Exogenous Melatonin Enhances Moisture Stress Tolerance in Mango (Mangifera indica L.) through Alleviating Oxidative Damages.
Study Goal
The researchers aimed to determine if foliar melatonin application could mitigate moisture stress in mango trees and improve fruit yield and quality.
Results Summary
Melatonin application significantly improved fruit yield and quality under moisture stress, reducing yield loss from 55.94% to 7.5% compared to non-treated trees. It also enhanced chlorophyll content and antioxidant enzyme activity, similar to irrigated conditions.
Population
16-year-old mango trees in subtropical regions.
Effective Dosage
20, 50, 100, and 150 μM melatonin applied three times at different fruit development stages.
Duration
Three years.
Interactions
None mentioned.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
foliar application of 20, 50, 100 and 150 μM melatonin | decrease | oxidation state | mango trees | - | helped to maintain a reduced oxidation state | #1 |
melatonin application | increase | fruit yield of mango | mango trees | - | improved | #2 |
moisture stress | decrease | yield | mango trees | 55.94% | decreased yield by | #3 |
melatonin treatment | decrease | yield | mango trees | 7.5% | decreased yield by | #4 |
melatonin-treated conditions | increase | 'A' grade fruits | mango trees | - | more 'A' grade fruits were harvested | #5 |
melatonin treatment | increase | total chlorophyll content in the leaves | moisture-stressed mango trees | 12.58 mg.g-1 fresh weight vs 6.77 mg.g-1 | total chlorophyll content was well above | #6 |
melatonin treatment | increase | chlorophyll content | melatonin-treated plants | - | dose-dependent increase | #7 |
melatonin treatment | decrease | activities of catalase, peroxidase, superoxidase dismutase enzymes in leaves | mango trees | - | activities were lower than in non-irrigated condition | #8 |
melatonin treatment | decrease | superoxide free radial formation | moisture-stressed mango trees | 0.77 nmol H2O2.mg-1 protein vs 4.27 | superoxide free radial formation was lower | #9 |
melatonin treatment | neutral | antioxidants (total, reduced and oxidized glutathione and ascorbate) content and antioxidant enzymes' activities (i.e., glutathione reductase and ascorbate peroxidase) | mango trees | - | significant variations was found | #10 |
150 μM exogenous melatonin applied three times at different fruit development stages | neutral | management of transient moisture stress | mango trees | - | may be a sustainable and useful approach | #11 |
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-1 fresh weight) was well above non-treated trees (6.77 mg.g-1) and similar to irrigated trees (12.50 mg.g-1). 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 H2O2.mg-1 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.