Abstract

Cowpea is (Vigna unguiculata [L.] Walp.) is multipurpose legume grown for its edible grain and leaves and may be used as green manure or animal feed. The shoot biomass or fodder production of cowpea nodulation and effectiveness are seldomly considered in screening and release studies, yet such information is important for the use of the crop. A field study was therefore conducted Bunda College, (14° 35 S’; 33° 50 E’, Lilongwe, Malawi in the 2012 to 2013 cropping season to evaluate the performance of eight elite cowpea lines originally from the International Institute of Tropical Agriculture (IITA), compared to two released varieties (Sudan 1 and IT82E-16) for fodder production, nodulation and grain yield and yield components in a randomized complete block design. The results showed there were significant differences (P<0.05) in grain yield (1.1  to  3.1 t ha^-1), fodder (1.1 to 3.0 tha^-1) plant height at flowering (25 to 67 cm), pods m^-2 (55 to 224), seeds per pod (10-14), cumulative leaf fall (0.9 to 1.8 tha-1) and nodules per plant (9 to 21). There were no significant differences on % nodule effectiveness (mean 95%) and canopy width at flowering (mean 51 cm). The elite line IT98K-205-8 produced the highest grain yield of 3,085 kg/ha followed by the variety Sudan 1 with 3,065 kg/ha and then elite line IT98K-205-9, which produced 2,763 kg ha^-1. The lowest yielding elite line was IT93K-693-2 which gave 1,092 kg ha^-1 of grain. Cumulative leaf fall accounted 31 to 94% of total fodder dry matter. Sudan 1 also had the highest nodules per plant (22) followed by IT82E-16 and IT99K1060. Estimated fodder N content was 2.4% giving 24 to 72 kg ha^-1 as potential N in fodder. Although these lines were not selected as dual purpose, the results show opportunity for selecting dual purpose lines through evaluating for biomass. The released variety Sudan 1 notably had high grain yield, number of nodules and pods per plant.

Key words: Cowpea nodulation, biomass production, natural leaf fall.