Cowpea reactions to Alectra vogelii II: effect on yield and nutrient composition

Field trials were conducted in 1993-1995 wet seasons to evaluate the influe nce of artificial inoculation of plots with the seeds of Alectra vogelii on the grain yield, yield components and nutrient composition of 16 cowpea va rieties. This include 11 resistant varieties: IT81D-985, IT81D-994, IT89KD- 245-1, TN93-80, TN121-80. IT90K-76. IT90K-59, IT86D-534, IT86D-833, B301 an d IT89KD-245, two tolerant varieties: KANO 1696 and VITA 3 and three suscep tible varieties: SAMPEA 7. TVX 3236 and IT82D-849. Alectra inoculation redu ced the pod number and weight and grain yield of all the cowpea varieties i n the late planted crop. Alectra infestation resulted in higher reduction o f grain yield, yield components and grain total soluble carbohydrate (TSC) content in most of the late than early planted cowpea varieties in 1993 and 1994, respectively. In the early planted trial in 1994, the grain yield of the resistant varieties such as IT81D-985, IT81D-994, IT86D-843, IT90K-76, IT90K-59: TN93-80, B301, IT86D-534 and TN121-80 was increased while that o f VITA 3, TVX 3236, SAMPEA 7 and IT82D-849 was reduced. Generally, the grai n TSC content of the resistant cowpea varieties that had increased grain yi eld was reduced but that of the susceptible varieties with reduced grain yi eld was increased in the early-planted trial in 1994. Alectra infestation g enerally resulted in low percentage increase in the grain protein content o f most of the cowpea varieties in the two trials, with greater increase in the late than in the early-planted crop. (C) 2001 Elsevier Science Ltd. All rights reserved.