Abstract:
【Objective】 This study was conducted to explore an evaluation system for the field resistance to borers of sugarcane germplasms. In this study, the borer resistance of 163 different sugarcane germplasms were evaluated, the performance of borer resistance of each germplasm was studied, and superior germplasms with good borer-resistant performance were screened, in order to provide reference for the innovation of sugarcane germplasms with resistance to borers, the selection and breeding of new varieties, and the promotion and application of sugarcane germplasms with resistance to borers. 【Method】 Sugarcane germplasms were infested by sugarcane borers by its natrural population in the field. A total of 163 sugarcane germplasms were tracked and investigated for three years(including one year of new plants and two years of ratoons). The dead heart rate at seedling stage and the rate of bored internodes at middle and late growth stage were calculated. ROC22 was used as the control variety for borer resistance, relative borer damage reduction rate for each sugarcane germplasm was calculated compared to the control variety. Relative borer damage reduction rate and a corresponding classification evaluation system of sugarcane borer resistance were both used to evaluate and screen the sugarcane germplasms for borer resistance. 【Result】 In the 163 sugarcane germplasms, the dead heart rates at stages of one year of new plants and two years of ratoons ranged from 1.74% to 21.75%, and the rates of bored internodes ranged from 1.17% to 9.74%. Among these tested germplasms, only CP09-4707 ranked among the top 20 with the most damaged dead heart rate at seedling stage for three consecutive years, 0 germplasm ranked among the top 20 with the least damaged dead heart rate at seedling stage for three consecutive years, and 0 germplasm ranked among the top 20 with the least or most damaged rate of bored internodes at middle and late growth stage for three consecutive years. The results of borer resistance evaluation showed that there were 96, 151, 48, 88, 106 and 147 germplasms respectively, were evaluated to be with moderate to above level of borer resistance at seedling stage, middle and late growth stage of new planting, seedling stage of the first year ratoon, middle and late growth stage of the first year ratoon, seedling stage of the second year ratoon, middle and late growth stage of the second year ratoon. Using Venn diagram analysis, 11 sugarcane germplasms were selected with moderate to above level of borer resistance at the 6 growth stages, they were GT03-571, GT03-1438, GT03-2887, YT96-86, GT02-467, Q200, T6, T5, ROC22, T8 and GT42. 【Conclusion】 An evaluation system has been established that can effectively integrate the regional trials of sugarcane germplasms, with easily accessible control variety, simple operation method, and the ablility to evaluate the borer resistance of sugarcane at 6 different growth stages.There are great differences in infestation rate, and difference of borer resistance among different sugarcane germplasms exists. Eleven sugarcane germplasms with moderate to above level of borer resistance at 6 growth stages are selected, which can be used for the selection and breeding of new sugarcane varieties with borer resistance.