Direct Defense of Common Bean Accessions Against Two-Spotted Spider Mite (Tetranychus urticae Koch.) Attack - Abstract
In order to find direct defense of seedling resistance of common beans, ten cultivars (Naz, Dorsa, Akhtar, Pak, 65-062-107, 65-071-98, 65-071-306, 65-071-410, 65-071- 400, and 65-071-405) were evaluated by resistant mechanisms, morphological and physiological attributes against two-spotted spider mite in 2017 at Iran. Among four kinds of resistant mechanisms such as antixenosis, antibiosis, tolerant tests and PRI index, antibiosis mechanism determined to be the most accurate test in evaluating of common bean resistance against TSSM attack. Delaying germination, development and fast growth, early maturity, erected posture, small cotyledon area, the more leaf thickness along with the dark-colored demonstrated as escape mechanism of tolerant genotypes of common beans against TSSM attack. Some epidermal traits as the first defense barrier on common bean like hook-shaped and high density of trichome especially on adaxial epidermis by having trapping behavior showed high relationship with tolerant genotypes. In fact, in tolerant beans, related-traits to trichome on leaves entrapped the body parts of TSSM such as leg tarsi, mouthpart and ovipositor and prevented to move, feed and reproduction of mites and therefore, these features decreased damage leaf area of Phaseolus vulgaris as well. The lines of 65-071-98 and 65-062-107 and NAZ, were certainly categorized as the most tolerant cultivars while, Akhtar and 65-071-400 were introduced as the most susceptible accessions numbers of common beans, respectively.