Shade improves growth, photosynthetic performance, production and postharvest quality in red pitahaya (Hylocereus costaricensis)

Abstract

High solar radiation impairs the successful cultivation of Hylocereus (Cactaceae) species. This investigation aimed to evaluate shading as a strategy for coping with high solar radiation in red pitahaya (Hylocereus costaricensis), through a long-term field experiment. To this end, we studied growth, physiological performance, productivity and postharvest quality of red pitahaya grown under four shade levels, namely, 35, 50, 65 and 80%, compared to plants under full sunlight (control). Red pitahaya showed superior performance under shading compared to the control, especially plants under about 35% shade. Shading improved initial plant growth followed by high physiological performance, i.e., increased maximum quantum efficiency of photosystem II (Fv/Fm) along with the accumulation of total chlorophyll content, with no photoinhibition and sunburn. Shaded plants showed improved yields along with production precocity, as seen through comparison with the local cultivation under full sunlight. In the second year, a maximum estimated yield of 18.7 t ha−1 was observed under about 35% shade, which is a production increase of 70% vs plants under full sunlight (10.9 t ha−1). Shading improved fruit quality through increased fresh weight, pulp yield, pulp firmness and reddish pulp coloring, indicating the accumulation of betalain pigments. Our findings support shading as a valuable strategy for coping with stress induced by extremely high solar radiation in field plantations, thus providing increased productivity by preventing bleaching and death of Hylocereus, especially in drylands.