The Potential Role of Cu²⁺ and Combined Action with IAA on Tolerance Strategy of Two Broad Bean Cultivars

Abstract

The present work was conducting to study the strategy response of two broad bean cultivars Assiut 84 and Assiut 125 to different Cu 2+ concentrations 100 ppm, 200 ppm, 300 ppm and 350 ppm in addition to control and interactions with IAA treatments. The dry matter exhibited the biphasic effect of Cu 2+ on the growth criteria of the two broad bean cultivars. While the lower and moderate doses of Cu 2+ (100 ppm and 200 ppm) stimulated the growth of the two cultivars, the higher dose s revealed the opposite event where the growth dropped in both cultivars. This effect was more pronounced in cv. Assiut 84 than in cv. Assiut 125 and also at the higher Cu 2+ concentration the growth dropped slightly in cv. Assiut 84 and highly significantly in cv. Assiut 125. The percent of increase in dry matter at 200 ppm in stem and leaf of cv. Assiut 84 was 120.45% and 155.31%, otherwise this percent of increase in these organs of cv. Assiut 125 was 114.29% and 131.41%. However the percent of reduction at 350 ppm Cu 2 + in root and stem of cv. Assiut 84 was 74.13%, 79.23% and in root, stem and leaf of cv. Assiut 125 was 59.27%, 70.91%, 70.76% compared with control plants. Soluble carbohydrate in cv. Assiut 84 and cv. Assiut 125 was markedly increased while soluble protein was decreased in root, stem and in leaves at lower Cu 2 + concentration. Also while Cu 2+ -stressed cv. Assiut 84 maintained potassium and magnesium levels around the control values and some promotion occurred especially in roots and stems, these cations dropped markedly in cv. Assiut 125 as a result of Cu 2+ treatments. While Cu 2+ had a marked stimulatory effect in the absorption and accumulation of calcium in the different organs of cv. Assiut 84, it, on the other hand, significantly inhibited the accumulation of this cation in the different organs of cv. Assiut 125. Treatments broad bean cultivars with Cu 2+ plus IAA induced an increase in growth parameters, soluble suga, soluble protein, K + , Ca ++ and Mg ++ in different parts of two tested cultivars. The uptake, translocation and distribution of mineral ions are affected by various growth regulators among others by IAA. This strategy might be important in heavy metals tolerance mechanisms of crop plants.