Production potential, weed dynamics and energetics of maize + greengram/blackgram intercropping system

A field experiment was conducted during rainy seasons of 2002 and 2003 at Kanpur to study the effect of row ratios of legumes in maize (Zea mays L.) intercropping systems on production and associated weeds under rainfed conditions of central Uttar Pradesh. Maize was planted at normal (60 cm) and paired rows (30/90 cm) with 1 and 2 rows of blackgram [Vigna mungo (L.) Hepper] and greengram [Vigna radiata (L.) Wilczek], respectively, as intercrop. Maize was planted as control under both planting patterns. The maximum mean maize-equivalent yield (54.1 q/ha) and production efficiency (168.2%) were obtained with greengram as an intercrop in maize (normal row planting) with a row ratio of 1:2, followed by maize + blackgram (1:2) with same planting pattern, however lower values of these were associated with maize + blackgram (2:1) under paired row planting. In general, normal row planted maize in intercropping system irrespective of row ratios recorded higher values of yield attributes, viz., cobs/plant, grains/cob and 1000grains weight, grain and stover yield, and maize equivalent yield and significant reduction in weed population and weed dry-matter accumulation than paired row planting. Maize + legumes under normal row planting with a row ratio of 1:2 recorded lowest weed population, weed dry-matter accumulation and highest weed control efficiency. Highest weed population, weed dry-matter accumulation and lowest weed control efficiency were recorded with maize (paired row planting) intercropped with either of legumes under 2:1 row proportion. Similarly, intercropping of maize with normal row planting irrespective of intercrops produced higher total out put energy (203.63–209.69 x 10³ MJ/ha) and energy productivity (342–361 g/MJ). However, energy use-efficiency of maize + greengram/blackgram in normal row planting with a row rario of 1:1 was highest. Thus, 1:2 was the best row ratio for maize + legume intercropping systems with normal row planting (60 cm).