The Stability Analysis And Effects Of Environment Factors On Resistance Of Rice Verrieties To Brown Planthopper

In this dissertation, effects of environmental factors including light intensity, seedling stage, nitrogen fertilizer, temperature and sunshine times on resistance of rice varieties to different rice brown planthopper(BPH) biotypes (including biotype â…¡and biotype Bangladesh) were studied. After that, the methods proposed by Tai (1971) and AMMI model were applied as the methods to study the stability of rice varieties to different BPH biotypes. The main results were as follows:1) The influences of light intensity and nitrogen fertilizer on resistance of rice varieties to different BPH biotypes and the dead speed of rice seedlings damaged by different BPH biotypes were obvious. The resistance of rice varieties to different BPH biotypes was reduced with the decrease of light intensity and the increase of nitrogen fertilizer. But the expression of resistance and the dead speed of rice seedlings affected by light intensity and nitrogen fertilizer exhibited different levels in various varieties. The interactions between varieties and light intensity, varieties and nitrogen fertilizer, light intensity and nitrogen fertilizer, and among varieties, light intensity, nitrogen fertilizer were significant. 2) The influences of seedling stage and light intensity on resistance of rice varieties to different BPH biotypes and the dead speed of rice seedlings damaged by different BPH biotypes were obvious. But the expression of resistance and the dead speed of rice seedlings affected by seedling stage and light intensity exhibited different levels in various varieties. The interactions between varieties and seedling stage, varieties and light intensity, seedling stage and light intensity, and among varieties, seedling stage, light intensity were significant. 3) The influence of seedling stage and nitrogen fertilizer on resistance of rice varieties to different BPH biotypes was obvious. But the expression of resistance affected by seedling stageand nitrogen fertilizer exhibited different levels in various varieties. The interactions between varieties and seedling stage, varieties and nitrogen fertilizer, and among varieties, seedling stages, nitrogen fertilizer were significant. For BPH biotype Bangladesh, the interaction between seedling stage and nitrogen fertilizer was significant. For BPH biotype â…¡, the interaction between two factors was not significant. 4) The influence of seedling stage, light intensity and nitrogen fertilizer on resistance of rice varieties to different BPH biotypes was obvious. The resistance of rice varieties became strong with the growth of seedling. The resistance of rice varieties was reduced with the decrease of light intensity. The resistance of some rice varieties became strong or reduced with the increase of nitrogen fertilizer. But the expression of resistance of rice varieties to different BPH biotypes affected by seedling stage, light intensity and nitrogen fertilizer exhibited different levels in various varieties. There were significant or most significant interactions among some environmental factors. 5) Stability of resistance of rice varieties to different BPH biotypes was analysed by the method proposed by Tai. The results indicated that the influence of seedling stage, light intensity and nitrogen fertilizer on stability of rice varieties to different BPH biotypes was obvious. Among rice varieties resistant and susceptible to BPH biotype â…¡, the susceptibility of TN1 was very stable. The resistance of RHT, No. 50, Ptb33 were very stable. The susceptibility of Guihuazhan, Foshanyouzhan, IR26 were relatively unstable. The resistance of IR36, ASD7, IR56 and the moderate susceptibility of GuojingNo. 4, Mudgo were very unstable. Among rice varieties resistant and susceptible to BPH Bangladesh, the susceptibility of TN1, Guihuazhan, Foshanyouzhan, IR26 and IR36 were relatively stable. The resistance of No. 50, Ptb33 were unstable. The resistance of IR56, RHT and the susceptibility of guojingNo.4, Mudgo, ASD7 were very unstable. 6) AMMI model was used to evaluate the stability of 12 rice varieties r...