The Evaluation Of Sugarcane Varieties Resistance To Chilo Infuscatellus Snellen

Chilo infuscatellus Snellen is widely distributed in sugarcane production areas in China, which is one of the most important pests in sugarcane production. The whole sugarcane growing periods are harmed by C. infuscatellus. The C. infuscatellus causes dead heart at the seedling stages, and bored internodes in the elongation period and mature period, which affect the normal growth and sucrose accumulation of sugarcane. From February 2013 to December 2014, the experiments of sugarcane resistance to C. infuscatellus were carried out at Guangdong Zhanjiang experimental station, which include the resistance level, the morphological characteristics of borer resistance, the index of borer resistance and the stability of borer resistance at the sugarcane seedling stages, the middle and late growth stages. The mechanism of sugarcane lines resistance to C. infuscatellus is discussed and the results are as follows:1. The oviposition selectivity and resistance identification of C. infuscatellus at the sugarcane seedling stages.The oviposition preference of the C. infuscatellus in different seedling sugarcane varieties, the evaluation of borer resistance in the field and the morphological characteristics of borer resistance were studied by the oviposition preference in the room and the infection of natural population in the field. The fecundity of C. infuscatellus adult is significant difference among 19 sugarcane lines under the selectivity condition in the room which explained that the adult of C. infuscatellus has oviposition preference to the sugarcane genotyes. The results were consistent with the borer resistant identification under the natural population in the field and the ovipositional preference in the room, showing that borer resistance of the seedling period might due to the oviposition selectivity. In the sugarcane seedling, the eggs amount of C. infuscatellus and the width of leaves was significantly positive correlation, same as the leaf inclination and the dead heart rate caused by borer in the field.2. The identification of sugarcane resistance to C. infuscatellus at the middle and late sugarcane growth stages.The level and the morphological characteristics of borer resistance in the middle and late sugarcane growth periods were studied under the normal population in the field by two borer resistance index (the percentage of bored internodes and the adult emergence rate). The significant differences of sugarcane resistance to C. infuscatellus at the middle and late sugarcane growth stages were observed among the different lines. There was no significant correlation between the percentage of bored internodes and the adult emergence rate, which indicated the various borer resistance mechanism might exist in different sugarcane lines. There was no significant correlation between the rate of dead heart at sugarcane seedling stage and the percentage of bored internodes at the middle and late growth stages, which mean that the borer resistance may differ at different sugarcane growth stages. At the middle and late sugarcane growth stages, the percentage of bored internodes was significantly negative correlated with the sugarcane epidermic hardness and the leaf area index. The adult emergence rate of C. infuscatellus was significant positive correlated with the leaf area index, but however it was significant negative correlated with the fiber content of sugarcane.3. The comprehensive evaluation of sugarcane resistance to C. infuscatellus at the middle and late sugarcane growth stages.According to the percentage of bored stalks, the percentage of bored internodes, the borer damage index, the percentage of bored tips, the number of tunnels per stalk, the tunnels length per individual stalk and the adult emergence rate collected at the middle and late sugarcane growth stages, the resistance of nineteen sugarcane lines under the natural population of the target pest were assessed by the factor and cluster analysis. The results showed that except the percentage of bored stalks, the values of all the six candidate parameters have potential to be used to evaluate the borer resistance. A correlation was investigated between each of the six parameters to the loss of sugarcane stalk weight and the loss of sucrose content, but only the borer damage index was found to be a significant positive correlation with both of the loss, suggesting that the parameter of the borer damage index is the best one for evaluation of the sugarcane damage. In term of the results of factor analysis, the six parameters could be simplified to three main factors including damage factors of plant, anatomy factors of borer tunnels, growth and development factors of borer. The nineteen sugarcane lines were clustering analysis according to the scores of factors, in which YT42 showed to be a highest borer resistance and FN38, YG29, LC03-1137 and YG31, were the opposite.4. The stability analysis of sugarcane resistance to C. infuscatellus at the middle and late sugarcane growth stages.The percentage of bored internodes was used as borer resistance index at the middle and late sugarcane growth stages, and the borer resistance stability was analyzed with 3 pilots and 19 lines by AMMI model. The results indicated that environment effect, the genotype effect and the interaction effect had highly significant effects on the resistance of sugarcane lines to C. infuscatellus, and the environmental effect on the overall variation was the largest. Base on the resistance level and stability of the sugarcane lines resistant to C. infuscatellus, the YT60 and YG42 were the most stable borer resistance varieties among the experiment sugarcane lines, and the LC03-1137 was the most stable borer susceptibility among the experimental lines.