Sistemas de cultivo sem solo para a cultura do tomateiro sob uma perspectiva de baixo impacto ambiental

Abstract

Tomato crop in soilless growing systems with recirculation of drain nutrient solution can be a viable alternative for obtaining high yield and quality of fruit, as well as optimize the productive resources, with low environmental impact. In this sense, to study both closed substrate growing and hydroponic cultivation systems is necessary. At the same time, the choice of varieties to respond positively to the proposed technologies is very important. Within this context, two experiments were carried out in a plastic greenhouse, located at the Campus of the ‘Universidade Federal de Pelotas’, in the municipality of Capão do Leão/RS in the agricultural year 2014/15. The experiment 1 aimed to evaluate the effects of adding organic compost (OC) to the raw rice husk (RRH) on the physical and chemical properties of the substrate [through the comparison between the RRH (100%) and RRH (80%) + OC (20%)] and on plant growth and fruit production responses of four tomato hydrid varieties [Ivety, Sophia, Sheila Victoria and Lumi (Sakata ® Seed)]. The experiment 2 aimed to determine the thermal time, the water consumption and the water use efficiency (WUE), as well as the yield components and fruit quality of two small tomato varieties [Wanda and Dolcetto (Isla ®)] grown in NFT hydroponic system. In relation to the results obtained in experiment 1, for all variables analyzed, there was no significant interaction between substrate and Variety. The addition of OC has improved the physical and chemical proporties of the substrate, however, did not affect the major plant growth and fruit production characteristics or the crop. The four varieties showed similar plant growth and fruit yield, but Sheila Victoria stood out by the highest concentration of total soluble solid contents. The obtained yields are considered high, ranging from 6.3 kg.plant-1 for the varieties Sophya and Sheila Victoria, passing 6.5 kg.plant-1, for variety Lumi, up to 7.0 kg.plant-1 obtained for the variety Ivety. The results indicate be unnecessary addition of OC to RRH and that the four varieties adapted similarly to the proposed system. In relation to the results obtained in experiment 2, the variety Wanda is earlier than the variety Dolcetto. The period of greatest accumulation of degrees day, for both 11 varieties, was in the phenology phase IV (harvest). Variety Dolcetto presented lower total water consumption. Maximum daily water demand was 1.53 and 2.12 liters-1 plant- 1 day-1 and the total water demand was 190.6 and 261.7 liters.plant-1, respectively to 'Dolcetto ' and 'Wanda'. The varieties presented similarity with respect to WUE. For the production of one kg of fruit fresh matter, it was necessary 50.5 and 48.3 liters of water, respectively, for 'Wanda' and 'Dolcetto'. Variety Wanda presented higher yield (15.34 kg m-2, in front of 12.14 kg m-2 obtained with 'Dolcetto') and larger fruit. However, Dolcetto produced more fruits, with higher soluble solid contents and presented lower fruit loss. Considering the characteristics evaluated, one can infer that variety Dolcetto is best suited for the growing of the small tomato in hydroponic system.