Lawrence Brian T, Melgar Juan Carlos
Department of Plant and Environmental Sciences, Clemson University, Clemson, SC, United States.
Front Plant Sci. 2018 Dec 17;9:1819. doi: 10.3389/fpls.2018.01819. eCollection 2018.
A delay of leaf senescence resulting from variable fall climate may allow for additional nutrient resorption, and storage within reserve organs. Autumn leaves and reserve organs (<1 year shoots, >1 year shoots, stem above and below the graft union, the tap root, and fine roots) during dormancy of young peach trees were evaluated following warmer fall temperatures and limited soil moisture on two cultivars ('Scarletprince' and 'Autumnprince' both on Guardian rootstock) over two seasons. Four treatments were established for the two cultivars: (1) well-watered trees (100% ET needs) in ambient outdoor temperatures; (2) water deficient trees (50% ET needs) in ambient outdoor temperatures; (3) well-watered trees grown within a greenhouse; and (4) water deficient trees within a greenhouse. The greenhouse environment was on average 5°C warmer than the ambient outdoor temperature. Senescence was delayed on greenhouse-grown trees both years with leaf number and area similar in the greenhouse and outdoor environments prior to senescence. Across leaf samples, leaf nitrogen and phosphorus concentrations were lower within delayed senescence tree leaves while potassium was lower in leaves experiencing normal senescence. During dormancy, multiple reserve organs showed higher nitrogen, phosphorus, and potassium in trees with delayed senescence than normal senescence and similar increases were observed in water-deficient trees compared to well-watered trees. Phosphorus and potassium concentrations were also higher in multiple reserve organs within 'Autumnprince' trees compared to 'Scarletprince' trees. This study suggests variable climate conditions of increased temperatures or reduced soil moisture during autumn resulting in delayed senescence influence the process of nutrient resorption and increase nutrient storage within reserve organs.
秋季气候多变导致叶片衰老延迟，这可能会使树木有更多时间进行养分再吸收，并将养分储存在储备器官中。在两个生长季中，研究人员对两个品种（均为嫁接到“守护者”砧木上的“猩红王子”和“秋王子”）的幼龄桃树在秋季温度较高且土壤水分有限的情况下，休眠期的秋叶和储备器官（1年生以下枝条、1年生以上枝条、嫁接部位上下的树干、主根和细根）进行了评估。针对这两个品种设置了四种处理方式：（1）室外环境中水分充足的树木（满足100%蒸发散需求）；（2）室外环境中水分不足的树木（满足50%蒸发散需求）；（3）温室中水分充足的树木；（4）温室中水分不足的树木。温室环境平均比室外环境温度高5°C。两年里，温室中生长的树木叶片衰老均延迟，衰老前温室和室外环境中的叶片数量和面积相似。在所有叶片样本中，衰老延迟的树木叶片中氮和磷的浓度较低，而正常衰老的叶片中钾的浓度较低。在休眠期，多个储备器官中，衰老延迟的树木比正常衰老的树木氮、磷和钾含量更高，与水分充足的树木相比，水分不足的树木也观察到了类似的增加。与“猩红王子”树相比，“秋王子”树的多个储备器官中磷和钾的浓度也更高。这项研究表明，秋季气温升高或土壤水分减少等多变的气候条件导致叶片衰老延迟，会影响养分再吸收过程，并增加储备器官中的养分储存。
