Produção de mudas de alface Americana e Crespa em diferentes substratos

Abstract

Lettuce is a leafy vegetable widely consumed in Brazil, being the species propagated by direct sowing at the definitive site or with the production of seedlings in trays. Tray propagation provides good initial development under adverse conditions as well as the choice of seedlings to be used, and this form of propagation depends on several factors, including substrates. Therefore, the objective of the present study was to evaluate the initial development of seedlings of two lettuce varieties as a function of different substrates. The experiment was conducted in a nursery with shading of 50% of the Medicinal Plant Garden of the Faculty of Agrarian Sciences of the Federal University of Grande Dourados, in a factorial scheme 5 (S1- 100% soil; S2-100% substrate; S3-75%). soil and 25% substrate; S4- 50% soil and 50% substrate; S5- 25% soil and 75% substrate) x 2 (American lettuce and Crespa lettuce) arranged in a randomized complete block design with six replications. The commercial substrate used in soil concentrations was Tropstrato HT, containing pine bark, peat, vermiculite, simple superphosphate and macronutrients, with different soil proportions (very clayey dystroferric Red Latosol). Sowing was carried out in 200-cell Styrofoam (polystyrene) trays and the emergence, fresh root and shoot masses, root and shoot length, stem diameter as well as root and root dry mass were evaluated. aerial part. Data were subjected to the F test at 5% probability and when significant differences were detected as a function of the seasons they were subjected to regression analysis, and within each season to the t test (varieties) or Tukey (soil / commercial substrate ratio) both. 5% probability. At 10 days after sowing (DAS) substrate S2 presented the highest percentage (93.71%) of seedlings emerged. For fresh shoot mass (MFPA) the highest values at 25 DAS were 0.4381 g and 0.3949 g for substrates S3 and S5 of the Americana and Crespa varieties, respectively. Shoot dry mass (MSPA) presented maximum values of 0.0431g in substrate S3 (Americana) and 0.0221 g in substrate S1 (Crespa). Dickson's highest quality index (IQD) at 25 DAS was 0.0034 for American lettuce and 0.0026 for Crespa, when produced on substrates S3 and S1, respectively. It was concluded that the best results for the American variety were observed in substrate S3 and for Crespa variety in substrate S1.