Author : Samran Meesorn-iem

Summary : Two sorghum row spacings (75 cm r1 and 100 cm r2) and 2 croppings systems, namely: monoculture (short sorghum Sgs and tall sorghum Sgt, early Sye and late Sy1 soybean, and early Mge and late Mg1 mung bean) and intercropping (Sgs + Sye, Sgs + Sy1, Sgs + Mge, Sgs + Mg1, Sgt + Sye, Sgt + Sy1. Sgt + Mge and Sgt + Mg1), were used in wet and dry season experiments, with sorghum as the main crop. A split plot design with four replications were used. Sorghum row spacing served as main plots and the cropping systems, as subplots. Narrow row spacings on both seasons increased the grain yield (GY) and the total dry matter (TDM) of sorghum and soybean. The GY and TDM of mung bean, however, remained the same. The highest GY and TDM yield of short sorghum, soybean, and the mung bean were from monoculture, and from SgtMg1 combination in the wet season and SgtMge in the dry season. The TDM was the predominant factor affecting GY of sorghum, soybean, and mung bean crop combinations; increase in TDM was due to narrow row spacings. In estimating the TDM of the crops, the leaf area index (LAI) was found more important than the leaf area duration (LAD). Varying the intercropping combination with height and maturity resulted to a decrease of certain yield components of the crops, and decreased the GY and TDM as compared with monoculture. But the total grain yield of the crops in the intercropping sytem was comparatively economically higher than that of the crops in monoculture, although the GY of each intercropping system crop was relatively lower than that in the monoculture. Percentage of light intercepted at 50 days after seeding (DAS) in the wet season was more significant in determining GY and TDM of sorghum and soybean instead of 30 DAS. However, this was not applicable for mung bean. During the dry season, 30 and 50 DAS were both important for all crops. Narrower row spacings and closer cropping canopy increased the percentage of light intercepted.