| To selcet the varietiey with rich-absorption in selenium, as well as endurance to selenium, 63 hybrid rice late varieties in Hainan were conducted in field experiements and germinatial experiments. Based on the reseach work referred above, pot experiments was carried out to study the physiological mechanism of different genetypic varieties in selenium-absorption, which was hoped to offer some scientifical basises for the futher study and further on rice varieities rich in selenium.The result of this research were summarized as followed:1,There are significant discrepencies in the 63 rice varietes with different genetypes. And under the stress of high concentraion (12mg/kg) of selenium, Jie Fengyou 629 was superior to other varieties in this study with 92.50% in germination 96.67% in potentiality of seed,2.04 centimeters in maximum seeld length,0.16 centimeters maximum root length and 0.10 grams seeld weigth.2,Under high concentration selenium stress, all varities tested was classed into three types: endurance type,midle type and sensitive type in terms of the five germination characteristics stress indexes. And during the three varieties of endurance type, Jie Fengyou 629 was founded to be the candidate, which was with the best endurance to selenium on germination characteristics.3,Wide variations (several to more than 10-fold) was proved to exist in different genetypic rice varieities, which also meant the ability of uptake in selenium differed significantly with different rice varieties.4,all the hybrid rice in this research could be also clustered into three types:rich-absorption,middle -absorption and low-absorption in selenium,3 species was included in rich-absorption type, and 49 in low absorption. Among rich-absorption type varieties, Jie Fengyou 629 was carried out to be the strongest in uptakeing selenium with the highest concentraion of selenium brown rice(0.25 mg/kg) and polished rice(0.15 mg/kg). BoⅡYou 15 ,whose concentraion of selenium in brown rice was 0.07 mg/kg, and polished rice 0.05 mg/kg, showed the least absorption- ability in selenium among the 49 low-absorption type5,Selenium contents in plants was significantly correlated with the concentration of soil in which rices planted. Compared to poor-absorption variety BoⅡYou 15, Jie Fengyou 629 was much stronger in selenium accumulation. In the soil with high concentration of selenium, accumulation of selenium in Jie Fengyou 629 reached 159.76 ug, while Bo II You 15 with selenium accumulation of only 44.69 ug.6,In the soil with high concentraion selenium, the two varieties with different absorption-ability in selenium, were studyed to be differentiatial in selenium distribution in differ plant organs. Selenium distribution in Jie Fengyou 629 presented in the way of root>grains>stem>leaf; while Bo II You 15 described as root>stem>leaf>grain.7,The selenium distribution in grains of Jie Fengyou 629 was:brown rice>chaff; polished rice>embryo. And accumulations of selenium in brown rice,polished rice were positively correlated with the e contens of selenium in soil. BoⅡYou 15 selenium atrribution in grains were presented in the the way of:chaff>brown rice,polished rice>embryo, and the accumulation of selenium in chaff,embryo increased with the increasing of selenium concentraion in soil.8,In the soil with high concentraion of Se, subcellar distribution of selenium varied largely in the two rice cultivars with genetypic difference was showed that:1,the sequence of Jie Fengyou 629 was in a order that: cell wall>chloroplast>mitochondrion>nucleous; 2,BoⅡYou 15 was confirmed to be chloroplas,mitochondrion,nucleous>cell wall and soluble cytoplasmic9,On the level of plant oragns, mechnism on endurance to selenium in rich-absorption varieties Jie Fengyou 629 was be more superior to BoⅡYou 15. As the content of selenium in soil where Jie Fengyou 629 was planted increasd grandually, the reserves of root,which was proved to be the most endurable in the plant organs increased accordingly, while the content of selenium in stem,leaf and grains reduced deservely. While BoⅡYou 15 was carried out to be in the oppsited as the selenium content in soil increased, which meant selenium absorped by whole plant was be more inclined to be transffered to nutritional organs—stem,leaf, however, the quantity of selenium transfferd to endurable organ -root and edible organ-grain decreased.10,On the level of subcellar, rich-absorption variety Jie Fengyou 629 was confirmed to have more advantages in torelance to high concentraion of selenium than BoⅡYou 15. As the contents of selenium in the soil increased, the content of Se in cell wall transffered from Jie Fengyou 629 rice plant was improved gradually, while the accumulation of selenium in organlles of BoⅡYou 15 increased with the rasie of selenium contents in soil. In the soil with high selenium concentraion, compared to BoⅡYou 15,whose organlles was promoted to accumulate most of the selenium uptaked from soil, cell wall of Jie Fengyou 629 became the most important place where selenium reserved.11,The enzyme (SOD,POD and CAT) activities was proved to be more active in rich-absorption variety Jie Fengyou 629 than BoⅡYou 15. and as the content of selenium in soil increased, SOD,POD and CAT activity of Jie Fengyou 629 were promoted to some degree, but MDA content declined gradually; however, as the selenium concentraion in soil reducted, the changes of enzyme activity and MDA content were on the oppsite of Jie Fengyou 629.
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