Evaluation of organic and mineral fertilizers on plant growth, minerals, and postharvest quality of celery (Apium graveolens L.)

Fertilizer type and rate may influence the quality of fruits and vegetables. This study compared plant growth, yield, minerals concentration, and postharvest quality of celery as affected by fertilizer type (organic and chemical) and nitrogen rate. Organic fertilizers were vermicompost (VER) and bio-organic fertilizer [compost plus Trichoderma harzianum (COM)]. Chemical fertilizers were urea (46% N) at high rate [322 kg center dot ha(-1) N (UREA_HIGH)], optimal rate [196 kg center dot ha(-1) N (UREA_OPT)], and low rate [138 kg center dot ha(-1) N (UREA_LOW)]; ammonium nitrate [35% N (AN)] at 196 kg center dot ha(-1) N, and an unfertilized treatment used as a control. Plants fertilized with UREA_HIGH had the highest plant height and yield. Yields with VER and COM were similar to those of UREA_OPT, UREA_LOW, and AN. Celery fed with organic fertilizers had reduced petiole nitrate accumulation and improved mineral content (N, P, and K). Organic fertilizer treatments were the most effective in maintaining celery quality (petiole color, weight loss, titratable acidity, pH, and total soluble solids). There was an enhancement of phytochemical compounds such as vitamin C, total phenols, and antioxidant activity in celery grown with organic fertilizers. Organic fertilizers released N more slowly into the soil, resulting in reduced plant growth and yields but increased celery's nutritional quality. Celery quality attributes with organic fertilizers were similar to those with the UREA_LOW treatment suggesting that the improved celery quality with the organic fertilizers may be attributed to reduced soil N.