ICAR - Central Institute for Subtropical Horticulture, Lucknow, India.
ICAR-National Bureau of Fish Genetic Resources, Lucknow, India.
Physiol Plant. 2024 Sep-Oct;176(5):e14566. doi: 10.1111/ppl.14566.
In subtropical regions, April to June represents a temporary moisture stress for mango trees, leading to huge economic loss. Although water is available in the deep root zone, the upper soil surface, which has fibrous roots, is dry, and the tree transpiration rate is high. Moisture stress causes an increased oxidation state, which is detrimental to fruit growth and development. Finding substitutes for moisture stress management is important for sustainable mango production. To manage this moisture stress in mango, we tested if foliar application of 20, 50, 100 and 150 μM melatonin helped to maintain a reduced oxidation state in the cells. Applications were made at three phenological stages of fruit development (marble, egg and mature fruit stages) in 16-year-old trees and the same plants for each treatment were followed over three years. Melatonin application indeed improved the fruit yield of mango. Moisture stress decreased yield by 55.94% compared to irrigated trees but only by 7.5% in melatonin treatment. Also, more 'A' grade fruits were harvested in irrigated and melatonin-treated conditions than in non-irrigated and non-treated conditions. Indeed, the total chlorophyll content in the leaves of moisture-stressed melatonin-treated trees (12.58 mg.g fresh weight) was well above non-treated trees (6.77 mg.g) and similar to irrigated trees (12.50 mg.g). A dose-dependent increase in the chlorophyll content of melatonin-treated plants was found. Similarly, the activities of catalase, peroxidase, superoxidase dismutase enzymes in leaves of irrigated and melatonin-treated trees were lower than in non-irrigated condition, and superoxide free radial formation was lower in moisture-stressed melatonin-treated trees (0.77 nmol HO.mg protein) and irrigated trees (0.65) than moisture-stressed non-treated trees (4.27). Significant variations was found in antioxidants (total, reduced and oxidized glutathione and ascorbate) content and antioxidant enzymes' activities (i.e., glutathione reductase and ascorbate peroxidase) in irrigated, melatonin-treated and non-irrigated conditions. Overall, 150 μM exogenous melatonin applied three times at different fruit development stages may be a sustainable and useful approach to manage transient moisture stress in mango trees thanks to its positive action on the antioxidant system.
在亚热带地区，4 月至 6 月是芒果树暂时缺水的时期，这会导致巨大的经济损失。尽管深层根系中有水分，但表面的上层土壤（含有纤维根）是干燥的，而树木蒸腾速率很高。水分胁迫会导致氧化状态增加，这对果实的生长和发育不利。寻找替代水分胁迫管理的方法对于可持续的芒果生产很重要。为了管理芒果的这种水分胁迫，我们测试了叶面喷施 20、50、100 和 150μM 褪黑素是否有助于维持细胞的还原氧化状态。在 16 年生的树上，在果实发育的三个物候阶段（大理石期、蛋期和成熟果期）应用褪黑素，对同一植株进行了三年的跟踪。褪黑素的应用确实提高了芒果的产量。与灌溉树相比，水分胁迫导致产量下降了 55.94%，但在褪黑素处理中仅下降了 7.5%。此外，在灌溉和褪黑素处理条件下收获的“A”级果实比在非灌溉和非处理条件下更多。事实上，水分胁迫下褪黑素处理的叶片中总叶绿素含量（12.58mg/g 鲜重）远高于未处理的叶片（6.77mg/g），与灌溉的叶片相似（12.50mg/g）。褪黑素处理植物的叶绿素含量呈剂量依赖性增加。同样，在灌溉和褪黑素处理的叶片中，过氧化氢酶、过氧化物酶、超氧化物歧化酶的活性低于非灌溉条件，水分胁迫下褪黑素处理的叶片（0.77nmol HO.mg 蛋白）和灌溉的叶片（0.65）中的超氧自由基形成低于非灌溉和非处理的叶片（4.27）。在灌溉、褪黑素处理和非灌溉条件下，抗氧化剂（总、还原和氧化型谷胱甘肽和抗坏血酸）含量和抗氧化酶（即谷胱甘肽还原酶和抗坏血酸过氧化物酶）的活性都有显著变化。总之，在不同的果实发育阶段三次叶面喷施 150μM 外源褪黑素可能是一种可持续和有用的方法，因为它对抗氧化系统有积极作用，可以管理芒果树的暂时水分胁迫。
