PRODUCTIVITY OF CORN (ZEA MAYS L.) AND MUNG BEAN (VIGNA RADIATA L.) INTERCROPPING SYSTEMS WITH SPECIAL REFERENCE TO PLANT POPULATION, ROW SPACING, AND NITROGEN RATE IN THE DRY ZONE OF SRI LANKA (MULTI CROPPING, MIXED, POLYCULTURE)

An intercropping experiment was conducted at the Dry-Zone Agricultural Research Station at Maha Illuppallama, Sri Lanka, during the wet season, 1983/84 and the dry season, 1984. Twin rows of corn (Zea mays L., cultivar Thai Composite) planted at 50,000 or 60,000 plants/ha and single rows of mung beans (Vigna radiata L. Wilczek, cultivar Type-51) planted between corn rows at 133,333 or 266,666 plants/ha were tested at two row spacings, 120 or 150 cm, and three N levels, 30, 60, and 90 kg/ha. Yield and yield components from corn and mung beans in intercrops were compared to yields from respective sole crops. Sole crop corn was planted in 60 cm rows at 50,000 plants/ha and sole crop mung bean was planted at 400,000 plants/ha.;Average grain yields of intercropped mung beans were significantly lower than sole crop during both seasons. Intercropped mung beans in 120 cm rows produced significantly higher yields than those planted in 150 cm rows.;Land equivalant ratios (LER's) above 1.25 were obtained from 60,000 plants/ha of corn planted in 120 cm rows with 60 or 90 kg/ha N during the wet season. LER's above 1.65 were obtained during the dry season from 120 cm rows and 90 kg/ha N.;Leaf area index and light penetration values indicate that corn did not interfere with the growth and yield of mung beans during either season.;Grain yields for intercropped corn were significantly lower than sole cropping during the wet season but showed no difference during the dry season. During the wet season, 60,000 plants/ha of corn with 60 kg/ha of N significantly increased grain yields of intercropped corn. In the dry season, 120 cm rows with 90 kg/ha N produced the highest intercropped corn yield.;Intercropping gave greater gross returns, carbohydrate, protein and energy yields per hectare than the sole cropped corn during both cropping seasons.