Rare earth transfer films enhance the photosynthetic efficiency of strawberry plants, thereby improving fruit quality and yield

Light plays a particularly important role in the growth and development of plants, affecting almost all growth stages. Light conversion film can provide the red‒orange light and blue‒violet light necessary for plant photosynthesis, promoting the growth and development of crops and nutrient absorption. Strawberry ( Fragaria×ananassa Duch.) is a major economic crop worldwide, and its related industrial chain drives the economic development of various countries. Therefore, this study investigated the effects of rare earth light conversion films (RPOs) on strawberry cultivation. The temperature, light intensity, light transmittance and proportion of spectra beneficial to the crop production of RPO greenhouses were all greater than those of the control. Compared with those of the control, spongy tissues were sparser in RPO1 and RPO2 leaves. The cross-sectional lengths of the main vascular bundles of strawberry petioles in RPO1 and RPO2 increased by 10.85% and 29.56%, respectively, and the cross-sectional widths decreased by 9.11% and 9.60%, respectively. Compared with those of the control, the total leaf area, photosynthetic rate, stomatal conductance, activity of Rubisco and gene expression levels of Rub-af1 , RubLα , RubLβ , and Rib-cs of RPO1 and RPO2 increased by 29.98%, 10.88%, 49.55%, 42.87%, 10.09%, 9.23%, 10.45%, and 7.27% and 31.51%, 23.61%, 157.67%, 44.94%, 9.95%, 8.71%, 9.46%, and 6.13%, respectively, and the intercellular CO ₂ concentration decreased by 32.76% and 37.20%, respectively. Compared with those of the control, the single fruit weight, yield, soluble solids, soluble sugar content, Vc content, and flavonoid contents of RPO1 and RPO2 increased by 30.21%, 13.25%, 32.58%, 24.04%, 8.32%, and 27.94% and 33.37%, 23.83%, 33.48%, 33.48%, and 54.87%, respectively. In conclusion, RPO promotes photosynthesis in strawberry plants by optimizing light intensity and temperature in greenhouses; adjusting the spectrum to change the total leaf area, pigment content, spongy tissue structure, petiole vascular bundles, and Rubisco activity; and regulating the expression of the Rubisco gene, thereby increasing the quality and yield of strawberry plants. Compared with RPO1, RPO2 could be a more suitable film for strawberry production.