Quantification of carbon-water dynamics in soil-perennial grass (Bothriochloa ischaemum) feedbacks under drought stress following a double isotope-labelled pulse experiment
Quantification of carbon-water dynamics in soil-perennial grass (Bothriochloa ischaemum) feedbacks under drought stress following a double isotope-labelled pulse experiment
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DOI：
10.1016/j.agrformet.2022.109270
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发表时间：
2023-02
影响因子：
6.2
通讯作者：
Y. Liu;Peng Li;Yunxia Wang;Xiaoyan Xu
中科院分区：
文献类型：
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作者：
Y. Liu;Peng Li;Yunxia Wang;Xiaoyan Xu
目前的研究利用整个植物或特定器官的参数来描述植物的光合作用和水力过程。草地生态系统干旱响应中碳和水资源消耗及植物器官间耦合的定量研究尚不清楚，但对预测碳和水耦合过程具有重要意义。在对照（CK）、轻度胁迫（MS）和重度胁迫（SS） 3种干旱处理下，选取13c - 18o脉冲标记后0、6、24、48、216和360 h为样本，测定了水分输送参数与叶片、茎、枝和根碳分配的相关性。结果表明：(1)根系、土壤和根际土壤中13c的总和均高于根系呼吸的13c量。土壤中碳储量与呼吸量之比显著低于对照，说明地下草土系统是碳汇而非碳源。(2)施用180o标记水216 h后，MS处理植株地上部分180o标记水的比例高达60%，显著高于SS处理（36.5%）和CK处理（45.9%）。轻度干旱胁迫下根系密度主要分布在0 ~ 15 cm土层。这两个结果都表明，禾草对轻度干旱的响应是通过增加表层土壤根系密度来吸收土壤水分，并提高植物地上部分的水分转运比。(3)双标试验期间，轻度干旱条件下根系13c积累与18o消耗之比显著高于其他处理。干旱条件下，老叶和老茎的这些比值显著低于对照处理，说明b。在轻度干旱胁迫下，植物根系碳和水分利用增加，老叶和老茎碳和水分利用减少。
Current studies have described photosynthetic and hydraulic processes in plants using parameters from the whole plant or particular organs. Quantification of carbon and water resource consumption and coupling between plant organs is poorly understood but important for predicting carbon and water coupled processes in grassland ecosystem drought responses. We determined the correlations between water transport parameters and carbon allocation in leaves, stems, branches, and roots of the grassBothriochloa ischaemum, sampled 0, 6, 24, 48, 216, and 360 h after13C-18O pulse-labeling under three drought treatments: control (CK), mild stress (MS) and serious stress (SS). We found that: (1) The sum of13C in roots, soil, and rhizosphere soil was higher than the amount of13C respired by roots under all treatments. The ratio of stored to respired13C in the SS had a significantly lower than CK, indicating that the underground grass-soil system was a carbon sink rather than a carbon source. (2) 216 h after the application of18O-labeled water, the proportion of18O-labeled water in the aboveground portion of plants was up to 60% under MS, significantly greater than under SS (36.5%) and under CK (45.9%). Root density was mainly distributed in the 0–15 cm soil layer under mild drought stress. Both results suggest that grasses respond to mild drought by increasing topsoil root density to absorb soil water and improve the water transfer ratio to the aboveground portion of the plants. (3) During the double-labeling experiment, the ratio of13C accumulated to18O consumed in roots under mild drought was significantly higher than in other treatments. In contrast, these ratios in old leaves and stems under drought were significantly lower than in the control treatment, indicating thatB.ischaemumexperiences a trade-off between increasing root carbon and water utilization and reducing old leaf and stem carbon and water utilization under mild drought stress.