The Effect of Humic Acid and Amino Acid Organic Fertilizers on Growth of Greenhouse Tomato Fruits Harvested at Four Growth Stages

Due to ever increasing greenhouse cultures, using organic fertilizers for enhancing healthy products is necessary. To investigate the effect of two types of these fertilizers on tomato, in a factorial experiment, based on completely randomized design with 3 replications, with 2 pots in each replication, 0 g/kg humic acid (Humic0) and 1 g/kg (Humic1) and amino acid at 3 levels of 0 g/kg (Amin0), 1 g/kg (Amin1) and 2 g/kg (Amin2), were fertigated once every 10-day. Fruit characteristics at first and second harvests in green, orange, pink and red phases were studied. Results showed that fruit dry weight was less affected by humic acid and amino acid than fruit fresh weight, especially in green and orange phases. In pink and red phases, in the first harvest, fruit dry weight was increased with amino1 and amino2, in both concentrations of humic acid, as compared with control. Amin1 and humic1 had the highest total soluble solids. Fruit phosphorus concentration in humic1 and amin2 was the highest. Potassium concentrations in amino1 and amino2 in both humic acid concentrations were higher than control. Nitrogen concentration in humic1 and amin2 was increased. Therefore, it is recommended that greater amount of these fertilizers or more application times, be used in nutrient solution of tomato at fruit ripening stage and first harvest. Since using these fertilizers is more effective on fresh weight than on dry weight, it is recommended to use them for fresh tomato consumption than for processing tomato for paste.