Etiology of crop growth variability in groundnut in Niger.
Six field trials conducted during the 1987-88 rainy seasons and 1988 dry season at ICRISAT Sahelian Center, Niger investigated the effects of soil application nematicides, inorganic fertilizers and 20 t FYM/ha on spatial variability of groundnut growth and yield. Soil samples from the rhizosphere and geocarposphere zones of stunted plants showed high numbers of plant-parasitic nematodes (Scutellonema clathricaudatum, Telotylenchus indicus and Xiphinema parasetariae). Carbofuran alone at a rate of 10 kg a.i./ha or in combination with FYM greatly reduced the population densities of plant-parasitic nematodes in the soil and roots, and increased pod and haulm yields. Joint application of inorganic fertilizers (N, P, S, Ca, B, Zn, Fe and Mo), FYM and carbofuran gave the highest pod yield of 2.24 t/ha at Sadore. Dibromochloropropane reduced the variation in crop growth and significantly increased pod and haulm yields. Soil solarization (covering with clear polyethylene) did not affect crop growth or yield.