GRAIN-YIELD, COMPETITIVE INDEXES AND WATER-USE UNDER SOYBEAN (GLYCINE-MAX) - BASED INTERCROPPING SYSTEMS IN SOUTH-EASTERN RAJASTHAN

A field experiment was conducted during rainy season of 1990-91 to 199 2-93 at Kota to study the effect of intercropping soybean [Glycin max (L.) Merr.] with sorghum [Sorghum bicolor (L.) Moench.] and pigeonpea [Cajanus cajan (L.) Millsp.] in 2 : 1, 4 : 1 and 6 : 1 rows 30 cm apar t on productivity, water use and competitive indices. Intercropping sy stems were found more productive than sole soybean. Intercropping soyb ean with pigeonpea in 4 : 1 row arrangement proved superior to other t reatments and yielded 712 kg/ha soybean and 830 kg/ha pigeonpea seed, which amounted to 1 493 kg/ha soybean-equivalent yield compared with 1 086 kg/ha sole-soybean yield. This system also recorded the highest la nd-equivalent ratio (1.26). Intercropping systems showed higher water use and water-use efficiency than sole soybean. The values of competit ive ratio (CR), relative crowding coefficient (RCC) and aggressivity i ndicated that sorghum and pigeonpea were dominant over soybean. The ag gressivity values of soybean were negative in all the intercropping sy stems, whereas CR and RCC values remained <1. Sorghum showed higher co mpetitiveness with soybean than with pigeonpea.