Foliar treatment with melatonin to prevent cold injury of bananas in pre- and post-harvest

• Grant number: 23/13151-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2024
• End date: January 31, 2025
• Field of knowledge: Agronomical Sciences - Agronomy
• Principal Investigator: Juliana Domingues Lima
• Grantee: Ricardo Campinas Gonçalves
• Host Institution: Faculdade de Ciências Agrárias. Universidade Estadual Paulista (UNESP). Campus do Vale do Ribeira. Registro , SP, Brazil

Abstract

Bananas, being a tropical fruit, are very sensitive to cold, tending to show damage to the peel at temperatures below 12oC, which appear as brownish areas and compromise visual quality. Browning is caused by the oxidation and polymerization of phenols as result of membrane disruption, which occurs due to the greater rigidity of lipids or the direct action of reactive oxygen species (ROS). Exogenous melatonin serves as an antioxidant and/or growth regulator, as well as a probable signaling molecule. It is capable of stabilizing cell membranes and increasing the cell's resistance against ROS. In banana, melatonin treatment alleviated chilling injury in cold storage. In this study, we propose to evaluate the effect of treating banana plants cv. Nanica with melatonin in reducing cold injury in fruits, pre- and post-harvest. Two experiments will be conducted, the first with plants treated with melatonin in spring or summer and the harvested fruits exposed to the cold post-harvest, and the second, with plants treated with melatonin in early autumn and the fruits exposed to the cold in the field just before harvest. The experimental design will always be completely randomized, with two treatments, water and 100 µM melatonin, with five replications. The treatments will be sprayed on the leaves. The fruits used in the experiments will be collected from the 4th bunch from the top to the base of bunches harvested at the commercial harvest point. The evaluations will consist of determining the cold injury index, the color characteristics of the peel, as well as the malondialdehyde, proline and phenol content. It is expected to verify whether melatonin can be used as a plant treatment to allow the reduction of post-harvest storage temperature, and consequently the extension of the green life of the fruit, or even, whether it is possible to prevent cold injury during the fruit development in autumn and winter.