Effects of chemical fertilizer reduction combined with seaweed complex application on yield, fruit quality and nutrient absorption of grape

Abstract: 【Objective】The study aimed to investigate the effects of chemical fertilizer reduction com-bined with seaweed complex application on yield, quality and nutrient absorption in grape to provide a theoretical basis for rational fertilization in vineyards.【Methods】Field experiments were conducted in the vineyards in Zhengzhou and Xinxiang. Shine Muscat Grape was used as experimental material, and six treatments were as follows: F (full dose of traditional water soluble fertilizer), HF (full dose of tradi-tional water soluble fertilizer combined with seaweed complex), F1 (25% reduction in traditional water soluble fertilizer), HF1 (25% reduction of traditional water soluble fertilizer combined with seaweed complex with ), F2 (50% reduction of traditional water soluble fertilizer), HF2 (50% reduction of tradi-tional water soluble fertilizer combined with seaweed complex with ). Three repeats were set for each  treatment, with a single plot and random block arrangement. Grape plant spacing was 1.5 m×3.5 m and 1.5 m×3.0 m respectively in Zhengzhou and Xinxiang vineyards. The nitrogen fertilizers were urea and potassium nitrate, and potassium dihydrogen phosphate was used for phosphorus fertilizer and potassium fertilizer, in which the deficiency of potassium fertilizer was supplemented by kalium nitrate fertilizer. In all treatments, the fertilizers were applied in the bud break stage, young fruit stage, expansion stage, and 20 days before harvest, respectively. In each stage, the proportion of pure N, P2O5, K2O in total fertilizer application was 40%- 15%- 15% , 30%- 40%- 15% , 20%- 30%- 40% , 10%- 15%- 30% , respectively, which were applied by simple fertilization gun. Other field management measures were consistent with the local traditional management.【Results】The single fruit weight and yield of grapes in Zhengzhou and Xinxiang vineyards were improved by the HF treatments compared with the F treatment. Under the con-dition of reduced fertilization, the single fruit quality and yield of the HF1 and HF2 treatments were high-er those of the F treatment. There was no significant difference in single fruit quality between the HF1 and HF2 treatments in Zhengzhou vineyard, while the yield of the HF2 treatment significantly increased by 9.50%; in Xinxiang vineyard, the single fruit quality and yield of the HF1 treatment were significantly increased by 26.52% and 66.31%, respectively, compared with the F treatment. There was no significant difference in fruit quality between the treatment of traditional water-soluble fertilizer treatment combined with seaweed complex and the treatment of traditional water-soluble fertilizer treatment in Xinxiang vine-yard. Under the condition of 25% reduction combined with the seaweed complex, the soluble solid sub-stance was significantly increased by 31.46%, and fruit hardness was significantly increased by 22.39% in Xinxiang vineyard, compared with the full dose of traditional water-soluble fertilizer treatment. How-ever, there was no significant difference in fruit quality in Zhengzhou vineyard. The F treatment had the highest leaf nitrogen content in Zhengzhou and Xinxiang vineyards, which were increased by 7.25% and 4.22% respectively compared with the HF treatment. Under the condition of equal fertilization treatment, except for the 50% fertilization reduction in Zhengzhou vineyard, the leaf nitrogen contents of the treat-ment of traditional water-soluble fertilizer combined with seaweed complex application were lower than that of the treatment of traditional water-soluble fertilizer treatment in two vineyards. In Zhengzhou and Xinxiang vineyards, there was no significant differences in phosphorus contents of leaves between the treatment of traditional water-soluble fertilizer combined with seaweed complex application and the treat-ment of traditional water-soluble fertilizer. Compared with F treatment, HF increased the potassium con-tents of leaves, and under the conditions of fertilizer reduction, the potassium contents of leaves treated with the treatments of water soluble fertilizer combined with seaweed complex application were still higher than that of the treatment of traditional water soluble fertilizer treatment in Zhengzhou vineyard, and there was no significant difference in potassium contents of leaves between the treatment of tradition-al water-soluble fertilizer and the treatment of same amount of traditional water-soluble fertilizer com-bined with seaweed complex application in Xinxiang vineyard. In the same amount of fertilization, the fruit nitrogen contents under the treatment of water-soluble fertilizer combined with seaweed complex ap-plication were lower than that of the treatment of traditional water-soluble fertilizer, in which the 50% re-duction of chemical fertilizer combined with seaweed complex application treatment had the lowest nitro-gen content of the fruit. Moreover, HF treatment could promote the phosphorus and potassium content of the fruit, and under the conditions of chemical fertilizer reduction, the phosphorus content of the fruits of HF1 treatment was still higher than those of the other fertilization treatments, however, compared with HF treatment, HF2 treatment significantly decreased the potassium content of the fruits in two vinyards. In terms of fruit coloration, compared with F treatment, the color saturation of HF treatment was signifi-cantly increased by 11.23% in Zhengzhou vineyard, but decreased by 12.01% in Xinxiang vineyard. Un-der the condition of fertilizer reduction, the color saturation of the HF1 treatment and HF2 treatment in Zhengzhou vineyard were significantly improved compared with the F treatment, while the HF2 treat-ment in Xinxiang vineyard significantly decreased the brightness and color saturation of the fruits.【Conclusion】Under the current conditions of two vineyards, fertilizer reduction could increase the yield of grapes and the phosphorus contents of the fruits. Under the conditions of fertilizer reduction, the solu-ble sugar contents, phosphorus, and potassium contents of the fruit of HF1 treatment were higher than that of the HF2 treatment. Comprehensive analysis showed that HF1 treatment had a better effect on grape yield, fruit quality, and nutrient absorption.