Reviewing the Tradeoffs between Sunburn Mitigation and Red Color Development in Apple under a Changing Climate

Abstract

Orchard systems have drastically changed over the last three decades to high-density plantings that prioritize light interception that is evenly distributed throughout the entire canopy. These conditions allow the production of fruit with a high red color that meets consumer demands for uniformly colored fruit without external disorders. However, these systems also expose a higher proportion of fruit to full-sunlight conditions. In many semi-arid apple production regions, summer temperatures often exceed thresholds for the development of fruit sunburn, which can lead to >10% fruit losses in some regions and some years. To combat this, growers and researchers use sunburn mitigation strategies such as shade netting and evaporative cooling, which bring a different set of potential fruit quality impacts. Often, there is a tradeoff between red color development and fruit sunburn, particularly for strategies that affect light intensity reaching the fruit surface. In this paper, we review agronomic and environmental factors leading to reductions in red color and increases in sunburn incidence, along with advancements in management practices that help mitigate these issues. Furthermore, we also identify gaps in knowledge on the influence climate change might have on the viability of some practices that either enhance red color or limit sunburn for apple orchards in semi-arid environments. There is a need for cost-effective management strategies that reduce losses to sunburn but do not inhibit red color development in bicolor apple cultivars.

Cap. 27: Noroeste. En: La Quinta Evaluación Nacional del Clima

“…El aumento de la exposición a temperaturas extremas puede inducir efectos cosméticos (p. ej., quemaduras solares en las manzanas) que hacen que los cultivos sean cada vez menos comercializables 218 . Se espera que la presión de las plagas aumente debido al cambio climático; sin embargo, las investigaciones preliminares indican que la eficacia del control no químico de las plagas también puede aumentar, ofreciendo oportunidades para reducir el uso de plaguicidas y beneficios medioambientales 217 .…”

“…En últimas décadas, múltiples estudios revisados por expertos han establecido cómo el cambio climático afecta diversos sistemas de cultivo anuales y perennes 216,217,218,219,220,221,222,223 , sistemas pesqueros 225,247,248,249,250,253 , sistemas forestales 233,234,236,237,242,244 y la industria turística 16,79,256,257,258,261 .…”