Produtividade de cultivares de alface baby leaf (Lactuca sativa (L.)) em diferentes fotoperíodos no cultivo hidropônico indoor

Abstract

The adaptability of lettuce cultivars to environmental factors is directly related to productivity and depends on the genotype, photosynthesis, photoperiod and circadian cycle of the plants. Innovation in agriculture caused by technologies 4.0 has allowed significant advances in the way of production, in the quality of the final product and in sustainability. Thus, the objective of this work was to evaluate the effect of photoperiod on different lettuce cultivars in indoor hydroponic cultivation with artificial lighting for the production of baby leaves. For this, the lettuce cultivars BSAC0055, BSAC0155 and BSAL0071 were evaluated in an NFT hydroponic system, under a photoperiod of 14, 16, 18 and 20 hours with photosynthetically active radiation of 248 μmol m-2 s-1 and maintaining the other environmental conditions constant. Twenty-seven days after seed germination, assessments were made of fresh mass of leaves and stems, fresh mass of roots, total dry mass of the plant, plant height and diameter, number of leaves and number of leaves larger than 10 centimeters. The effects of the cultivars x photoperiods interaction were significant, with cultivars behaving differently for each photoperiod and vice versa. The BSAC0055 cultivar, regardless of the photoperiod, was superior to the others and adapted to indoor cultivation. As the hours of light increased, there was also an increase in the means of the variables up to a peak point and after that, as the hours of light increased, there was a decrease in the variables. For cultivar BSAL0071, photoperiod was not significant. For cultivars BSAC0055 and BSAC0155, the photoperiod was significant with a quadratic effect for the number of hours/day, demonstrating the optimum fresh mass of leaves and stems close to 16 hours and 45 minutes. It is concluded that cultivars have different management and it is possible to select specific cultivars for indoor production; cultivars respond differently to photoperiods, with cultivars BSAC0055 and BSAC0155 being similar to each other and superior to BSAL0071; photoperiods cause differentiated growth of lettuce plants, showing growth as the hours of light increase to a maximum point, after which productivity declines as the hours of light increase.