Interrelations of leaf area and non-structural carbohydrate status as determinants of the growth of sub-tropical grasses

Under the normal moisture and nutritional stresses of the sub-coastal southern Queensland pasture environment, leaf growth in green panic and buffel grass was not sufficient to intercept all light, and wide variations in the frequency and intensity of defoliation caused little difference in the annual yield of shoot growth. Heavy use promoted increased leaf growth and N content, and reduced root growth and carbohydrate accumulation. When moisture and nutrients were adequate, growth was more positively dependent upon LAI than on carbohydrate status. The results of growth analyses are discussed and attention directed to the equilibration of component growth factors which reduce defoliation-treatment effects