YIELD RESPONSE OF GROUNDNUT (ARACHIS HYPOGAEA L.) VARIETIES TO GYPSUM AND RHIZOBIA INOCULATION IN THE NIGERIAN SAVANNA

Yield and yield parameters of two groundnut (Arachis hypogaea L.) varieties under varying rates of gypsum and rhizobia inoculation levels were studied under field condition in 2012 wet seasons and 2012/13 dry season at the Institute for Agricultural Research Farm, Ahmadu Bello University, Samaru and Irrigation Research Station of the Institute for Agricultural Research, Kadawa respectively. The treatments consisted of factorial combinations of two varieties of groundnut (SAMNUT 22 and SAMNUT 23), five levels of gypsum (0, 50,100,150 and 200kg ha- 1) and two levels of rhizobiainoculation (inoculated and uninoculated). The treatments were arranged in a randomized complete block design and replicated three times. Results of the experiment from the two locations showed that application of gypsum and rhizobia inoculation had no significant effect on the parameters examined. However, SAMNUT 22had a significantly higher values of 100 kernel weight, shelling percentage, kernel yield plant-1, pod yield plant-1 in Samaru and harvest index in Kadawa compared to SAMNUT 23. Significant interactions wererecordedbetween; gypsum rates andrhizobiainoculation in 100 kernel weight at Samaru and between gypsum rates and variety on the pod yield in Kadawa. Based on the results obtained from the two locations, gypsum fertilization and rhizobia inoculation did not influence the yield and yield parameters, while SAMNUT 22 performed better than SAMNUT 23. In conclusion, application of gypsum may not be necessary on soils high in calcium while further inoculation studies should be carried out on groundnut with the right strains of bacteria and SAMNUT 22 can produce better yield in both seasons.