Katholieke Universiteit Leuven, Dept. of Earth and Environmental Sciences, 3000 Leuven, Belgium; and Corresponding author. Email:
International Potato Center (CIP), PO Box 1269, Kigali, Rwanda; and Africa Rice Center (AfricaRice), PO Box 33581, Dar es Salaam, Tanzania.
Funct Plant Biol. 2019 Oct;46(11):1009-1022. doi: 10.1071/FP19002.
Drought and low P availability are major limitations for rainfed rice (Oryza spp.) production. Root anatomy plays a key role in resource acquisition and tolerance to P and water limitations. Root anatomical responses of three contrasting rice varieties to combinations of different levels of P (deficient to non-limiting) and water availability (water stress to submergence) were evaluated in two pot trials. P availability was the dominant growth-limiting factor, but anatomical root responses to water availability were more prominent than responses to P availability. Cortical cell file number and number of xylem vessels decreased as a response to water stress, but stele and xylem diameter increased. Low P availability induced thinner xylem vessels and a thinner stele. Drought tolerance related to an overall thicker root stele, thicker xylem vessels and a larger water conductance. Some root traits were observed to be more responsive to water and P availability, whereas other traits were more robust to these environmental factors but highly determined by variety. The observed genotypic variation in root anatomy provides opportunities for trait-based breeding. The plasticity of several traits to multiple environmental factors highlights the need for strategic trait selection or breeding adapted to specific target environments.
干旱和低磷供应是雨养水稻（Oryza spp.）生产的主要限制因素。根系解剖结构在资源获取和对磷和水分限制的耐受中起着关键作用。在两项盆栽试验中，评估了三个不同水稻品种对不同水平磷（缺磷到非限制）和水分供应（水分胁迫到淹没）组合的根系解剖结构响应。磷供应是主要的生长限制因素，但对水分供应的根系解剖结构响应比对磷供应的响应更为突出。皮层细胞层数和木质部导管数量随着水分胁迫而减少，但中柱和木质部直径增加。低磷供应导致木质部导管变薄，中柱变细。耐旱性与整体较厚的根中柱、较厚的木质部导管和较大的水分传导率有关。一些根系特征对水和磷供应更敏感，而其他特征对这些环境因素更稳健，但高度由品种决定。观察到的根系解剖结构的基因型变异为基于特征的育种提供了机会。几种性状对多种环境因素的可塑性突出表明需要进行有策略的性状选择或培育适应特定目标环境的品种。
