■由于预计降水模式将变得越来越不稳定,温带森林的功能维护是森林管理者面临的关键挑战。在这项研究中,选择了2年大的麻树幼苗,以阐明它们对土壤水分波动和干旱硬化对植物碳水化合物动力学的影响的响应机制。
■在不同的土壤水分条件下训练幼苗2个月:干旱(D),充分浇水(W),1个月干旱,然后1个月水分充足(D-W),和1个月的水分充足,然后是1个月的干旱(W-D)。在硬化期结束时,探索了水和碳利用策略中涉及的功能特征。与W组幼苗相比,D组幼苗,D-W,和W-D增加了碳吸收的潜力(即,光饱和点,最大核酮糖-1,5-二磷酸(RuBP)饱和率,和电子传输速率)和吸水(即,细根与粗根的比率)和下调的生长和线粒体呼吸以减少碳消耗。水波动硬化后,我们进行了1个月的连续干燥实验,以检测碳水化合物动力学,并探索预先硬化引起的适应。
■我们的结果表明,在D硬化的幼苗中,叶片中分配了更多的可溶性糖,茎和根中分配了更多的淀粉,W-D,D-W处理比W处理中硬化的幼苗。未发现总非结构性碳水化合物的显着变化。此外,在干燥实验结束时,我们发现结构生物量的生长接近零(通过D和D-W处理训练的幼苗)或负(通过W-D处理训练的幼苗),显著低于W硬化幼苗。这表明,在反复发生的土壤干旱下,碳储存和生长之间的分配模式发生了变化,可以通过干旱记忆来加强。我们得出的结论是,Q.麻酸幼苗根据水分波动调整了水和碳的利用策略,而压力记忆可以增强他们在再次发生干旱中的整体表现。因此,利用压力记忆是森林苗圃中一个很有前途的管理策略,和干旱训练的幼苗可能更适合在以土壤含水量波动为特征的地点进行造林实践,考虑到正在进行的全球气候变化。
UNASSIGNED: As precipitation patterns are predicted to become increasingly erratic, the functional maintenance of warm-temperate forests constitutes a key challenge for forest managers. In this study, 2-year-old Quercus acutissima seedlings were selected to elucidate the mechanisms whereby they respond to soil water fluctuations and the drought hardening effects on plant carbohydrate dynamics.
UNASSIGNED: Seedlings were trained under different soil water conditions for 2 months: drought (D), well-watered (W), 1-month drought and then 1-month well-watered (D-W), and 1-month well-watered and then 1-month drought (W-D). The functional traits involved in water- and carbon-use strategies were explored at the end of the hardening period. Compared with seedlings in group W, seedlings in groups D, D-W, and W-D had increased potential for carbon uptake (i.e., light saturated point, maximum ribulose-1,5-bisphosphate (RuBP) saturated rate, and electron transport rate) and water uptake (i.e., fine root-to-coarse root ratio) and downregulated growth and mitochondrial respiration to decrease carbon consumption. After water fluctuation hardening, we performed a successional dry-down experiment for 1 month to detect carbohydrate dynamics and explore the acclimation caused by prior hardening.
UNASSIGNED: Our results revealed that there were more soluble sugars allocated in the leaves and more starch allocated in the stems and roots of seedlings hardened in the D, W-D, and D-W treatments than that of seedlings hardened in the W treatment. No significant changes in total non-structural carbohydrates were found. In addition, we found near-zero (seedlings trained by D and D-W treatments) or negative (seedlings trained by W-D treatment) growth of structural biomass at the end of the dry-down experiment, which was significantly lower than that of W-hardened seedlings. This suggests that there was a shift in allocation patterns between carbon storage and growth under recurrent soil drought, which can be strengthened by drought memory. We conclude that Q. acutissima seedlings adjusted water- and carbon-use strategies in response to water fluctuations, whereas stress memory can enhance their overall performance in reoccurring drought. Therefore, taking advantage of stress memory is a promising management strategy in forest nurseries, and drought-trained seedlings might be more suitable for afforestation practices in sites characterized by fluctuating soil water content, considering the ongoing global climatic changes.