RECOVERY AND GROWTH PATTERNS OF COASTAL BERMUDA GRASS AS INFLUENCED BY NITROGEN LEVEL AND DEFOLIATION FREQUENCY

Abstract

The interrelationships among residual leaf area following defoliation, leaf area development patterns and mean crop growth rates of Coastal bermuda grass as influenced by nitrogen levels (20, 50 and 100 kg/ha/mo) and defoliation frequency (2, 4, and 8-week intervals) were evaluated. Residual leaf area index (LAI), dry matter (DM), LAI accumulation at weekly intervals, and mean crop growth rate (CGR) were determined.
During the first 2 weeks, DM development was more rapid following more frequent defoliation and at higher N rates. The effect of N on DM accumulation increased after the first 2 weeks and DM did not peak in any of the harvest intervals. Residual LAI was greater with more frequent harvest, but LAI evolution was not significantly influenced by N until the sixth week. Initial regrowth, however, appeared to be related more to N than to residual LAI. Higher N and more frequent defoliation produced denser turf which in turn provided more sites for origin of new leaves and this seems to be more important for rapid regrowth than residual leaves. Mean crop growth rate in all harvest frequencies significantly increased from the first to the second week and was considerably higher with increasing harvest frequencies. Since N was applied at 4-week intervals, these results suggest that N applications more frequent than at 4-week intervals and at rates higher than 100 kg/ha/mo, are required to maximize growth of Coastal bermuda grass.