Water use efficiency of grape tomatoes subjected to different types of substrates, methods of conduction and irrigation management strategies

Abstract

Considering the climate uncertainty, an increase in world population and the need to produce food under low water availability, studies showing alternatives for vegetable production, having in mind the rational use of water, are extremely necessary. The aim of this study was to evaluate the effects of the type of substrate, sprout thinning and irrigation management strategies on water use efficiency (WUE) and grape tomato (Solanum lycopersicum L.) yield in a protected environment. Tomatoes were grown with one, two, three and four stems. Additionally, the impacts of “fixed” and “variable” rates of irrigation on the crop productivity and water consumption of the plants were verified. The used substrates were: 100% local soil; 80% local soil + 20% carbonized rice husk; and commercial substrate Carolina Soil XVI®. Plant spacing was 1x0.7 m. The plants were arranged in a completely randomized experimental design in a protected environment. The 3x4x2 factorial scheme (3 substrates, 4 ways of conducting stems and 2 ways of managing irrigation) resulted in 24 treatments and five replications. Water use efficiency and plant yield were evaluated. No difference in the averages of the production variables in relation to irrigation management strategies was observed. The fixed and variable rate of irrigation did not influence productivity, both in mass and number of fruits. However, when grape tomato was grown with only one stem, the production was reduced, compared to the crop grown using two, three and four stems. WUE was 8.9 g/L when the crop was grown with 1 stem; when growing with 2 stems, an increase in WUE was noticed, 30.8% (11.6 g/L); from 1 to 3 stems an increase of 53.4% (13.7 g/L) was noticed, and from 1 to 4 stems, the authors observed an increase of 55.8% (13.9 g/L). An increase in the number of stems per cultivated plant resulted in greater WUE. The types of substrates influenced the total mass obtained; plants grown in commercial substrate showed an average of 14.9 g/L, whereas when growing in soil and mixture of soil + rice husk no significant variations were observed, 10.3 g/L and 10.1 g/L, respectively.