Beyer Marco, Peschel Stefanie, Weichert Holger, Knoche Moritz
Institute for Agronomy and Crop Science, Department of Horticulture, Martin-Luther University Halle-Wittenberg, D-06099 Halle (Saale), Germany.
J Agric Food Chem. 2002 Dec 18;50(26):7600-8. doi: 10.1021/jf020441x.
The effects of the chloride salts LiCl, CaCl(2), MgCl(2), AlCl(3), EuCl(3), and FeCl(3) and the iron salts FeCl(2), FeCl(3), Fe(NO(3))(3), FeSO(4), and Fe(2)(SO(4))(3) on water conductance of exocarp segments (ES) and rates of water uptake into detached sweet cherry fruit (Prunus avium L. cv. Adriana, Early Rivers, Namare, Namosa, and Sam) were studied. ES were excised from the cheek of mature fruit and mounted in stainless steel diffusion cell; water penetration was monitored gravimetrically from donor solutions containing the above mineral salts into a PEG 6000 (osmolality = 1.14 osM, pH 4.8, 25 degrees C) receiver solution. Conductance of ES was calculated from the amount of water taken up per unit of surface area and time by dividing by the gradient in water activity across ES. LiCl, CaCl(2), MgCl(2), FeCl(2), and FeSO(4) had no significant effect on conductance, but AlCl(3), FeCl(3), Fe(NO(3))(3), and Fe(2)(SO(4))(3) significantly reduced conductance compared to water only as a donor. Also, EuCl(3) lowered conductance; however, this effect was not always significant. Effects of salts on water conductance of ES and rates of water uptake into detached fruit were closely related (R 2 = 0.97***). Upon application of an FeCl(3)-containing donor conductance decreased instantaneously. FeCl(3) concentrations of <6.6 x 10(-)(4) M had no effect on conductance, but concentrations at or above this threshold decreased conductance. FeCl(3) lowered water conductance at a receiver pH of 4.8, but not at pH < or =2.6. The effect of FeCl(3) on conductance was largest in cv. Namare and smallest in cv. Adriana. There was no significant effect of FeCl(3) on conductance for transpiration. Formation of aluminum and iron oxides and hydroxides in the exocarp as a result of a pH gradient between donor and receiver solution is discussed as the potential mechanism for Fe(3+) and Al(3+) reducing conductance for water uptake.
研究了氯化物盐LiCl、CaCl₂、MgCl₂、AlCl₃、EuCl₃和FeCl₃以及铁盐FeCl₂、FeCl₃、Fe(NO₃)₃、FeSO₄和Fe₂(SO₄)₃对樱桃外果皮段（ES）水分传导率以及离体甜樱桃果实（Prunus avium L. cv. Adriana、Early Rivers、Namare、Namosa和Sam）水分吸收速率的影响。从成熟果实的侧面切下ES并安装在不锈钢扩散池中；通过重量法监测从含有上述矿物盐的供体溶液到PEG 6000（渗透压=1.14 osM，pH 4.8，25℃）受体溶液中的水分渗透。ES的传导率通过单位表面积和时间内吸收的水量除以ES两侧水分活度梯度来计算。LiCl、CaCl₂、MgCl₂、FeCl₂和FeSO₄对传导率没有显著影响，但与仅以水作为供体相比，AlCl₃、FeCl₃、Fe(NO₃)₃和Fe₂(SO₄)₃显著降低了传导率。此外，EuCl₃降低了传导率；然而，这种影响并不总是显著的。盐对ES水分传导率和离体果实水分吸收速率的影响密切相关（R² = 0.97***）。施加含FeCl₃的供体后，传导率立即下降。FeCl₃浓度<6.6×10⁻⁴ M对传导率没有影响，但达到或高于此阈值的浓度会降低传导率。FeCl₃在受体pH为4.8时降低水分传导率，但在pH≤2.6时则不会。FeCl₃对传导率的影响在Namare品种中最大，在Adriana品种中最小。FeCl₃对蒸腾作用的传导率没有显著影响。讨论了由于供体和受体溶液之间的pH梯度在外果皮中形成铝和铁的氧化物及氢氧化物，这是Fe³⁺和Al³⁺降低水分吸收传导率的潜在机制。
