Nitrogen fertilization of okra (Abelmoschus esculentus) in an intercropping system with cassava (Manihot esculenta) and maize (Zea mays) in south-western Nigeria

Abstract

Nitrogen fertilization of okra (Abelmoschus esculentus) when intercropped with cassava (Manihot esculenta) and maize (Zea mays) was studied using three N rates (0, 60 and 120 kg/ha) in two field experiments in Nigeria between 1995 and 1997. The okra was grown between the cassava and maize rows. The effect of using two contrasting maize cvs. TZE Composite 3 Cl (less-tall, early-maturing with narrow leaves) and DMRSR-Y (tall, late-maturing with broad leaves) on N response of okra in the mixture was also investigated. Intercropping with maize or cassava and maize significantly increased stem elongation, delayed pod harvest, and decreased branch or pod formation and marketable pod yield in okra. In the cassava/maize/okra combination, maize had greater effect than cassava in determining most growth and pod yield attributes of the okra crop, regardless of N rate. However, the effect was relatively less severe in mixtures with early-maize cv. TZE Composite 3 Cl than with late-maize cv. DMRSR-Y. Although applied N at rates above 60 kg/ha in intercropping increased maize grain and cassava tuber yields, this did not result in a further significant gain in pod yield of the associated okra crop. The present recommendation of 60 kg/ha for N fertilization of cassava/maize intercrop was found to be applicable to okra grown between the cassava/maize rows using the less-tall, early-maize cultivar with relatively narrow leaves, and possibly reduced leaf area.