Preparation of Fish Protein Water-soluble Animo Acid Fertilizer and Its Uitilization Effect on Crop Growth and Development

The water-soluble amino acid fertilizers are a novel type of functional organic fertilizers for plants. In order to explore the influence of water-soluble amino acid fertilizers on plant growth, in this paper, the fish product waste was utilized as the raw material, and the water-soluble amino acid fertilizers were prepared by reasonably optimizing the ratio of feed to water, the types and amounts of proteases, and the hydrolysis conditions. Subsequently, through hydroponic experiments, the fish protein water-soluble fertilizers with different dilution multiples were applied to the wheat Bainong Aikang 58 to determine the optimal dilution multiple. Moreover, the two fertilization methods of spraying and pouring were respectively used to fertilize the tomato Xinzhongshu No.4, thus to investigate the effects of different fertilization treatments of water-soluble amino acid fertilizers on the growth and development of crops. The results indicated that under the condition of 1∶3 liquid-solid ratio, with the addition of 0.1% alkaline protease and enzymatic hydrolysis at 50℃ for 4 hours, the fish protein waste could be used to prepared the fish protein water-soluble fertilizer with a total soluble amino acid content of 16.925 mg·g⁻¹ and a high proportion of amino acids (about 50%) that could be easily used by plants. The hydroponic experiments indicated that the optimal application concentration of the fish protein amino acid water-soluble fertilizer was diluted 100 times (DB100). DB100 significantly enhanced the germination rate and vitality index of wheat seeds, and promoted the root length and root-shoot ratio of wheat seedlings (P＜0.05). With DB100 as the dilution standard, the foliar spraying of amino acid fertilizer on the potted tomato seedlings significantly increased the plant height (22.9%), leaf area (38%), and leaf chlorophyll content (33.3%) of tomato seedlings (P＜0.05), and decreased the malondialdehyde content in tomato leaves by 26.7% (P＜0.05). However, there was no significant difference between the application of water-soluble fertilizer through irrigation and the control CK（P＞0.05）. The pot experiment demonstrated that foliar spraying of water-soluble fertilizer could directly provide nutrients to plants, which were readily absorbed and utilized, thereby promoting the growth and development of tomatoes, enhancing the photosynthetic efficiency of plant leaves, and improving the antioxidant capacity of plants. In conclusion, the rational use of water-soluble amino acid fertilizer could significantly promote plant seed germination and seedling growth, while the foliar spraying of water-soluble amino acid fertilizer significantly promoted the photosynthetic efficiency of plant leaves and the growth of plants.