Photo-selective shading screens as a cover for production of purple lettuce

Abstract

Photo-selective shading screens are emerging practices that aim to combine crop physical protection with different solar radiation filtration to achieve desired physiological responses. The objective of the present study was to evaluate the effect of photo-selective shading screens on the growth and physiology of purple lettuce for two transplanting seasons in tropical climate in Brazil. A 2 × 4 factorial arrangement was used, being considered the first factor, the transplanting season (spring and fall), and the second factor is the three 35% shading photo-selective shading screens (red, black and silver) and full sun control. The experimental design was a randomized complete block with four replications. The variables studied were: total fresh matter, total dry matter, leaf number, stem diameter, stem length, leaf area, SPAD chlorophyll index, nitrogen balance indexes, chlorophyll, flavonoids and anthocyanins. The photo-selective shading screens influenced the microclimate and the growth variables of purple lettuce, mainly when these plants were sown in the fall. Planting lettuce during spring may result in lower yields due to the higher investment of plants in secondary metabolites to defend against abiotic stress. According to the results, photo-selective shading screens are an appropriate agronomic technique to reduce phenolic compounds and improve lettuce cultivation conditions and can be implemented within protected cultivation practices to improve crop performance.

Not All Light Spectra Were Created Equal: Can We Harvest Light for Optimum Food‐Energy Co‐Generation?

“…The majority of these studies, although sometimes with contrasting results, suggest that some parts of the light spectrum are less efficient in terms of carbon assimilation and water use and could be more effectively used to produce solar energy. Studies under field conditions where photo‐selective shade nets were applied to lettuce (Amaro de Sales et al., 2021), apple trees (Bastías et al., 2021), and grapevine (Marigliano et al., 2022; Martínez‐Lüscher et al., 2017) also suggest that proper sunlight management can lead to improved crop performance, higher water use efficiency (WUE), and mitigation of heat wave damage.…”