Avaliação do desempenho da cultura de alface em campo aberto e sombrite sob diferentes níveis de irrigação e adubação

Abstract

Lettuce (Lactuca sativa L) is one of the main vegetables produced in Mozambique. However, there are several factors that limit its productivity. Applying the appropriate amount of water and nutrients, associated with the cultivation environment and genetic potential of the varieties, allows to maximize the productivity of lettuce. In this sense, the present study was carried out with the objective of evaluating the performance of lettuce grown in open fields and in the shade under different levels of irrigation and nitrogen doses. The trial was conducted at the Experimental Field of the Faculty of Agronomy and Forestry Engineering, Eduardo Mondlane University, in Maputo, from July to October 2023 in sandy soil. A completely randomized design in a factorial arrangement was used, considering 2 cultivation environments (open field and shaded field), 2 irrigation levels (optimal level - 100% ETc and intermediate - 50% ETc) and 2 nitrogen fertilization levels (optimal level - 30 kg/ha and intermediate - 15 kg/ha), totalizing 8 treatments with 3 replicates. To evaluate crop performance, growth and production variables were analysed at 15, 30 and 45 days after transplanting. Meteorological variables, temperature and relative humidity of the air and soil temperature were monitored. Data were subjected to analysis of variance by the F test (p < 0.05) and those that obtained significant differences were tested for comparison of means, using the Tukey test at the 5% probability level. The analysis of the results revealed that all growth parameters determined were significantly influenced by the different growing environments, water levels, and nitrogen doses, with an increase in plants under shaded areas, a water level of 100% crop evapotranspiration, and a nitrogen dose of 30 kg.ha -1 . The fresh yield of lettuce was higher with the use of shaded areas than in the open field, being equivalent to approximately 20 ton.ha -1 . With the use of a nitrogen dose of 30 kg.ha -1 , the yield was 20 tons.ha-1, and with the use of an irrigation level of 100% ETc, the yield was 19 tons.ha-1. Based on these results, it is recommended to produce lettuce crops under shaded areas in the summer