Impact of innovative optically active greenhouse films on melon, watermelon, raspberry and potato crops

Adaptation of the light spectrum to the greenhouse cultivated crops is considered as one way to improve plant production. Light quality might be increased by the incorporation of optically active light shifting dyes in the greenhouse plastic films which adapt the photosynthetically active radiations (PAR) to photosynthesis and consequently might improve plant growth and yield. This present study aims to evaluate the effects of an increase in the blue (400-500 nm) and in the red (600-700 nm) wavelengths induced by the registered “Light Cascade^®” technology (LC^®) on the low and high tunnels cultivated crops i.e., 'Charentais' melon, watermelon, raspberry and early potato. The experiments were performed in different experimental farms and in growers' farms located in France and Spain and qualitative and quantitative parameters were evaluated. The results obtained for the melon and watermelon crops showed globally i) an increase up to 10% of the yield at the first harvests, ii) an increase of the fruit size or weight, and iii) a maintained even increase of the sugar content in comparison to the standard film. It was observed that the effect of the LC^® is more significant in unfavourable weather conditions (reduced sunlight) on melon. The raspberry showed underneath the LC^® films an increase of both fruit production at the first harvests and the sugar content. Concerning the early potato crop, the results showed an early harvest time reaching 8 days and an increase of 12% of the final net yield especially for desired small sized tubers. These results suggest that the efficiency of the LC^® films appeared to be optimal on periods when the sunlight and temperature are insufficient (winter and spring). Further research is ongoing to evaluate the effect of the LC^® technology on other crops (red fruits, tomato and cut flowers), in relation with additional parameters (temperature regulation, plant disease management and use efficiencies of water and nitrogen).