Effect of Photosynthetic Photon Flux Density on Paprika Seedling Growth Using Rockwool Block

This study was conducted to investigate the effects of different levels of photosynthetic photon flux density on the growth of paprika seedlings cultivated in rockwool blocks. The seedling height and internode length were significantly shorter in LED light treatments than in sunlight, and there was no difference among the PPFDs of LED light. On the other hand, leaf number and area of seedlings were significantly higher and wider, respectively, in sunlight than in 150 μmol·m^-2·s^-1 treatments. The influence levels on the dry weight were 20% lighter than those on the fresh weight. The higher the PPFD of LED light, the better the seedling quality. The leaf area and dry weight of seedlings in 200 μmol·m^-2·s^-1 treatments were 582 cm²/plant and 2.01 g/plant, respectively, higher by 35% and 70%, respectively, than in 100 μmol·m^-2·s^-1 treatments. The leaf area (Y₁) had a significant dependence on PPFD (x), as Y₁ = 75.3x + 368 (R² = 0.9307 **). Also, the dry weight (Y₂) of the seedlings showed a linear regression equation, as Y₂ = 0.415x + 0.811 (R² = 0.9674 **). The chlorophyll content based on the SPAD value significantly increased as the light intensity increased to 50 μmol·m^-2·s^-1. When the results were synthesized, the seedling quality was lower in the natural light conditions than in the 150 μmol·m^-2·s^-1 treatments.