ADDITION OF PEARL MILLET STRAW TO SOIL FOR REDUCTION OF SOUTHERN BLIGHT IN COMMOM BEAN

Abstract

Many plants, such as pearl millet (Pennisetum glaucum), have been cultivated with the purpose of covering or being incorporated to soil. This practice might improve soil chemical, physical and biological characteristics. These changes in soil features can affect diseases, especially those caused by soil-borne pathogens, such as Sclerotium rolfsii. In this study, a group of experiments was conducted in a randomized block design to evaluated the effects of pearl millet straw addition (N = 0.8%; P = 0.14%; K = 1.76%; Ca = 0.52%; Mg = 0.22%; S = 0.12%; B = 6.8 mg kg^-1; Cu = 12.7 mg kg^-1; Fe = 412 mg kg^-1; Mn = 39.5 mg kg^-1; Zn = 30.3 mg kg^-1; and Na = 360 mg kg^-1) and seed inoculation with Bradyrhizobium japonicum on common bean (Phaseolus vulgaris) southern blight, cultivated in a greenhouse, and also on the fluorescent Pseudomonas spp. native population. The addition of straw (10 t ha^-1, 20 t ha^-1, and 30 t ha^-1) reduced the severity of the disease, while the seed inoculation with Rhizobium did not. There was a significant increase of fluorescent Pseudomonas populations in soils with straw. These results indicate that the addition of pearl millet straw to soil can reduce the disease and favour the fluorescent Pseudomonas population growth.

KEY-WORDS: Sclerotium rolfsii; Pennisetum glaucum; Phaseolus vulgaris; fluorescent Pseudomonas spp.