GENOTYPE X CROPPING PATTERN INTERACTIONS OF TROPICAL SORGHUM, MAIZE, AND COWPEA CULTIVARS IN TANZANIA

Most small farmers in East Africa grow their cereals in association with other crops. Food crops research has focused on development of efficient cultivars in monocropping. Breeding programs should consider the importance of developing cultivars that would perform well in complex cropping systems. The task of this research was to determine whether the varieties bred for monocropping could be equally suitable for intercropping systems. Statistical significance was determined for the effects of genotypes, cropping patterns, and their interactions on the morphological traits, maturity characteristics, yield and yield components. Calculations of interactions allow not only the study of implications for breeding programs but also the evaluation of breadth of adaptation of cultivars. Results can lead to an understanding of the type of demonstration/extension program which could be organized for small farmers. The average of two single-row dry seed weight was recorded as yield per plot. The yield per plot was then converted to yield in Kg/ha. Of the sorghum cultivars evaluated, intercropping did not change the ranking of genotypes among cropping systems for morphological and maturity characteristics. Sorghum yield and yield components were significantly influenced by cropping systems. Days to maturity of cowpea cultivars was affected by cropping patterns. This was probably because physiological maturity coincided with the grand period of growth of the associated species. The cowpea/maize association outyielded the cowpea/sorghum mixture. Monoculture maize was consistently taller than associated maize. Earliness to silking also was affected by cropping systems. The type of companion crop in mixture with maize had an influence on earliness to maturity. Yield and yield components were influenced by cropping systems. These studies suggested that farmers in the Ifakara-Kilosa area would benefit by growing maize and cowpea mixtures. The significant genotype x cropping pattern interactions indicated that the ranking of genotypes for the agronomic variables evaluated was not consistent across cropping systems. The observed interactions suggested that breeding for specific cropping patterns may be necessary in complex cropping systems