| Poplar is one of the important cultivated species in north of China. With the expansion ofpoplar planting area, there were few varieties and low disease resistance among the varietiesof poplar in recent years. Poplar canker, in particular, had increasingly grave harm on poplarplantation. In China, poplar canker, which mainly infected the branch of the poplar, is causedby Botryoshpaeria dothidea. So far, there were not effective pesticides for poplar canker.Therefore using traditional selective breeding is a good method to screen fine varieties ofdisease-resistance.In this paper, testwoods, excised branches and callus tissues of two kinds of clones,natural hybrids of Populus deltoids CV.’I-69/55’ and Populus alba×(P. alba×P. glandulos)clones, were used as materials to investigate the degree of canker resistance. We used fieldsurvey method to analyze the infection index and infection rate. Then, we studied theresistance of artificially inoculated excised branches with B. dothidea and the activity ofdefensive enzymes to analyze the infection index, infection rate and the degree of cankerresistance. Last but not the least, we studied the resistance of artificially inoculated callustissues with B. dothidea and the activity of defensive enzymes to analyze the infection index,infection rate and the degree of canker resistance.The main results were as following:1. Based on the field investigation of canker resistance of two new selection poplarclones, few resistant rotation poplar breeds were screened out. The results showed that: Innatural hybrids of Populus deltoids,03-south-2-21, poplar69,03-north-27-1and03-north-3-1have high degrees of the resistance. What’s more,03-south-5-11,03-south-1-13and03-south-4-24have resistance to canker. However,03-south-4-1,03-north-1-7,03-south-3-2and03-north-1-15show high susceptibility to canker. In Populus alba×(P. alba×P.glandulos) clones, highly canker resistant clones are02-9-22,02-11-10, the white poplar30,poplar101,02-8-21and Heibei. In addition, moderate canker resistant clones are02-12-29,02-14-26,02-5-9and02-4-22. Resistance clones to disease are02-8-30,02-8-26,02-13-26,02-4-32,02-4-5,02-4-36and02-10-20. Whereas, moderate susceptibility clones are02-15-5,02-20-24,02-21-30,02-7-23,02-15-18,02-21-11,02-6-2,02-21-33,02-5-22,02-6-26,02-3-20and02-12-26. Moreover, highly susceptibility clones to canker are02-12-33and 02-7-22.2. Based on the onset of days of artificially inoculated excised branches with B. dothidea,the infection indexs of excised branches are calculated. The results showed that: In naturalhybrids of Populus deltoids, the resistance of excised branches to canker sorted by theinfection index as below: poplar69＞03-north-3-1＞03-south-1-13＞03-south-4-1＞03-north-1-15. In Populus alba×(P. alba×P. glandulos) clones, the canker resistance ofexcised branches sorted by the infection index as follow:02-9-22＞the white poplar30＞poplar101＞02-8-21＞84K＞02-12-29＞02-21-13＞02-3-32.3. According to the activity of POD, SOD and PPO of the artificially inoculated excisedbranches with B. dothidea sampled once every two days in ten days after inoculation, wefound that: In natural hybrids of Populus deltoids, the canker resistance of excised branchessorted by the activity of defensive enzymes as below: poplar69＞03-north-3-1＞03-south-1-13＞03-south-4-1＞03-north-1-15. In Populus alba×(P. alba×P. glandulos) clones theresistance of excised branches to canker sorted by the activity of defensive enzymes as follow:02-9-22＞the white poplar30＞poplar101＞02-8-21＞84K＞02-12-29＞02-21-13＞02-3-32.4. On the basis of the coverage area of the mycelium after artificial inoculation of callustissue with B. dothidea in72h, the infection indexs of callus tissue are calculated. The resultsshowed that: In natural hybrids of Populus deltoids, the resistance of callus tissue to cankersorted by the infection index as below: poplar69＞03-north-3-1＞03-south-1-13＞03-south-4-1＞03-north-1-15. In Populus alba×(P. alba×P. glandulos) clones, the cankerresistance of callus tissue sorted by the infection index as follow:02-9-22＞the white poplar30＞poplar101＞02-8-21＞84K＞02-12-29＞02-21-13＞02-3-32.5. According to the activity of POD and PPO of the artificially inoculated callus tissuewith B. dothidea sampled once every12hours in96hours after inoculation, we found that: Innatural hybrids of Populus deltoids, the resistance of callus tissue to canker sorted by theactivity of defensive enzymes as below: poplar69＞03-north-3-1＞03-south-1-13＞03-south-4-1＞03-north-1-15. In Populus alba×(P. alba×P. glandulos) clones theresistance of callus tissue to canker sorted by the activity of defensive enzymes as follow:02-9-22＞the white poplar30＞poplar101＞02-8-21＞84K＞02-12-29＞02-21-13＞02-3-32. |
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