Effect Of An Improved Hydro-Priming Technique On Seed Germination Of Sesbania Sesban

Dormancy breaking techniques combined with hydro-priming pretreatment is rarely used to improve the seed germination and emergence. Present study developed an improved two-step priming technique which combined hot water (95℃) treating and control hydro-priming together to break Sesbania sesban seed dormancy and enhance its seed germination. The effect of two-step hydro-priming treatment on seed germinations for seed lots with different hardseededness levels and for seeds under different germinated conditions were also investigated. The results are summarized as follow:1. The results of germination experiments for 37 seed lots of 4 accessions which had been stored for 12-18 years in genebank showed that the mean germination percentage of all seed lots ranged from 26% to 84%, and mean percentages of hardseeds ranged from 10% to 70%. Significant differences fo reach of the above parameters existed among the seed lots of each accession but not between the accessions (p<0.05).2. Following a series of experiments which included to determine the optimal soaking time after boiled water adding to the seeds, the optimal temperature and time for priming, amount and times of water added during priming process. A two-step hydro-priming technique for Sesbania sesban seed was developed through which was: firstly pouring 95℃water over seeds (the weight proportion of water to seeds was 5:1), then leaving them to soak at the room temperature for 60min, secondly priming seeds under control water conditions at 15℃for 3 days. The water added to seeds were operated by adding water at Oh, 6h, 24h with 30%, 40% and 30% of total water (equals to the initial weight of seeds).3. The two-step hydro-priming technique significantly (P<0.05) enhanced germination percentage, germination rate and seedling growth. In compared to optimal germination condition, a better primed effect was observed under drought conditions. For instance, under drought germination condition, the primed seed improved germination percentage and reduced T₅₀ time by 41% and 3.7 days compared to control seed. But only by 34% and 2 days under optimal condition. The seedling shoot length increased by 79% under drought condition but only 54% under optimal condition.4. The two-step hydro-priming technique significantly (P<0.05) reduced hard seeds and enhanced germination and seedling growth in all seed lots with different initial hard seed levels. However, overall considering the tested parameters including hardseed, germiantion percentage, germination speed, T₅₀, and seedling length, indicated that the priming effective was greater for high level hardseed (66%) seed lots than those of low (12%) and medium (27%) hard seed level seed lots (p<0.05). For example, the average hardseed percentage was decreased by 64% after priming treatment for high hardseed level seed, but only decreased by 26% in medium and low hardseed level seed lots; consistent with that, the germination percentage was increased by 56.5% and T₅₀ was reduced by 4.5 days for high level hardseed seed lots but only 30% and 1.5- 4 days respectively in medium and low hardseed level seed lots.