The Fungus causing Ascochyta blight is one of the most important biological factors limiting chickpea cultivation and production in most parts of the world, including Iran.

The present study was conducted to evaluating genetic sources of resistance of 20 chickpea genotypes in three seedling, Flowering, and podding stages in greenhouse conditions at University of Mohaghegh Ardabili. Disease damage was recorded using a 9-degree scale after observing complete death in the sensitive control genotype. Analysis of variance of the studied traits of chickpea genotypes was conducted via factorial experiment in a completely randomized design at two levels for factor A (disease-free and disease-contaminated conditions) and 18 levels (genotypes) for factor B (Given that the 13 and 15 genotypes were lost due to high susceptibility to disease in the first stage of growth, Samples were taken from 18 genotypes). Kolmogorov-Smirnov test used to evaluate the normality of data distribution.

The results showed that the resistant and susceptible genotypes were more accurately distinguished from each other in the podding stage. At this stage, 9 genotypes with a degree of damage 1, 2, and 3 (less than five) showed high resistance to the causative agent of Ascochyta blight. Physiological and biochemical traits involved in disease resistance were measured. The results showed that all traits except chlorophyll a, chlorophyll b and polyphenol oxidase had significant differences at 1% probability level in terms of disease stress. Chlorophyll a, chlorophyll b and polyphenol oxidase traits were significantly different at 5% probability level. Genotypes were significantly different in terms of chlorophyll a and total chlorophyll traits. In interaction of disease × genotype, only catalase was significantly different among all studied traits. The amounts of peroxidase and polyphenol oxidase have been affected by the disease and their rates increased. The highest coefficient of variation for Content soluble protein was 74.1 and the lowest for soluble sugar was 16.5. Significant interaction of genotype in stress showed that the trend of genotypes for traits under normal and stress conditions was not the same and superior genotypes under normal conditions were not necessarily recommended for disease stress conditions.

A positive relationship between polyphenol oxidase level and pathogen resistance was observed in the plants. The amount of damage that stress inflicts on crops leads to further efforts to understand the effects of disease on different plant mechanisms and requires understanding of appropriate adaptive responses to this environmental factor.