- Volume 11 Issue 2
Forage productivity of two sorghum hybrids, Pioneer(P) 931 and P 956 and a sorghum-sudangrass hybrid, P 988, was studied. The 1st-cut of sorghun hybrids was made for silage 6 times from heading stage at a week-interval and regrowth (2nd-cut) was harvested on Oct. 13 although plants were not reached the same growth stage of 1st-cut. However, the 1st- and 2nd-cut of sorghum-sudangrass were made for green fodder 6 times from 4 weeks before heading stage at a week-interval. 1. Percent dry matter(DM) of 1st-cut of sorghum and 1st- and 2nd-cut of sorghum-sudangrass increased as growth stage advanced. Percent DM of 2nd-cut of sorghum decreased as the 1st-cut date delayed due to insufficient growing period on Oct. 13. 2. In the 1st-cut of sorghum the proportion of leaf blade (LB) or culm+leaf sheath (LS) to total DM decreased, but that of panicle increased as growth stage advanced. The panicle proportion of P 956 increased and culm+LS decreased more rapidly compared with those of P 931. IIowever, in sorghum-sudangrass hybrid the proportion of LB decreased and culmf LS increased as growth stage advanced through heading stage. 3. In the 1st-cut of sorghum hybrids crude(C) protein and C. fiber decreased, but nitrogen free extract (NFE) increased as growth stage advanced although C. fat and C. ash were similar among the growth stages. In the 2nd-cut of sorghum C. protein and C. ash increased, but NFE decreased as harvesting date delayed due to plants were younger although C. fat and C. fiber were similar among the harvesting dates. In the sorghum-sudangrass C. protein of 1st-cut decreased, but C. fiber of 1st-cut and NFE of the 1st-and 2nd-cut increased as growth stage advanced. 4. DM yield of 1st-cut of sorghum increased from heading stage to 3 weeks after heading and then levelled off, but total DM including regrowth was similar among the harvesting time. In the sorghum-sudangrass hybrid DM yield of 1st-cut and total DM yield including 2nd-and 3rd-cut increased as the harvestingtime delayed.