Estimation of Yield, Photosynthetic Rate, Biochemical, and Nutritional Content of Red Leaf Lettuce (Lactuca sativa L.) Grown in Organic Substrates

This study aimed to evaluate the effect of organic substrates on the growth yield, photosynthetic response, and nutritional profile of red leaf lettuce grown in different compositions of cocopeat (CP), sawdust (SD), and rice husk (RH). The result showed that the properties of substrates were influenced variably by their mixing ratios. The highest water holding capacity and moisture content were found in CP, and it provided the preferable pH, electrical conductivity, bulk density, and air-filled porosity in association with other categories of the substrate. Cocopeat-based media provides ample microclimate conditions in the root region of plants and increased their height, number of leaves, and fresh biomass components. The utmost dry biomass of plant parts also remarkably increased in CP; L*, a*, and b* chromaticity of leaves remained unchanged. The maximum chlorophyll content was attained in CP substrate, except for chlorophyll a/b, which was higher in RH. The net photosynthetic rate (PN), transpiration rate (E), and nitrate in leaves were enhanced substantially in CP, while it was lower in SD. Biochemical compositions and nutrients in leaves were likewise stimulated under the culture of cocopeat-based media. Results indicate that cocopeat, sawdust, and rice husk are a possible substrates mixture in a volume ratio of 3:1:1, which would be a better choice in the cultivation of red leaf lettuce.