ENHANCEMENT OF DROUGHT TOLERANCE IN MUNGBEAN THROUGH OSMO AND HYDRO PRIMING

Abstract

In order to evaluate the effect of pre-sowing seed treatment with mannitol on germination behavior of mungbean (Vigna radiata L.) (BARI Mung 3 and BARI Mung 6) in relation to drought tolerance and to optimize the priming time of the best priming solution concentration on germination behavior of mungbean an experiment was conducted under the laboratory conditions of the Department of Agronomy, Sher-e-Bangla Agricultural University, Dhaka from 13 May, 2014 to 15 July, 2014. The whole experiment was divided into three experiments. In first experiment, BARI Mung 3 and BARI Mung 6 were primed in 3, 6, 9, 12, 15, and 18 hours under 2%, 4%, 6%, and 8% mannitol solution and distilled water, respectively. After priming the electrical conductivity (EC) of seed, leachates from 3, 6, 9, 12, 15, 18 hours primed seeds, hydro primed seeds and non primed seeds were measured after 24 hours of soaking in distill water. 9 hours priming time showed the best result for its lowest EC value. In second experiment, two mungbean varieties were surface sterilized with 75% alcohol solution, soaked in water and mannitol (2%, 4%, 6%, and 8%) for 9 hours and dry seed used as control. The highest total germination percentage (98.38%), germination index (87.78), vigor index (186.9), relative water content (65.64%), water retention capacity (21.22) and lowest water saturation deficit (34.36%) were obtained from seeds primed in 2% mannitol for BARI Mung 3 compare to total germination percentage (93.09%), germination index (85.41), energy of emergence (97.31%), vigor index (136.5), relative water content (77.22%), water retention capacity (15.94) and lowest water saturation deficit (22.78%) were obtained from seeds primed in 6% mannitol for BARI Mung 6. In the final experiment, seeds were primed with distilled water and 2% mannitol for BARI Mung 3 and 6% mannitol for BARI Mung 6 by 9 hours; dry seed used as control and were exposed to 0%, 5%, 10%, 15%, and 20% Polyethylene Glycol (PEG) induced drought stress conditions in Petri dishes. Priming with mannitol followed by water were more effective than the control seed in inducing drought tolerance of mungbean cultivars owing to enhanced germination and growth parameters under drought stress condition. From the results of the study, it was observed that seeds primed with 2% mannitol for BARI Mung 3 and 6% mannitol for BARI Mung 6 by 9 hours showed the best result in comparison to water primed seed and dry seed.