Effects And Merchanisms Of Enviromental Factors On Rice Varieties Resistant To Brown Planthopper(BPH)

Brown Planthopper (BPH), Nilaparvata lugens(Stal), is one of important pest on rice in China. This pest breaks quickly and cause rice fail to harvest on a suitable environmental conditions. To know clearly the effects and mechanisms of environment factors on rice varieties to BPH, the influence of light intensity, seedling stage, nitrogen fertilizer level and flooding stress on rice varieties resistant to different BPH biotypes and content of jasmonic acid (JA) and secondary metabolites of rice will be study in this paper. The main results were summarized as follows:1. Light intensity, seedling stage and nitrogen fertilizer level reveal influence on rice variety resistant to BPH. TN1 remains susceptibility to BPH, the resistance of IR56, B.W, RHT to BPH were decreased or vanished. Under the treatment of 13-day of seedling stage,4 layer that irising the light intensity and zero-nitrogen,Ptb33 shows resistant to BPH while vanish on the other treatments. RP1976-18-6-4-2 express resistant to BPH on 8-day of seedling stage,zero layer that irising the light intensity and 15kg nitrogen and 13-day of seedling stage,zero layer that irising the light intensity and 30kg nitrogen, but the resistance disappears on the other treatments in our experiment. The resistance of 570011 to BPH only decreases on 8-day of seedling stage,2 layer that irising the light intensity and 30kg nitrogen, 18-day of seedling stage,4 layer that irising the light intensity and 15kg nitrogen treatments.2. The research on light intensity, seedling stage and nitrogen fertilizer level to JA content of rice leaf were studied in this paper, and the results indicated that the influence of single factor of light intensity, seedling stage and nitrogen fertilizer level to JA content of TNI, IR56 and 570011 was not obvious, While light intensity, nitrogen fertilizer level was significantly influenced the JA content of RHT.3.Drowning stress on rice varieties to BPH biotype II and Bangladesh have different effects. The feeding amount of BPH biotype II on B.W, RP1976-18-6-4-2 and 570011 are biggest influenced after flooding. The feeding amount of BPH biotype II on TN1 and RHT increases and then decreases after flooded, while it decreases in the early and later days, and increases in the middle of flooding time after flooded on IR56 and Ptb33. The feeding amount of BPH biotype Bangladesh on B.W, RHT, Ptb33 and RP1976-18-6-4-2 are biggest influenced after flooded, while it decreases on B.W and increases on RHT, Ptb33 and RP 1976-18-6-4-2. The feeding amount of BPH biotype Bangladesh on TN1, IR56 and 570011 decreases in the early days and increases in the late days after flooded.4. Different flooding treatments make difference effects on JA of rice leaf. The JA content of TN1,IR56 firstly increased then decreases later after flooding. The JA content of B.W, RHT, Ptb33 and RP 1976-18-6-4-2 undulate relatively great. The JA content of 570011 increases after flooded. The JA content of different rice varieties change different on the same flooding treatment. Under un-flooded (CK) and 7-day flooded treatments, the JA content of TN1 was significantly higher than others. The JA content of TN1 was significantly lower than Ptb33, and not significantly with the remains on 1-day flooded treatments. Under 3-day flooded treatment, the JA content of TN1 was significantly higher than B.W, Ptb33 and 570011, while not significantly with the rest. Under 5-day flooded treatment, the JA content of TN1 was significantly higher than IR56, B.W, and RP 1976-18-6-4-2 while not significantly with the rest.5. The results indicated that the influence of flooding stress on secondary metabolites of resistant variety was obviously, but it’s different in different varieties. The content of oxalic acid in Ptb33 and 570011, content of total phenols in TN1, IR56, B.W and RP 1976-18-6-4-2, and the content of tannin in RHT were increased and higher than control after flooded. On the contrary, the content of tannin in TN1 and content of total phenols in Ptb33 were decreased and lower than control. While the content of oxalic acid in RP1976-18-6-4-2, content of total phenols in RHT and 570011, content of tannin in B.W, Ptb33 and 570011 has fluctuated greatly after drowned with water.The regression analysis results indicated that the feeding amount of BPH biotype II on 570011 was significantly negative correlation with the content of oxalic acid and total phenols, while Bangladesh on RHT was significantly positive correlation with the content of total phenols.