美国黄松、班克松和油松的抗寒性比较

通过人工冰冻和电导率的测定，对黄土丘陵沟壑区引种载培的美国黄松、班克松和乡土树种油松的抗寒性进行了鉴定，并探讨其抗寒机理.结果表明，班克松的抗寒性比油松强，而美国黄松的抗寒性比油松稍弱.班克松的束缚水/自由水比值高达7.0，组织中ABA含量高达164.3 μg·g^-1 FW；但可溶性糖和K⁺含量较低，分别为12.0%和2 450 μg·g^-1 DW.油松则是可溶性糖、K⁺和ABA含量都较高，分别为18.68%、4 538 μg·g^-1 DW和95.8 μg·g^-1 FW；束缚水/自由水比值较低，为2.58.美国黄松的可溶性糖含量较高，18.05％；但束缚水/自由水比值、K⁺和ABA含量都较低，分别为2.18、2 275 μg·g^-1 DW和63.3 μg·g^-1 FW，可能是其抗寒性较弱的内在原因.班克松较低的叶绿素含量和较高的类胡萝卜素/叶绿素比值对其抗寒性也有贡献.说明3种树种虽然都是抗寒树种，但其内在机理仍有差异.

Cold hardiness of Pinus ponderosa, P. banksian and P. tabulaeformis

By the method of artificial freezing, this paper made a comparative study on the cold hardiness of Pinus ponderosa, P. banksiana and P. tabulaeformis, with their inherent mechanisms approached. The results showed that the cold hardiness of these three species was in the sequence of P. banksiana > P. tabulaeformis > P. ponderosa. P. banksiana had high bound water/free water ratio (7.0) and ABA content (164.3 microg x g(-1) FW) but low K+ (2450 microg x g(-1) DW) and soluble sugar (12.0%) , P. tabulaeformis had higher contents of ABA (95.8 microg x g(-1) FW), K+ (4538 microg x g(-1) DW) and soluble sugar (18.68%) but low bound water/free water ratio (2.58), while P. ponderosa had high soluble sugar content (18.05%) but low bound water/free water ratio (2.18) and K+ (2275 microg x g(-1) DW) and ABA (63.3 microg x g(-1) FW) contents. These differences might be the reasons resulting in the different cold hardiness of these three species. Low chlorophyll content and high carotenoid/chlorophyll ratio might also contribute to the cold hardiness of P. banksiana. Therefore, though the test species are all of cold hardiness, their inherent mechanisms may be different.