Abstract
The seed scarcity of Sudan grass plagues the pasture industry in the livestock sector, especially in arid and semiarid regions. The current study was initiated to tackle this challenge. The study evaluates the response of the grain yield and yield components of Sudan grass to cutting numbers, potassium rates, and intrarow spacing over 2 years. A field experiment was conducted using a randomized complete block split-split design with 2 cutting numbers (no cutting and cut 1 time), 2 potassium rates (60 and 120 kg K2O ha(-1)), and 3 intrarow spacings (15, 20, and 25 cm between hills) as the main plot, split plot, and split-split plot, respectively. The results showed that the zero-cut treatment produced, as averaged over the 2 seasons, 52.3% and 74.5% higher grain yield and hay yield per hectare than the one-cut treatment, respectively. However, the latter treatment had harvest index and sum of hay and green forage yield values that were 17.0% and 19.9% higher than those of the zero-cut treatment, respectively. The application of potassium at a rate of 120 kg ha-1 resulted in the maximum grain yield and yield components as compared to the lower potassium rate (60 kg ha(-1)), with the exception of 1000-grain weight, hay yield, and sum of hay and green forage yield, which were not significantly different from each other. Averaged over 2 seasons, as the intrarow spacing between hills was increased from 15 cm to 20 and 25 cm, grain weight per panicle decreased by 11.3% and 25.7%, grain yield per hectare decreased by 6.6% and 15.7%, and harvest index decreased by 12.0% and 23.5%, respectively. The interaction among 3 factors had a significant effect on yield and yield components; the highest values for grain and hay yields per hectare were obtained by growing Sudan grass at 15 or 20 cm intrarow spacing under the zero-cut treatment with the application of potassium at rate of 120 kg ha(-1). At 15 or 20 cm intrarow spacing, the values for grain yield per hectare under the one-cut treatment and high potassium rate were occasionally comparable to those for the zero-cut treatment and low potassium rate. Finally, when seed production is desired, Sudan grass should not be cut. If growers are interested in producing green forage and grain simultaneously, Sudan grass can be cut 1 time; however, it should be grown at 15 cm intrarow spacing with application of potassium at a rate of 120 kg ha(-1).