Yield Formation And Absorptions Of Nitrogen And Potassium In Trangenic Bt Rice Under Different Nitrogen And Potassium Fertilizer Applications

Pests cause huge yield reduction in rice in China, Which is estimated at 10% every year. The Bt toxin protein expressed by Bt rice can kill stemborers and leaffolders, and does not have much effects on environmental. At the same time, the cost of rice production is also decreased with Bt rice. So it is useful to develop transgenic insect-resistance rice to ensure our food safety. In this study, six transgenic Bt rice cultivars were used, they were MH63(cry1C*), MH63(cry2A*), MH63, SY63 and Bt-SY63(cry1C*),Bt-SY63(cry2A*).We used three different rates of nitrogen(0,15,195kg N/ha) in both 2009 and 2010, respectively. For potassium applications, three rates (O,45,135kg K2O/ha) in 2009 and four rates(0,45,90,135 kg K2O/ha)in 2010 were used, respectively.The study focused on (1) The effects of different nitrogen rates on agronomic traits, grain yield and nitrogen use efficiency of Bt rice. (2) The effects of different potassium rates on agronomic traits and grain yield, and potassium use efficiency of Bt rice. So outcomes of the studies would be used in commercial production of Bt rice. The results are as follows:1. Significant differences in grain yield were observed under different nitrogen rates. (1) Grain yield was significantly increased with nitrogen application in comparison with zero treatment. The highest gain yield was occurred at rate of 150 kg/ha nitrogen. Grain yield was not increased with more nitrogen than 150 kg/ha. (2) The application of nitrogen had a positive effect on panicles per m2, spikelets per panicle and biomass. N application also had a negative effect on grain filling percentage. (3) The nitrogen had significant effects on agronomic traits too, such as plant height, tiller number, leaf area index and dry matter accumulation and partitioning. (4) Nitrogen use efficiency decreased when nitrogen application increased.2. There were significant differences in grain yields among different Bt cultivars. (1) MH63(crylC*) had lower yield grain filling percentage, and harvest index in comparison with MH63(cry2A*) and MH63. (2) No significant differences were observed in plant height, tiller number and dry matter accumulation and partitioning among MH63(cry1C*), MH63(cry2A*) and MH63. (3) The hybrid SY63 and Bt-SY63(cry7C*), Bt-SY63(cry2A*) had no differences in yield and plant height, tiller number, dry matter accumulation and partitioning.3. Compared with no-transgenic cultivars, Bt cultivars had higher LAI 4. There were no significant differences in grain yield of Bt cultivars and no-transgenic control under different potassium rates. (1) The grain yields and its components of Bt cultivars and their no-transgenic control had no significant differences. (2) There were no significant differences in plant height, tiller number, dry matter accumulation and partitioning under differencet potassium rate. (3) Similiar results were observed in potassium accumulation and contents of grain and stem between different transgenic cultivars.