低氮胁迫对谷子苗期性状的影响和耐低氮品种的筛选

筛选和培育耐低氮能力强的作物品种,是提高作物氮素利用效率,减少氮肥施用量,降低环境污染的有效措施。本研究以45份谷子品种为试材,采用水培的方法,在低氮(0.1mmol·L~(-1))和正常氮(5mmol·L~(-1))条件下,测定苗高、根长和根数等22个氮效率相关指标,采用综合耐低氮系数法以及基于主成分分析的隶属函数法评价参试谷子品种的耐低氮性。结果表明,与正常氮条件相比,低氮胁迫下,谷子苗期根长、根冠比、地上部氮素生理效率、地下部氮素生理效率、单株氮素生理效率有不同程度提高,其余17个指标都有不同程度降低。两种评价方法均根据45个谷子品种的耐低氮能力将其划分为强耐低氮型、耐低氮型、中间型、较敏感型和敏感型5类。筛选出耐低氮性较强的品种5份,编号分别为11、14、17、35和39。利用GGE双标图对品种-耐低氮相关指标的分析表明,编号39和14的耐低氮品种主要耐低氮性状为地下部干重、地下部鲜重、根长;编号为11、35和17的耐低氮品种主要耐低氮性状为地上部鲜重、叶片数、叶宽、叶长、单株氮累积量、地上部氮累积量、单株干质量、地上部干重、地下部氮累积量、根数、苗高和SPAD。可见不同谷子品种的耐低氮机制存在一定差异,研究结果可为谷子耐低氮品种的选育提供材料基础。

Effects of low nitrogen stress on foxtail millet seedling characteristics and screening of low nitrogen tolerant varieties

Screening and cultivating low-nitrogen-tolerant crop varieties can be used as an effective measure for increasing the nitrogen-use efficiency of plants, reducing nitrogen fertilizer use, as well as limiting environmental pollution during cultivation. In the present study, 45 foxtail millet varieties were grown in different nitrogen conditions, low nitrogen (0.1 mmol·L^-1) and normal nitrogen (5 mmol·L^-1), using hydroponic methods. Nitrogen efficiency of plants was subsequently measured based on 22 indicators about growth, biomass, nitrogen content, nitrogen accumulation and physiology efficiency. The low nitrogen tolerance of the tested foxtail millet varieties was evaluated by using the comprehensive low nitrogen tolerance coefficient method and the membership function method based on principal component analysis. The results showed that foxtail millet seedlings exposed to low nitrogen stress demonstrated varying degrees of improvement compared to seedlings grown in normal nitrogen condition for root length, root-shoot ratio, number of root; and root, shoot, and plant nitrogen physiology efficiency. The remaining 17 indicators demonstrated different levels of reduction under low nitrogen stress. Forty-five foxtail millet varieties were subsequently divided into five categories (strong resistant, resistant, medium resistant, sensitive, and highly sensitive) for screening; five varieties with relatively strong low nitrogen tolerance were screened (varieties 11, 14, 17, 35, and 39). A GGE double plot was used to analyze the variety-low nitrogen tolerance related indexes. The predominant low nitrogen tolerance traits of low nitrogen tolerant varieties 39 and 14 were dry weight of root, fresh weight of root, and root length; while varieties 11, 35, and 17 were identified as having traits fresh weight of shoot, leaf number, leaf width, leaf length, nitrogen accumulation of plant, nitrogen accumulation of shoot, dry weight of plant, dry weight of shoot, nitrogen accumulation of root, root number, seedling height, and SPAD. Our results suggest that there are some differences in the low nitrogen tolerance mechanisms of different millet varieties. These findings provide a material basis for the breeding of foxtail millet varieties with low nitrogen resistance.