Sweet potato (Ipomoea batatas L.)-based strip intercropping: I. Interspecific interactions and yield advantage

Abstract

A field experiment was conducted at the Regional Centre of the Central Tuber Crops Research Institute, Dumduma, Bhubaneswar for three consecutive years (2006–2008) under rainfed conditions on Alfisols to quantify the effects of strip intercropping on crop yields and yield components. A significantly higher yield was obtained from sweet potato (Ipomoea batatas L.) border rows when pigeonpea (Cajanus cajan (L.) Millsp.) was intercropped. Analyses of sweet potato yield components indicated that the number of roots/plant, root length and root diameter were significantly higher in border rows when rice (Oryza sativa L.), finger millet (Eleusine coracana L.) and pigeonpea were used as intercrop compared to monoculture sweet potato. The number of tubers/plant of sweet potato in border rows was significantly lower when maize (Zea mays L.) was intercropped, but the root length and root diameter were found to increase compared to sole sweet potato. The yields of rice, finger millet, maize and pigeonpea in inside rows in strip cropping were a little higher than in monoculture. The yield difference was mainly due to an increase in the number of seeds/panicle or cob. Sweet potato was the dominant crop when grown with rice or finger millet, but it was the subordinate crop when grown along with maize or pigeonpea. Sweet potato yields were consistently higher in strip intercropping than in monoculture when calculated across all the strips on an equal area basis. A strip intercropping system involving sweet potato + pigeonpea resulted in a higher land equivalent ratio (1.31) and net return ( $623.9) compared to the other forms of intercropping and to monocropping.