<正>用溶液培养的方法研究了缺磷胁迫下不同种源马尾松和杉木苗木根系有机酸的分泌。结果表明：缺磷胁迫下杉木和马尾松苗木根系有机酸的兮泌量显著增加，在Po（KH2PO4，0mmol/L）、PI（KH2PO4，0.03mmol/L）和P.（KH2PO4，0.09mmol/L）3种缺磷水平下。马尾松根系有机酸的平均分泌量分别比正常供磷P，（KH2PO4，0.5mmol/I。）时提高328.6%、267.9%和126.4%，其中浙江马尾松根系分泌有机酸最多；浙江杉木根系有机酸分泌量分别比正常供磷时提高325.0%、150.0%和50.0%。缺磷胁迫下，不同种源的杉木和马尾松增加分泌有机酸的种类不同，浙江马尾松主要增加分泌草酸、酒石酸、柠檬酸和苹果酸。广西马尾松主要增加分泌草酸和酒石酸，贵州马尾松主要增加分泌酒石酸、草酸和苹果酸：杉木主要增加分泌草酸和酒石酸。

The experiment adopted peel-grafting method to inoculate the 2 a Pinus thunbergii seedling with strong and weak pathogenicity Bursaphelenchus xylophilus as well as non-pathogenicity Bursaphelenchus mucronatus. The observation results showed that the strong pathogenicity Bursaphelenchus xylophilus spreaded more quickly inside the Pinus thunbergii. The needle begins to turn yellow in 4d. The new tip of pine seedling begin to wilt in 7d, and died completely in 10d. The amount of the nematode was much more than that of inoculated because the nematode reproduced in a great deal inside of the seedling. The weak pathogenicity Bursaphelenchus xylophilus spreaded relatively slowly inside the Pinus thunbergii. The needle turned yellow in 7d. The new tip begins to wilt in 15d. The seedling died in 25d. The amount of nematodes began to increase. After non-pathogenicity Bursaphelenchus mucronatus had been inoculated, only small amount of nematodes from the tree top was separated in 7d. Some needles on the tip turned yellow. The nematode didn’t reproduce basically. The nematode can not be separated from the seedling in 25d. The needle symptom on the tip hasn’t strengthened which doesn’t lead to the death of the new seedlings. Therefore, after the Pinus thunbergii was infected with nematode, whether it wound come down with disease was closely related to the nematode survival inside the pine seedling. The symptom of the disease has direct relations to the nematode spread speed inside the pine seedling as well as whether it can reproduce considerably.