Atta Alisheikh A, Morgan Kelly T, Hamido Said A, Kadyampakeni Davie M
Southwest Florida Research and Education Center, University of Florida, 2685 SR 29 N, Immokalee, FL 34142, USA.
Citrus Research and Education Center, 700 Experiment Station Rd, Lake Alfred, FL 33850, USA.
Plants (Basel). 2020 Apr 9;9(4):483. doi: 10.3390/plants9040483.
Understanding citrus tree root development and dynamics are critical in determining crop best nutrient management practices. The role of calcium (Ca) and magnesium (Mg), manganese (Mn), Zinc (Zn), and boron (B) on huanglongbing (HLB) affected citrus trees' root growth and lifespan in Florida is not fully documented. Thus, the objective of this study was to determine the impact of foliar and ground-applied essential nutrients on seasonal fine root length density (FRLD; diameter (d) < 2 mm) and coarse roots (d > 2 mm), FRLD dynamics, root survival probability (lifespan), and root-zone soil pH of HLB-affected sweet orange trees. Results indicated that Ca treated trees budded on Cleopatra (Cleo) and Ca and Mg combined treatments on Swingle (Swc) rootstocks significantly increased seasonal FRLD of fine (< 2 mm) and coarse roots. The highest median root lifespan of Ca treated trees was 325 and 339 days for trees budded on Cleo and Swc rootstocks, respectively. In the second study, the coarse roots showed a significantly higher reaction to the nutrition applied than the fine roots. Meanwhile, the 2× (1× foliar and 1× ground-applied) treated trees showed a significantly higher median root lifespan compared to the other treatments. Thus, the current study unwraps future studies highlighting the combined soil and/or foliar application of the above nutrients to stimulate FRLD and improve root lifespan on HLB-affected sweet oranges with emphasis on root-zone soil pH.
了解柑橘树根的发育和动态对于确定作物最佳养分管理实践至关重要。钙（Ca）、镁（Mg）、锰（Mn）、锌（Zn）和硼（B）对佛罗里达州受黄龙病（HLB）影响的柑橘树根生长和寿命的作用尚未得到充分记录。因此，本研究的目的是确定叶面喷施和地面施用必需养分对受HLB影响的甜橙树的季节性细根长度密度（FRLD；直径（d）<2毫米）和粗根（d>2毫米）、FRLD动态、根存活概率（寿命）以及根际土壤pH值的影响。结果表明，在克利奥帕特拉（Cleo）砧木上进行钙处理的树以及在斯温格尔（Swc）砧木上进行钙和镁联合处理的树，细根（<2毫米）和粗根的季节性FRLD显著增加。钙处理树的最高中位根寿命分别为：在Cleo砧木上的树为325天，在Swc砧木上的树为339天。在第二项研究中，粗根对施用的养分的反应明显高于细根。同时，与其他处理相比，2倍（1倍叶面喷施和1倍地面施用）处理的树中位根寿命显著更高。因此，本研究为未来的研究指明方向，强调通过土壤和/或叶面联合施用上述养分来刺激FRLD并提高受HLB影响的甜橙的根寿命，重点关注根际土壤pH值。
