EFFECT OF PHOSPHORUS AND PLANT DENSITY ON THE YIELD COMPONENTS OF COW-PEA (Vigna unguiculata L. Walp): MORFOLOGICAL CHARACTERISTICS

Abstract

A field experiment was carried out on a distrophic Red Yellow Latosol Text, in the State of Bahia, Brazil, to evaluate the effects of population densities and levels of phosphorous dressing on some morphological characteristics of cow-pea (Vigna unguiculata L Walp), Cv “Tv x 1836-013J”, with a determinate growing habit. Population densities of 40, 80, 160 and 320 thousands of plants per hectare and phosphorus levels at 0, 40, 80 and 160 kg P205 per hectare were applied. Early and late flowering measurements were taken for number of knots on stems and sprouts, foliar area, foliar area index and dry matter production per plant. At harvest date, were taken for number of knots on stems and sprouts. From the observations made at early flowering, only foliar index was affected by plant density. An increment of about 531% was observed on foliar area index by increasing plant density from 40.000 to 320.000 plants per hectare. Data collected at late flowering showed a significant effect of plant density on the number of knots per sprout, total number of knots per plant and foliar area, that diminished with increasing plant density. Phosphorus levels had a significant and positive effect on those variables. However, increasing plant density caused a significant reduction on total dry matter yield per plant and a significant increase on foliar index. At harvest, a significant and negative effect of plant density was observed on the number of stem knots, number of sprout knots and total number of knots per plant, with increasing plant densities for 40.000 to 320.000 plants per hectare.