Daytime or Edge-of-Daytime Intra-Canopy Illumination Improves the Fruit Set of Bell Pepper at Passive Conditions in the Winter

Abstract

Optimal light conditions ensure the availability of sufficient photosynthetic assimilates for supporting the survival and growth of fruit organs in crops. One of the growing uses of light-emitting diodes (LEDs) in horticulture is intra-canopy illumination or LED-interlighting, providing supplemental light for intensively cultivated crops directly within their canopies. Originally developed and applied in environmentally controlled greenhouses in northern latitude countries, this technique is nowadays also being tested and studied in other regions of the world such as the Mediterranean region. In the present work, we applied intra-canopy illumination for bell pepper grown in passive high tunnels in the Jordan Valley using a commercial LED product providing cool-white light. The study included testing of daytime (‘LED-D’) and edge-of-daytime (‘LED-N’) illumination, as well as a detailed characterization of fruit set and fruit survival throughout the growth season. We found that both light regimes significantly improved the fruit set and survival during winter, with some benefit of LED-N illumination. Notably, we found that western-facing plants of illuminated sections had a higher contribution toward the increased winter fruit set and spring yield than that of illuminated eastern-facing plants. Greater plant height and fresh weight of western-facing plants of the illuminated sections support the yield results. The differences likely reflect higher photosynthetic assimilation of western-facing plants as compared to eastern-facing ones, due to the higher daily light integral and higher canopy temperature of the former. This study provides important implications for the use of intra-canopy lighting for crops grown at passive winter conditions and exemplifies the significance of geographical positioning, opening additional avenues of investigation for optimization of its use for improving fruit yield under variable conditions.

Evaluation of Agronomic Performance and Fruit Quality of Four Genotypes of Bell Pepper under Greenhouse Conditions

“…With reference to the color of the fruit and its chromatic characteristics, this is a qualitative aspect of the fruits, the pepper is a widely consumed product, especially due to its colorful and striking appearance, sweet taste and healthy appeal [41,42]. The color of the fruit and its brilliance turns out to be a quality character, as well as its shape and size, these depend on the specific physiological processes that occur during maturity and his genetics [43].…”

The Effects of LED Light Spectra and Intensities on Plant Growth

“…The influence of light intensity on Lactuca sativa and Brassica rapa var. nipposinica in vertical farms [ 7 ] and of daytime or edge-of-daytime intra-canopy illumination on the fruit set of Capsicum annuum [ 8 ] were also studied.…”