Study On The Relationship Between Drought Resistance And Water Utilization Of Wheat Seedlings

The relationship between drought-resistance and water utilization were studied under osmotic stress in the paper using two different winter wheat varieties which one is Jinmai47 came from the dry-land and belongs to small root system and another is Shi4185 came from the irrigable-land and belongs to big root system. The water use efficiency, root hydraulic conductivity, photosynthetic rate, respiration rate, osmotic potential and other parameters of these two varieties were measured. The results are following:Under the osmotic stress,the lengths of coleoptile and primary root for two varieties were shorten. The ratios of coleoptile length compared with control in Jinmai47 were 71.0%,89.0% and 55.5%, and that in Shi4185 were 61.8% 48.9% and 24.1% respectively under the -0.3MPa,-0.5MPa and -0.8MPa osmotic stress. The ratios in Jinmai47 were higher than that in Shi4185 significantly. The average coleoptile length of Jinmai47 was closed to Shi4185 first and then surpass it along with the strengthen of stress. The primary root length was changed as a similar trend as the coleoptile. Under the osmotic stress, the ratio of primary root length in Shi4185 was higher than that in Jinmai47. According to the coleoptile length as drought resistance index, it was proved that the drought-resistance of Jinmai47 was higher than that of Shi4185.In well water condition, the water use efficiency in root, water use efficiency in shoot , water use efficiency per seeding in Jinmai47 were all higher than that in Shi4185. Under the osmotic stress, the water use efficiency in root, water use efficiency in shoot, water use efficiency per seeding both varieties were enhanced differently, but the water use efficiency in root, water use efficiency per seeding in Jinmai47 were still higher than that in Shi4185. For Shi4185, the changing range of water use efficiency in root was higher significantly than that in shoot , and surpassed that of Jinmai47 .After rewatering, it was found that two peaks of the ratio of root hydraulic conductivity were emerged in Jinmai47, but it was not obvious in Shi4185. It meaned that the root hydraulic conductivity in Jinmai47 was much stronger and the adjustive capability of root hydraulic conductivity was expressed more sensitive than that in Shi4185. The root hydraulic conductivity (Lpr) for Jinmai47 was inhibited heavilly than that for Shi4185 after treated with HgCl2. It was showed that the root hydraulic conductivity for Jinmai47 depended on aquaporins (AQP) more.In well water condition, the JinmaiI47 expressed"the water utilized excessively",and under the drought stress, it was by reducing the transpiration and evaporation to maintain the growth and tolerance under osmotic stress. For Shi4185, it showed the characteristic of big root system under normal condition, and under osmotic stress, the water use efficiency was enhanced obviously and it changed more in roots than that in shoots, indicating that Shi4185 could developed its root system to endure drought under osmotic stress. These results verified the important and the difference of roots between two wheat varieties in the process of regulation to drought-resistance.