Physiological quality of sweet sorghum [Sorghum bicolor (L.) Moench.] seeds in response to planting density in semi-arid region

Abstract

Sweet sorghum is a bioenergy crop that produces high amount of ethanol per hectare even under semi-arid conditions, serving as an alternative to sugarcane inter-season in Brazil. The aim of this study was to evaluate the influence of planting density on the physiological quality of sweet sorghum seeds. Two sweet sorghum cultivars (BRS 506 and SF-15) were submitted to a spacing of 50, 60, 70 and 80 cm between rows, and 8, 12 and 16 cm between plants. The experimental design was of randomised blocks with four replications in a 2 x 4 x 3 factorial scheme, comprising two cultivars, four row spacings and three spacings between plants. The following were evaluated from the collected panicles: seed quantity, 100 seed weight, water content, germination, first germination count and speed of germination, accelerated ageing, and seedling vigour. It was found that both the cultivar and the arrangement of plants in the field affect the physiological quality of sweet sorghum seeds. The BRS 506 cultivar is recommended for seed production under semi-arid conditions, at a spacing of 16 cm between plants and 80 cm between rows, and a density of 75,000 plants per hectare.