Physiological Study of the Efficacy of Archer® Eclipse in the Protection against Sunburn in Cucumber Plants

Sunburn is an important issue affecting the yield of many crops, mainly in arid and semi-arid regions. Excessive solar radiation and high temperatures can reduce growth and cause leaf chlorosis, oxidative stress, and photosynthesis impairment. It is thus necessary to develop agricultural techniques to protect plants in a cost-effective and reproducible manner. A potential method is through the spray of protective compounds based on particulate films, such as those based on kaolin. The objective of this study is to evaluate the effects of spraying the protective product Archer® Eclipse, created by Atlántica Agrícola S.A. (Alicante, Spain), on sunburn damage in a sensitive species such as the cucumber plants (Cucumis sativus L.). To evaluate the effects of sunburn on the plants, parameters related to biomass, leaf temperature, photosynthesis, and oxidative stress were analysed. Plants sprayed with Archer® Eclipse showed fewer sunburn symptoms and obtained 43% more shoot biomass than those that were not treated. In addition, plants sprayed with Archer® Eclipse showed 3 °C lower leaf temperatures, higher photosynthesis performance, 88% more water use efficiency, and 21% more chlorophyll concentration. Finally, plants treated with Archer® Eclipse presented 6% less accumulations of carotenoids and 67% less total phenols, but lower oxidative stress indicators. In conclusion, this study confirms the efficiency of Archer® Eclipse in protecting a sensitive vegetable plant such as the cucumber from sunburn-inducing conditions.