Variability in Phenotypic traits and resistance to blast in interspecific finger millet progenies

Finger millet (Eleusine coracana (L.)Gaertn.ssp. coracana) is an important food, food security and cash crop in eastern and southern Africa where small-scale farmers grow it in low input farming systems. The crop has food security, nutritional, cultural, medicinal, and economic value with high industrial potential. Use of host plant resistance is the most feasible and economical viable means of managing finger millet blast especially for resource-poor farmers. The purpose of this study was to assess the performance of advance populations derived from three interspecific crosses between finger millet and two wild relatives E. kigeziensis and E. Africana. F3 and F4 progeny deriving from thse interspecific crosses i.e. E. kigeziensis X E. coracana (Pese 1), E. africana X E. coracana (Seremi 1) and E. africana X E. coracana (Seremi 3) were uses. Two studies were conducted (i) on resistance to finger millet blast disease among F3 and F4 under controlled conditions of humid chambers and greenhouse using an aggressive M. grisea isolated obtained from Ngora in Eastern Uganda. The second study focused on variability of phenotypic traits (according to the finger millet descriptors, IPGR 1985) at two sites, Makerere University Agricultural Research Institute, MUARIK (MUARIK) and National Semi-Arid Resources Research Institute (NaSSARI) in NaSAARI. In both studies, experiments were established following the alpha lattice design. Significant variations were observed among the finger millet accessions for various agronomic traits with the maturity and growth traits having the greatest contribution to the total phenotypic variation captured which was consistent with reports of previous studies. A number of accessions were identified for their good performance for specific traits; 36 for early flowering; 12 accessions for early maturity; 22 for more number of fingers; 10 for high basal tiller number and 24 accessions for long fingers, and 19 for tallness. 20 accessions were identified as multi-trait specific accessions, which were found to be sources of more than one trait. These accessions could be utilized for simultaneous transfer of multiple traits in finger millet improvement programme. Out of 48 accessions at F4 generation, of the finger millet interspecific progenies, a total of 39 accessions were identified as trait specific for six important yield-contributing traits. 21 Multi-trait specific accessions were identified, which were found to be sources for more than one trait. Highly significant differences among the F3 interspecific progenies for the leaf blast (P< 0.001) were found, with the highest mean square variance recorded at 56 days after planting. The leaf blast severity ranged from 1.7 to 2.6 on a 1-5 scale compared to 2.2 on resistant check (Gulu E) and 3.2 on susceptible check (KATFMI). Among the 48 F3 progeny, nine lines (19%) were resistant, 38 lines (79%) were moderately resistant and only one line (2 %) was susceptible. No lines showed total immunity (highly resistant) and high susceptibility to the leaf blast disease. The minimum score was recorded on line 19c-b (1.7) followed by 19c, 24b, 13a, 6b, 2b, 20b, 24c-b and 22c-b all with a score of 1.9. All these were categorized as resistant. The maximum score was recorded on line 16c-b (2.6) categorized as susceptible, followed by 12a with a score of 2.4 and 26b, 8a, 1a, 17b, 18c-b, 7c-b, 5b, 25c-b all with a score of 2.3 and categorised as moderately resistant. Highly significant differences among the F4 interspecific progenies for the leaf blast (P< 0.001) were found with the highest mean square variance recorded at 56 days after planting. The leaf blast severity ranged from 1.8 to 2.7 on a 1-5 scale compared to 2.2 on resistant check (Gulu E) and 2.7 on susceptible check (SER 2). Among the 48 F3 progeny, five lines (10%) were resistant, 37 lines (77%) were moderately resistant and six lines (13 %) was susceptible. No lines showed total immunity (highly resistant) and high susceptibility to the leaf blast disease. The minimum score was recorded on line 25a (1.8) followed by 18b, 19b, 25c-b, 7b all with a score 1.9 and categorized as resistant. The maximum score was recorded on line 28a (2.7) followed by 22c-b, 23a, 14c, 20c with a score of 2.5 and categorized as susceptible. Significant differences among the F4 progeny for all the three forms of blast disease were found, with the highest mean square of variance being for Neck blast, followed by head blast and least leaf blast. Two lines (25a and 25c-b) were resistant to all the three forms of blast disease, thirteen lines (8b, 6b, 8a, 24b, 22b, 22a, 21b, 20b, 19c, 19c-b, 17b, 13c-b, 13a) were resistant to neck blast and head blast and moderately resistant to leaf blast; six lines (14c, 20c, 22c-b, 23a, 28a, 5b) were resistant to neck and head blast but susceptible to leaf blast. The study also found that progeny deriving from the two different male wild parents remained distinct. Principle component analysis identified the key traits that could be used for selection i.e. the maturity traits such as days to 50% flowering and days to 50% maturity and phenological growth traits such as flag leaf length and plant height. Detailed results and discussions are presented in the thesis.