GROWTH AND GREEN MANURE POTENTIALS OF TWO VARIETIES OF COWPEA (Vigna unguiculata (L.) Walp.) FOR LOW INPUT LEAF VEGETABLE PRODUCTION IN IBADAN, NIGERIA

Abstract

Nitrogen (N) requirement is a critical factor in crop production. However, excessive and inefficient use of inorganic N fertilizers increases production costs and poses  economic and environmental risks. Topromote sustainable vegetable production andreduce dependence on chemical fertilisers, the effects of two cowpea (Vigna unguiculata (L.) Walp.) varieties—Akidi and FUAMPEA-2—used as green manure  (GM) were evaluated in the cultivation of Amaranthus cruentusL. and Celosia argentea The study was carried out in Ibadan, Nigeria during the rainy season. Seeds of the varieties of cowpea were sown separately in pots containing 5 kg soil at 5 seeds/pot to assess growth attributes.The GM experiments were laid in a completely randomized design with six treatments and five replications: Akidi incorporated (AKGMIn), Akidi removed (AKGMRm), FUAMPEA-2 incorporated (FUGMIn), FUAMPEA-2 removed (FUGMRm), urea fertiliser (200 kg/ha), and control. Cowpea shoots (n=5) were either incorporated into or removed from the soil at 42 days after sowing. Two week-old seedlings of A. cruentus and C. argentea were transplanted three weeks after incorporation/removal. Growth parameters and biomass were measured four weeks after transplanting. FUAMPEA-2 produced greater biomass and nodulation than Akidi. The GM treatments performed comparably to urea and significantly better than the control in promoting the growth and biomass of both vegetables. The best performance was recorded underFUAMPEA-2 green manure. The results suggest that these cowpea varieties effectively enhanced the growth and yield of Amaranthus and Celosia, indicating their potential to replace or supplement inorganic nitrogen fertilisers.