Abscisic acid (ABA) and Stomatal Resistance Changes in Leaf tissues of Drought Resistant and Susceptible Chickpea (Cicer arietinum L.) Genotypes

Abscisic acid (ABA) is a stress hormone that plays multifunctional roles in adaptation of plants to stressful environments. An optimal increase of internal ABA concentration of leaves causes water saving through stomatal closure. In order to explore the effect of drought stress on leaf tissue ABA concentration and stomatal resistance of chickpea, a greenhouse experiment was conducted using five genotypes (Three tolerant genotypes including: ICCV93040, MCC13, MCC10 and two sensitive genotypes consisting of: MCC120 and MCC180) and two levels of water availability, growing at field capacity and at 25% of field capacity. Seeds were sown in 50 × 12 cm ‍ plastic tubes which were filled by washed sands. Nutrient elements were prepared using Hoagland nutrient solution. Leaf ABA concentration, determind using High Pressure Liquid Chromatography (HPLC). Results showed that drought stress imposed an increase in leaf ABA content up to flowering, but after this stage, leaf scenesence caused a reduction in leaf ABA. Genotypes showed different ABA concentrations and stomatal resistances in the presence of drought stress. The highest and lowest amount of ABA were observed in MCC13 (drought tolerant) and MCC120 (drought sensitive) respectively. ABA concentration of MCC13 and MCC120 were 29 and 3ngg-1 (fw) which is a 10 fold difference between them. Stomatal resistance of tolerant genotypes were more than sensitive ones, in sress and non-stress conditions. A significant positive correlation between leaf stomatal resistance and ABA concentration were observed (r = 0.87), but in non-strss conditions this relationship was not significant (r = 0.21).