Sorghum [Sorghum bicolor (L.) Moench] is one of the most important forage crops in arid and semiarid regions, and its yield and nutritive value are affected by the harvesting stage. A 2-year field experiment was carried out during the 2017 and 2018 growing seasons to evaluate the forage potential of sorghum cultivars at different harvesting stages. Experimental factors included four harvesting stages (grain milk stage, grain soft dough stage, grain hard dough stage, and grain physiological maturity stage) and seven sorghum cultivars. The highest dry matter and protein yields (38.13 and 3.11 Mg ha⁻¹, respectively) were obtained from cultivar Mashhad-1 at the grain physiological maturity stage, whereas the maximum relative feed value was recorded in cv. Karaj-16 at the grain milk stage. Moreover, the highest crude protein content (116 g kg⁻¹), digestible organic matter (734 g kg⁻¹), and metabolizable energy (2.73 Mcal kg⁻¹) were obtained at the grain milk stage. The maximum panicle dry matter yield (19.39 Mg ha⁻¹) and panicle ratio (552 g kg⁻¹) were found in cv. Karaj-9 at the grain physiological maturity stage. The results of the principal component analysis also showed that with increasing maturity, forage yield increased, and its quality decreased. Overall, when both high forage yield and quality were considered, forage harvesting between the grain soft dough and grain hard dough stages could be recommended. Among the cultivars, the cv. Mashhad-1 with the maximum dry matter and protein yield and high metabolizable energy, digestible organic matter, and crude protein content could be introduced as the superior genotype.

高粱[ Sorghum bicolor (L.) Moench]是干旱和半干旱地区最重要的牧草作物之一，其产量和营养价值受收获阶段的影响。在 2017 年和 2018 年生长季节进行了为期 2 年的田间试验，以评估不同收获阶段高粱品种的牧草潜力。试验因素包括4个收获阶段（谷物乳期、谷物软面团期、谷物硬面团期和谷物生理成熟期）和7个高粱品种。最高的干物质和蛋白质产量（38.13 和 3.11 Mg ha ^-1，分别）从品种 Mashhad-1 在谷物生理成熟期获得，而最大相对饲料值记录在 cv. 谷物牛奶阶段的 Karaj-16。此外，在谷物奶阶段获得了最高的粗蛋白含量（116 g kg ^-1）、可消化有机物（734 g kg ^-1）和代谢能（2.73 Mcal kg ^-1）。最大穗干物质产量（19.39 Mg ha ^-1）和穗比（552 g kg ^-1) 在简历中找到。籽粒生理成熟期的卡拉吉-9。主成分分析结果还表明，随着成熟度的增加，牧草产量增加，品质下降。总体而言，当同时考虑高草料产量和质量时，可以推荐在谷物软面团阶段和谷物硬面团阶段之间进行草料收获。在品种中，cv。具有最大干物质和蛋白质产量以及高代谢能、可消化有机物和粗蛋白含量的Mashhad-1可以作为优良基因型引入。