Alterations in source-sink relationships in cowpea under varying population density

Abstract

A field trial was carried out under irrigation, in 2001, in Fortaleza, Ceara, Brazil, in order to analyse the source-sink relationship in cowpea [Vigna unguiculata (L.) Walp.], cvs. Epace 10 and Seridó, by changes on intro plant competition. The populations studied were 41,666; 83,333; 125,000 and 166,666 plants.ha-1. An increase in light interception, leaf area index, leaf area duration and in the crop growth rate (45 and 60 days after seeding ) were observed in response to increase of plant density. It was not possible to achieve the total soil canopy coverage using these populations of plants. The increase of population determined reduction in number of branches, in the potential and in the capacity of reproductive sinks, and alterations in source-sink relationships. The number of flowers, pods and seed weight per leaf area showed a decreasing tendency. The population levels studied did not affect reproduction efficiency and productivity. The cv. Epace 10 was more productive than the cv. Seridó.