Chlorophyll Index and Productivity of Lettuce Cultivars in Hydroponic and Soil Cultivation under High Temperatures

Abstract

High temperatures limit performance, especially if the soil is hot, causing stress to the plant. In Pará, there are no cultivars adapted to the region, and producers use varieties that, although not specific to the North, show good productivity. Therefore, it is essential to identify adaptable cultivars to guide local producers. The experiment was conducted at the experimental area of Horticulture at the Federal Rural University of Amazonia, Paragominas campus, and on the property of B&A Hydroponics during periods of high temperatures. A completely randomized design (CRD) was used in a factorial scheme 3x2, with three cultivars and two cultivation systems, with four repetitions and four plants in each repetition. Three lettuce cultivars were evaluated: SVR, SCALERT, and LIRICE, and two cultivation systems (hydroponic and soil). Evaluations were conducted on biometric parameters of the plants, including leaf count, plant height (cm), plant weight (g), leaf area (mm²), length (mm), width (mm), Fac Ratio (mm), perimeter (mm), shape factor, productivity (g-plant⁻¹), root weight (g), stem diameter (cm), total number of leaves, dry weight of the plant (g), dry weight of the root (g), leaf area, length (cm), and chlorophyll A, B, and total. The analyses showed that all three evaluated cultivars had good results; however, the best performances for these parameters were related to the Lirice cultivar grown in soil and the SVR cultivar grown in hydroponics. It is concluded that the Lirice cultivar showed higher productivity in the soil system while the SVR cultivar showed higher productivity in the hydroponic system. Thus, depending on the cultivar used by producers under edaphoclimatic conditions in Paragominas, the cultivation system will differ.

Keywords: hydroponic system; soil; analysis; cultivars