Calcium particle films promote a photoprotection on sweet potato crops and increase its productivity

Abstract

Environmental conditions, such as high air temperature, can limit sweet potato cultivation in tropical areas. The calcium particle film application has been used to minimize the effects of adverse climate conditions on plants, with the potential to increase crop yield. This study aimed to evaluate calcium oxide particle films (CaO, particle size ≤ 2 µm, reflectance > 90%) on photoprotection and productivity of sweet potato crops in the Brazilian Northeast region. Three concentrations of CaO (5, 10, and 15%) and water (control) were applied. CaO films were daily monitored through a colorimeter and reapplied whenever the brightness was reduced to maintain their reflectance status. In the pre-harvest period, the chlorophyll content (a and b), leaf temperature, and chlorophyll a fluorescence was measured. At 10 and 15%, CaO films seem to promote an effect similar to an artificial shading on the sweet potato crop, increasing the content of chlorophylls a, b, and total, reducing the chlorophyll a/b ratio and leaf temperature. Both concentrations also promoted an efficient control of the energy absorption and electron transport flux into photosystems and electron transport chains. As a result of CaO film application, the productivity of sweet potato increased by 2%, 62%, and 43% to CaO 5, 10, and 15%. Therefore, CaO particle films at 10 or 15% seems to promote some photoprotection on sweet potato crops, leading to a yield increase. Thus, this tool may improve sweet potato cultivation in regions with adverse weather conditions.