Manipulation of the castor bean growth through the pruning at different planting densities

Abstract

The experiment was conducted at Quixadá, CE, Brazil, aiming to evaluate the effect of pruning of the main shoot in castor bean plants, at different stages of the plant cycle, on growth, grain yield and oil content of cv. BRS 149 Nordestina grown at two plant spacings. The experimental design was of randomized blocks, with four replications and treatments arranged in a 5 x 2 factorial. The treatments consisted of the combination of five times of pruning (unpruned or pruned at the 6^th; 10^th; 14^th and 18^th node of the main stem from the soil), with two planting spacings (2.0 m x 2.0 m; 2.0 m x 1.0 m). The nipping of the apical shoot at the 6^th; 10^th and 14^th node of the main stem reduced the plant height, but it did not affect seed yield. In the spacing 2.0 m x 2.0 m there was an increase in the number of branches per plant, number of racemes per plant, length of the raceme, number of fruits per raceme and mass of raceme, the yields of grains and oil were higher in the spacing of 2.0 m x 1.0 m. The secondary racemes had a higher participation in the grain yield as compared with the primary and tertiary ones.