PDF(Pubmed)
Abstract：
In crops like wheat, terminal drought is one of the principal stress factors limiting productivity in rain-fed systems. However, little is known about root development after heading, when water uptake can be critical to wheat crops. The impact of water-stress on root growth was investigated in two wheat cultivars, Scout and Mace, under well-watered and post-anthesis water stress in three experiments. Plants were grown outside in 1.5-m long pots at a density similar to local recommended farming practice. Differences in root development were observed between genotypes, especially for water stress conditions under which Scout developed and maintained a larger root system than Mace. While under well-watered conditions both genotypes had shallow roots that appeared to senesce after heading, a moderate water stress stimulated shallow-root growth in Scout but accelerated senescence in Mace. For deep roots, post-heading biomass growth was observed for both genotypes in well-watered conditions, while under moderate water stress, only Scout maintained net growth as Mace deep roots senesced. Water stress of severe intensity affected both genotypes similarly, with root senescence at all depths. Senescence was also observed above ground. Under well-watered conditions, Scout retained leaf greenness (i.e. stay-green phenotype) for slightly longer than Mace. The difference between genotypes accentuated under moderate water stress, with rapid post-anthesis leaf senescence in Mace while Scout leaf greenness was affected little if at all by the stress. As an overall result, grain biomass per plant (\'yield\') was similar in the two genotypes under well-watered conditions, but more affected by a moderate stress in Mace than Scout. The findings from this study will assist improvement in modelling root systems of crop models, development of relevant phenotyping methods and selection of cultivars with better adaptation to drought.
摘要：
在像小麦这样的作物中，最终干旱是限制雨养系统生产力的主要胁迫因素之一。然而,对抽穗后的根系发育知之甚少，当水分吸收对小麦作物至关重要时。在两个小麦品种中研究了水分胁迫对根系生长的影响，童子军和梅斯,在三个实验中，在充分浇水和花后水分胁迫下。植物在1.5m长的盆中生长，密度与当地推荐的耕作方式相似。在基因型之间观察到根发育的差异，特别是在水分胁迫条件下，Scout发育并维持了比Mace更大的根系。虽然在水分充足的条件下，两种基因型都有浅根，在抽穗后似乎衰老，适度的水分胁迫刺激了Scout的浅根生长，但加速了Mace的衰老。对于深深的根源，在水分充足的条件下观察到两种基因型的抽穗后生物量生长，在中等水分胁迫下，只有Scout在Mace深根开始时保持净增长。严重强度的水分胁迫对两种基因型的影响相似，在所有深度都有根衰老。在地面上也观察到衰老。在水分充足的条件下，Scout保持叶绿色（即保持绿色表型）的时间比Mace稍长。在中度水分胁迫下，基因型之间的差异加剧，梅斯的花后叶片迅速衰老，而Scout的叶片绿色几乎不受胁迫的影响。作为一个整体的结果,在灌溉良好的条件下，两种基因型的单株谷物生物量（“产量”）相似，但受梅斯适度压力的影响比Scout更大。这项研究的结果将有助于改进作物模型的根系建模，相关表型方法的发展和对干旱适应性更好的品种的选择。
