Phenotypic Diversity of Sorghum on farmers' fields in Northern and Eastern Uganda

Abstract

Sorghum is a marginal environment crop with needs for constant breeding to respond to the changes in the fragile agricultural production environment. Therefore understanding and utilizing the genetic variation in sorghum accessions is essential for improving the crop. The loss of local sorghum varieties was reported, but there is limited available information on on-farm sorghum diversity in the major sorghum growing areas of Northern and Eastern Uganda hence limiting the utilization of diversity for improvement of the crop. The objectives of this study were: a) determine the levels and spatial distribution of diversity of sorghum on farmers’ fields in the districts of Agago, Apac and Serere; b) determine the phenotypic relationship between accessions from the three districts. Field surveys were conducted on farmers’ fields across the three districts. One hundred eighty fields were sampled across the study areas and diversity was determined using the diversity indices (Shannon-Weaver and Simpson). Agago had the highest levels of sorghum diversity (4.47) followed by Serere (3.93) and finally Apac (1.60). In the second study, 100 accessions that were collected during preliminary surveys were used to determine phenotypic diversity and relationships between accessions. Phenotypic evaluation was done for two seasons at Makerere University Agricultural Research Institute Kabanyolo in Wakiso district and in Pakor village in Agago district. Data was collected on both quantitative and qualitative traits. By Ward cluster analysis, the 100 accessions were grouped into two major clusters which were further subdivided into five sub clusters. The largest cluster had 30 accessions and the smallest cluster had five accessions. The five clusters varied with respect to plant height (202.8 to 379.9 cm), days to 50% flowering (77.3 to 163), number of leaves per plant (10.9 to 24.6), 100 grain weight (2.5 to 4.6 g) and yield (1977.4 to 3475.6 kg ha-1). The study showed that different levels of diversity exist on farmers’ fields in the sorghum growing areas in Northern and Eastern Uganda. The highest levels of sorghum diversity were observed in Agago, Serere and Apac respectively. Findings also showed that, sorghum diversity is spatially distributed on farmers’ fields (fields close share most sorghum types). The sorghum accessions showed a high variability in phenotypic characteristics and hence a high potential for crop improvement. The existing on-farm sorghum diversity offers opportunity for improving sorghum through breeding for high yielding, pest and disease resistant varieties. Future diversity studies on sorghum should involve more regions where sorghum is grown.