Effects Of Ultrasonic Treatment On Rice Seed Vigor And Cold Resistance Of Rice Seedlings

For improving the seeding performance of rice seeds,six rice varieties(early rice: ZZ39,LYZ17,medium rice: HHZ,WLY1133,late rice: XWX13 and JLY47)were used for the test.The seeds were treated with ultrasonic(20kHz-100kHz)at different times(1,2,3,4 and 5 min),the aim of the study was in order to determine the effect of ultrasound on rice seed vigor and screen best time of ultrasonic treatment;In additional,it was studied the effect of the cold resistance of rice seedlings with three leaves on the treatment of the seeds by the ultrasound.Rice varieties(ZZ39,HHZ,LYZ17,WLY1133)were used for the test.The condition of seedling treatment was low temperature(6?)for 3 days.The results were shown as follow:(1)Ultrasonic treatment could improve the rice seed vigor,the most economic and effective time was 2min.Compared with the CK,the germination energy,germination rate,and germination index of the seed standard germination test with ultrasonic treatment for 2min significantly increased.The germination rate was significantly increased under other germination test,including the low temperature germination test,the aging germination test,the flooding germination test,and the artificial germination test.(2)2min of the ultrasonic treatment increase the emergence rate of rice seeds in the paddy field.Compared with CK,the seedling emergence rate of ZZ39 and LYZ 17 increased 4.2% and 4.8%,that of HHZ and WLY1133 increase significantly 4.6% and 5.8%,and that of XWX13 and JLY 47 were significantly increased 6.1% and 5.4%,respectively.(3)The initial germination rate could affect the ultrasonic treatment.The germination rate of rice seeds by ultrasonic treatment increased by 11.8-18.0% with the initial germination rate of rice seeds was 61.5-73.7%.The germination rate of rice seeds by ultrasonic treatment was relatively small with the initial germination rate was above 85.7%.(4)It could improve the cold resistance of rice seedlings with the treatment of the seeds by 2min with the ultrasonic.Under the condition of the seedlings with three leaves at low temperature(6?)for 3 days.Root dry weight of the seedlings was significantly higher than that of CK,and dry weight of above-ground part,root number,root length,and seedling height were significantly increased.In additional,2min by ultrasonic treatment significantly increased proline content,and increase the activities of SOD,POD and CAT of the seedling leaves;In additional,ultrasonic treatment increased significantly the activities of SOD and POD in the roots of rice seedlings,increased proline content and soluble proteins,increased the relative electrical conductivity.Consequantly,the ultrasonic treatment could improve rice seed vigor,and was effective for different ecotypes of rice(early rice,middle rice,and late rice).The optimal ultrasonic treatment time was 2min,ultrasonic treatment was beneficial to improve the cold resistance of rice seedlings.