Abstract

Under dry and warm environmental conditions, the main Tunisian pistachio cultivar Mateur does not show a normal ‘On/Off’ cycle with highly variable nut yield, which could be affected by the tree nutritional status. In this context, Potassium (K) is considered a key nutritional element for nut development and for yield. The current study investigated the effects of alternate bearing and flower bud removal on seasonal dynamics of potassium in fruiting and non-fruiting branches of mature pistachio trees (cv. Mateur) in arid land. Three disbudding treatments were considered in reference to untreated trees taken as a control (T₀): removal of all flower buds for one year (T₁), or two successive years (T₂) and removal of 50% of flower buds each year (T₃). Similar K concentrations were detected early in the season in leaves, current shoot and one-year-old wood for all treatments. Current shoot begin the cycle with higher K concentrations, which declined during the lignification of endocarp and seed growth stages to finally accumulate K during postharvest. Inversely, one-year-old wood stored a large amount of K during the stage I and II of nut development, and became the main sink for K of the bearing shoot. Leaf K concentration explained 75% of yield variation. Yearly removal of 50% of flower buds induced less variation of leaf K concentrations (ranged between 0.5-0.8% DM) with regular nut yield compared to bi-annual On-Off cycle. Thus, under severe climatic conditions, the annual pruning could be applied to improve the nutritional status of pistachio trees.

摘要

在干燥和温暖的环境条件下，突尼斯开心果的主要品种 Mateur 没有表现出正常的“开/关”循环，坚果产量变化很大，这可能会受到树木营养状况的影响。在这种情况下，钾 (K) 被认为是坚果发育和产量的关键营养元素。目前的研究调查了交替生育和去除花蕾对干旱地区成熟开心果树 ( cv. Mateur)果枝和非果枝中钾的季节性动态的影响。参照未处理的树木作为对照（T ₀），考虑了三种脱芽处理：去除所有花蕾一年（T ₁）或连续两年（T ₂) 和每年去除 50% 的花蕾 (T ₃）。对于所有处理，在本季早期在叶子、当前枝条和一年生木材中检测到类似的 K 浓度。当前的芽以较高的钾浓度开始循环，在内果皮的木质化和种子生长阶段下降，最终在收获后积累钾。相反，一年生木在坚果发育的I和II期储存了大量的K，成为承重枝K的主要库。叶钾浓度解释了 75% 的产量变化。与两年一次的开关周期相比，每年去除 50% 的花蕾会导致叶片 K 浓度（范围在 0.5-0.8% DM 之间）的变化较小，坚果产量正常。因此，在恶劣的气候条件下，每年修剪可用于改善开心果树的营养状况。