EVALUATION OF SLOW RUSTING COMPONENTS IN PEA

Abstract

Information about slow rusting resistance to pea rust (Uromyces fabae) is limited. Five slow rusting components, i.e. area under disease progress curve (AUDPC), latent period (LP), number of pustules per leaf (NPL), pustule size (PS), number of aecial cups (NAC) and sensitivity of leaf to rust (SLR), were evaluated in 38 pea genotypes under field conditions. Estimates of correlation coefficients indicated a high negative association of LP with AUDPC (r = -0.751; P ≤ 0.001), NLP (r = -0.808; P ≤ 0.001), PS (r = -0.458; P ≤ 0.001) and NAC (r = -0.476; P ≤ 0.001). However, significant positive association was found between AUDPC and NPL (r = 0.78; P ≤ 0.001), PS and NAC (r = 0.545; P ≤ 0.001). Factor analysis showed that, three of the slow rusting components, i.e. AUDPC, LP and NPL accounted for 49.77 % of the total variance as the first main factor, while the other three traits distributed within the next two factors determined 26.34% and 10.46% of the total variance, respectively. A multiple regression analysis showed that the variation in AUDPC was significantly explained by number of pustules followed by latent period. Selection for slow rusting could be based on one component since they are interdependent but, for accumulating more partial resistance in a line, selection should be based on more than one component studied.