Effects of a Preparation Containing Amino Acids on Pakchoi Nutrient Absorption, Yield, and Quality When Grown in Saline-Alkali Soil

Saline-alkali stress adversely affects crop growth and nutrient absorption, thereby reducing crop yield and quality. Exogenous amino acids have multiple synergistic effects; however, whether a preparation containing amino acids increases the resistance of pakchoi to saline-alkali soil remains unclear. This study investigated the effects of a patented “preparation” containing amino acids on crop growth, nutrient absorption, and tolerance to saline-alkali stress in pakchoi ( Brassica chinensis L.), using a pot culture experiment with three successive plantings. The preparation was made using tail liquor generated during the production of monosodium glutamate. Topdressing with the preparation had little effect on pakchoi growth, yield, quality, or nutrient accumulation, compared with no topdressing treatment. However, the addition of the preparation to water-soluble fertiliser increased crop yield by 11.9–17.6%, with a 15.4% cumulative increase over the three crops. The concentrations of vitamin C, soluble sugar, and soluble protein increased by 10.2–12.4%, 11.9–22.3%, and 3.0–14.3%, respectively. The fertiliser utilisation ratio for the three crops increased by 30.5%, while the nitrate content decreased by 8.5–20.4%. The fresh weight significantly decreased when the dosage of water-soluble fertiliser was reduced to 20%. However, the addition of the preparation to the reduced-dosage water-soluble fertiliser compensated for this reduction, especially in the third crop. Our results show that the preparation improves pakchoi resistance to saline-alkali stress and restores agricultural productivity.