Enhancing forage quality through appropriate nitrogen dose, seed rate and harvest stage, in sorghum cultivars grown in Pakistan

Sorghum is an important forage crop having good drought tolerance and high dry matter accumulation in a short growing season, and grown under diversified environments. Based on this, a 2-year field study was executed to evaluate the effect of seed rate and nitrogen (N) levels on the fiber quality of forage sorghum cultivars harvested at different growth stages under semiarid condition. Three forage sorghum cultivars (JS-2002', JS-263' and Chakwal Sorghum') were sown with three N levels (0, 60 and 120kgha(-1)) by using three seed rates (75, 100 and 125kgha(-1)). Results showed that cv. JS-2002' had higher contents of neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL) and cellulose, while JS-263' produced greater soluble carbohydrate, total digestible nutrients (TDN), relative feed value (RFV) and net energy (NE) than other cultivars. Increasing N rates (0-120kgha(-1)) enhanced ADF, ADL, RFV and NE, but not NDF and TDN. Similarly, increased seed rate enhanced accumulation of NDF, ADF and ADL, while caused reduction of TDN, RFV and NE. In conclusion, cv. JS-2002' performed better than the other two cultivars, whereas, sorghum seeded at 75kgha(-1) with 120kgNha(-1) application produced better quality forage at 50% heading stage.