Research On The Effect Of Elevated CO₂ Concentration On Laodelphax Striatellus Fallen Acquiring Virus,Transmitting Virus And Carrying Virus

In recent years, the small brown planthopper (Laodelphax striatellus Fallen) not only transmits rice stripe virus (Rice Stripe Virus, RSV)causing stripe virus disease, which does a great damage in rice, but also because of its huge population that causing a direct impact on the growth of rice, such as blacken the rice panicle and grain which affecting grain quality. There are divergent views on the reason about the large outbreak of the small brown planthopper and stripe virus disease. With the economic development, the rise speed of greenhouse gases concentration mainly CO₂ increases significantly. This paper researched into the changes of atmospheric environment whether or not would have an effect on the small brown planthopper especially its ability of acquiring virus,transmitting virus and carrying virus, and on the extent of the impact. This paper also measured the activation of SOD,POD and the content of oxalic acid,SiO2 in rice plants under elevated atmospheric CO₂, based on this result we could research stripe virus disease trends, and this result provide a theoretical basis to control stripe virus disease.Through simulating CO₂ concentration by the way of gas cell, this paper researched into the ability of small brown planthopper to acquire virus under the condition of 370ppm,470ppm and 570ppm. The results showed that the number of virus small brown planthopper acquired was in proportion to the time fed. Virus acquired after fed 32h was clearly outnumbered that after fed 1h. Under different CO₂ concentrations, there was differences in the number of individuals carried virus in the same feeding time, but did not reach significant level. The study also found that the number of the small brown planthopper carried virus under 370ppm (CK) after feeding 1h, 2h, 4h, 32h respectively was 1.67, 2.00, 2.33, 4 out of 30 small brown planthopper, the number were all higher than that of 470ppm, 570ppm CO₂ in the same feeding time, but no significant difference. Through extracting RNA of rice leaves determinated whether small brown planthopper transmitted virus or not and how much they transmitted. The study showed that CO₂ concentration affected the ability to pass virus. The ability under 570ppm was weakest, so least virus in rice; while small brown planthopper transmitted most virus under 470ppm, the highest proportion of virus in rice. The study also showed there was all virus in rice after fed 1h by small brown planthopper, indicating the ability to transmit virus is very strong. Of course, how much virus transmitted was related to the time small brown planthopper fed, longer fed, the much virus rice acquired.This study measured the persistence of small brown planthopper carried virus under different CO₂ concentration. Either same CO₂ concentration but different feeding days or same feeding days but different CO₂ concentration, the number of viruliferous small brown planthopper was not significantly different. The results also showed that there was little change on small brown planthopper carrying virus at different feeding days under 470ppm CO₂ concentration, that showed 470ppm of CO₂ may be more suitable for small brown planthopper carrying virus.Elevated CO₂ concentration have an effect on the SOD activity of rice plants. The SOD activity under 370ppm (CK) CO₂ concentration was 397.96â–³OD/g that was maximum, The SOD activity under 470ppm concentration was 321.69â–³OD/g that was minimum, and there was a Significant difference compared to that of 370ppm (CK) and 570ppm. POD activity in rice plants was proportional to the concentration of CO₂, POD activity in rice plants increased with the going up of CO₂ concentration.The content of Oxalic acid and SiO2 in rice plants was positively correlated with CO₂ concentrations. The results indicated that there was a significant difference in the content of Oxalic acid and SiO2 under three different CO₂ concentration. The content of oxalic acid under 570ppm was 0.038mg/g that was 1.8 times that of 370ppm (CK) which was 0.021mg/g. Finally, the paper discussed the relationship between activity of enzymes, the content of oxalic acid,SiO2 and the resistance of rice.