Interaction of maturity stage and defoliation duration in the simulated grazing of irrigated lucerne

Abstract

Abstract A simulated grazing study was conducted during the summer on vigorous, irrigated lucerne. Four defoliation durations, 0, 1, 2, and 3 weeks, were imposed at three maturity stages, mid-vegetative, 1% bud, and 1% flower. Experimental technique caused the four defoliation durations within a maturity stage to commence together. Thus new growth after the final “cut” of each defoliation duration was measured and compared on an equal regrowth period basis. Defoliation duration and plant maturity stage were found to interact. Within the limits of the treatments employed, the more mature the lucerne at the start of defoliation, the shorter was the defoliation duration that resulted in the most rapid resumption of regrowth. Basal shoot counts indicated these results were due to both the time of appearance of basal shoots and to the level of interference during the final cut of each defoliation duration. Previous work on this subject is discussed on the basis of these findings, and implications for lucerne grazing management are outlined.