Summer Forage Sorghum Yield, Protein and Prussic Acid Contents as Affected by Plant Density and Nitrogen Topdressing

Two similar field experiments were carried out at Kushkak and Fars Agricultural Ex-perimental Staties to determine the effects of plant densities and nitrogen topdressing (NT) rates on forage yield, some agronomic traits, protein and prussic acid contents of forage sorghum (Sorghum bicolor L. Moench var. Sudenense). Both experiments were conducted as spilt plots arranged in randomized complete block design with four replica-tions. Plant density consisted of ۲۵, ۳۳ and ۵۰ plants m-۲ in the main plots and nitrogen topdressing rates were ۰, ۱۰۰, ۲۰۰ and ۳۰۰ kg N ha-۱ as urea in the sub-plots. Increasing plant density increased main stem height (MSH), leaf area index (LAI), total tiller num-ber m-۲ (TTN), total fresh forage (TFF), total dry matter (TDM), leaf dry matter (LDM), and stem dry matter (SDM) yields. However, it decreased crude protein percentages (CPP) and had no effects on leaf-stem ratio at both locations. Increasing nitrogen rates in-creased MSH, LAI, TTN, TFF, TDM, CPP, forage prussic acid percentage (FPAP) and decreased leaf-stem ratio. Optimum plant densities and NT rates for these experiments were ۵۰ plants m-۲ and ۲۰۰ kg N ha-۱, respectively at both locations. Nitrogen applications had more effects on the second than the first out. The reaction of forage yields and most agronomic traits to the treatments were extremely similar at both locations.

کلیدواژه ها:

Plant density ، Crude protein ، Dry forage ، Fresh forage ، Prussic acid ، Total tillers number