Root Length and Its Relationship to Root Plasticity and Root Life-Span

根长与根干重之比（比根长 SRL）在植物物种之间变化很大。 由于水和养分 吸收受根长的影响大于根质量， 较高SRL可能更有效地投资其根系生物量 低SRL的物种。 然而，一个更全面的成本分析， 必须包括根的寿命。 物种构建 细根（高SRL）可能倾向于在有利条件下增殖根 土壤体积和脱落的根在不利的土壤体积更多 比粗根（低SRL）的物种更容易。 因此 高SRL根的短期效率可能被较高的 与较高的根周转率相关的成本。 这项建议 测试SRL与根可塑性和根寿命的关系- 通过使用插入透明管中的微型摄像机来跨越 埋在地里 柑橘砧木试验， 有着基因多样的根系， 相同的芽，将作为模型植物系统。 这项研究将提供有关影响因素的信息， 根的死亡和周转，以及如何洞察 根特征的种间差异可能影响 养分和水分的获取，根的周转，以及，最终， 工厂生产力。 在植物育种中，选择基于 很少研究具体的根性状。 虽然柑橘 砧木试验是一个很好的模式系统， 研究根系特征和根系之间的基本关系 周转率，所获得的信息也有直接的实际意义 应用，因为研究中的砧木都是 经济重要性。 此外，这些信息将 对生态系统模型很有价值， 估计全球气候变化，因为根周转是一个主要的 排放到大气中的二氧化碳的来源。

The ratio of root length to root dry weight (specific root length SRL) varies widely among plant species. Since water and nutrient uptake is influenced more by root length than mass, species of high SRL may appear to invest their root biomass more efficiently than species of low SRL. A more complete cost-analysis, however, must include the life-span of the root. Species that construct fine roots (high SRL) may tend to proliferate roots in favorable volumes of soil and shed roots in unfavorable soil volumes more readily than species with coarse roots (low SRL). Thus, the short-term efficiency of high SRL roots may be offset by higher costs associated with higher root turnover rates. This proposal tests the relationship of SRL to root plasticity and root life- span by using a microvideo camera inserted into transparent tubes buried in the ground in the field. A citrus rootstock trial, with genetically diverse root systems grafted to genetically identical shoots, will serve as the model plant system. This study will provide information on factors that influence root death and turnover as well as insights into how interspecific differences in root characteristics may influence nutrient and water acquisition, root turnover, and, ultimately, plant productivity. In plant breeding, selection based on specific root traits is seldom undertaken. While the citrus rootstock trial serves as an excellent model system with which to examine basic relationships between root characteristics and root turnover rates, the information gained also has direct practical applications, since the rootstocks in the study are all of economic importance. Additionally, this information will be valuable for ecosystem models that are being used to help estimate global climate change, since root turnover is a major source of carbon dioxide efflux into the atmosphere.