| In the wheat-producing areas of Huang-Huai-Hai of our country,winter wheat often encountered drought and other adverse conditions during the sowing season and late growth development period,which seriously affected the seed germination and emergence of wheat seeds,leading to seedling rupture in the field.This directly affected the number of basic seedlings and plant growth.In addition,this also easy to cause the number and quality of field population decline,and ultimately lead to decline in yield.How to solve the drought caused by the disaster is the problem we need to solve in time.In this study,119 wheat cultivars were used as experimental materials to simulate the drought at the seedling stage.According to the length of the coleoptile to identify and analysis the drought resistance of 119 different wheat cultivars.The wheat varieties with different drought resistance were selected as the experimental materials to research the differences of proline and soluble sugar contents in the coleoptile,leaf and root of different drought-resistant cultivars during drought stress and rehydration process.The differences of drought resistance between different varieties were discussed,to provide a certain basis for wheat varieties distribution,production and breeding in the selection of varieties in the future.The main results are as follows:1.The length of the coleoptile of most wheat varieties was significantly shortened under 20%PEG-6000 stress,but the length of the coleoptile was slightly increased in the very few wheat cultivars(Lumai 11,Shannong 18,DH-155,etc.).Therefore,according to the clustering analysis of the length of the coleoptile under 20%PEG-6000 stress,119 wheat varieties were divided into three types: Linhan51241,Luohan13,Youmai 3 and other 12 wheat cultivars were strong drought resistant varieties.Taishan 9818,Liangxing 99,Wennong 6 and other 31 varieties of wheat varieties were middle drought resistant varieties;Xinong 979,Zhoumai 23,Jimai 19,Jimai 22 and other 76 wheat varieties were weaker drought-resistant varieties.2.After 20%PEG-6000 stress,the content of proline in the leaves and roots of the coleoptile and roots at the seedling stage increased first and then decreased,and reached the maximum at 12 h.The content of proline in drought-tolerant cultivars was higher than that in drought-sensitive cultivars at the time of 6,12,24 h at 20%PEG-6000 stress,and maintained at a high level.The increase of proline content in drought-tolerant wheat cultivars Luohan 13,Linhan51241 were significantly higher than that in Xinong 979 and Jimai 22 drought-sensitive cultivars.The increase in leaf was 132.8 μg/g,which was more than 2 times higher than that of Xi Nong 979 and Jimai 22 under 20%PEG-6000 stress at 12 h.The increase of proline in the roots of wheat cultivars in Luohan 13,Linhan51241 were 436.1 and 467.8% higher than that of Ximeng 979,respectively.The increase of proline in the roots of two drought tolerant wheat cultivars was increased by 216.9%、235.1 %,respectively.The content of proline in drought tolerant cultivars remained at a high level even at the lowest point.3.After 20%PEG-6000 stress,the content of soluble sugar in the coleoptile and root of the germination period showed a slow descending trend.The drought-resistant cultivar of Luohan 13 decreased more slowly and remained in a stable state,and remained at a high level at 24 h.The content of soluble sugar in leaves and roots of seedling increased first and then decreased,and the content of soluble sugar in drought-sensitive cultivars reached the maximum value earlier than that of drought-tolerant cultivars.The increase of soluble sugar in the leaves of Luohan 13 was increased by 501.8% compared with that of Jimai 22 at 12 h after low water potential stress.The increase of soluble sugar in Linhan 51241 was 372.0% higher than that in Xinong 979.The increase of soluble sugar in drought-tolerant cultivars was significantly higher than that in drought-sensitive cultivars,even when the increase was relatively reduced at 24 h.4.In the process of rehydration,the content of proline and soluble sugar in the leaves and roots of the seedling decreased at the seedling stage,and returned to the level of stress and before stress.The decline rate of drought tolerant cultivars was lower than that of drought sensitive cultivars.The content of proline and soluble sugar in drought-tolerant cultivars remained at a high level after rehydration 24 h.5.Correlation coefficient of both coleoptile length and proline incremental of coleoptile,leaf and root is 0.9824、0.9353、0.9682,respectively,to achieve very significant correlation level.But,soluble sugar incremental reached significant correlation level. |
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