Abstract:In order to explore the physiological and biochemical response patterns of Casuarina equisetifolia against infection of Ralstonia solanacearum, the disease-resistant assessment and selection of different C. equisetifolia families were studied based on the correlations between physiological and biochemical traits and disease-resistant characteristics. The results showed that the disease index (DI) and relative disease intensity (RDI) of 26 C. equisetifolia families were significantly different after inoculated with R. solanacearum. The differences of superoxide dismutase (SOD), catalase (CAT), phenylalanine ammonialyase (PAL), polyphenol oxidase (PPO), total phenolics (TP) and flavonoid (Flav) among the families were significant or very significant, indicating that the tested families had huge variation at resistance against R. solanacearum and great selection potential is expectable. The disease incidence and intensity of the 26 families presented negative correlation with the six physiological and biochemical indexes at significant or very significant level. It was indicated in a certain range that the more defense enzyme activities or secondary metabolite contents, the lower disease incidence and intension were detected. Two disease characteristics and six physiological and biochemical parameters were used to evaluate and select C. equisetifolia families against R. solanacearum, eight resistant families, including 201, 206, 198, 207, 202, 213, 208 and 195, were preliminarily selected according to the selection rate of 30%. The mean RDI and DI of eight resistant families were 25.94% and 28.93%, respectively, which was lower than those of overall mean values. And the activities of SOD, CAT, PAL, PPO, and contents of TP, Flav in these eight families were 11.90%, 13.50%, 24.77%, 12.71%, 25.68% and 18.76% higher than those of overall mean values, respectively. Therefore, the selected 8 families showed low disease degree, few wilting branches, and plant growth was not affected, indicating strong disease resistance and could be widely used in subsequent production.