The reaction of groundnut (Arachis hypogaea L.) to Alectra parasitism, as influenced by nitrogen and phosphorus fertilization at Samaru, Nigeria.

A field study was undertaken from 1998 to 2000 wet season at Samaru (11°11′N; 07°38′E); located in the northern Guinea Savannas ecology of Nigeria. The objective was to assess the efficacy of nitrogen and phosphorus fertilizers in ameliorating the effect of Alectra parasitism on groundnut (Arachis hypogaea L.). Three groundnut genotypes (SAMNUT - 11, SAMNUT - 16, SAMNUT - 18), were tested using three N levels (0, 25, 50 kg N ha-1) and three P rates (0, 22, 44 kg P ha-). Mean performance over the years has shown that application of 25 and 50 kg N ha-1 markedly reduced Alectra incidence at 12 and 15WAS. Crop injury was decreased with increasing nitrogen rates from 0 to 50 kg N ha-1. However only 50 kg N improved crop vigour at 12WAS and significantly increased mean pod yield compared to zero and 25 kg N ha-1. Phosphorus application increased pod yield only in 1999 at 44 kg P ha-1.