Evaluation of finger millet genotypes for partial resistance to leaf blast caused by Pyricularia grisea

Abstract

Blast of finger millet (ragi) caused by Pyricularia grisea is disastrous disease to limit the potential yield levels in the farmers field. The pathogen affects the crop at all growth stages and the most susceptible stage for leaf blast is seedling stage. Use of resistant cultivars for minimizing losses due to leaf blast at early stage of crop growth is a viable and economical alternative. In the present study, partial resistance to leaf blast in fourteen genotypes of finger millet was assessed under field conditions. None of the genotypes were highly resistant to leaf blast. However, two genotypes namely PR 10-30 and VL 368 were shown resistance. Seven genotypes namely VR 988, VL 353, VL 348, TNAU 1214, GPU 45, VL 369, KOPM 942 were found moderately resistant, three namely PPR 2773, KRI 007-01, VR 708 were susceptible and two namely TNAU 1226 and REC 69 were highly susceptible. The correlation coefficients between leaf blast severities (LBS) with different components of partial resistance of slow blasting were significant. Low value of coefficient of infection (CI), apparent infection rate (r), area under disease progress curve (AUDPC), lesion number (LN), lesion area (LA), lesion circumference (LC) and high value of incubation period (IP) were recorded in resistant genotypes of finger millet, whereas, higher values of CI, r, AUDPC, LN, LA, LC and low values of IP were recorded in highly susceptible genotypes. A significant positive correlation was found in leaf blast severity with CI (r=0.948*), r (r=0.829*), AUDPC (r=0.998*), LN (r=0.967*), LA (r=0.957*), LC (r=0.976*) whereas IP (r=-0.825*) was negatively correlated with blast resistance. PR 10-30 and VL 368 showed higher degree of partial resistance or slow blasting resistance against P. grisea infection on finger millet.