Evaluation Of Resistance Level Among Different Wheat Varieties To Sitobion Miscanthi

The wheat aphid belongs to Hemiptera and is a worldwide wheat stinging pest.Hexi of Gansu region is drought-prone and little rain,and is the hardest hit area for Sitobion miscanthi and Schizaphis graminum,among which Sitobion miscanthi is the dominant population in Hexi of Gansu region.This experiment starts with the main defence mechanisms of wheat--nonpreference and antibiosis,we evaluated the resistance level among 13 wheat varieties commonly found in Gansu Province from four aspects:aphid quantity ratio,biological parameters of aphids,leaf surface morphology of wheat,and changes in secondary metabolites of wheat before and after feeding.The main results are as follows:1.Study of the comparison of biological parameters and their correlation with the level of Sitobion miscanthi resistance among 13 wheat varieties.The results showed that Yongliang15 had the longest developmental duration,and its weight gain,aphid ratio,intrinsic increasing capacity?r?,finite rate of increase???,mean relative growth rate?MRGR?were all the smallest,except Ganchun 29 and longchunza 2,which were high-sense varieties,and others were susceptible,however,the biological parameters and aphid ratios were still significantly different among different species;MRGR was significantly positively correlated with R₀?P<0.05?,extremely significantly positively correlated with r and??P<0.01?,and extremely significantly negatively correlated with Tb?P<0.01?,so MRGR can replace the time-specific life table to some extent;aphid ratios were significantly positively correlated with R₀,r and??P<0.05?,extremely significantly positively correlated with MRGR and weight gain?P<0.01?,and significantly negatively correlated with Tb?P<0.05?.2.Observation of leaf surface morphology leaf hairs of 13 wheat varieties by SEM showed that leaf surface leaf hair length and leaf hair density varied significantly among different wheat varieties;the leaf surface hairs length and density of wheat at the same resistance level were significantly different;the correlation between leaf surface hairs length and density and aphid resistance was not significant?P>0.05?.3.Analysis of the changes in the levels of secondary metabolites total phenols and flavonoids before and after the feeding of 13 wheat varieties to Sitobion miscanthi showed that total phenols and flavonoids were associated with wheat resistance and that the changes in total phenols and flavonoids before and after the feeding of wheat to the aphid were more significant among varieties;the highest levels of total phenols and flavonoids were found in Yongliang 15 before and after feeding;the mean content of total phenols after feeding was significantly positively correlated with population doubling time?Tb??P<0.05?,and the higher the content of total phenols in wheat after feeding,the longer Tb of Sitobion miscanthi;the average content of total phenols and flavonoids was extremely significantly negatively correlated with weight gain after feeding?P<0.01?,and the higher the content of total phenols and flavonoids after wheat feeding,the smaller weight gain of aphids and the poorer their adaptation to wheat.