Abstract: 【Objective】Melatonin has multiple beneficial effects on plants. However, its active chemical properties limit its application in agricultural production. In this study, urea slow-release functional fertilizer containing melatonin (hereinafter referred to as functional fertilizer) was prepared by coating technology, and its effects on tomato growth, yield, quality and phosphorus use efficiency were studied. In order to provide theoretical basis for the efficient.【Method】The release rate of melatonin in functional fertilizer was studied by water bubble method. Then the effects of melatonin-functional fertilizer on the growth of tomato seedlings were studied by plug seedling. Finally, a pot experiment was conducted to study the effects of functional fertilizer on plant growth and dry matter distribution, root growth, phosphorus absorption and distribution, phosphorus utilization rate and fertilizer yield contribution rate, root phosphatase activity, fruit yield and quality. Four treatments were set, namely, phosphorus application (+P) and non-phosphorus application (?P), and then urea slow-release fertilizer (?P and +P) or functional fertilizer (?P+M and +P+M) were added respectively. 【Result】The real melatonin content after coating is 35% of the total melatonin concentration when coating. When water bubbled to 60 d, the amount of melatonin residue in functional fertilizer was 6.61%. The application of functional fertilizer in conventional tomato seedlings could significantly promote seedling growth, and the seedling index was increased by 70.2% compared with the control. The pot experiment showed that the biomass of tomato roots, stems, leaves and fruits under ?P treatment decreased by 19.64%, 18.51%, 28.99% and 28.73% compared with that under +P treatment, respectively. The dry matter distribution ratios of roots and stems increased by 10.03% and 11.63%, and the dry matter distribution ratios of leaves and fruits decreased by 2.74% and 2.39%, respectively. The application of functional fertilizer could significantly increase the biomass accumulation of all tissues under the two phosphorus treatments. The dry matter distribution ratio of root under the condition of increasing +P was 12.14%, the dry matter distribution ratio of stem and leaf under the condition of reducing -P was 6.00% and 5.90%, and the dry matter distribution ratio of fruit increased by 9.06%. ?P treatment reduced the total length, total surface area and total volume of roots, and increased the number of root tips. The application of functional fertilizer could increase the total length, total surface area, total volume and number of root tips under two phosphorus levels. ?P treatment significantly reduced the phosphorus content in roots, stems, leaves and fruits of tomato plants, increased the phosphorus distribution in roots, stems and leaves, and reduced the phosphorus distribution ratio in fruits. The application of functional fertilizer could significantly increase the phosphorus content of all tissues under the two P treatments, increase the phosphorus distribution ratio of roots under +P treatments, decrease the phosphorus distribution ratio of stems and leaves under ?P treatment, and increase the phosphorus distribution ratio of fruits. The application of functional fertilizer can significantly improve phosphatase activity, whole plant phosphorus uptake, fertilizer utilization rate and fertilizer yield contribution rate. ?P treatment reduced tomato yield, but application of melatonin functional fertilizer significantly increased yield under ?P treatment reduced the tomato yield by 17.57%, but the application of functional fertilizer under ?P treatment increased the yield by 21.32%, and had no significant effect on the yield under +P treatment. In addition, the application of functional fertilizer could comprehensively improve the quality of tomato fruits under ?P or partial +P conditions.【Conclusion】The application of melatonin coated in slow-release fertilizer could significantly reduce the amount of melatonin, improve the growth quality of tomato seedlings and plants in the whole growth period, increase the utilization efficiency of phosphorus fertilizer, and improve the yield and fruit quality.

Key words: tomato, urea slow-release functional fertilizer containing melatonin, phosphate fertilizer treatment, growth, yield and quality, phosphorus utilization rate