辣椒苗期不同生长阶段对疫霉根腐病的抗性研究.

It has great significance for screening pepper germplasm or breeding new cultivars to identify accurately the resistance levels of peppers. In this paper, the resistance levels of pepper seedlings to Phytophthora root rot at different growth stages were investigated by irrigating inoculation with zoospore suspension of Phytophthora capsici isolates that belonged to prevalent race 3 from Yunnan. The results showed that resistance, moderate resistance and susceptible pepper seedlings against Phytophthora capsici had significant differentiation under 20 - 25 °C when inoculated at 20 d ( cotyledon stage ), 40 d ( 3 - 4 leaf stage ), 60 d ( 5 - 6 leaf stage ) and 90 d ( early squaring ). That is, resistance levels from strong to weak at different growth stages of pepper seedlings were 90 d > 60 d > 40 d > 20 d, which suggested that resistance levels of peppers were positively correlated with seedling ages. The pepper seedlings inoculated by irrigation at 60 d ( 5 - 6 leaf stage ) could reflect the true resistance of different pepper cultivars. This study defined the suitable growth stage for resistance evaluation of Phytophthora root rot disease on pepper and also provided a scientific basis for screening and identification of the pepper germplasms or resistance cultivars. [ABSTRACT FROM AUTHOR]