Srudies On Resistance Of Different Cassava Varieties(Strain) To Teranychus Cinnabarinus

Eight cassava varieties(XX048,NZ199,SC205,SC8,GR4,1742,D346 and F50)were used as the materials.The damage degrees of different cassava varieties at the first Tetranychus cinnabarinus hazard peak were investigated and their mite resistances were also detected.Nutrient substance and secondary substance in leaves of different cassava varieties and their leaf morphological and structural characters were determinate,and the relations between each index and mite damage degree were analyzed to investigate resistance mechanism of cassava to T.cinnabarinus.During the harvest stage,yields and related traits of six cassava varieties to select the ones with fine comprehensive traits,high yield and strong mite resistance.The results are as follows:1.The study has identified eight cassava varieties resistance to T.cinnabarinus and its mite resistance index was:GR4>1742>SC205>SC8>NZ199>F50>D346>XX048.And XX048,D346 and F50 were moderate resistant varieties,SC205 and GR4v were susceptible varieties.2.Mite damage indexes had not significant positive correlation with wax content,thickness of leaf and upper epidermis,length and width of the biggest lobed leaf,thickness of palisade tissue and spongy tissue,leaf tissue compactness and structure porosity.Mite damage indexes had negative correlation with thickness of lower epidermis.Lower epidermis thickness can be used as a morphological and structural characteristics index to identify the resistance of cassava to T.cinnabarinus.3.Mite damage indexes had not significant positive correlation with soluble sugar content,water content and SPAD.Soluble protein content and free amino acids content can be used as nutrient substance index to identify the resistance of cassava to T.cinnabarinus.4.Mite damage indexes had significant negative correlation with tannin content and flavonoid content.Besides,the indexes had extremely significant negative correlation with total phenols content.They all can be used as secondary substance index to identify the resistance of cassava to T.cinnabarinus.5.Among the eight varieties,XX048 has the strongest mite resistance,its yield related traits are fine,and the yield is the highest among them all.Therefore,it can be promoted in planting areas where T.cinnabarinus hazards occur frequently.