Abstract:

To clarify the resistance level of Chinese cabbage varieties against clubroot in Chengdu plain, a total of 45 main cultivars of Chinese cabbage were screened for resistance in three counties, Longxing in Chongzhou, Mengyang in Pengzhou and Taixing in Xindu in 2018. The identification was carried out under field condition by using the method of natural infection, and the resistance level analysis was conducted by investigating the symptom on plant roots. The results showed that the resistance level of the tested Chinese cabbage cultivars to clubroot disease was variable. Four cultivars showed immune to clubroot (disease index=0) in the Chongzhou natural disease nursery, and the ratio was 8.9%, and the other cultivars showed susceptibility (35<disease index≤55) or high susceptibility (55<disease index≤100), accounting for 91.1%. The evaluation of resistance identification in Pengzhou showed that six cultivars were immune to clubroot, eleven cultivars were tolerant to clubroot disease (15<disease index≤35), and the remaining twenty eight cultivars were susceptibility or highly susceptibility. But in Xindu, only two cultivars showed immune resistance, sixteen tolerant cultivars were screened out and twenty six cultivars showed susceptibility or high susceptibility. The resistance of most of the cultivars was susceptible to clubroot, and the resistance of some cultivars showed instability in different areas. Only cultivar Meichun and Shangpin exhibited stable immune to clubroot in the three regions, which were suitable for planting in the epidemic areas of clubroot disease, and could be used for further study on resistance breeding.

Key words: Chinese cabbage, clubroot, resistance level, disease index