AGCSATECH UPDATE AGCSATECH UPDATE
The
root of all things One of the greatest challenges turf managers face is trying to maintain a deep extensive root system on finely cut turf. AGCSATech environmental agronomist Bruce Macphee takes a closer look at arguably the most important facet of managing a healthy turf surface – the root system.
Above: Regular inspections of the turfgrass root system can aid in gaining an understanding of root growth patterns and overall root health. Often an issue showing up on the surface can be traced back to a problem below ground 34
T
he primary role of roots is in the uptake of water and nutrients and to provide anchorage for the plant. The fibrous root system of turfgrasses has the ability to take up extraordinary amounts of water and nutrients due to the large surface area of fine root hairs created by modification of individual epidermal cells. Root hairs are microscopic and cannot be seen by the naked eye with Beard (2001) stating that the surface area of these hairs is approximately five to 10 times the size of the primary root area. Understanding how environmental, cultural and chemical factors can affect the plant’s root system and the ability to uptake water and nutrients is vital in creating a healthy resilient turf surface. Unlike the above ground portion of the turfgrass plant where the tip of the leaves contain the oldest cells and the growing point is down at the base of the stem or crown (this allows us to mow at low heights as we are generally not removing the growing portion of the plant), in the case of the roots it is the opposite. Roots have their meristematic tissue (growing point) right at the tip of the root. This active portion of a root tip is white and a highly dynamic region of the plant where growth, water and nutrient uptake all takes place. As the root matures, the cells behind the growing point elongate, turn brown and become more specialised, forming a series of interconnecting hollow tubes for transportation of water and nutrients throughout the plant. New root initiation in bunch type grasses generally develops from the crown of the plant (adventitious roots) or in the case of creeping grasses from the nodes of stolons or rhizomes.
AUSTRALIAN TURFGRASS MANAGEMENT 18.6
ROOT LIFE CYCLE Most turfgrasses are perennial, but many have root systems that could be considered annual in nature. Both cool- and warm-season grasses have periods of extensive root growth and decline. Cool-season grass root systems are most active in spring when soil temperatures are between 10oC and 17oC. During late spring to early summer, when temperatures rise to between 17oC and 23oC, coolseason grasses will transfer efforts towards shoot growth and production. Soil temperatures above 23oC see a reduction in growth of both roots and shoots and a decline in the overall mass of the root system, sometimes referred to as summer dormancy. Root production resumes again in autumn to a lesser extent when temperatures cool below 23oC. Conversely, warm-season grasses have a period of root decline in the period just prior to spring when soil temperatures are at their lowest (below 15oC). The period of highest root production for warm-season grasses is in late spring and summer when temperatures are between 23oC to 28oC. Beyond these temperatures is when warmseason turf growth comes into its own, thriving in temperatures up to 35oC, provided adequate moisture and nutrients are available. Peak growth periods are a time essential for setting the plant up with an extensive root system for the summer season. Any cultural or chemical application works during this period that could potentially impede root development should ideally be avoided. It is important to understand periods of root activity and decline and the potential