RESPONSE OF GROUNDNUT (Arachis hypogaea L.) TO EXOGENOUS Bradyrhizobium sp STRAINS INOCULATION AND PHOSPHORUS SUPPLY IN TWO AGRO-ECOLOGICAL ZONES OF BENIN, WEST AFRICA

Abstract

The aim of this study was to assess the response of phosphorus and some Bradyrhizobium sp strains inoculation on the growth and development of Arachis hypogaea L. Fields trials were carried out in twelve farms located in the north and center of Benin. The experimental design is a randomized complete block with two factors dispersed to six repetitions. The first factor is inoculation of Bradyrhizobium with four levels (control, STM 5945, STM 5894 and WSM 4412) and second factor is phosphorus with two levels (0 and 50 Kg.ha-1). After 50 days of sowing, parameters related to growth, nodulation and nitrogen accumulation in aerial biomass were collected. After harvesting, fallen leaves yields biomass and pods yield have been assessed. The best height was obtained in treatment containing rhizobial STM 5945 and it was 25 % higher than the control. In case of number of leaves, there were an increase of 79% in treatment containing WSM 4412 + Phosphorus while this number was 63% higher in treatment having STM 5894 + Phosphorus whereas the single treatment of strains induce 38% (STM 5894) and 33% (WSM 4412) increases over the control. In the center, the pods yields were increased 135% (WSM 4412 + phosphorus) and 113% (STM 5945+phosphorus) over the control. In the north, the treatments with STM 5945 strains only induce pods increase of 51 % and 21 % for WSM 4412. In the north, the best increase of nitrogen accumulation was 196% in the combination of WSM 4412 + phosphorus as compared to the control. These results augur the possibility to use these Bradyrhizobiums strains as biologic fertilizer to increase the growth and the productivity of the groundnut in Benin.