Effects of Tetranychus cinnabarinus infection time on physiological parameters of cassava

ObjectiveIn order to provide theoretical basis for breeding mite-resistant cassava varieties,changes of physiological parameters of different cassava varieties were investigated after being infested by Tetranychus cinnabarinus.MethodThe population quantity of T. cinnabarinus were explored on cassava varieties SC8,Nanzhi 199,and SC205 through field investigation. The physiological and biochemical parameters including contents of chlorophyll,soluble su-gar,soluble protein,free proline,malonaldehyde(MDA),superoxide dismutase(SOD)activity and peroxidase(POD)ac-tivities of leaves infested by T. cinnabarinus(treatment)and healthy leaves(control)were compared with pot method.ResultThe population quantity of T. cinnabarinus on different cassava varieties appeared a peak during the period of in-vestigation(near October 30). Largest population quantity at the peak was showed on SC205(105.6±6.9 T. cinnabarinus/leaf),followed by Nanzhi 199(53.2±8.6 T. cinnabarinus/leaf),the smallest quantity was on SC8(38.7±3.8 T. cinnabari-nus/leaf). Compared with control group at the same period,the chlorophyll content of all cassava varieties decreased after being damaged by T. cinnabarinus;soluble sugar,soluble protein,free proline and MDA content increased firstly and then decreased generally,activities of SOD and POD showed a rising tendency overall. Soluble sugar,soluble protein,free pro-line content,and activities of SOD and POD of mite-resistant variety SC8 had larger increase range than that in the con-trol. However mite-susceptible variety SC205 had smaller increase range in terms of the above parameters.ConclusionDuring feeding press of T. cinnabarinus,different cassava varieties present significant differences in soluble sugar con-tent,soluble protein content,free proline content,activities of SOD and POD. It is referred that the variation of these pa-rameters can be used to identify mite resistance of cassava varieties.