A simple cold tolerance test for banana cultivars

Abstract

Cooler growing conditions in subtropical environments adversely affect banana fruit yield and quality. Crop cycling is longer, plants and fruits can be damaged by low temperatures, and bunches and fruits develop abnormally. These cooler temperatures also predispose some cultivars to pest and disease susceptibility. There is also consumer purchasing resistance to the dull gray/yellow fruit exhibiting under-peel discoloration caused by chilling. A simple prototype sap flow test shows promise as a practical, objective measure of cold tolerance to support the standard evaluation measures, chlorophyll photo-oxidation, black spotting of leaves, petiole blackening and vigour ratings. Sap flow tests were conducted between July and November 2016 at the Duranbah cultivar trial site in New South Wales, Australia. In this study, the top hand from the bunch was removed from the peduncle immediately after harvest, and the number of drops of sap in the first minute from the cut surface of the hand was measured. None of the ten Cavendish types (AAA) tested exhibited any sap flow during winter, and only two had sap flow in mid-November, well into the Australian spring. All four tetraploid cultivars, two AAB cultivars and one ABB cultivar tested showed sap flow right through the winter months. Significant differences in sap flow were found between some of the cultivars. Cold tolerance is a major selection criterion for potential new cultivars for the Australian subtropics, and this simple sap flow test shows promise as a practical, objective measure of cold tolerance to complement the standard evaluation measures. © 2020 International Society for Horticultural Science. All rights reserved.