Performance of Brachiaria brizantha cv. Xaraés subjected to shading

Abstract

Results about the effects of shading on cowpea plants of the species Brachiaria brizantha are scarce in literature, specially that on the cultivar Xaraés, which may be used in pasture areas in Brazil, for sustainable systems such as the ley and alley cropping. This study aimed to evaluate the influence of four levels of artificial shading (0; 25; 50 and 75%) at three sampling times (45; 60 and 75 days after planting) on 14 plant variables (leaf area; root, stem, leaf and whole plant dry matter; nodule production; leaf/stem ratio; shoot/root ratio; specific leaf area; leaf area ratio; leaf mass ratio; stem mass ratio; and root mass ratio) of the cultivar Xaraés of B. brizantha. The experimental design was in randomised blocks with split-plots, with three replicates. Shading levels was the main plots and sampling time, the sub-plots. Correlations were observed among variables. The statistical analysis of the results was performed by factorial analysis, using the software SAEG 9.0. The first rotational factor (F1), that explained more than half of the observed variance (51.20%), showed that 50% shading brought about the highest total dry matter production but the lowest allocation of dry matter to shoots due to the smaller photosynthetic area at 95 and 110 days after planting. The opposite was observed under 75% shading that indicated that plants of cv Xaraés have a preferential allocation of dry matter to aerial tissues under reduced light in consequence of high availability of photosynthetic surface.