Adaptation of pearl millet (Pennisetum typhoides) to coastal New South Wales. 3. Comparative productivity of pearl-millet cultivars and a Sudan grass-sorghum hybrid

Abstract

Two experiments were carried out at Camden, New South Wales, to compare the productivity under defoliation of an early-maturing (cv. Tamworth) and a late maturing (cv. Katherine Pearl) pearl millet with the sorghum-sudan grass hybrid, Sudax SX-11 A. In experiment 1, harvests were taken at 30 cm stubble height at 3 and 6-week intervals. Total forage dry matter and protein content were similar for all species. Total forage yields were higher and protein content was lower with the 6-week cutting interval. In experiment 2, cutting frequency was kept constant at 3-week intervals, while cutting height was maintained at a. 30 cm and b. above the average apical meristem height until booting and then at 30 cm. Total forage dry matter yields were highest for Sudax and lowest for Tamworth. Regrowth yields generally declined with time, though for Katherine Pearl a relatively high late-season yield was harvested from cutting treatment b. Protein content was maintained at reasonable levels at all harvests. Sudax foliage generally had the highest protein content. Estimated in vivo organic matter digestibility values were little affected by cultivar or cutting regime but showed severe mid-season depression. A significant negative association of digestibility with mean minimum temperature during the regrowth period was noted (r = -0.81 3). In both experiments, the removal of apical meristems reduced the amount of regrowth. Sudax was less susceptible to decapitation because of the substantial contribution of secondary tillers to regrowth.