Evaluation of Cowpea Genotypes for Adaptation to Agro-Ecologies of Mozambique.

Cowpea is an important food crop and essential component of the cropping systems in arid and semi-arid regions of Mozambique. It is a major source of dietary protein for both rural and urban poor. Despite, its importance yields are very low due in part to limited access to improved varieties and information on better crop and soil management practices. The objectives of this study are to identify high-yielding cowpea genotypes adapted to the major agro-ecological zones of Mozambique and identify the optimum planting date for the selected genotypes. Field experiments were conducted on clay loam and sandy clay loam soils at several locations in 2008-2012 using several genotypes developed by IITA in Nigeria. Fifteen promising genotypes were selected from more than 500 genotypes that were screened for further evaluation. The selected lines were evaluated for the best planting date and their response to P application. For the planting date trials, seeds were planted at various locations on three or four different dates at 14-day intervals beginning in January. At the site with relatively high rainfall, planting during late February to early March produced the highest grain yield, whereas planting within the second half of January is the best time to plant in low rainfall areas in a year with normal rainfall. The highest grain yields across the agro-ecologies ranged from 1.2-2.2 tons/ha. The maturity durations of the cowpea lines estimated as days after emergence to physiological maturity ranged from 64-80 days. Three cowpea lines IT97K-1069-6, IT00K 126-3 and IT98K-131-2 performed well across most of the agro-ecologies. Phosphorus application generally had no consistent effect on cowpea yields across locations; where P application was required 20 kg P/ha was the optimum.