Factors Affecting Root Life-Span in Citrus

在一系列生态系统中，地下的年生物量产量大于地上。尽管根系生物量产量巨大，但关于影响根系死亡的因素的信息却非常少。根系碳成本可分为用于根系建设的碳成本和用于根系维持的碳成本。维持呼吸作用可以在短短两到三周内超过根系建设的总成本，而许多物种的根系平均寿命为八个月或更长。因此，植物需要在长寿命根和高寿命维护成本之间进行权衡，而短寿命根需要更频繁地构建，但寿命维护成本较低。我们预测具有高比根长（SRL；根长/质量）的小直径根的物种可能比低比根长的物种有更高的维持呼吸成本，这可能反过来影响根的寿命。此外，当土壤温度升高引起维持呼吸增加时，根系寿命可能会缩短。在不同土壤湿度、土壤温度和SRL条件下，将对盆栽中单根和全根系统的根系维持呼吸和根系寿命进行研究，以验证这些预测。这项工作对于更好地理解气候变化对全球二氧化碳可持续农业和植物生长的影响具有重要意义。＊＊＊

9306872 Eissenstat In a range of ecosystems, there is greater annual biomass productionbelow ground than aboveground. In spite of the magnitude of root biomass production, there is extremely little information on factors influencing root death. Root carbon costs can be divided into that used for root construction and that used for root maintenance. Maintenance respiration can exceed the total cost of root construction in as little as two to three weeks, whereas roots of many species live an average of eight months or longer. Thus, plants experience a tradeoff between having long-lived roots and paying high lifetime maintenance costs vs. shorter lived roots that need to be constructed more often but with lower lifetime maintenance costs. We predict that species with small diameter roots of high specific root length (SRL; root length/mass) may have higher maintenance respiration costs than species of low SRL, which may in turn affect root- life span. Furthermore, when maintenance respiration increases, as caused by increases in soil temperature, root- life span may decrease. Root maintenance respiration and root life-span of individual roots and whole-root systems in pots will be examined to test these prediction in a combination of controlled laboratory under conditions where soil moisture, soil temperature and SRL are varied. This work has important implications for better understanding the effects of climate change on global CO2 sustainable agriculture and plant growth in general. ***