Pre- and Postharvest Management of Sunburn in ‘Granny Smith’ Apples (Malus × domestica Borkh) under Neotropical Climate Conditions

Abstract

Sun damage on apples is attributed to the occurrence of high temperatures, incident radiation, and fruit and plant water parameters, all dependent on climatic conditions and management. The development of new production areas and climate changes increase the interest in studying the behavior of the fruit under different conditions. The effect on sun damage of three nets and two chemical protectants was evaluated in a commercial orchard of ‘Granny Smith’ in a neotropical climate during the 2012–2016 seasons. We recorded the evolution, incidence and severity of sunburn and sunscald. Fruit surface temperature, fruit size, sprouting and return to flowering was also recorded. Incident radiation and air temperature were considered for the assessment of the crop’s microclimate. The transmittance in PAR wavelength and the air temperature variation on netting treatments reached 0.4 and 9 °C, respectively. The fruit surface temperature for the White-Net and Black-Net-50% treatments was always lower than 46 °C. For the sun damaged fruits, the Black-Net-50% treatment showed the highest proportion of slightly sunburned fruits (94%) and the lowest proportion of heavy damages, with a sunscald index equal to or less than 2 (on a scale of 1–4) in all the tested conditions. In a neotropical climate, protectant applications did not reduce the incidence of sunburn, but with the use of nets it was possible to reduce both sunburn and sunscald without affecting growth processes dependent on leaf net assimilation.

Daño de sol y potencial hídrico de tallo y tejidos del fruto de manzanas (Malus domestica) ‘Brasil Gala’, ‘Cripps Pink’ y ‘Granny Smith’

“…On the one hand, the exposed surface in small fruits is insufficient to absorb solar radiation (6) ; on the other hand, the predisposing conditions, air temperature and air vapor deficit, increase as the season progresses (22) , as well as irradiance (33) . Both aspects were present in this trial during the first 96 days after full bloom (5) . Previous results indicate that the tissues exposed to the sun have lower water potentials, activating a cascade of responses to abiotic stress, mediated by sugars and ethylene, to cope with environmental stress caused by high irradiation and heat.…”

“…The energy intercepted by the nets, not reaching the plant tissues, results in a lower temperature increase. The radiation under the black net showed less energy in the near-infrared compared to the environment under the white nets (5) . This is consistent with the lower water potential of the crop under white netting (Figure 1).…”

“…This is consistent with the lower water potential of the crop under white netting (Figure 1). The increase in infrared radiation (>740 nm) has a great caloric value (5) (32) and could be related to the increases in air temperature recorded in this treatment and the lower water potential of the crop under the white net (Figure 1). The black nets, on the other hand, intercepted an approximate proportion of 0.6 at all wave lengths (5) and similarly reduced the air temperature (5)(28-31) and the surface temperature of the fruit (5) (12) , supporting the results of improved water conditions in the crop observed here.…”

“…The climatic variability of the region (4) and its connection with the damage determine significant differences between years, both in magnitude and in the timing of damage development (2) . This physiological disorder is a major cause of fruit quality loss in apples before harvest (2) , and the study of management measures for its mitigation is recent (5) .…”

Estado Oxidativo Y Calidad De Frutos De Pera Variedad Beurré D´anjou Con “Blush”

“…Asimismo, Zhao et al (2016) indicaron cambios en el estado oxidativo de los frutos desarrollados bajo distintas intensidades de luz, observando incrementos en el contenido de antioxidantes y actividad de enzimas antioxidantes en frutos con blush. Estas variaciones del estado oxidativo afectan la susceptibilidad a fisiopatías como el escaldado por sol a lo largo del almacenamiento (Severino et al, 2021;Torres y Mogollon, 2022). Por otro lado, Serra et al (2018) profundizaron en la influencia de la incidencia de la luz según la posición de los frutos en el árbol sobre el metabolismo y la composición de la piel en pera.…”