Genotypic variation in growth and physiological responses of common bean (Phaseolus vulgaris L.) seedlings to flooding
Tolerance to flooding stress in root regions of some common bean genotypes (Beyaz Fasulye, Boncuk Sırık, Kökez, Oturak and Sırık) was investigated in terms of morphological and physiological. Plants were grown in a plant growth chamber at 26/18°C (day/night) temperature with RH 70% and 450 m-2 s-1 light intensity. Seedlings were exposed to flooding stress for 3 days when the plants had developed 3 to 4 true leaves. The results obtained showed that root dry weight and leaf area were reduced significantly by flooding treatment. The changes in leaf area showed differences between genotypes. It was found that flooding treatment did not affect the leaf relative water content (RWC) value. Flooding treatment decreased total chlorophyll content significantly. It was observed that some increases and decreases in the total sugar and lipid peroxidation (MDA) contents in root and leaf parts depend on genotypes and treatment. Beside that cell membrane injury and influence of flooding for each genotype were determined measuring the electrical conductivity. It was determined that the tolerance to flooding of five evaluated common bean genotypes, were change depending on root and leaf part. The results also showed that different genotypes responded differently to excess water in the soil, which could be linked to variation in growth and physiological responses. According to the evaluation, these results possibly suggest that ‘Boncuk Sırık’ ‘was relatively tolerant genotype, whereas ‘Sırık’ and ‘Kökez’ were determined as more sensitive genotypes.
Key words: Phaseolus vulgaris L., common bean, excess water stress, flooding, lipid peroxidation, membrane injury, waterlogging.