| Brassica napus is the main oil crop in China and plays an important role in the national economy.The Yangtze River Basin is the main planting area of rape in winter,but the planting area of rape has been reduced in recent years,which is mainly caused by the contradiction between the transfer of labor force to the city in rural areas and the use of more workers in the traditional way of rapeseed seedling transplanting.With the emergence of problems,researchers have developed and established direct rape cultivation methods suitable for mechanized planting.However,in order to improve the quality of many japonica rice,the harvest period was delayed to the middle and late October,which led to the production of live rape suitable sowing period from mid-October to late October or even early November.If the sowing time of rape is delayed,if the germination period encounters low temperature,it will lead to the decrease of seed germination rate,the delay of germination time,and the disadvantage of seedling weakness.Previous studies have found that H2O2 seed soaking can promote the low temperature germination of rape,but it is not explained whether the seed soaking temperature can affect the H2O2 seed soaking effect.Therefore,the effect of seed soaking at room temperature(25℃)and low temperature(8℃)on H2O2 germination,antioxidant properties during germination and early seedling growth was studied.The mechanism of different temperature on seed soaking was expounded,which provided a strong basis for improving H2O2 seed germination technology.The results show that:1.H2O2 seed soaking at room temperature significantly reduced the content of MDA and H2O2 during seed germination at low temperature.Compared with low temperature seed soaking,the H2O2 content decreased earlier,effectively reduced the accumulation of MDA and H2O2,and reduced the oxidative damage during seed germination at low temperature.2.H2O2 seed soaking at room temperature significantly improved the antioxidant performance in low temperature germination compared with low temperature seed soaking.At room temperature,H2O2 immersion activated the A-G circulatory syste at the early stage of germination(before 48h),and alleviated the damage of reactive oxygen species to seeds by relying on the high initial contents of GSH,MDHAR,DHAR and APX enzymes and increasing AsA.After 48h,with the decrease of A-G circulation-related substances and enzyme activity,SOD,POD and CAT enzyme activity gradually took the dominant role in scavenging reactive oxygen species.Indicating that the normal temperature condition is more favorable for the activation of H2O2 seed soaking anti-oxidation system.3.H2O2 seed soaking at room temperature significantly promoted the improvement of amylase activity,the decomposition and utilization of starch(the content of 0 h was significantly lowest),significantly increase glucose content and promote sucrose metabolism and the consumption of soluble sugar(the decrease was large after 24 h);accelerated the decrease of soluble protein content(0h and 24 h),significantly increased the content of free amino acids(after 24h)and proline(48 h),and promoted the decomposition of storage substances in seeds,while improving the osmotic regulation ability of seed germination at low temperature.At low temperature there was no significant difference between H2O2 soaking and flooding.4.H2O2 seed soaking at room temperature can significantly promote the low temperature germination of rapeseed,increase the germination rate,germination potential,germination index and vigor index of seeds,and significantly shorten the average germination time of seeds.H2O2 soaking seeds at room temperature significantly promoted seedling growth,and the root length,stem length,fresh and dry weight of roots,aboveground parts,and root-crown ratio(dry weight)were significantly increased.At low temperature H2O2 soaking seeds to promote seed germination,but significantly promoted the growth of root length,not significant effect on other indicators.indicating that H2O2 seed soaking was carried out at room temperature was more favorable for seed germination and seedling growth at low temperature. |
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