Effects of CO2 concentration, light intensity and nutrient level on growth of leaf lettuce in a plant factory.

摘要

An experiment was conducted to establish the optimum conditions for the growth of leaf lettuce (Lactuca sativa var. crispa cv. Grand Rapids). Plants were grown under various CO2 concentrations of 400, 1000, 2000 and 3000 mg/litre. At each CO2 treatment, the effect of photosynthetic photon flux densities (PPFD) of 100, 150, 200 and 300 鎚ol m-2 s-1 was also analysed. In addition, the effect of varying nutrient levels (1.2, 1.8, 2.4 and 4.8 mScm-1) was analysed. Data were recorded for number of leaves, leaf length, leaf width, leaf fresh weight, root fresh weight, leaf dry weight and root dry weight after 30 days following treatments. Relative chlorophyll content was measured after 30 days, and transpiration rate, CO2 assimilation rate and stomatalresistance were measured after 16 days. Based on these parameters, CO2 enrichment up to 1000 or 2000 mg/litre and PPFD of approximately 200 鎚ol m-2 s-1 was found to be optimum for leaf lettuce growth and photosynthesis. In contrast, varying nutrient levels had no significant effect on the growth of leaf lettuce.