EFFECT OF SEED SIZE AND PHOSPHORUS LEVELS ON THE GROWTH AND YIELD OF COWPEA (Vigna unguiculata [L] walp) VARIETIES

EFFECT OF SEED SIZE AND PHOSPHORUS LEVELS ON THE GROWTH AND YIELD OF COWPEA (Vigna unguiculata [L] walp) VARIETIES

Abstract:

This experiment was conducted during the rainy season of 1989 in Samaru in Northern guinea Savanna to investigate the effect(s) of seed size and phosphorus levels on the yield and yield components of cowpea [Vlgna unguicutata [L.] Walp) varieties. Treatments consisted of two cowpea varieties (improved local S.L 1696 and improved Sampea-7), three seed sizes (large, medium and small) and three phosphorus level (0, 37.5 and 75.0kg P20c/ha). Possible combination of all the treatments were laid in a split-plot design and replicated three times. The investigation showed that while large sized seeds produced slightly higher yield and yield components than the remaining two seed sizes, large seed size irrespective of the variety planted produced significantly plants with longer vines, wider leaf area, heavier dry shoot, heavier dry leaf; more leaves all at 4 WAP and more branches at: 8 WAP than the small seed size. Application of phosphorus slightly decreased the yield and yield components, although these reductions were not statistically significant. Crude protein content of the seed however increased with application of phosphorus (P) fertilizer. Improved local S.L 1696 variety was more vigorous in vegetative growth than Sampea-7. This variety (Sampea-7) on the other hand significantly produced higher grain yield (2.62 tons ha”1) than improved local S.L 1696 (1.5 tons ha” ). Interactive effect of seed size and cowpea variety significantly influenced number of leaves at 4 WAP; branches at 8 and 10 WAP and 100-seed weight at harvest. Improved local S.L 1696 variety irrespective of seed size produced significantly higher number of leaves; and 100-seed weight than Sampea-7. Grain yield was significantly and positively correlated with yield components (number of flowers, pods, seeds and seed weight per plant) and vegetative growth characters (plant height and leaf area per plant). From these findings, it can be concluded that grain yield increased by 9.4% when large rather than small seeds were sown. There is therefore no significant yield advantage in selecting large seeds for planting. Yield and yield components decreased slightly with P-levels, the residual P in the soil as evident from the soil test results, was more than sufficient to raise a good crop of cowpea without P-fertilization. It is therefore a waste of time and resources applying P-fertilizer where soil test results prior to planting reveal high level of residual-P.

EFFECT OF SEED SIZE AND PHOSPHORUS LEVELS ON THE GROWTH AND YIELD OF COWPEA (Vigna unguiculata [L] walp) VARIETIES

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