further helps in the production of secondary metabolites that affects the medicinal potency of the plant (Nasim and Dhir, 2010; Ditta et al., 2022). For instance, Ocimum tenuiflorum was cultivated in Hoagland solution (5%) containing variable concentrations of Cr to examine the eugenol content, a key component of Ocimum oil. A significant increment in eugenol content up to 100 μM in comparison to control was found. Similarly, the effect of chromium on two therapeutically important secondary metabolites phyllanthin and hypophyllanthin of Phyllanthus amarus was reported (Rai and Mehrotra, 2008). The Robinia pseudoacacia is an indicator of soil pollution including Zn and Cd and is determined as a sensitive biomarker species for contaminated areas (Nadgorska-Socha et al., 2013a,b; Nadgorska-Socha et al., 2016).

The plants have bioaccumulation and metal-tolerant properties, heavy metals do obstruct their metabolism and consequently induce morphological and ecophysiological changes (Maleci et al., 2014). Reynoutria japonica and Solidago Canadensis are the two different species that are highly tolerant to environmental pollution (Vanderhoeven et al., 2005). It was reported that Achillea millefolium can be used to monitor Pb and Cu accumulation (Pilegaard and Johnsen, 1984). Many

other explanations of the effect of heavy metal pollution on plants in terms of damage detection, repair, acclimation, and adaptation response have been given in the Chapter 8. Crude petroleum oil hydrocarbons are one of the most common groups of persistent organic pollutants (Abdollahzadeh et al., 2019; Odukoya et al., 2019; Gamage et al., 2020). Petroleum hydrocarbons are recognized as toxic to many living organisms due to their mutagenic and carcinogenic properties (Ma et al., 2018; Rusin et al., 2018). The low rate of decomposition of oil and oil products in the environment triggers their accumulation and a gradual increase in their concentration in the soil. After getting into the soil, crude oil products destroy its structure, upset the air-water balance (Abdollahzadeh et al., 2019), alter the soil's physicochemical properties (Peretiemo-Clarke and Achuba, 2007; Achuba, 2014), hinder the microbial propagation (Abdollahzadeh et al., 2019), interrupt the soil enzymatic activity (Otitoju et al., 2017), and have a negative impact on terrestrial and soil mesofauna, as well as on plant growth and development.

The growth and development disorder of plants, growing on oil-contaminated soils, is caused by several reasons. The absorption of toxic petroleum molecules by plants can change the permeability and structure of the plasma membrane (Peretiemo-Clarke and Achuba, 2007), modify the shape and size of the parenchyma tissue, reduce the intercellular space in the cortex of the stem and roots, and inhibit the mitotic activity of the root meristem (Bellout et al., 2016). The insufficient aeration caused by air displacement from the pore spaces between the soil particles by crude oil leads to low water availability and root stress to the plant (Athar et al., 2016). Furthermore, oil pollution minimizes the percentage of organic matter accessible to plants and reduces the amount of mineral nutrients such as phosphates, sodium, potassium, sulfates, and nitrates (Otitoju et al., 2017; Achuba and Ja-anni, 2018). The response of plants to oil pollution can manifest itself at various levels such as physiological, biochemical, and molecular levels. It has been studied that crude oil pollution reduces overall chlorophyll contents and photosynthetic activity in plants. Distinguished symptoms noted in plants growing on oil-polluted soil also include a decrease in the activity of starch metabolizing enzymes (Achuba and Ja-anni, 2018) and a decrease in the content of total carbohydrates, and total proteins/amino acids (Al-Hawas et al., 2012).

The most hazardous disorder, resulting from the impact of petroleum hydrocarbons on plants, is oxidative stress which leads to the formation of many reactive oxygen species with high oxidizing capacity in cells. In one respect, the ROS destroys intracellular reactions, cell-membrane complexes and disrupts transport processes and by this means inhibits growth activity (Zaid and Wani, 2019). Contrastingly, plants use ROS as a second messenger in many signal transduction cascades, and therefore ROS accumulation is essential to plant development and defense. Various studies have shown a change in the contents of proline, non-protein thiols (Rusin et al., 2020), ascorbic acid, riboflavin, and anthocyanins (Chupakhina and Maslennikov, 2004), phenolic compounds, and flavonoids, in plants growing on oil-contaminated soils.

6. Plant response to water pollution

The main sources of water pollution are industrial effluent, runoff from agricultural fields, and raw sewage. Agricultural runoff includes toxic chemicals from fertilizers and pesticides. Fertilizers can cause an explosive growth of algae, damaging plants and decreasing

6. Plant response to water pollution 11

1. Plants and their unexpected response to

the amount of available oxygen necessary for the survival of aquatic plant species. Another source of water pollution is improperly disposed of plastic bags, fishing lines, and other materials that may accumulate in the water creating problems in plant biodiversity. The problem of environmental pollution due to the dispersion of nitrate in surface water or groundwater is very topical. In this context, many plant species are capable to tolerate even high nitrate quantities for environmental remediation. Bravo and Hill (2012) found that high nitrate concentration in the groundwater did not affect Thuja occidentalis growth. Nitrate increases can improve transpiration without adverse effects on the species leading to increases in biomass (Chen et al., 2016). Accumulation of toxic heavy metals in living plant cells results in various deficiencies, reduction of cell activities, and inhibition of plant growth (Farooqi et al., 2009; Ditta et al., 2022).

The soluble salts and other contaminants in ground water, such as toxic metals, can accumulate in the root zone, and other plant parts, thus affecting overall vegetation growth (Teng et al., 2018; Jha and Porwal, 2022; Kumar et al., 2022a,b). Sarma et al. (2011) have reported that sewage water and sludge contain different inorganic and organic metal ions which create adverse situations in plants. The impact of abiotic stress as well as pollutants on secondary metabolites production has been described and exhibits plasticity to maintain balance under adverse environmental situations (Husen, 2022; Bachheti et al., 2021). The upregulation of plant secondary metabolites depends upon the amount and time interval of pollutants exposure. Several topics related to water pollution and plant tolerance mechanisms have been discussed in Chapter 13.

7. Plant response to noise pollution

Sound is acoustic energy in the form of an oscillatory concussive pressure wave transmitted through gases, liquids, and solids. The physiological effect of environmental factors such as light, wind, moisture, and temperature on plant stimulus and growth has been well understood. However, little information is available on the effects of noise on plants. Audible sound wave technology has recently been applied to plants at various physiological growth stages such as seed germination, callus growth, endogenous hormones, and mechanism of photosynthesis and transcription of certain genes. The noise stimulation could enhance disease resistance and decrease requirements for chemical fertilizers and biocides for plants (Zhang, 2012). Plants also can absorb and vibrate to specific external sound frequencies (Hou et al., 1994). Sound waves can alter the cell cycle (Wang et al., 1998). Sound waves shake the plant leaves and speed up the protoplasmic movement in the cells (Godbole, 2013).

Some stress-induced genes might be switched on under noise wave stimulation and the level of transcription increased (Wang et al., 2003a). Sound frequency technology stimulates leaf stomata to open, and thereby the plant will be able to increase its uptake of spray fertilizer and dew. Sound waves were found to be efficient at getting the herbicide into the plant. Mature weeds can be sprayed with 50% less herbicide and biocide if also treated with sound waves. Therefore, sound waves can decrease the requirements for chemical fertilizers and pesticides (Carlson, 2013). Both sound energy and light energy could convert and store as chemical energy, which enhances the photosynthesis system (Meng et al., 2012). Sound waves have been applied to okra and zucchini seeds by using the natural sounds of birds and

environmental pollution

echoes. It was observed that natural sounds had a higher statistically significant effect on the number of sprouted okra and zucchini seeds for the main condition and over exposure time (Creath and Schwartz, 2004). Rideau wheat seeds and seedlings were exposed to various signal frequencies. The treatment at a sound frequency of 5 kHz and sound pressure level (SPL) of 92 dB stimulated tiller growth coupled with an increase in plant dry weight and number of roots (Weinberger and Measures, 1979).

In contrast, Wang et al. (2003a,b) reported the biological impact of sound waves on paddy rice seeds. It was found that the germination index, stem height, relative increase rate of fresh weight, activity of root system, and the penetrability of cell membrane were significantly increased at the sound frequency of 0.4 kHz and SPL of 106 dB. When the sound wave stimulation exceeded 4 kHz or 111 dB, it inhibits the growth of paddy rice seeds. Therefore, sound waves could greatly change the cell cycle of paddy rice cells and speed up their reproduction rate. Sound wave also transfers energy into the cell and drives cytoplasmic streaming. Sound waves may affect the membrane materials to change the biological function of the membrane and enhance cell metabolism.

The cell membrane is very sensitive to environmental stimulation and its penetrability influences the plant's resistance to harmful materials in poor environments. Recent evidence illustrated that the young root tips of Zea mays clearly bend toward a continuous sound source (Gagliano et al., 2012). Sound wave stimulation was applied to Actinidia chinensis in tissue culture, especially on callus growth. The sound waves have dual effects on the root development of A. chinensis plantlets with a significant difference (Arts et al., 2000). Sound waves stimulation increased the root activity, total length, and number of roots whereas, the permeability of cell membranes decreased (Yang et al., 2004).

Furthermore, it was found that adenosine triphosphate (ATP) significantly increased at SPL of 100 dB and sound frequency of 1 kHz. ATP is a high-energy molecule used for energy storage by organisms. The increase in ATP content indicates that the anabolism was strengthened in cells. The content of soluble proteins and the activity of Superoxide dismutases (SOD) increased at 1 kHz and 100 dB. However, those indexes decreased when sound waves stimulation exceed 1 kHz and 100 dB (Yang et al., 2002; Yang et al., 2003). Effects of sound stimulation on the metabolism of Chrysanthemum roots illustrated that the growth of roots accelerated under certain sound stimulation. The soluble sugar content, protein, and amylase activity increased significantly by sound stimulation, but it had no obvious effect on the permeability of membranes (Jia et al., 2003b). The increase in soluble sugar and protein illustrated that sound simulation accelerated the anabolism of Chrysanthemum. In addition, the increase in amylase activity showed an advancement of sugar decomposition, hence the catabolism changed highly after the sound stimulation. The influence of sound waves on the microstructure of plasmalemma for Chrysanthemum roots illustrated that the sound stimulation enhanced the fluidity of lipids and sound could also influence the secondary structure of protein not only in cell wall but also in plasmalemma. Soundwaves decreased the phase transition temperature. Thus, the decrease in thermodynamic phase transition illustrates the enhancement of the fluidity of the cell wall and membrane, which also enhances the cells to grow and divide faster and easily.

The enhancement of cell wall fluidity is one of the mechanisms of the promotion of plant growth by sound waves. Moreover, the electric potential of cell membranes could be changed by the sound field stimulation. Plasmalemma exists in the outermost part of cells, consisting

7. Plant response to noise pollution 13

1. Plants and their unexpected response to environmental pollution of membrane lipid and protein. It is the most sensitive and important part of sensing the environmental factors and many substances related to signal transduction exist in plasmalemma (Sun and Xi, 1999; Jia et al., 2003a).

8. Plant response to nanoparticles

Because of the enormous production and unintentional use of nanoparticles (NPs) or nanomaterials (NMs), the whole environment is affected. Though many of them are beneficial, some are toxic to plants, algae, and microorganisms. They may, therefore, pose a potential risk to the environment. NPs/NMs creation has expanded big interest due to their huge applications (Husen and Siddiqi, 2014b; Husen and Iqbal, 2019a; Husen and Jawaid, 2020; Sharma et al., 2021; Siddiqi and Husen, 2021; Kumar et al., 2021a,b, 2022a,b; Alle et al., 2022; Sharma et al., 2022; Adnan et al., 2022). Accelerated production, and release of these materials into the environment, perhaps emerged as another kind of environmental pollution (Boykov and Zhang, 2021). As they are very minute entities ranging from the size 1 to 100 nm. The ravage materials from agriculture, industries, and medical products are the main sources of escalating the nanowaste in the environment. The plants are stationary living beings with two primary sinks of the environment, i.e., water and soil; they cannot get away from the harsh effects and consecutive metabolism changes due to nanopollution. However, nanoparticles are also used as nanopesticides, nanofertilizers, and herbicides which are helpful to enhance the productivity of crops, control unnecessary uses of chemicals fertilizers, and also boost survivability against biotic stress (Husen and Pandey, 2020; Kumar et al., 2021b, 2022a,b). They control plant development and augment metabolic activity (Husen and Siddiqi, 2014a; Siddiqi and Husen, 2016, 2017, 2021).

NPs may have a negative or positive impact on the plant growth species depending on their nature and concentration (Husen, 2020a,b). Some reports have also shown both promotive and inhibitory impacts of carbon-based NMs on the rhizosphere microorganisms (Wagay et al., 2019). However, thus far, the impact of these materials on the food chain and ultimately on the health of consumers (animals and humans) are unknown. NPs enter the plant cells and disrupt the electron transport system cycle of chloroplast and mitochondria and trigger oxidative burst due to increased reactive oxygen species (ROS) concentration. ROS have both hydroxyl radical and superoxide free radical and nonradical singlet-like oxygen and hydrogen peroxidase (Hossain et al., 2015; Dimkpa et al., 2013). It functions as a transporter molecule, excess levels of ROS cause adverse impacts in the cell known as oxidative stress (Faisal et al., 2013). When cells are exposed to surplus levels of ROS induces oxidation of protein, destruction of DNA, lipid peroxidation, and membrane damage finally causing programmed cell death (Van Breusegem and Dat, 2006). In an experiment, Rui et al. (2017) used Arachis hypogaea seedlings and examined their yield, quality, physiological, and biochemical response in the amended sandy soil with various concentrations of silver NPs (50, 500, and 2000 mg kg 1) for 98 days. All growth-associated parameters, namely plant height, biomass, grain weight, and yield were remarkedly reduced in a dose-dependent manner. Du et al. (2011) have reported that zinc oxide and titanium dioxide NPs decreased the biomass production in Triticum aestivum. It has also been found that the titanium dioxide NPs adhere to the root tip cell wall of periderm cells, while zinc oxide NPs dissolved in the soil, therefore