Agronomic and economic evaluation of different planting methods and dates of forage sorghum [Sorghum bicolor (L.) Moench] cultivars

To evaluate the effect of planting management on forage production in hybrid and open-pollinated sorghum cultivars, a two-year experiment based on split plot factorial in randomized complete block design with three replications was conducted at the Seed and Plant Improvement Institute, Karaj, Iran. Planting date at four levels (July 1, 10 and 23, and August 1), was considered as the main factor and the factorial combination of planting method at three levels (without priming as control, seed hydropriming, and transplanting) and genotype at two levels (Pegah cultivar and Speedfeed hybrid) as the sub-factor. The results showed that delayed planting on July 10th and 23rd, and August 1st reduced forage yield by 15.1, 32.7, and 48.7%, respectively, compared to the July 1st planting date. The highest silage yield in the first and second harvests (106.21 and 62.78 ton.ha-1, respectively) were obtained by the transplanting Pegah and Speedfeed on the July 1st, respectively, whereas the seed hydropriming of Speedfeed produced the highest total forage yield (147.80 ton ha-1). The results of the economic evaluation showed that the highest net income (99.11 million Rials.ha-1) and the maximum benefit-to-cost ratio and sales return (2.52 and 60.35%, respectively) were obtained by planting the hydroprimed seeds of Speedfeed hybrid on the July 1st. The transplanting of Pegah cultivar was uneconomical in all the studied planting dates, whereas transplanting Speedfeed hybrid from July 1st to July 23rd was superior to the conventional sowing method. In total, the results of this study showed that to produce the maximum yield and economic profit, it is recommended to carry out the planting operation at the earliest possible time with hydroprimed seeds of Speedfeed hybrid.