| We have discussed the adaptability of cold , aridity photosynthesis and so on of Betula pendula x Betula pendula var. carelica Sok (1786, 2/86) ,taking the local birch as comparison ,in order to provide more exoteric gist of birch indraught. The thesis mostly includes hereinafter five aspect contents.(l)Taking the adaptability analysis of Betula pendula x Betula pendula var. carelica Sok ,which come from the autumn investigation result of birch which grow at Fengning in the same year. As a result, 1/86, 2/86 keep the high surviving rate , serving as 74.1 % , 64.4%,the high growth serve as 40.5cm, 31.1 cm,thereinto, 1/86 grows the fastest in the four varieties,more2-3cm in the high growth than the other two comparisons. 2/86 grows the most slowly in the four viirieties. Taking the analysis for three breeds indicate that there are not prominence different in breeds , that show 1/86, 2/86 can giow in the zone of birch in growing season . But it's grows are lower in the zone than in Germen , they growing superiority did not expressed ,this is to say 1/86 and 2/86 are not completely comfort to the climate in the zone .(2) Through observation to exterior form and phonological period of birch, we summarize the exterior form , growth behavior and birch using in production .And particular noted leaf bug time, unfold leaf time, defoliation time etc. We have a summarize on the feasibility of birch indrought on whole too. The result show that the phonological period of 1/86 and 2/86 are latter than CK's, so we can not ensure 1/86 and 2/86 could resist the cold or not in autumn in the zone. But the leaf of 1/86 and 2/86 drop is later than CK 19-25 days, that show 1/86 and 2/86 can not grow in the zone of CK's northest.(3) We analyse the adjustment of the birch reeds to the cold and drought from the conductance, K+ filtrate, SOD, POD, MDA, content of the water-soluble protein, penetration of the bioplasm film, photosynthesis and fluorescence.The result indicates that the conductance and the K+ filtrate of the birch breeds rise quickly after -10#, the value of the conductance and the K+ filtrate of all the birch breeds exceed 60% when the temperature come to -15#.We think that the leaves of the birch breeds have been dead at -15#, that is, the birch can endure the temperature beyond -10#. Compositive evaluate to every physiological index indicates the order of the birch breeds' capacity to resist the cold is CK>2/86>1/86. Though the difference of 1/86, 2/86 and CK have reached the 0.01 level on the K+ filtrate of the branch, the most index of 1/86 and 2/86 didn't have marked difference on cold resistance . We consider that 1/86 and 2/86 could grow in most zone of CK, in that the CK could grow, on some degree. At the same time, we could find that 1/86, 2/86 have some difference on resist-cold ,and 1/86 , 2/86 shatter more latter than CK . Because the resist-cold of leaf is lower than thatof CK, so 1/86 , 2/86 might not resist the cold on the northest zone of CK in the autumn. The conductance and the content of the protein of the clone also achieve the significant level comparing to CK in the time, plants' dormancy was being finished and the growing time was coming. And the conductance and the content of the protein was important index on resist-cold, so we consider that the difference are marked between l/86,2/86 and CK. Now we have an appraise on the resist-cold of 1/86 and 2/86 on the whole, we could find that there are some difference between 1/86- 2/86 and CK, and the difference are marked in the winter, but the three breeds are not much different on a lot of index, that show 1/86, 2/86 have a rather strong cold resistance.Through the analysis of the change of SOD ,, POD,MDA, protein proline and light index in 30% water content , we can find that the ad-drought of 1/86, 2/86 is lower than CK. But the direction of the three breeds'change are identical. Through analysis , we find that the difference of the three breeds are not notability , 1/86 and 2/86 can grow through the whole drought season in...
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