Cultivo do tomateiro em sistema sem drenagem: respostas agronômicas a diferentes substratos e à enxertia de plantas sob diferentes condutividades elétricas da solução nutritiva

Abstract

In the agricultural sector, the demand for reducing impacts on the environment is growing. Systems that seek to optimize the use of water, fertilizers and cultivation media have gained ground among producers. The drainageless cultivation system has this potential, in addition to being another alternative to substrate cultivation. As it is a more complex system, as it tends to salinize the substrate and root environment, it is necessary to study the viability and adaptation of different substrates to this system. Grafting in vegetables has grown considerably and has been a management alternative for overcoming adverse soil cultivation conditions, going beyond just conferring resistance to soil pathogens, as it is also used to overcome abiotic stresses. In this sense, grafting can be an ally in soilless cultivation, as, according to producers' experiences, the technique, in addition to ensuring greater vigor, can give the grafted plants a greater capacity to absorb water and mineral nutrients, and increase longevity. of plants. This thesis seeks to resolve some questions about the behavior of two substrates and the performance of grafted tomato plants in cultivation systems without drainage subjected to different electrical conductivities of the nutrient solution, given that studies are practically non-existent, and there is not enough scientific evidence that prove their productive superiority. Therefore, this work aims to assess the effect of substrates, grafting and electrical conductivity on growth as well as evaluate fruit productivity and quality in soilless cultivation systems under appropriate temperature and light conditions. The work was carried out in a cultivation system on fresh rice husk substrate and commercial substrate. The variables analyzed were regarding plant growth (number of leaves, leaf area index, leaf area, specific leaf area, dry mass of root, stem, leaves, fruits and total) and production (number, average weight, production, total soluble solids content and fruit size). The commercial substrate promoted greater production of dry mass of stem, leaves, fruits and total, number of fruits, fruit production and total soluble solids. Fresh rice husk promoted a higher concentration of fruit sugars (SST). The electrical conductivity of the nutrient solution of 1.3 dS m-1 favors the average fruit weight and, consequently, a higher fruit yield. EC 2.6 dS m-1 favors the production of stem, leaf and total dry mass. Plant grafting favors root and stem growth of plants, leaf expansion, production of a greater number of fruits and greater yield. Grafting does not affect the average weight and size of the fruits. Using a nutrient solution with EC 2.6 dS m-1, it is possible to obtain fruits with a higher concentration of sugars from grafted plants than from non-grafted plants. The electrical conductivity of the nutrient solution of 2.6 dS m-1 favors leaf expansion, the production of a greater number of fruits and, consequently, its yield. The data obtained show the technical feasibility of growing saladete tomato plants in a cultivation system in substrate without drainage.