Resistance and physiological basis of different cassava cultivars to Tetranychus cinnabarinus

【Objective】To explore the resistance and physiological basis of different cassava cultivars to Tetranychus cinnabarinus, in order to provide reference for the breeding and promotion of mite resistant cultivars. 【Method】Six cassava cultivars, including GR4, SC205, GK26, SC124, NZ199, and XX09 were used as materials. In areas with high incidence of cassava T. cinnabarinus, no control measures were taken and T. cinnabarinus were allowed to harm. After the peak period of harm of T. cinnabarinus, the mite damages of different cassava cultivars were investigated and identified.The contents of soluble sugar, soluble protein, total phenol, flavonoids, tannin and the activities of peroxidase(POD) and catalase(CAT) in the leaves of the injured and uninjured leaves were measured. The relationship between the changes of the indexes above and damage of T. cinnabarinus to different cassava cultivars was explored. 【Result】There were obvious differences in the resistance of different cassava cultivars to T. cinnabarinus, with a mite damage index of 61.86%-91.34%, the order of mite damage index for six cultivars was: NZ199>SC205>GR4>SC124>GK26>XX09.NZ199 and SC205 were highly susceptible to T. cinnabarinus, GR4, SC124 and GK26 were susceptible, XX09 was moderately resistant. The results showed that the contents of total phenol, flavone, tannin and the activities of POD and CAT in leaves of XX09, the least mite damaged cultivar, were the highest, and the content of soluble sugar was the lowest; and the contents of total phenol, flavone, tannin and the activities of POD and CAT were the lowest and the soluble sugar content was the highest in leaves of NZ199, the most mites severely damaged cultivar. The differences in these indicators between the two cultivars reached extremely significant level(P<0.01). 【Conclusion】It can be seen that different cultivars of cassava have different resistance to T. cinnabarinus, and the contents of soluble sugar, total phenols, flavonoids, tannins and the activities of POD and CAT in cassava leaves were closely related to cassava's resistance to T. cinnabarinus.They can be used as physiological indicators for evaluating cassava's resistance to T. cinnabarinus.