EVALUATION OF SALT TOLERANCE OF MUNGBEAN GENOTYPES AND ITS SALT TOLERANCE MECHANISMS

Abstract

Two experiments (germination and seedling growth test for experiment 1 and yield traits and yield in pots for experiment 2) were conducted at the laboratory and shading house, respectively, Department of Agronomy, Hajee Mohammad Danesh Science and Technology University (HSTU), Dinajpur during February to July 2016. For the first experiment, germination and seedling growth of 7 mungbean genotypes were tested in three salinity levels (0, 75 and 150 mM NaCl) for 10 days in sand cultured plastic pots with three replications. The germination percentage (GP) of all mungbean genotypes was significantly reduced by the salt stress at 150 mM NaCl as compared to the control. The GP was less affected in BARI Mung-8 but Binamoog-5 were highly affected due to salinity levels. The longest shoot and root length were recorded at BARI Mung-8 under saline conditions. The variety BARI Mung-8 showed the best performance in terms of root and shoot growth (fresh and dry weight) and proved to be a tolerant genotype to salinity and Binamoog-5 was affected seriously in terms of fresh and dry weights by saline environment. After screening from experiment one BARI Mung-8 appeared as the most salt tolerant and Binamoog-5 showed the most salt sensitive genotype. Experiment 2 was conducted using BARI Mung-8 and Binamoog-5 at 0, 40, 80 and 120 mM NaCl with four replications. Relative water content (RWC), water saturation deficit (WSD) and exudation rate were affected by salinity. The water relation in Binamoog-5 was affected more than that in BARI Mung-8. The degree of reduction of flowering time, pod formation time and time of maturity were higher in Binamoog-5 than BARI Mung-8 with the increment of salinity. Plant height, total dry matter plant-1, number of pods plant-1 , number of seeds plant-1, thousand grain weight and grain yield plant-1 were gradually decreased with increasing levels of salinity compared to control for both the genotypes. Salinity inhibited pod set more in Binamoog-5 than that in BARI Mung-8. Number of seeds pod-1 was higher in BARI Mung-8 than in Binamoog-5 at all salinity levels. Salinity also decreased 1000-grain weight more in Binamoog-5 than in BARI Mung-8 at all salinity levels. Seed yield plant-1 was higher in BARI Mung-8 than in Binamoog-5. Salt treated Binamoog-5 plants showed higher content of Na+ than salt treated BARI Mung-8. Salinity decreased the accumulation of K+ and Binamoog-5 showed larger reduction than BARI Mung-8. The amount of Mg2+ and Ca2+ in both the genotypes was gradually decreased with the increasing salinity though statistically insignificant. It can be concluded that BARI Mung-8 could be treated as the most salt tolerant and Binamoog-5 as the most salt sensitive genotype.