Environmental Engineering Reference
In-Depth Information
water and nutrients from the soil and transport them to the stem; they
store carbohydrates for later use and also send hormonal signals to the
above-ground portion of the plant. Most turf-grass species have plentiful
roots. A small patch of turf-grass may include thousands of individual
plants. Each plant has its own fibrous root system intertwined with
hundreds of root systems from neighbouring plants. Together, all these
roots form a dense mat that may be much thicker and stronger than the
above-ground portion of the turf. This layer of living and vigorous
organic matter is truly efficient in absorbing water and nutrients that
move down from the surface. Roots act as an efficient organic filter,
catching almost everything useful that passes nearby (Fig. 1.11).
Roots of turf-grasses are sensitive to environmental changes and
management practices. Because roots do not carry out photosynthesis,
they depend entirely on the above-ground parts of the plant. Any stress
to the plant top results in stress to the roots. Excessively low mowing
height, for example, reduces photosynthesis and deprives the roots of
food. Starving roots grow much more slowly and may even die.
A mowing height sufficient to sustain root growth in the dry season,
when sunshine is abundant, may be too low during the rainy season,
when increased cloud cover dramatically reduces photosynthesis. Failure
to increase mowing height can result in substantial thinning out of the
turf, as roots suffer starvation. When warm and cloudy weather is com-
bined with short days, the problem worsens because photosynthesis is
reduced while the high temperature increases respiration, and carbohy-
drate reserves can be depleted even further. This situation arises in the
tropics during the rainy season and is often viewed as the biggest chal-
lenge to tropical turf managers.
Fig. 1.11. The root system occupies a large volume of soil, efficiently absorbing
water and nutrients. (Drawing by R. Castro.)
