International Journal of Agriculture and Biology, vol.14, no.6, pp.879-886, 2012 (SCI-Expanded)
Forage sorghum (Sorghum bicolor (L.) Moench) is one of the most important fresh fodder and silage sources in the world, and its quality and yield are directly related in the harvesting time. In this study, four forage sorghum cultivars(Sorghum bicolor (L.) Moench) were compared to determine effects of delayed harvesting time on the changes in yield and forage quality. Field experiments were conducted during the 2010 and 2011 growing seasons. Four forage sorghum cultivars(Early Sumac, Leotti, Nes, Rox) were harvested at four different growing stages (panicle emergence stage (PE), milky stage (MS), dough stage (DS) and physiologic maturity stage (PM)). Dry matter, fresh forage yield, plant height, dry matter content, panicle proportion, protein yield, lignin content and relative feed value (RFV) tended to increase with advanced plant maturity, while leaf proportion, protein content, neutral detergent fiber content (NDF), acid detergent fiber content (ADF), cellulose content and hemicellulose content tended to decrease. Dry matter contents of all sorghum cultivars harvested during the PE and MS stages were below 247 g kg-1. Among whole plant organs, stem proportion was higher than those of leaf and panicle proportions. Mean dry matter yields of cultivars were ranged from 18.75 t ha-1 to 20.15 t ha-1. These findings have shown that suitable harvesting time of forage sorghum is PM stage for high yield and fodder quality, but it may be harvested at DS stage due to increasing lignin content. None of these sorghum cultivars should be harvested before DS stage for ensilage due to low dry matter content. Nes can be preferred because of the high forage and protein yield. © 2012 Friends Science Publishers.