RESUMEN
The use of effluent from fish farming in the greenhouse increases the availability of water and reduces the risk of environmental contamination due to improper disposal. Therefore, a study in a greenhouse was carried out to evaluate the effects of fertigation utilizing fish farming effluent at different phenological stages of cherry tomato. Plants of cherry tomato were fertigated with fish farming effluent (E) alternated with tap water (W) at the four phenological stages of the crop (growth, flowering, fruit formation and ripening). The growth, gas exchange, chlorophyll a fluorescence, chloroplast pigments, electrolyte leakage, production and postharvest quality were evaluated. The fertigation with fish farming effluents did not reduce the growth of tomato plants. The fertirrigated plants with fish farming effluents obtained photosynthetic rates and photochemical efficiency similar or superior to the control. There was no interference on photochemical quenching when the plants were fertigated with fish farming effluents. When applied at the flowering stage, fish farming effluent reduces the average fruit weight and increases acidity. For greenhouse cultivation, each application of fish farming effluents, two successive applications of tap water are required.Novelty statement: Use of fish farming effluent did not compromise the growth and photosynthetic activity of cherry tomato plants. Cherry tomato production was compromised when the effluent was applied during growth, flowering and, beginning of fruit set. The fish farming effluent can be used in irrigation without yield losses if alternating with tap water.