Resistance to anthracnose leaf blight on tropical maize progenies

An increase in no-till areas without crop rotation has favored the incidence and severity of leaf anthracnose in most corn-growing areas in Brazil. The objectives of the current work were to characterize the resistance of the maize progenies to anthracnose leaf blight and estimate the genetic parameters associated with resistance. The inbred lines L04-2 (resistant) and L95-1 (susceptible) were crossed to generate the F2:3 progenies, which were evaluated in three trials conducted in a randomized block design with three replications. The treatments consisted of 121 progenies, parental inbred lines and F1 generation. Plants were inoculated twice at weekly intervals V6 and V7 stages. Three evaluations of the severity were performed at the VT, R2 and R3 stages through a note scale. The foliar inoculation confirmed a high pathogenicity of the Colletotrichum graminicola isolate, for it brought about a greater severity of the disease in the susceptible inbred line L95-1. The F1 generation showed intermediate position in severity between the parental inbred lines, regardless of the period and form of disease assessment. The frequency distribution showed a higher number of maize progenies in the most resistant classes of the three experiments. The high magnitudes of the genetic variance, heritability and quotient, confirm the genetic potential of L04-2 source to transmit the resistance genes to anthracnose leaf blight as well as the possibility of genetic gains with artificial selection in this pathosystem.