土培条件下玉米萌发期耐旱鉴评技术体系研究

【目的】中国玉米主产区多为干旱、半干旱地区,播种后遇旱问题时常发生,生产上实现良好的出苗与成苗率是保障玉米高产稳产的基础。鉴于不同的玉米品种对萌发期干旱胁迫反应不一,构建玉米萌发期耐旱评价技术体系,鉴定不同品种萌发期耐旱性,为玉米品种筛选与应用奠定基础。【方法】以从田间耕层采集的土壤为介质,设置从种子不能发芽到全部发芽的土壤含水量13个梯度,在25℃光照培养箱条件下测定5个代表性品种种子发芽率,建立不同土壤水分胁迫条件与发芽率的Logistic拟合方程,确立50%种子发芽率时土壤含水量(GW50);在此基础上,以5个品种GW50平均值作为干旱处理强度,对32份品种的发芽率等11个性状进行测定,通过相关性分析、聚类分析和主成分分析等方法,解析种子发芽率与其他相关性状间的关系。【结果】在13个水分梯度下5个品种的发芽率拟合Logistic方程的决定系数R 2为0.978—0.992,基于Logistic方程估算GW50为18.2%—18.7%,GW50平均值为18.5%。以18.5%土壤含水量作为干旱胁迫处理水平,对32份品种的发芽率等11个性状的分析结果显示,发芽率与胚芽鲜重、胚根鲜重、...

Establishment of Evaluation System for Drought Tolerance at Maize Germination Stage Under Soil Stress

【Objective】The main maize-producing areas in China are mostly arid and semi-arid areas, in which drought often occurred after sowing. The sufficient germination rate is key precondition for maize production. However, the decreasing germination rate caused by drought threatens the production of maize. Thus, it is of great importance to discover the drought tolerant maize varieties at germination stage, which relies on the establishment of evaluation system for drought tolerant maize at germination stage. 【Method】In the present study, 13 soil water content treatments, which represented the maize germination rates from 0 to 100%, were set using field soil and the germination rates of five representative maize hybrids were analyzed. The 50% germination rate soil water content (GW₅₀) was determined based on the Logistic formula of germination rate and soil water content in five representative maize hybrids. Subsequently, 32 maize hybrids were treated with GW₅₀ as drought condition. The relationships between germination rates of 32 hybrids and other 10 traits were investigated using correlation, cluster and principal component analyses. 【Result】The fitting degree (R²) of Logistic regression between germination rate of five representative maize hybrids and thirteen soil water contents ranged from 0.978 to 0.992. The GW₅₀ of five representative hybrids, which were estimated by the Logistic regression formulas, ranged from 18.2%-18.7%, with mean of 18.5%. Under drought treatments of 18.5% soil water content, the germination rates of 32 hybrids showed significant correlation with germ fresh weight, radical fresh weight and storage material transport rate, but the correlation coefficients were all lower than 0.5, which was 0.36, 0.40 and 0.38, respectively. While the germination rates under GW₅₀ showed no significant correlation with other seven traits such as radicle number. Besides, cluster analysis based on 10 other traits divided 32 hybrids to three clusters, each containing thirteen, ten and nine hybrids, respectively. However, the mean germination rates of the three clusters showed no significant difference. PCA analysis revealed germination rate, germ dry weight and storage material transport rate had highest eigenvalue in first principal component, which could explain 36.3% of the total variance. These three traits could be considered as key targets for drought tolerance evaluation at germination stage. Using the soil drought method and key traits for evaluation of drought tolerance at germination stage, four, twenty-two and seven of the thirty-four hybrids were identified as drought tolerant, intermedium and drought susceptible types, respectively. 【Conclusion】In this study, soil drought treatment method of GW₅₀ was established for maize drought tolerance evaluation at germination stage. The germination rate, germ dry weight and storage material transport rate were identified as the key traits for high-throughput drought tolerance evaluation. Thus, an evaluation system for drought tolerance at maize germination stage was established.