Effects of legume type, planting pattern and time of establishment on growth and yield of sweet sorghum-legume intercropping

Sweet sorghum is a popular grain crop grown in water stress prone areas in the world. Its sole stand leaves ample resources untapped. This study evaluated the feasibility of intercropping sweet sorghum using eight intercropping patterns composed of 2 x 2 x 2 factorial combinations of two legumes (viz. mung bean and soybean), two row patterns [viz. alternate single row (ASR) and double row (ADR)] and two seeding times (simultaneous and staggered seeding) with sole crops of sweet sorghum, mung bean and soybean in a randomized complete block design with three replicates during dry and wet seasons (2009-2010). Plant height, leaf area index (LAI) and grain yield between sole and intercropping were compared. The results showed that growth and grain yield of sweet sorghum were significantly (p ≤ 0.001) reduced when intercropped with mung bean in both the seasons, except the yield with ASR pattern and staggered seeding in the dry season. However with soybean, sweet sorghum established in staggered seeding increased the grain yield in both ASR and ADR patterns in the dry season (5.5 t ha), and at par in the wet season compared to its sole crop (5.4 t ha). All intercropping patterns had land equivalent ratio (LER) above unity. Overall outputs of carbohydrate, protein, fat, and total digestible energy during the dry season were increased by 0.4, 0.4, and 0.3 t, and 22 MJ ha, respectively, and during the wet season by 0.1, 0.4 and 0.2 t and 14 MJ ha, respectively, in sweet sorghum-soybean intercropping compared to sole cropped sweet sorghum.