Effects of cutting frequency on yield and quality of forage sweet sorghum cultivar ‘3701’ in an arid region

This study examined the effects of two cutting treatments to improve yield and forage quality of new forage sweet sorghum cultivar ‘3701’ in Xinjiang region. Treatment 1 involved cutting once a year; treatment 2 involved cutting twice a year, divided into the first and second cut. The study focused on assessing the impact of these treatments on yield, agronomic traits, nutritional quality, and feeding value of forage sweet sorghum. The optimal cutting frequency for this cultivar in this arid region was also evaluated. The results showed differences in the main agronomic traits, yield, and quality content of ‘3701’ under different cutting treatments. Effects of cutting frequency on plant height, stem diameter, leaf area, leaf number, and sugar content were highly significant, except for chlorophyll content. Under different cutting treatments, plant height, stem diameter, sugar content, and number of leaves followed the order: cutting once a year > cutting twice a year (first cut) > cutting twice a year (second cut). Plant height of 375.66 cm and sugar content of 16.46% were obtained in treatment 1. The difference in yield between different cutting treatments reached a highly significant level. Treatment 1 provided an annual fresh grass yield of 147.60 t·hm⁻², 29.66% higher than that of treatment 2. The nutritional quality content of different parts of forage sweet sorghum cultivar and distribution pattern of each nutritional quality showed that the contents of crude protein, crude fiber, and neutral detergent cellulose were higher in the leaves than in the stems, whereas soluble carbohydrate content was higher in the stems than in the leaves. The relative feed value content reached the highest value of 88.24% in treatment 1. Except for total digestible nutrients content, no significant differences in dry matter digestibility, dry matter intake, net lactation energy, and relative feed value contents were found among the different treatments. In summary, from the perspective of yield, nutritional quality, and feeding value, it is recommended to cut the ‘3701’ cultivar once a year in the wax ripening period in this experimental area.