Components of resistance that reduce the rate of blast epidemic in GULU-E finger millet variety of northern Uganda

There is a large demand for finger millet in East Africa, which is produced in the lake region countries of Uganda, Kenya, Tanzania, and Rwanda among others. In Uganda, finger millet is second only to maize as a major cereal crop, and occupies more than 400,000 ha/a (500,000 t grain). The most affected part is classified as semi-arid hillside systems, including the Teso area. Northern region accounts for 40% of the national production, followed by the Eastern region with 21%. In Kenya, 65,000 ha/a are planted in the Western, Nyanza and Eastern provinces. Blast caused by Magnaporthe grisea (anamorph Pyricularia grisea) has been identified as the highest priority constraint to finger millet production in East Africa. As is the case for many pathogen and host plants, resistance of P. grisea cannot be considered durable without knowledge of the mechanism of resistance in the finger millet cultivars. There is limited information on components of resistance in Gulu-E, millet (Eleusine coracana) variety that has displayed stability and durability of resistance to highly virulent pathogen strains since 1960s up to date. This variety shows lower infection incidence and symptom severity in pathological studies involving race identification and virulence tests. The Knowledge of components of resistance is important in practical breeding for resistance, since it is possible to combine different mechanisms into one variety so as to achieve increased levels of stability of resistance to blast in new varieties developed from Uganda. This was determined from a combined trial of F2, F1 and backcrosses to Gulu-E. They were screened against NGR1, virulent pathogen isolate causing blast disease in finger millet identified from Ngora in eastern agro-ecology of Uganda. The experiment was laid in a randomised block design, with unequal number of replications during the first rains of 2013 (February - June season) at the Makerere University Agricultural Research Institute Kabanyolo. The data were collected from older plants in a glasshouse at heading time after inoculation at seedling stage, since at maturity stages a number of adaptive traits are expressed which correspond to field resistance. Latent period and infection of the flag leaf varied significantly (p < 0.001) and these components of resistance were found not to be statistically correlated. The expression of resistance in form of increased latent period, low frequency of successful infections in terms of number of lesions while allowing some sporulation meant evidence of both horizontal and vertical resistance. However, there is need to determine gene action and the heritability of such components of resistance in the host cultivar, so that such traits can be exploited in breeding for durable resistance in Uganda.