Department of Agrotechnology Science, Chihuahua State University, Escorza 900, P.O. Box 31300, Chihuahua, Mexico.
J Sci Food Agric. 2012 Jun;92(8):1672-8. doi: 10.1002/jsfa.5530. Epub 2012 Jan 6.
Zinc (Zn) deficiency is a typical nutritional disorder in pecan trees [Carya illinoinensis (Wangenh.) C. Koch] grown under field conditions in calcareous soils in North America, including northern Mexico and south-western United States. The aim of this study was to assess the morphological and nutritional changes in pecan leaves affected by Zn deficiency as well as the Zn distribution within leaves.
Zinc deficiency led to decreases in leaf chlorophyll concentrations, leaf area and trunk cross-sectional area. Zinc deficiency increased significantly the leaf concentrations of K and Ca, and decreased the leaf concentrations of Zn, Fe, Mn and Cu. All nutrient values found in Zn-deficient leaves were within the sufficiency ranges, with the only exception of Zn, which was approximately 44, 11 and 9 µg g(-1) dry weight in Zn-sufficient, moderately and markedly Zn-deficient leaves, respectively. Zinc deficiency led to decreases in leaf thickness, mainly due to a reduction in the thickness of the palisade parenchyma, as well as to increases in stomatal density and size. The localisation of Zn was determined using the fluorophore Zinpyr-1 and ratio-imaging technique. Zinc was mainly localised in the palisade mesophyll area in Zn-sufficient leaves, whereas no signal could be obtained in Zn-deficient leaves.
The effects of Zn deficiency on the leaf characteristics of pecan trees include not only decreases in leaf chlorophyll and Zn concentrations, but also a reduction in the thickness of the palisade parenchyma, an increase in stomatal density and pore size and the practical disappearance of Zn leaf pools. These characteristics must be taken into account to design strategies to correct Zn deficiency in pecan tree in the field.
在北美钙质土壤条件下，尤其是在墨西哥北部和美国西南部，田间种植的山核桃树[Carya illinoinensis (Wangenh.) C. Koch]容易缺锌。本研究旨在评估缺锌对山核桃叶片形态和营养的影响，以及叶片内锌的分布。
缺锌导致叶片叶绿素浓度、叶面积和树干横截面积下降。缺锌显著增加了叶片中 K 和 Ca 的浓度，降低了叶片中 Zn、Fe、Mn 和 Cu 的浓度。所有在缺锌叶片中发现的养分值都在充足范围内，只有 Zn 是个例外，在 Zn 充足、中度缺锌和重度缺锌叶片中，Zn 的含量分别约为 44、11 和 9 µg g(-1)干重。缺锌导致叶片厚度减小，主要是由于栅栏组织变薄，同时气孔密度和大小增加。使用荧光探针 Zinpyr-1 和比率成像技术来确定 Zn 的定位。在 Zn 充足的叶片中，Zn 主要定位于栅栏组织区，而在缺锌叶片中则检测不到信号。
缺锌对山核桃叶片特征的影响不仅包括叶片叶绿素和 Zn 浓度降低，还包括栅栏组织厚度减小、气孔密度和孔径增大以及 Zn 叶片库的实际消失。在田间设计纠正山核桃缺锌的策略时，必须考虑到这些特征。
