Optimizing light conditions for enhanced strawberry growth in tropical lowlands

Light-emitting diodes (LEDs), as an artificial light source, can modify the conditions for strawberry cultivation in the tropics. In Indonesia, strawberry cultivation is limited to areas with an elevation of >800 meters above sea level. This study aimed to optimize light intensity, quality, and duration required for cultivating strawberries in lowlands based on physiological, gene expression, and metabolomics analyses. The physiological analysis revealed the highest levels of CO2 in 15-h light treatments, and the highest stomatal conductance and transpiration rate in 21-h treatments. Medium-intensity blue light irradiation for 15 h (B15-4) resulted in the highest amount of chlorophyll a, and high-intensity blue: red light (2:1) treatment for 15 h (2C15-5) resulted in the highest amount of chlorophyll b. Medium-intensity blue: red light (1:1) combination treatment for 15 h caused the most significant accumulation of glucose, while irradiation for 15 h with medium-intensity blue and red light (B15-4 and R15-3, respectively) and the blue/red light combination (C15-4) resulted in the highest fructose accumulation. Diazepam, phthalic acid, 2-ethylhexyl undecyl ester, and 2-(3-chlorophenyl)-tetrazole-5-carboxylic acid ethyl ester showed the highest abundance in specific treatments and therefore were designated as specific compounds. The expression analysis of genes related to the plant response to LEDs showed that <i>CRY1</i> and <i>ANS</i> were highly expressed under low-intensity light and polychromatic light, respectively, while <i>HRB1, HY5, PHYA</i>, and <i>SPA2</i> were highly expressed under low to medium-intensity light.