Mungbean (Vigna radiata L.) Residue and Nitrogen Rate Affected Growth and Yield of Direct Seeded Rice (Oryza sativa L.) In Rainfed Riceland

An experiment was conducted in a farmer’s field in Ban Muong village, Muang district in Khon Kaen province in 2003. The objective of this study was to investigate the effect of mungbean (Vigna radiata L.) residue and nitrogen rates (0, 30 and 60 kg N ha-1) on growth and yield of direct seeded rice (Oryza sativa L.) in rainfed riceland. The results showed that mungbean residue had no effect on tiller number, leaf area index and total top dry weight of rice in rice-mungbean intercropping or sole rice cropping. Also, mungbean residue had no significant effect on panicle number m-2, spikelets number per panicle, 1,000 grain weight, percentage filled grain, harvest index or grain yield However, mungbean residue tendes to increase rice grain yield over sole rice by 0.33 t ha-1(13 %) with had no nitrogen application. Rice grain yield was significantly affected by nitrogen rates. The highest rice grain yield (2.7 t ha-1) was obtained with a nitrogen rate of 30 kg N ha-1. Nitrogen fertilizer application at a rate of 60 kg N ha-1 decreased grain yield, when compared with 30 kg N ha-1.