Stand losses in temperate grasses after summer defoliation of
tall canopies inspired an investigation of microenvironmental and
plant responses in tall fescue. Microenvironment and regrowth of
tall fescue in response to mowing managements and nitrogen rates in
spring that created different canopy structures was studied. In
early spring, 50 and 160 kg/ha of N were applied. Mowing managements
were: clipping at 4 or 8 cm biweekly, monthly, and in late June.
In late June all 6 treatments were mowed to prescribed stubble
heights with a seventh unmowed check. Canopy light regimes, leaf
area index, and regrowth of tillers were monitored along with soil,
fair, and shoot temperatures in stubbles after the June harvest.
Mowing more frequently in spring decreased canopy yields of the June
harvest, but increased leaf area (LAI) of stubbles as compared to
spring—accumu1ated canopies. High nitrogen decreased specific leaf
weights (SLW) in stubble leaves and increased LAI except in springaccumulated
canopies. Increased LAI decreased light penetration and
canopy temperatures. Temperatures were highest in harvested springaccumulated
stubbles with a shift of 4-10 C between unharvested and
harvested stands while radiation penetration into the stubble increased
from 5 to 75% of total. Some large stand losses occurred in lodged portions of harvested Spring—accumulated plots. Generally,
regrowth yields were not affected by prior clipping managements.
Concentration of TNC was uniformly high with all treatments.
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