Potassium and irrigation levels in the production of lettuce grown in greenhouses

Abstract

Lettuce grown in greenhouses has increased considerably in recent years due to superior control of environmental factors, coupled with the use of irrigation and fertilization practices that contribute to increased yield and improved product quality. Therefore, an experiment was conducted in a greenhouse at the Federal Institute of Education, Science and Technology of the Mineiro Triangle / IFTM, in Uberaba-MG, in order to evaluate the effect of application of potassium doses and irrigation water in the production of lettuce. The experimental design was randomized blocks in a 4x4 factorial design with three replications, totaling 48 experimental units. We studied four potassium doses (30, 60, 90 and 120 kg ha-1) and four irrigation levels (60, 80, 100 and 120% of crop evapotranspiration-ETc). 66 days after transplanting, the stem diameter, head circumference, the number of internal and external leaves, the total weight of the plant and the commercial weight of the head were determined. Water use efficiency (WUE) was also determined based on the commercial weight ratio of the head / Total irrigation depth applied. There was significant effect, among irrigation water levels, for all variables studied, with growing response to values close to 100% of ETC. The superior USA 1.8 g mm-1 was obtained by applying 60% of the ETC.