Abstract:

To screen the drought resistance indicators of the main maize hybrids for relatively large acreages at germination and seedling stages， the released maize hybrids were used as test materials. 2 treatments were set up including control and drought stress （PEG-6000 with mass fraction of 20%）. Germination rate， germination potential and germination index were measured at germination stage， and MDA content， chlorophyll content， root dry weight， canopy dry weight， plant dry weight， plant fresh weight， root to shoot dry weight ratio and dry to fresh ratio were measured from the seedling stage to the three leaf one heart stage. A comprehensive evaluation of drought resistance and screening of drought resistance indicators for maize varieties were conducted using drought resistance coefficient， weighted drought resistance coefficient， principal component analysis， membership function analysis and other methods. The results showed that the germination rate， germination potential and germination index of maize hybrids showed different degrees of decline during the germination period. The drought resistance coefficients of germination rate, germination potential and germination index varied widely, ranging from 7.33 to 97.78, 14.81 to 97.69 and 33.25 to 98.59, respectively. Based on the drought coefficient and cluster analysis, the hybrids were divided into 3 categories: drought resistant, moderate and sensitive, which correspond to the total comprehensive evaluation values (T_i) of 0.00~0.35, 0.53~0.66 and 0.77~0.96, respectively. There were 11 sensitive varieties during the germination period, including Zhengdan 958 (V1), Jingdan 28 (V3) and Huanong 138 (V5) etc. There were 4 drought resistant varieties, including Xianyu 335 (V2), Jingke 968 (V4) and Xianyu 047 (V7) etc. The MDA and chlorophyll contents in the leaves of the maize varieties at the seedling stage were significantly increased compared to the control (CK), while the other 6 traits showed varying degrees of change. Based on principal component analysis and cluster analysis of drought resistance coefficient and weighted drought resistance coefficient, the varieties were grouped into 3 categories: drought resistant, moderate and sensitive. The mean values of their total comprehensive evaluation values (T_i) were 0.30, 0.49 and 0.55, respectively. There were 5 sensitive varieties during the seedling stage, including Xianyu 1140 (V8), MC817 (V16) and Zhengdan 958 (V1) etc. There were 7 drought resistant varieties, including Jingke 968 (V4), Xianyu 047 (V7) and Nongda 372 (V9) etc. Therefore, the identification of drought resistance at the germination and seedling stages of maize requires the application of comprehensive evaluation methods to effectively assess drought resistance, especially for maize production in Huanghuaihai region with scarce water resources and available water resources were severely limited. It was more important to study the drought resistance evaluation of maize varieties at the seedling and germination stages under the single seed sowing mode.

Key words: maize hybrids, drought stress, seed germination, seedling stage, drought resistance coefficient, cluster analysis

摘要：

为了筛选主推玉米品种萌发期和苗期的抗旱性指标，以审定玉米品种作为供试材料，设置对照和干旱胁迫（质量体积分数20%的PEG-6000）2个处理。在萌发期测定发芽率、发芽势和萌发指数，在苗期至三叶一心期测定丙二醛（malondialdehyde，MDA）含量、叶绿素含量、根干重、冠干重、株干重、株鲜重、干重根冠比和干鲜比。采用抗旱系数、加权抗旱系数并结合主成分分析、隶属函数分析等方法综合评价玉米品种抗旱性并筛选抗旱指标。结果表明，萌发期玉米品种的发芽率、发芽势和发芽指数表现出不同程度的下降。发芽率、发芽势和发芽指数的抗旱系数变化较大，分别为7.33~97.78、14.81~97.69和33.25~98.59。基于抗旱系数和聚类分析，将18个品种分为抗旱、中等和敏感型3类，其分别与抗旱性综合评价值（T_i）0.00~0.35、0.53~0.66和0.77~0.96相对应，萌发期敏感型品种包含郑单958（V1）、京单28（V3）、华农138 （V5）等11个，抗旱型品种包含先玉335 （V2）、京科968 （V4）、先玉047 （V7）等4个。苗期玉米品种的叶片MDA含量和叶绿素含量比对照（CK）显著提高外，其他6个性状均有不同程度的变化。基于抗旱系数及其加权抗旱系数的主成分分析和聚类分析，将17个品种分为抗旱、中等和敏感型3类，其抗旱性综合评价值（T_i）分别为0.30、0.49和0.55，苗期敏感型品种包含先玉1140 （V8）、MC817 （V16）、郑单958 （V1）等5个，抗旱型品种为京科968 （V4）、先玉047 （V7）和农大372 （V9）等7个。因而，玉米萌发期和苗期的抗旱性需应用综合评价方法进行有效评价，尤其对于黄淮海地区水资源匮乏和可利用水资源严重短缺的玉米生产及单粒播种模式下苗期和萌发期品种抗旱性评价研究显得尤为重要。

关键词: 玉米杂交种, 胁迫处理, 萌发期, 苗期, 抗旱系数, 聚类分析