Evaluation of Resistance Reaction of Maize Inbred Lines to Major Foliar Diseases in Ethiopia

Abstract

Maize (Zea mays L.) production in Ethiopia is constantly threatened by the potential outbreak of major foliar diseases such as Turcicum leaf blight (TLB), Gray leaf spot (GLS) and Common leaf rust (CLR). Improvement of host resistance to these diseases can provide an important component of integrated disease management, which is the most effective and practical method of managing maize diseases. This study was conducted to evaluate the reaction of maize inbred lines to TLB, GLS and CLR diseases in the rain seasons, during 2014 and 2015. The inbred lines were obtained from Bako National Maize Research Center, breeding program, and it was arranged using alpha-lattice design with two replications. The inbred lines were evaluated in TLB and GLS screening nurseries under artificial inoculation at Bako Agricultural Research Center, West Shewa, Ethiopia. For rust resistance, screening was done under natural infestation at Hawassa Maize Research sub- Center, Hawassa, Ethiopia. Disease severity (1-5 scale) was assessed at ten days interval from disease onset until the maize reached the dent stage. All the inbred lines showed symptoms of the three major diseases in both seasons, but the intensity of the diseases differed significantly (P<0.001) among the inbred lines. The interaction between genotype x year was observed non-significant for the observed foliar diseases, indicating that differences in each foliar diseases; TLB, GLS & CLR severity were mainly contributed by the genotypes. Meteorological data of both seasons/years showed almost similar rain fall & temperature values, which may explains the reasons behind this. Based on combined average severity, only six inbred lines; 30G 19F2-43-1-1-1-1-1-1, CML-197 x 142-1-e(F2) 60-1-1-2-1-1, CML383, (ZM-605-C2F2-428-3-B-B-B-B-B-B-B/F7215)-2-2-2-1-1, 30G 19F2-54-1-1-1and DE-38-Z-126-3-2-2-1-1, displayed a resistance reactions to all the three diseases evaluated when compared with the multiple-resistant check (142-1-e). About, 22 and 18 inbred lines were found resistant (score 1.0-2.0 on a 1-5 scale) to TLB and GLS under artificial epiphytotic conditions, respectively. Seventeen inbred lines exhibited resistance to CLR under natural infestation in the field condition. In the resistant inbred lines, a wide range of diversity was observed for agronomic traits such as plant height (cm), ear height (cm) Plant & ear aspect (1-5), and grain yield per hectare. The results from the present study reveal a shortage of lines with multiple-resistance to these diseases in the inbred lines currently used in mid-altitude maize hybrid production in Ethiopia. It is, therefore, indispensable to look for inbred lines that have resistance to multiple foliar diseases that could be used as source of resistance for conversion of the susceptible germplasm or for direct use as parents of commercial hybrids. Focus should also be given on pyramiding genes for resistance in the breeding programmes to develop varieties with multiple resistances to these major diseases in Ethiopia.

Keywords: Foliar diseases, Grain yield, Inoculation, Resistance, Zea mays