Effects of sunscreen protection and water management on the physiology and production of ‘Pera’ sweet orange orchards in sub-humid climate

Abstract

Abstract: The risks associated with climate events are the main factors responsible for sweet orange production losses in Brazil. For rainfed citrus cultivation, it is mainly due to soil water deficit, but also to citrus cultivation associated with extreme temperatures. The present study investigated the effects of water management in ‘Pera’ sweet orange orchards under sub-humid climate conditions and application of calcium carbonate-based sunscreen on the plant canopy, aiming to mitigate the effects of abiotic stresses on orchard physiology, production, and irrigation water use efficiency. The experimental design was in randomized blocks in a 3 x 2 factorial scheme. Treatments for water management factor were: full irrigation (100% ETc), irrigation with moderate deficit (65% ETc), and no irrigation; and for sunscreen protection: sunscreen use and no sunscreen. The factors have impacted gas exchange, fruit quality, and orchard yield. There was no isolated effect of soil water management on orchard productivity, but with sunscreen, citrus plants are more resilient based on gas exchange data, mitigating environmental effects (high temperatures and water deficit), resulting in improvements in fruit quality related to total fruit mass in plants grown without irrigation and with 12% increase in orchard productivity, regardless of soil water management. Productivity gains related to sunscreen indicate the need for the use of sunscreen protection regardless of soil water management in the region.

Keywords

• Citrus
• drip irrigation
• deficit irrigation
• physiological indicators
• gas exchange
• rainfed cultivation
• irrigation water use efficiency
• sunscreen