沃柑日灼果皮结构和生理生化指标观测分析

胡艺帆 葛聪聪 李凤琪 邱发发 黄世炎 韦杰 黄桂香

摘要：【目的】探究沃柑日灼的果皮形態和相关指标变化，初步明确沃柑日灼的生理机制，为防控柑橘日灼提供一定的理论依据。【方法】以5年生香橙砧沃柑为试材，以正常果为对照，对日灼的沃柑果皮进行石蜡切片与扫描电镜观察，测定果皮可溶性蛋白质及营养元素含量、酶活性及叶片的蒸腾速率、叶绿素，分析其变化规律。【结果】随着沃柑日灼加重，果皮表面油胞逐渐扩张破裂形成沟壑，灼伤部位从黄皮层到白皮层逐渐破裂，果皮可溶性蛋白质含量降低;沃柑发生日灼后，其叶片蒸腾速率增高、叶绿素含量降低;果皮中K、Ca、Cu和Zn的含量分别显著减少2.22 mg/g、1.95 mg/g、2.22%和9.84%（绝对值）（P<0.05），超氧阴离子（O2-）和丙二醛（MDA）含量分别上升85.5%和55.2%，过氧化氢酶（CAT）、过氧化物酶（POD）和多酚氧化酶（PPO）活性分别上升74.7%、64.2%和45.1%，超氧化物歧化酶（SOD）活性下降44.6%。【结论】沃柑果实随着日灼程度加重，对果皮细胞的保护能力下降;抵御外界光、热胁迫能力降低。因此，防控柑橘日灼可从增施水肥、补充所缺营养元素、降低叶片蒸腾速率、保护果皮及适当留晚夏梢等方面综合考虑。

关键词： 沃柑;日灼;果皮结构;生理生化指标

中图分类号： S666.101                       文献标志码： A 文章编号：2095-1191（2021）08-2220-07

Observation and analysis of pericarp structure，physiological and biochemical indexes of sunburn orah

HU Yi-fan1，2， GE Cong-cong1， LI Feng-qi1， QIU Fa-fa1， HUANG Shi-yan1，

WEI Jie1， HUANG Gui-xiang1*

（1National Demonstration Center for Experimental Plant Science Education， Department of Horticulture，

College of Agriculture， Guangxi University ， Nanning  530004， China; 2Guangxi Subtropical

Crops Research Institute， Nanning  530001， China）

Abstract：【Objective】In order to explore the changes of peel morphology and related indexes of orah sunburn fruits， the physiological mechanism of orah sunburn was preliminarily clarified to provide a theoretical basis for the prevention and control of citrus sunburn. 【Method】Five-year-old orange-rootstock orah was as material， and normal fruits were as control. Sunburn orah fruits peels were measured by means of paraffin sectioning and scanning electron microscope. The contents of soluble protein， nutrient elements， enzyme activity， leaf transpiration rate and chlorophyll in the pericarp were detected and the law of change was analyzed. 【Result】With the aggravation of orah sunburn， the oil cells on the pericarp surface gradually expanded and ruptured to form gullies， the burn site gradually ruptured from yellow skin layer to white skin layer， and the content of soluble protein in pericarp decreased. After sunburn， leaf transpiration rate increased and chlorophyll decreased. After sun burning， the contents of K，CA，Cu and Zn in peel of orah were significantly reduced by 2.22 mg/g， 1.95 mg/g， 2.22% and 9.84%（absolute value）， respectively（P<0.05）. While the contents of superoxide anion（O2-） and malondialdehyde（MDA） increased by 85.5% and 55.2%， activities of catalase（CAT） and peroxidase（POD）and polyphenoloxidase（PPO） increased by 74.7%， 64.2% and 45.1%， respectively， activity of superoxide dismutase （SOD）  decreased by 44.6%. 【Conclusion】The protective ability of orah fruit to pericarp cells decreases with the aggravation of sunburn. The ability to resist external light and heat stress decreases. Therefore， the prevention and control of citrus sunburn can be comprehensively considered from the aspects of increasing the application of water and fertilizer， supplementing the lacking nutrients， reducing the transpiration rate of leaves， protecting the pericarp and properly retaining late summer shoots.

Key words： orah; sunburn; pericarp structure;  physiological and biochemical indexes

Foundation item： National Key Research and Development Program of China（2018YFD0201500）; Guangxi Major Science and Technology Project（Guike AA17204097，Guike AA18118046）; Nanning Comprehensive Experimental Station of Citrus Innovation Team of Guangxi Modern Agricultural Industrial Technology System（nycytxgxcxtd-05-08）

0 引言

【研究意义】沃柑（Orah）因具有外观好、晚熟、丰产和品质优等特点，是广西推广发展积最快的柑橘品种。近10年以来，沃柑在广西已经被大面积推广种植，2018年广西柑桔产量创新高，达700万t，其中，沃柑种植面积约13万ha，产量约100万t，此后，种植面积和产量持续升高（清扬，2019）。但沃柑果实极易发生日灼，特别是桂南地区沃柑日灼发病率极高，严重的果园发病株率高达100%，日灼果约占总产量的30%，损失十分严重（汤狄华，2018）。观察沃柑日灼果皮的结构及其生理指标的变化并进行相关分析，初步明确沃柑日灼的生理机制，可为后续深入研究沃柑日灼的分子机制打下基础，也可为防控柑橘日灼提供一定的理论依据，对提高柑橘品质具有重要的现实意义。……