Environmental Engineering Reference
In-Depth Information
Overall the most crucial factor affecting root growth is mowing.
Greater leaf area results in more photosynthesis, which in turn results
in more roots and, especially important, more deep roots. Deep roots are
able to extract water from deeper zones, reducing the chance of moisture
stress and therefore improving the overall health of the turf and its
resistance to other stresses. For this reason, areas where irrigation is not
available should be mowed higher than irrigated ones, so that leaf area is
not so severely reduced and root growth is less restricted.
Fertilization promotes rooting - adequately fertilized turf has a
strong and healthy root system - but excessive nitrogen is detrimental
to root growth. Because nitrogen promotes shoot growth, too much of it
increases the shoot-to-root ratio. Rapidly growing shoots demand more
energy, usually at the roots' expense. Avoiding excessive nitrogen fertil-
ization is especially important when turf may be subject to other stresses,
such as low light levels, drought and increased traffic.
Low light levels in tropical locations may greatly reduce rooting.
Daylength near the Tropic of Cancer and Tropic of Capricorn ranges
from 13.5 to 10.5 hours. Closer to the equator, the range is even narrower.
Consider the performance of the same turf under temperate and tropical
conditions. At moderate temperatures under 15 hours of sunlight, it may
produce much more carbohydrate than it consumes. In the tropics, how-
ever, where the shorter days reduce photosynthesis but high temperat-
ures maintain high respiration, less carbohydrate will be available to
support root growth. The result is that carbohydrate reserves are often
inadequate for unrestricted growth, especially where a distinct rainy
season results in almost complete cloud cover, and therefore substantially
less light, for several months during the year.
Identification
Identification of grass plants requires careful observation of inflorescence
(flower or seed-head), leaves and stems. Botanists around the world have
described thousands of plants, not just grasses, using flowers as the major
guide, so the inflorescence is probably the single most important com-
ponent botanists use to identify grass species. In tropical turf-grasses,
however, the inflorescence is not always present, and many turf-grass
hybrids produce no inflorescence at all. In addition, managed turf-
grasses are mowed frequently, so seed-heads are often difficult to find.
Turf-grass managers therefore cannot depend on the inflorescence and
must observe and use other parts of the plant for identification.
Unfortunately, no single characteristic can be used to identify
individual turf-grasses with reasonable certainty. The process is
usually complex. Numerous characteristics must be examined, and the
