Wilt/Root-Rots Screening: for Resistance and Effect of Temperature on Growth of the Causal Fungi

Abstract

Studies were conducted to evaluate the resistance of chickpea genotypes to wilt/root-rots, identify the causal organisms associated with these diseases and determine the optimum temperature for the growth of the causal organisms. Out of the forty chickpea genotypes screened for resistance to wilt/root-rots diseases in the sick-plot at Shambat Research Station Farm in season 2007/08, thirty five were resistant, while the other five genotypes were moderately susceptible. The incidence of wilt/root- rots diseases in the different rows that were sown with the chickpea cv. Shendi as a repeated susceptible check after every two test entries ranged between 5% and 93%, indicating the non-uniformity of the disease in the sick-plot. Due to the non-uniformity of the disease in the sick –plot, the resistance of the thirty five chickpea genotypes needs to be verified in a uniformly infested sick-plot or in artificially inoculated pots. The fungal pathogens, Fusarium oxysporum f. sp. ciceris and Rhizoctonia bataticola, the casual agents of Fusarium wilt and dry root-rot of chickpea, respectively were consistently isolated from wilt/root-rots affected plants. The results of the effects of the tested temperature treatments (20, 25, 30, 35, 40˚C) on the growth of the identified wilt/root-rots fungi showed that F. oxysporum f. sp. ciceris was unable to grow at 35˚C and 40˚C, while R. bataticola was able to grow at all tested temperatures. The highest growth of F. oxysporum f. sp. ciceris and R. bataticola was observed at 25˚C and 30˚C, respectively.