Title : Response of Bradyrhizobium japonicum nodule variable to cucurbitacin-containing Nemarioc-AL phytonematicide in cowpea (Vigna unguiculata L.) on N-deficient soil.
The Curve-fitting Allelochemical Response Data (CARD) had been adopted to develop the non-phytotoxic concentration of phytonematicides, technically referred to as the mean concentration stimulation point (MCSP). The MCSP for cucurbitacin-containing Nemarioc-AL phytonematicide on Bradyrhizobium japonicum-nodulated legume crops had not been documented in low-input agricultural farming systems. The objective of this study was to determine the MCSP value of Nemarioc-AL phytonematicide on B. japonicum-nodulated cowpea (Vigna unguiculata L.) on nitrogen deficient soils. Inoculated cowpea seeds were sown in 20-cm diameter plastic pots containing steampasteurised N-deficient loamy soil and Hygromix at 3:1 (v/v) ratio. Experiment comprised seven treatments (0, 2, 4, 8, 16, 32 and 64%) Nemarioc-AL phytonematicide which were applied once weekly. At 56 days after the application of treatments, MCSP value for Nemarioc-AL phytonematicide on cowpea was 5.4 with overall sensitivity (Σk) of one. In conclusion, the observed MCSP and Σk values suggested that Nemarioc-AL phytonematicide was suitable for Bradyrhizobium japonicum-nodulated cowpea production systems on N-deficient soils.