Xylem, phloem, and transpiration flows in developing sweet cherry fruit
Xylem, phloem, and transpiration flows in developing sweet cherry fruit
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DOI：
10.1007/s00468-016-1415-4
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发表时间：
2016-10-01
影响因子：
2.3
通讯作者：
Knoche, Moritz
中科院分区：
文献类型：
--
作者：
Brueggenwirth, Martin;Winkler, Andreas;Knoche, Moritz
在韧皮部的流量增加发展甜樱桃，而木质部流量不断下降，导致在水果的水势是独立的树在水果maturity.Rain开裂的甜樱桃果实是与通过皮肤的水分吸收，但也可能通过血管的花梗。本研究的目的是量化的木质部，韧皮部和蒸腾作用的整体水分平衡的发展甜樱桃果实的贡献。使用线性可变位移传感器，水果直径的变化进行了监测，在未经处理的对照水果，水果的花梗已被蒸汽环带，水果的花梗已被切断（这些水果被分离，但留在原位在树冠）。果实体积随时间的变化推断从测量直径的变化。花梗木质部和韧皮部液流速率，和水果蒸腾速率，推断从水果体积的变化。日韧皮部流量低，在第二阶段（阶段的坑发展），但显着增加，在第三阶段（阶段的细胞扩大在肉）。木质部流量超过韧皮部流量在第二阶段，但不断下降，在第三阶段收获时几乎为零。蒸腾流基本上反映了木质部流在第二阶段，但超过木质部流在第三阶段。蒸腾流量与水汽压亏缺密切相关。韧皮部流动与单位时间内果实干重的增加呈线性相关。数据显示，在整个第三阶段木质部液流减少，导致在一个水的潜力，从树的成熟果实隔离。这种隔离将防止含糖果肉对木质部水的不受控制的渗透吸收和木质部中从果实到树的假定回流。
Flow in the phloem increased in developing sweet cherry, whereas xylem flow continuously decreased resulting in a fruit water potential that was independent from the tree at fruit maturity.Rain cracking of sweet cherry fruit is associated with water uptake through the skin, but probably also through the vasculature of the pedicel. The aim of this study was to quantify the xylem, phloem, and transpiration contributions to the overall water balance of developing sweet cherry fruit. Using linear variable displacement transducers, changes in fruit diameter were monitored in untreated control fruit, fruit whose pedicels had been steam-girdled, and fruit whose pedicels had been cut through (these fruits were detached, but remained in situ in the canopy). Fruit volume changes with time were inferred from the measured diameter changes. Pedicel xylem and phloem sap-flow rates, and fruit transpiration rates, were inferred from fruit volume changes. Daily phloem flows were low during stage II (phase of pit development), but markedly increased in stage III (phase of cell enlargement in flesh). Xylem flows exceeded phloem flows in stage II, but decreased continuously in stage III to nearly zero at harvest. Transpiration flow essentially mirrored xylem flow in stage II, but exceeded xylem flow in stage III. Transpiration flow was closely related to the water vapour pressure deficit. Phloem flow was linearly related to the increase in fruit dry mass per-unit time. The data reveal a decrease in xylem sap flow throughout stage III resulting in a water-potential isolation of the mature fruit from the tree. Such isolation would prevent uncontrolled osmotic uptake of xylem water by the sugary flesh and a putative backflow in the xylem from fruit to tree.