Research On Cold Resistance And Drought Resistance On Anatomical Structure Of Leaves Of Two New Poplar Clones

It is an importante field in genetic breeding to carry out stress resistance breeding of poplar. In winter, it is so cold and dry in the north part of our coutry that many plants can not go through winter, especially forest in the northwest area. Cultivating new poplar varieties with strong cold and drought tolerance ability is an effective means of providing materials for cultivation and getting great poplar productivity. In accordance with the principle of heterosis, it can be conquerd by the hybriding of good parents. Also the cultivation of new poplar varieties is of great significance for the construction of the ecological environment in northern China. In this research, two new poplar clones were studied to compare their cold resistance and drought resistance. Two new poplar clones were02-12-29and02-9-22, their parents (P. alba and84K) and P. tomentosa-30were studied too.Artificial low temperature stress was used to do the cold resistance research; water saturation deficit, relative conductivity, content of soluble sugar, content of Malondialdehyde and content of free proline were measured. Growth recover experiment of the poplar seedings was also carried out. Water saturation deficit was negatively correlated with cold resistance. Water saturation deficit value of84K, P. tomentosa-30and02-12-29had significant disparity compared with P. alba and02-9-22, water saturation deficit value of02-12-29and02-9-22is15.1006and20.9965respectively. Relative conductivity was negatively correlated with cold resistance. It rises differently under different low temperature processing, the value and the rate of change in P. tomentosa-30and P. alba were conspicuous, it is not so obvious in84K as in the two ones, it is the most stable in02-12-29. The content of proline in02-12-29and84K was significantly higher than in02-9-22and P. alba, P. tomentosa-30had less proline than02-9-22and P. alba. So02-12-29would synthsize great more proline than02-9-22to protect cells under cold condition. The content of Malondialdehyde was also negatively correlated with cold resistance.02-12-29had significant disparity compared with84K and02-9-22in content of Malondialdehyde after they were processed under low temperature,84K and02-9-22had significant disparity compared with P. tomentosa-30and P. alba. Soluble sugar would be synthesized greatly to protect membrane under stress condition, so it is usful for cells. The content in02-12-29and P. tomentosa-30had significant disparity compared with the other4poplars. So02-12-29would synthsize great more soluble sugar than02-9-22to protect cells under cold condition.The capability of recover experiment decreased in order of84K,02-12-29, P.alba,02-9-22and P. tomentosa-30.The drought resistance study was conducted with the purpose of comparing the ability of drought resistance on two new poplar clones base on the anatomical structure of leaf; the result could provide a theoretical basis for their cultivating. Anatomical structure of leaves of two new clones, their parents and P. tomentosa-30were observed, applying the paraffin method, eight drought resistance indexes including thickness of leaf blade, thickness of upper and lower epidermis, thickness of palisade tissue, thickness of spongy tissue, and so on, were measured. And then a comprehensive evaluation on drought resistance of them was given by the method of subordinate function. The results showed that the anatomical structures of leaves are definitely different. The thickness of leaf blade is arranged from162.73to245.52μm, thickness of upper epidermis is arranged from10.30to17.32μm, thickness of palisade tissue is arranged from71.58to116.34μm, thickness of spongy tissue is arranged from41.10to96.05μm, thickness of lower epidermis is arranged from7.72to12.73μm, SR is between25.25and48.24, so02-12-29had significant disparity compared with02-9-22in all of the above indexes; the ratio of the palisade tissue and spongy tissue is between0.77and2.58, CTR is between37.14and65.26, so02-9-22had significant disparity compared with02-12-29. The drought resistance capability of five poplars decreased in order of02-12-29,84K, P. alba,02-9-22, P. tomentosa-30. Base on the anatomical structure of leaves,02-12-29is active than02-9-22if planted in drought condition.