Studies on the sowing date of cotton in the Sudan Gezira: III. The effect of sowing date on yield and quality under different fertilizer and spraying treatments

Abstract

Field experiments from 1959–60 to 1963–4 showed that when blackarm resistant strains of Egyptian type cotton were sown around the beginning of August and adequately protected from fleabeetle, the resultant crop was of higher yield and considerably better average quality than that from the normal mid-to-late August sowings. Effective length, maturity ratio, standard fibre weight, bundle strength and lea-count × strength product were all improved. Sowing in early July, tested in one season only, gave rather better quality but lower yield than sowing in early August. Sowing in late August or in September depressed both yield and quality. The importance of direct climatic effects and of blackarm, fleabeetle, bollworm, other insect pests and wilt in controlling the choice of, and response to, sowing date is briefly discussed.Thanks are due to the Sudan Gezira Board for kindly supplying the results of the large-scale sowing date trials and for the grading of experimental cotton, to the Shirley Institute of Manchester for the fibre and spinning tests and to the Chief, Agricultural Research Division, Ministry of Agriculture, Sudan, for permission to publish this paper.