Studies On Priming Technology, Its Mechanism Of F₁ Seed And Genetic Analysis On Anti-Aging In Rice (Oryza Sativa L.)

Hybrid rice seed is one of the most important production materials in agriculture.The sales volume of hybrid rice fluctuanted periodly owing to the influence of weather and market changes.When demands surpass supply,the price will be up,area for hybrid rice seed production will be enlarged next year.When bumper harvests occurs for years running and F₁ seed supplies surpass demands,the seeds have to be stored for two or more years. Dispite the seeds are stored in low temperature storeroom,they will be gradually aging naturally and germination percentage down below 80 percent and become unqualified seeds because of long term storage.The cost for hybrid seed production is very high and thus the price is also very high,so the lose will be heavy once hybrid seed is sold as foodstuff.Seed priming is a technique which can increase germination percentage of aging seeds by controlling their water absorption.Therefore,it has great value to study priming technology and its biochemical mechanism in making full use of the aged seeds.In this study,several chemicals including PEG,PVA,KNO₃ were used to treat the aged hybrid rice seeds,to study their priming effects on seed germination in order to screen the best treating method.We studied the changes of biochemical characters of seeds by artificial aging method.We also studied the seedling estabalishment rate in field using the primed seeds and the mechanism of priming though the changes of of biochemical traits.In order to solve the aging question of rice seed,we also studied genetic basis of aging in rice seed.The main results we got are as the follows.1.In indica hybrid rice,the best priming effect was obtained after 1 day treating with 0.5%PVA+1.0%KNO₃ for Shan you 63 seed aged naturally.For Shan you 63 and Te you 559 seeds aged artifially,the best priming effect was got after 1 day treating with 1.0%PVA+1.0%KNO₃.For normal Shan you 63 and Te you 559 seeds,the best priming effect was observed after 1 day treating with 1.5%PVA and 2.0%PVA respectively. Compared with controls,germination percentage,vigor index of seeds primed increased significantly;germination rate,seedling weight and seedling height of seeds primed increased in different excent.2.After artificial aging,seed vigor,SOD,POD,CAT and dehydrogenase activity, soluble protein content decreased steadily with seed aging.However,electrical conductivity and soluble sugar in seed leakage and MDA contents increased steadily.Activities of SOD, POD,CAT and dehydrogenase,and soluble protein content positively correlated with seed vigor atα=0.01;while electrical conductivity,soluble sugar and MDA contents negatively correlated with seed vigor atα=0.01.3.Compared with controls,Shan you 63 and Te you 559 aged seeds after priming, SOD,POD,CAT and dehydrogenase activity,and soluble protein content increased significantly.However,soluble sugar in the leakage and MDA contents decreased significantly.Activities of SOD,POD,CAT and dehydrogenase,and soluble protein content positively correlated with seed vigor atα=0.05,while soluble sugar and MDA contents negatively correlated with seed vigor atα=0.05.4.Compared with controls,normal Shan you 63 and Te you 559 seeds after priming, dehydrogenase activity and soluble protein content increased significantly,while soluble sugar in the leakage decreased significantly.Activities of SOD,POD and CAT increased unmarkedly,MDA content decreased unmarkedly.Dehydrogenase activity and soluble protein content positively correlated with seed vigor atα=0.05,while soluble sugar content negatively correlated with seed vigor atα=0.05.SOD,POD and CAT activity and MDA content were not related to seed vigor.5.Compared with controls,both in year 2006 and 2007,seedling estabalishment rate in field of normal seeds and aged seeds increased significantly,while seedling height, seedling weight increased and mean time of seedling estabalishment decreased in different combinations.There was no significant correlation between priming and none priming in field.6.Relative germination percentage,relative germination rate,and relative germination index were studied using P₁,P₂,and 350 lines of a RIL population from the japonica rice (Oryza sativa L.japonica) cross of Bing 8979/C Bao.By means of mixed major gene plus polygene inheritance models,genetic analysis showed that relative germination percentage, relative germination rate,and relative germination index were controlled by two major genes plus polygenes.Both major genes and polygenes showed additive-epistatic effects. The additive effects were larger than epistatic effects in the two major genes.The heritability of major genes was larger than that of polygenes in all the three traits,indicating that the 3 traits investigated in the present study were mainly governed by major genes.