Grain Discoloration Severity and Upland Rice Yield at Different Cover Crops

The present study aimed to study the effect of different cover crops on grain discoloration severity and upland rice yield in order to make recommendations for agricultural practices that provide better performances. The experiment was carried out in the crop year 2011/2012 in Santa Carmen, northern state of Mato Grosso, Brasil, in an Oxisol that has been cultivated under the integrated crop-livestock systems for six years. The treatments were T1: intercropping system with cowpea (Vigna unguiculata) and Brachiaria ruziziensis, T2: intercropping system with Crotalaria ochroleuca and B. ruziziensis and T3 intercropping system with Sudan grass (Sorghum sudanense) and B. ruziziensis. The grain discoloration disease was responsible for 34% reduction in yield and a 10% reduction in weight of 100 grains. The results showed significant differences in treatment effects on grain yield, weight of 100 grains and grain discoloration severity. The intercropping system of previous crops that provided better yields and lower disease severity was that of B. ruziziensis and cowpea, being the most suitable to compose the system of crop rotation before planting rice.