Abiotic stress in neotropical climate influences pigment production, antioxidant capacity and expression of physiological disorders in apples

Abstract

Apple cultivation, which is labour-intensive and relevant in terms of food sovereignty, is experiencing a decrease in the number of producers. The fruit, of recognised organoleptic quality, often shows physiological disorders such as sun damage, scald, lenticellosis and bitter pit. These damages are associated with abiotic stresses and are expressed in the field or postharvest, reducing the economic sustainability of the crop in the neotropical climate. The objectives of the present work were: a) to determine climate factors that are limiting for adaptation under neotropical climate conditions, b) to evaluate physiological responses using spectroradiometry and analyse their potential for predicting disorders, and c) to evaluate management strategies capable of mitigating abiotic stress damage. Our results showed a high variability of predisposing conditions and damage development, with soil water availability being the condition most related to sun damage. Of the field treatments, 50% black netting was the one that reduced damage levels the most, reducing air and fruit temperature and presenting the least restrictive xylem potential (-0.54MPa), without affecting growth parameters. The treatments under netting always showed lower expressions of sunscald. Regarding damage prediction, water potential differences between fruit faces, proline concentration (destructive indicators) and PSRI480 spectroradiometry index (non-destructive indicator) showed the best characteristics.