Correlation Analysis On Physical Characters And Sitobion Avenae Resistance Of Wheat With Scanning Electron-microscope

Triticum aestivum (Linnaeus) is one of the most important crops in our country.However, aphids’ damage could result in the loss of10%to30%total yields of wheat everyyear. This has threatened national food supply, economy and social development.There hasbeen much clear in terms of physiological and biochemical mechanisms for Sitobion avenae（Fabricius）interaction with wheat.But mechanisms such as physical aphid resistance ofwheat remain unclear? In order to investigate the relationships between wheat leaf’s physicalfeatures(such as leaf hair density and length, stoma) and wheat aphid resistance, thedevelopmental time(DT),the weight gain between1stinstar lavae and adult (WG), meanrelative growth rate (MRGR) and nymph mortality (NM)of S. avenae which contacted11varieties of wheat materials, were recorded indoors. Scanning electron microscope was usedto observe the ultra-structures of leaf hairs and stomas. The results showed the developmenttime of S. avenae is different for different varieties of wheat materials. In particular, thedevelopment duration of S. avenae in L87and98-10-35is the equally longest and in O31isthe second. Significant differences of the duration can be seen among these varietiesexcept for A253, O63and Amigo. The shortest development time is for H19and the followedone is for L71or1376which are almost equal. These three time lengths largely differ withones for other wheat varieties except for H23and A33.The aphid weight gains also see difference in different wheat varieties of materials. Theaphid weight gain on98-10-35is the smallest, while the one is the biggest on H19. Thisindicates that H19is more suitable for aphid to live on than98-10-35.The MRGR as a integrated index can reflect the level that aphids adapt to the host plants.The bigger the MRGR is, the better adaptability aphids have for the host plants. The MRGRfor98-10-35is the smallest and the one for O31is the secondly smallest. The biggest MRGRbelongs to aphids on H19and the second is for1376and L71which are almost equal. Thedifferences among MRGR values for these varieties are significant while for other6varietiesare not. This implies that98-10-35and O31are resistant wheat varieties and H19,1376andL71are susceptible for aphid aggression. Statistical analysis suggested that nymph mortality of aphids take place randomly andirregularly on varied varieties of wheat materials. This may show stronger aphid resistance insome kinds of wheat does not mean directly killing more aphids, but inhibiting other types ofactivities to resist their attack..Overall, aphid resistance to11wheat varieties could be categorized as4levels: theparents98-10-35and their hybrid, O31shows good resistance to S. avenae with nosignificant difference; Amigo、L87、O63、A33、A253and H23stand at the moderate levelwhile L71and1376belong to bad level H19exhibits extremely bad resistance to S. avenae.Leaf hairs of11varieties of wheat were observed by Scanning Electron Microscope(SEM) and the results showed that densities and lengths of leaf hairs of different varietywheat had consistent differences with the corresponding MRGR. There was positivecorrelation between the parameters of back side and right side leaf hairs and thedevelopmental time(the correlation coefficients were0.903**、0.896**、0.910**、0.893**.).There was negative correlation between the parameters of back side and right side leaf hairsand the mean relative growth rate (the correlation coefficients were-0.986**、-0.980**、-0.983**、-0.977**). Stepwise regression equation is established based on the relationshipbetween mean density and length of leaf hairs and biological parameters. The results showedthat there was positive correlation just between the length of leaf hairs and developmentaltime(Stepwise regression equation is: Y1=6.489+0.01X2). There was negative correlation justbetween the density of leaf hairs and mean relative growth rate (Stepwise regression equationis: Y3=0.398-0.01X1). These results implyed the physical characters of wheat could besignificant part of wheat which were capable to resistant aphids.The result of the correlation analysis of stoma parameters and biological parametersshowed that there were no obvious relativity between stoma density and area and biologicalparameters of aphid.By analyzing the t-test results of hair density in right and back sides of leaves from11wheat varieties, respectively, it can be seen that the leaf hairs had a higher density on rightside than on back side except H19. And the leaf hairs had a longer length on right side thanon back side except H19and1376. It indicates that there are difference between right leafhairs and back leaf hairs.