北京杨溃疡病抗病性的研究

通过对不同地区北京杨溃疡病情况的调查研究，发现环境与抗病性密切相关，环境条件对树皮相对膨胀度（ＲＴ值）、树皮邻苯二酚含量、苗木带菌量等有较大影响，进而影响其抗病性，若改善环境条件，抗病性便有所提高，反之亦然。另外，树皮生理指标中ＲＴ值、磷、邻苯二酚、可溶性总糖和钾的含量与抗病性呈显著正相关，而氮、钙、镁、铁、锰、锌、葡萄糖、果糖、蔗糖，原儿茶酸和对－羟基苯甲酸的含量与抗病性无明显相关性.

Studies on the Resistance of Populus “Beijingensis”to Canker

The investigation of“Beijingenesis”canker in different areas shows the closecorrelation between the enviornmental conditions and host's resistance to canker:the enviro-mental conditions important effects on the relative turgidity(RT) of host's bark;the contentof catecbol in the bark and the amount of Dothiorella gregaria in the host,ect.,which affectthe resistance of P.“Beijingensis”.We found that the resistance rose when the environmen-tal conditions improved,otherwise they did not.After determining indices of the bark,wefound that the indices of RT,P,catechol,soluble sugar and K have positive correlations withthe host's resistance.But no correlations were found between thebost's resistance and thepresence of N,Ca,Mg,Fe,Mn,glucose,fructose,sucrose ,protocatechuic acid and P-hydroxybenzoic acid, ect.