Sistema “aberto” x sistema “fechado” de cultivo em substrato: crescimento, produção e consumo hídrico de minitomateiros

Abstract

The demand for mini tomatoes has increased over the years due to its excellent flavor, high added value, varied colors, and formats, which has encouraged producers to invest in its cultivation. Thus, the present work aimed to evaluate two mini tomato cultivars (grape type “Sorbetto” and Italian type “Dolcetto”), cultivated in two substrate growth systems (closed in gutters and open in pots) with two plant conduction systems (single stem and two stems); in addition to quantifying the consumption of water and fertilizers and assessing the potential for environmental contamination. The experiments were carried out in a greenhouse in the didactic and experimental field of the Department of Plant Science, Faculdade de Agronomia Eliseu Maciel/UFPEL/Capão do Leão, Rio Grande do Sul, Brazil; in two harvests, in spring 2018 and summer 2019. The variables analyzed regarding plant growth were number of leaves, leaf area index, specific leaf area, leaf area ratio, dry matter of roots, leaves, stem and fruits , dry matter partition of the different organs (roots, leaves, stem and fruits), root/shoot ratio; as for the productive variables, the number and mean weight of fruits, production, and harvest index were evaluated; as well as the evaluation of water and fertilizer consumption, volume of nutrient solution and leached fertilizers, and relations of efficiency in fruit production and degree of environmental contamination. In general, the cultivation system in gutters increases root growth and positively influences the production of photoassimilates from all plant organs of the Italian Sorbetto and grape Dolcetto mini tomato cultivars. Two-stemmed plants accumulate more photoassimilates than single-stemmed plants, regardless of cultivar. The yield of the fruits of the cultivars Sorbetto and Docetto is higher when the system of cultivation in gutters is adopted, and the plants are conducted with two stems. The recirculation of the drained solution in the closed system of gutters ensures significant savings of approximately 40 to 50% in the amount of water and fertilizers, with gains in mini tomato fruit productivity and low potential for environmental impact compared to the tomato cropping system free-draining pots. The reduced consumption of water and fertilizers observed in the closed system of gutters makes the cultivation of mini tomato plants show high efficiency in the use of both inputs compared to the cultivation in an open system of pots. The volume leached in the gutter system corresponds to a very small fraction of the nutrient solution supplied to the plants and represents only 2% of the amount leached in the open system of pots.