Research On Improving Rapeseed Stress Resistance By Seed Oil Extraction Technology

Rapeseed(Brassica napus L.)is an important oil crop in China and it has always been the main source of vegetable oil supply in our country.As the decrease of planting area and the increase of vegetable oil demand,and high oil content has become an important direction of rapeseed breeding.Although rapeseeds with high oil content can bring considerable economic benefits,it showed relatively lower resistance to waterlogging and had slower germination in some stress conditions.In this study,in order to improve the stress resistance of rapeseeds with high oil content,we used some physical and chemical methods to decrease the oil content without damaging seed structure and seed viability of rapeseeds.The main conclusions of this study are as follows:1.Among the organic solvent extraction methods,the oil extraction efficiency of nhexane,acetone,petroleum ether and chloroform were compared,and the oil extraction efficiency with n-hexane was the highest;the optimum extraction temperature was 30 ℃;the optimum extraction ratio was 25:1;the optimum extraction time was 24 h.The maximum relative oil extraction rate was 7.18% under the optimum extraction condition;the best carrier solution for ultrasonic-assisted extraction is n-hexane,the optimum treatment power is 100 W and the optimum treatment time is 60 min;the optimum treatment temperature is 30 ℃.The maximum relative oil extraction rate was 11.98% under the optimum extraction condition.2.The method with ultrasonic-assisted extraction or organic solvent extraction could significantly improve the waterlogging resistance of rapeseeds,and it had no significant effect on seed storability and drought tolerance.3.After organic solvent extraction and ultrasonic-assisted extraction,the waterlogging resistance of seeds had no significant correlation with the contents of antioxidant enzymes such as SOD,CAT and POD,but the MDA content of most seeds were increased,indicating that these two nondestructive oil extraction methods can change the content of IAA and ABA in seed.Under the two treatments,the increase of IAA content may be related to the improvement of seed waterlogging resistance.4.The results of scanning electron microscope showed that organic solvent extraction or ultrasonic-assisted extraction had no significant effect on the inner and outer surface and the thickness of the seed coat,but both of the two methods lead to the deepening of rapeseeds germination pores.Therefore,it is speculated that nondestructive oil extraction treatment can improve the waterlogging resistance by improving the permeability of rape seed germination pores;the observations by transmission electron microscope showed that organic solvent extraction and ultrasonic-assisted extraction could significantly increase the large and small oil body area,and ultrasonic treatment for 60 minutes could increase the large oil body area by more than 17 times.Therefore,it is speculated that the non-destructive oil extraction treatment may improve the waterlogging resistance by increasing the area of the oil body.