Irrigation, Planting Date And Intra-Row Spacing Effects On Soybean Grown Under Dry Farming Systems

Abstract

Two soybean cultivars (Glycine maxima (L) Merr.) differing in maturity period, leaf size and stem height were sown five times at fortnight intervals during the rainy season at four intra—row spacings under supplementary irrigation at one site and under rainfed conditions at another site in the central rainlands of Sudan. Cultivars responded differently to the system of production. Sowing date and moisture availability were the main factors controlling soybean production. The late maturing cultivar Semmes outyielded the early maturing cultivar Davis under supplementary irrigation whereas under rainfed conditions the reverse was true. Delayed sowings and wider intra—row spacings reduced grain of both cultivars under two systems of production. Irrigation increased grain yields and yield components of both cultivars markedly. The results seem to support the view that the optimum time of sowing both cultivars is over the period mid—June to mid—July, rather than a delayed date.