Potencial de cultivo de agrião hidropônico utilizando efluente da piscicultura

Abstract

In the management of fish farming in tanks, there is a daily renewal of part of the water followed by disposal, which can cause environmental pollution due to the presence of nutrients and organic matter. Therefore, hydroponics is studied as an alternative for the reuse of this fish wastewater. In this context, the present work aimed to evaluate the reuse of water from the production of tilapia in the growth phase, considering the growth and physiological responses of the hydroponic watercress culture cultivated in the NFT system. The experimental design was in subdivided plots with mixed factorial. As a randomized primary factor, five different water mixtures were used (S1: 100% water from fish farming; S2: 25% nutrient solution and 75% water from fish farming; S3: 50% nutrient solution and 50% water from fish farming; S4: 75% nutrient solution and 25% water from fish farming; S5: 100% nutrient solution). As a fixed secondary factor, two solution circulation time intervals were used (T1: 15 minutes; T2: 30 minutes) whose circulation time was common to both (T1 and T2: 15 min). With 4 repetitions, 40 experimental units were totaled. Plant growth and physiological data were submitted to analysis of variance (ANOVA) using Sisvar software. It was observed that the mixture of solutions factor was significant at 1% of probability to the growth variables, with S3 being the mixture that promoted the highest values. The solution circulation time interval was significant at 5% only for root length (CR), with T1 being the treatment that promoted a 17% increase in CR when compared to T2. The best gas exchange rates were obtained using the S5. Through regression, there is an optimal level of mixture with approximately 35% of water coming from fish farming and 65% of nutrient solution.. Therefore, using this proportion combined with T2 recirculation, water from fish farming positively affects the growth of hydroponic watercress without major physiological damage, making it possible to save fertilizers and electricity in its production.