Changes In Nitrate Reductase Activity Of Rice Cultivars With Different Released Years In Jilin Province

Since the1950s, with the genetic improvement of rice and the level raise of cultivation technology, the production of rice was sharply increased. But the researches about genetic improvement of rice are mostly around rice agronomic characters and yield components. And the changes of nitrate reductase activity (NRA) of rice varieties bred in different times at different growth stages are still not clear. In this study, the sample of33rice varieties bred of Jilin province from1958to2005were used to research the activity of nitrate reductase from booting stage. The changes of NRA of rice varieties bred in different times in genetic improvement progress and the relationship of NRA with net photosynthetic rate and yield were analyzed. Expect to provide certain theoretical basis of high-yielding rice breeding and cultivation of Jilin province.Research work was conducted in rice experiment field of Jilin Agricultural University in2010and2011. NRA, harvest index, net photosynthetic rat and the yield of different varieties rice were measured at booting, heading,10days after heading,20days after heading and30days after heading stages. The result as follows:1Changes of nitrate reductase activity of rice varieties bred in different times at different growth stagesThe changes of NRA of rice varieties bred in different times at different growth stages were have large differences. NRA of rice flag leaf at booting stage was low, at heading stage was highest, and continuously decreases after heading stage.2The relationship between leaf nitrate reductase activity of different rice varieties and breeding yearsLeaf NRA of rice varieties bred in different times at different growth stages were negatively correlated with breeding years, and was significantly negative correlation at booting and heading stages, at10days after heading and30days after heading stages were significant negative correlation. But at20days after heading stage it was not significant.3The relationship between leaf nitrate reductase activity of different rice varieties and yieldLeaf NRA of rice varieties bred in different times at different growth stages were significantly negative correlated with yield at booting and heading stages, and negatively correlated with yield at10days after heading,20days after heading and30days after heading stages. The sequence of relation degree at different growth stage as follows:heading> booting>30days after heading>10days after heading>20days after heading stages.4The relationship between leaf nitrate reductase activity of different rice varieties and net photosynthetic rateLeaf NRA of rice varieties bred in different times at different growth stages were negatively correlated with net photosynthetic rate, but only at booting and30days after heading stages were significantly negatively correlation, and not significant at heading,10days after heading and20days after heading stages. The results of this study showed that with the genetic improvement of rice varieties, leaf NRA were negatively correlated with breeding years and significantly negative correlated with yield at booting and heading stages. Net photosynthetic rate was significantly positive correlated with breeding yeas at heading stage. NRA were significantly negatively correlation at booting and30days after heading stages. Leaf NRA at booting and heading stages can as an index of breeding varieties of rice.Since always, breeding and cultivation workers of rice were mainly chose photosynthesis, biomass and the physiological indexes as high yielding varieties index. However, to date the research of NRA in the genetic improvement of rice has not reported. The flag leaf of rice has close relationship with yield, and has certain effect on production ability. So, NRA of rice flag leaf at heading stage as an index on high-yielding rice options is feasible.