The Effect Of Low Temperature Stress On Germination Of Watermelon Seeds

The watermelon large seed and small size seed were selected as experimental materials. During the process of seed germination, the different low temperature and duration were used to treat seeds, and discussed the effect of low temperature on seed germination or germ growth; Seeds were treated with different concentrations of PEG and GA3, and the same low temperature it is proceeds. Researched the influence of reagent treatment for the seeds germination, this paper introduces practical production discussed to improve techniques of emergence of seedling by the influence of low temperature. The results were as following:1. Between 0 ℃ and 20 ℃ range, it is relatively low temperature that has greater effects on germination of the watermelon seed and growth of bud, 5℃ had significant effects on germination indexes of seeds or bud after 12 h, 24 h accelerating germination, significantly reduce the seed germination potential, germination rate and germination index;10℃ also had significant influence for 24 h seed sprouting and bud; The influence of low temperature for watermelon big seeds was remarkable greater than small seeds, it was reflected on seed germination, status of bud growth and responses to low temperature of seed germination at various stages.2. After germination of 12-24 h(before and after germination), Low temperature treatment had remarkably effected on germination of the watermelon seed and growth of bud. And before the germination of influencing for germination index was more remarkable than after stirring. And when the bud of watermelon seed grew longer, the effect of low temperature gradually decreased; Low temperature significantly affected the seed germination index, even if the bud can continue growing, the germination and growth are also obviously affected. Mainly in axial root growth was strongly inhibited or even stopped, the number of lateral root and length was significantly reduced and shortened.3. The measurement results of low temperature test physiological indexes showed that the change regularity of content of Pro, soluble protein, soluble sugar and MDA between treatments was not significant, CAT, SOD and POD activity were decreased as the prolonger, in addition, the correlation of SOD and POD activity was stronger.4. PEG treatment have not effects on continuing growing to germination of low treatment of seeds or buds. But GA3 treatment had a promotion for germination and growth of low temperature treated seedlings(bud). Mainly showed that can improve the germination of seeds, time of duration of low temperature became shorter and seeds promoting effect was better, even make it can back to CK levels. However, low temperature treatment have a long time for watermelon seeds,the effect is poorer, and even have no effect. Meantime, the results of Physiological indexes demonstrated, in the low-temperature treatment combinations, soluble sugar was higher in shorter time than long time, the results showed that GA3 might promote the decomposition of nutrients on seeds.SOD and POD activity were reduced as the time prolonged. Therefore, GA3 treatment can produce good results in a relatively short treatment time.