HOW THE GROWTH OF AMAZONIAN SPECIES WITH HIGH ETHNOBOTANICAL VALUE IS AFFECTED BY LIGHT STRESS?

Research Paper

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E-ISSN No : 2454-9916 | Volume : 2 | Issue : 11 | Nov 2016

HOW THE GROWTH OF AMAZONIAN SPECIES WITH HIGH ETHNOBOTANICAL VALUE IS AFFECTED BY LIGHT STRESS? 1

Patrícia Chaves de Oliveira | Helton Luís Nina Lameira

2

1

Biodiversity and Forest Institute, Universidade Federal do Oeste do Pará, UFOPA, Av. Marechal Rondom, CEP 68040-070, Santarém, Pará, Brazil.

2 Water Science and Technology Institute, Universidade Federal do Oeste do Pará, UFOPA, Av. Marechal Rondom, CEP 68040070, Santarém, Pará, Brazil.

ABSTRACT The Amazon is a biome where in recent decades climate change has caused the increase in physiological plasticity of certain plant species. This plasticity characterized as resilience strategy of these species to environmental stress conditions such as light stress. The objective of this study was to evaluate the influence of shading on growth in height and leaf area of species Annona muricata L., Dipteryx odorata (Aubl.) Willd. AndCopaifera langsdorffiiDesf. The variables were TCA (Absolute Growth Rate) and TCR (Relative Growth Rate) in height and leaf area of young plants subject to the restriction of photosynthetically active radiation (PAR) for 4 months (50% light) and full sun in greenhouse conditions. Multivariate analysis jointly by the Hotelling showed significant differences (p <0, 0001) in height and leaf area beteween Graviola (soursoup), Cumaru (tonka bean) and Copaiba under two light levels. However, the Hotelling test specific to each species, showed that soursoup presented better growth rates in height and leaf area under 50% of light, the opposite was observed for Tonka bean (p = 0,0166 ). For Copaiba, rates of height growth were better to 100% of light and leaf area under 50% light. The Bartlett test showed similarity coefficient (phi = 68,01%) when the species were in full sun and dissimilarity (phi = 21,49%) under restriction. Regression analysis did not show a unique pattern of growth in different levels of shading, since the species plants have different strategies in their morphophysiological behavior when subjected to light stress.

KEYWORDS: Amazon, physiology, growth rates, light stress, Annona.

INTRODUCTION Understanding morphophysiological aspects in the early stages of development of species withhight ethnobotanical interest to tradicional Amazonian communities, such as Annona muricata,Dipteryx odorata and Copaifera langsdorffii are important to composition and implementation agro-ecosystems in the Brazilian Amazon. Among the species with high economic potential highlight the Cumaru or Tonka bean (Dipteryx odorata) belonging to Fabaceae family. In Brazil, the tonka bean occurs in the Amazon region, from the state of Acre to Maranhão, in the rain forest land and floodplain; beyond the state of Mato Grosso (Lorenzi 1998; Carvalho 2009). The economic potential is in the seeds that produce coumarin oil with medicinal properties (EMBRAPA 2004). Its wood used for construction, marine and furniture manufacturing (Lorenzi 1998). Have no preview studies of growth of this specie under light stress.

Copaíba (Copaifera langsdorffii) belonging to Fabaceaefamily, it is a tropical tree widely distributed in Brazil, occurs in all states of the Southeast, Midwest, some states in the North and Northeast (Carvalho 2003); beyond the state of Paraná (Lorenzi 2008). Its economic potential is the wood, used in construction and furniture manufacturing; furthermore provides copaiba oil with pharmacological properties; in the paint industry, varnishes and aroms in general (Sampaio, 2000).

The soursop (Annona muricata) is a tropical fruit widely cultivated in Brazil mainly in the North, Northeast, Midwest and Southeast (Junqueira et al. 1996).

The fruit is the greatest economic potential, both for use in the natural way or to production of juices, ice cream, jams and sweets(Gramacho et al. 2001). Its leaves also used in folk medicine in the preparation of teas to liver dysfunction (Branch et al. 1983).The photosynthetically active radiation (PAR) is an environmental factor that influences the plant growth and development, being the light stress limiting photosynthetic rates of plants to be primary energy source (Lima Junior et al. 2006). Studies relating the light intensity to the production of saplings of tree species of good quality are important for the development of forestry, fruit growing and conservation and reforestation programs (Monteiro and Ramos 1997).

According to Magalhães 1986, the growth analysis can lead to understanding of physiological conditions of plants at different intervals of time, allowing you to track the dynamics of productivity, measured by physiological indices. Growth analysis is a method used in the research to understand strategies and adaptabilities of species under adverse weather events (IPCC, 2014), competition effects, genotypic differences in productive capacity beyond the influence of agronomic practices.Actualy, we do not have prevew studies of growth of these spcies. The objective of this study was to evaluate the absolute and relative growth rates of young plants in Annona muricata L., Dipteryx odorata (Aubl.) Willd.

AndCopaifera langsdorffii Desf. Under different lighting conditions.

MATERIAL AND METHODS The experiment was carried out from February to May in the green house of Federal University of Western Pará - UFOPA, whose coordinates are 2o 25' 04,71" S and 54o 44' 26.61" W in the municipality of Santarém-Pará-Brazil. According to IBAMA 2004, the climate is Ami type according to Köppen. Santarém has an annual temperature variation with average ranging from 25.4 ° C to 33.0 ° C. The relative humidity of air are high throughout the year, with an average of 86.7% and rainfall with annual averages around 1920 mm (INMET, 2011).

Twenty individuals of each species with six months of age used. The plants were on black polyethylene bag, containing about 1.5 kg organic substrate. The Herbarium of Brazilian Company of Eastern Amazon Agricultural Research (EMBRAPA-CPATU) took the taxonomic identification of the species. The chemical composition of the substrate used for the development of seedlings was: granulometry: coarse sand - 153 g.kg-1, sand - 85 g.kg-1, silt - 483 g.kg-1 and the total clay - 280 g .kg -1; pH (H2O) - 5.3; Fertility: Total Nitrogen - 1.12% phosphorus - 150 mg.dm-³, potassium - 108 mg.dm-³, calcium - 9.2 cmolc.dm-³, more magnesium calcium - 12.6 cmolc.dm-³ and aluminum - 0.1 cmolc.dm-³ (EMBRAPA, 2011).

The experimental treatments were two levels of light (1.900 µmol. m-2. s-1 light = 100% and 950 µmol. m-2. s-1= 50%). The plants irrigated every day until field capacity (240 ml of water). For leaf area analysis, measurements made every seven days. The actual area scanned measured with the aid of Digital Determinator - DDA program, version 2.0 (Ferreira et al 2008). The correction of leaf area was performed by linear regression of leaf area measurement and the actual area (AR) obtained in the program, generating an adjustment equation with correction factor; AR = L x W x Fc (AR / C x L) where C is length L is wide and Fc is correction factor.

For the analysis in height, measurements made every seven days with 10 repetitions. The plant height achieved by means of a measuring from the plant base until its apex (apical meristem).

The variables were TCA (Absolute Growth Rate) and TCR (Relative Growth Rate) in height (126 days for all species) and leaf area (Soursop -124 days; Tonka bean -60 days and Copaíba -130 days) in plants with eleven months old.

The physiological indices were calculated according to the following formulas: TCA = (H2 - H1) / t); TCR = (LnH2 - LnH1) / t); TCA = (AF2 - Af1) / t); TCR = (LnAf2 - LnAf1) / t), where H = height, Af = leaf area, t = time.

Statistical analyzes were determined by BioEstat program. Version 5.0, through analysis of regression and Multivariate Analysis by Hotelling and Bartllet test (Ayres et al. 2007).

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RESULTS AND DISCUSSION Saplings of D. odorata and C. langsdorffii exposed to treatment of 50% light had reductions in absolute and relative growth rates in height when compared with plants in full sun. However, plants of A. muricata, had the highest absolute and relative growth rate in height observed under 50% of light at 126 days of observation (Figure 1A and 1B). These results indicate that the shading caused for competition with other species in the field, could negatively influence the growth of young plants that interest to small farmers. These data suggest that probably the activity of photosystems I and II is different between species, culminating in different growth of young plants. According to Franic et al 2015, high planting densities decrease the plant performance indices.

Figure 1. Absolute Groth Rate in height (TCA) (A) and Relative Growth Rate in height (TCR) (B) of young plants of Soursop (GR), tonka bean (CM) and Copaíba (CP) in greenhouse conditions under two light treatments (100% and 50% light).

Although Soursop is a tropical fruit of rapid growth, the best growth rates have 50% light, showing that the species may suffer photoinhibition when subjected to high irradiance and morphophysiological differences from tonka bean and Copaíba species. These rsultados repeated for plant Theobroma grandiflorum (Willd.

Ex Spreng.) Schum, which performed better in height, diameter and number of sheets to 50% light (Silva et al. 2007).

When we fix the species and observe the physiological behavior under light treatments, the Hotelling test showed significant differences (p = 0.0039) for young plants of Soursop, when grown in both environments (100% and 50% light) taking into account four variables (TCA and TCR in height and leaf area). The species had best absolute growth rates and relative height and leaf area to 50% light (Table 1), demonstrating that a species under PAR restriction presents important adjustment mechanism, focused on rapid growth when shaded to escape conditions low light intensity (MoraesNeto et al., 2000); and expand the leaf blade for increased light gathering. To Lima et al. (2010), the highest average for plant height of Hymenaea (Jatoba) obtained with shading level of 50%. Siebeneichler et al. (2008) working with Tabebuia heptaphylla observed that plants grown in 50% light environment showed better growth in height.

Table 1. Multivariate analysis using Hotelling test for comparison of young plants of Soursop, taking into account four variables (TCA cm.days-1 and TCRcm.cm-1.days-1) in height; (TCA cm².days-1 and TCR - cm².cm-2.days-1) in leaf area under two light conditions (100% and 50% light).* TCA means Absolute Groth Rate; TCR means Relative Groth Rate Soursop Treatments

The luminous intensity favored the growth of Cumarú (Tonka bean) and Copaíba (Figure 1), which at increased availability of light, tends to increase photosynthesis by increasing the carbohydrate content in leaves and providing enhanced growth in plants (Siebeneichler et al. 2008). The same strategies were observed

by Cohu et al 2014, when they observed increased photosynthetic rates, number of phloem cells and increase the width of the palisade tissue when low temperatures and high light intensity was applied in Spinacia oleracea L. cv. Giant Nobel; Arabidopsis thaliana (L.) Heynhold.

Moreover, Soursop (Graviola) showed differential strategy for Tonka bean and Copaiba, which under restriction 50% light increased their absolute and relative growth rate in height (Figure 1 A and B). Osunkoya and Ash 1991 and King 1994 reported that a greater height growth of plants in shaded environments is quite common and could attributed to increased investment in cell elongation for the greater search for light. Regarding the growth of leaf area (AF), the results showed that the species had a different behavior as their ontogenesis (A. muricata was 124 days D. odorata 60 days and C. langsdorffii 130 days). However, the absolute and relative growth rate of leaf area in Soursop and Copaíba were higher in shading (50% of light), the reverse was observed for Tonka bean, demonstrating that species acquire various strategies to adjust its leaf tissue under a full and constraint light environment (Figure 2A and 2B). This data is according to Gonçalves et al 2007, who observed in Copaifera multijuga a decrease of 69% in the activity of photosystem II in plants subjected to high light intensity, a fact that can lead to high rates of leaf growth, attempt to minimize the decline of photosystem II.

Figure 2. Absolute Growth Rate (TCA) of leaf area (A) and Relative Growth Rate of leaf area (TCR) (B) of young plants of Soursop (GR), Cumaru (CM) and Copaíba (CP) in grenhouseconditions under two light treatments (100% and 50% light).

Multivariate Analysis from the application of BartlletTest showed that under 100% of light, the species have a very similar physiological behavior when taking into account all four variables (TCA and TCR of plant height and TCA and TCR of leaf area) with maximum coefficient of verisimillarityPhi = 68.01%,while under 50% light showed Phi = 21.49%.

Thus, under light stress the species showed heterogeneity physiological response, given the low similarity demonstrated by Phi where each chosen different strategies to tolerate low radiation. Once, Tonka bean is a climax species of fast growing and demanding light, unlike Copaíba having secondary growth, but with rapid initial growth and subsequent reductions in property rates, requiring then expand their leaf surfaces in funding for assimilates (2004 Ferraz et al;Duboc 2005).

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VARIABLES TCA height TCR height (cm.days-1) (cm.cm-1.days-1)

TCA Leaf TCR Leaf Area area (cm².cm-2.days-1) (cm².days-1)

100% Light

6,47

0,08

10,22

1,58

50% Light

14,11

0,31

20,67

1,75

(p) =

0,0039 14,47

0,23

33,78

1,15

50% Light

12,13

0,19

5,80

0,38

(p) =

0,0166

---

---

---

100% Light

24,84

0,54

7,48

1,14

50% Light (p) =

14,18 0,0005

0,46 ---

12,74 ---

1,36 ---

Tonka bean 100% Light

Copaíba

For tonka bean plants, the Hotelling test (Table 1) also showed significant differences (p = 0.0166) compared under both light conditions (100% and 50% light).

Dipteryx odorata tended to increase photosynthesis in greater availability of light, with increase carbohydrate content in leaves via stomata, which influenced the increase in leaf surface. Uchida and Campos (2000) found that tonka bean seedlings have better status and growth in full sun and excess shadow hurt growth. Lima et al. (2008) found that young plants of Caesalpinia ferrea grown in full sun allows for better growing conditions.

As for copaíba the Hotelling test showed significant differences (p = 0.0005) for comparison between young plants under two light conditions (100% and 50% light) as well as Table 1. The TCA and TCR of height were better in 100% light and the TCA and TCRof leaf area were more significant in 50% of light as the species D. odorata, C. langsdorffii achieved best growth rates in height in full sun. It is proving to be a species that reduces their growth under lumen restriction; however, this condition of lower brightness, increase leaf area as well as the species A. muricata providing greater amount of assimilates for their growth. For Ronquim et al. (2009), the leaf area C.langsdorffiii showed higher values under full irradiance (100% Brightness). Thus, an increase in the level of shading, the leaves undergo morphological and physiological changes to increase light absorption and maximize the total gain carbon (Osunkoya et al. 1994). Such as increasing leaf area, number of leaves and biomass allocation (Poorter, 1999).

The regression analysis to determine the best growth curve for height young plants of soursoup showed that TCA on the treatment of 100% light has been exponential model or slow growth in the first day and more pronounced in the last days of observation (Figure 3A). However, under treatment of 50% of light, the growth model is logarithmic in the 10% significance level, or the growth of young plants of soursoupquite pronounced in the first days, becoming more stable in recent days (Figure 3B). For TCR in treating 100% light, there was a standard growth curve, but under treatment 50% of light, the model was sigmoidal, pronounced in the first days and lowering the end of the observation period (Figure 3C). Thus, there was a unique pattern of growth in height for soursoupspecie, suggesting that each individual develops different strategies as the provision of light.

TCA in leaf area of young plants of Soursop under treatment 100% light was sigmoidal, as (Figure 3D). Regarding TCR treatment in 100% and 50% of light, the

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growth was exponential model showing further expansion of the leaves during the first days and marked reduction in the last days of ontogenesis (Figures 3E and 3F). So for the TCR was a unique pattern of leaf growth, even under different lighting conditions. Environmental stresses caused by several factors, including the availability of light, may result in an atypical development. On the other hand, biological systems have an inherent tendency to seek to maintain its stability, understood as the system's ability to maintain its organization and individuality despite morphophysiological changes stimulated by environmental variations (Souza andOliveira, 2004)

in leaf area to 50% light (D) over 150 days of observation.

As for the Copaíba specie, the only growth pattern observed in relation to the height under a TCA treatment at 100% of light. The same has an exponential behavior, ie a slow growth during the first days and quite pronounced at the end of the observation period (Figure 4B) to the other growth rates in different treatments there was no growth pattern. We suggest that at the beginning of development, the young plants are still with their root system in training, but over time the system becomes more efficient in the uptake of minerals and nutrients to the plant as well as the emergence of the leaves start to photosynthesize better and thus translates into a rapid growth (Ferri, 1985).

The leaf development model for copaiba specie was geometric, taking into account TCA in a treatment at 100% light, demonstrating having an upward growth of almost all period of ontogenesis and lowering the end of the observation period (Figure 4C). Thus, the species respond in a particular way as the total light supply and this reflected in the increase in height. The TCR of leaf area in 50% of light showed a geometric pattern of growth, ie fairly pronounced in the first days and lowering the end of the development period (Figure 4D).

CONCLUSIONS Heterogeneity of physiological responses of growth in the studied speciesobserved. Growing in full sun favored the formation of higher plants in Dipteryxodorataand Copaifera langsdorffii while Annona muricata grew better in environments with light restrictions. The species Copaiferalangsdorffii and Annona muricata accelerated the growth rate of leaf area under light restriction as a strategy to get out of stress. The physiological plasticity of the species on bright stresses reflected in growth rates (height and leaf area) indicate scenarios of good adaptability to climate change currently observed in the Brazilian Amazon.

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Figura 3.Absolute Growth Rate (TCA) in height of young plants of soursop (A and B), Relative Growth Rate (TCR) in (C), TCA and TCR in leaf area (D and E respectivelly) under different light treatments (100% and 50% light) over 126 days of observation For Cumarú (tonka bean) specie, TCA was higher than 50% light showed a logarithmic growth, ie pronounced in early days and slow in the last days of observation (Figure 4A). The shading of 50% influenced the growth pattern height of saplings of tonka bean. Overall, the results related to use of light and form of plant growth in both environments showed different development strategies, demonstrating the ability of D. odorata in acclimatise to contrasting light environments.

This indicates the potential phenotypic plasticity of this species, here understood as the ability of a particular genotype produce different phenotypes under various environmental conditions (Bradshaw, 1965; Valladares et al 2007).

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