Comprehensive Evaluation On Cold-tolerance And Leaf Anatomical Structures Of Populus Alba × Populus Tomentosa

Poplar play a very important role in cultivated species in northwest of China. Particularly in afforestation and ecological protection as well as the production of wood products, so it is important to carry out drought and low temperature resistance breeding of poplar in order to adapt the ecological environment in northwest of China. It is necessary to expand the scope of distribution and cultivation of poplar, and get great poplar productivity, besides, making the ecological environment in northwest of China better. Taking annual dormancy branches and leaf anatomical structure of four hybrid clones of I-101×Poplar tomentosa produced by Northwest A & F University and four control clones(84k, I-101, P.alba, P.tomentosa NO.30) as experimental materials, we studied their ability of cold stress and dry resistance respectively, which can provide a theoretical basis for the suitable cultivation area for poplars. The conclusions were as follows:1. According to the comparison of conductivity,they have the same trend, just like a converse ‘S’. Calculating the LT50 of each clones, The 03-4-22 clone material showed the best cold resistance to cold stress of all the hybrid materials, with the lowest LT50(-33.95℃),which belonged to the cold resistance clone. The 03-4-9 clone material showed the worst resistance to cold stress, with the highest LT50(-18.13℃).The sequence of LT50 in nine hybrid clones was as follows: 03-4-22, 84 k, I-101, Poplar alba, 03-5-17, Poplar tomentosa NO.30, 03-6-11, 03-4-9.2. In the process of the low temperature stress, the 03-4-22 clone material showed a better adaptability compared to other clones, which prepared lower MDA content and higher POD activity, SOD activity, soluble protein content.3. The changes of LT50, MDA, soluble protein contents, SOD and POD activities of eight poplar clones were analyzed by using membership function method.The results as follows: There were obvious differences among the clones of the ability of cold resistance.The order was 03-4-22, 84 k, I-101, poplar alba, 03-5-17, poplar tomentosa NO.30, 03-6-11, 03-4-9.4. Nine xeromorphic indicates, including leaf thickness, thickness of vein, thickness of sponge tissue, thickness of palisade and so on, were found significant difference between different clones.5. Thickness of vein, thickness of sponge tissue and thickness of palisade were selected by variance analysis and principal component analysis.6. A comprehensive evaluation on drought resistances of eight poplar clones were given by the method of subordinate functions. Results from this study indicated that there were obvious differences in the ability of drought resistance among the tested clones, and the order was03-4-22, 84 k, poplar alba, I-101, 03-5-17, poplar tomentosa NO.30, 03-6-11, 03-4-9. 03-4-22 showed the best resistance to drought stress.