Abstract
Melatonin can directly or indirectly eliminate reactive oxygen species, regulate hormone levels, and improve drought-stressed soybean crop resistance, yield, and quality. The nutrient contents of soybeans grown under normal conditions (WW), drought stress (D), and drought stress with exogenous melatonin (D + M) ( p < 0.05 ) were compared. The differences in the quality of natto from the three groups of soybeans were also analyzed. The results showed that compared with soybeans under normal conditions, those grown under drought stress had reduced yield and carbohydrate, protein, essential amino acid, soybean isoflavone, and other nutrient contents. Besides, natto presented low nattokinase levels (674 U/mL), natto drawing ability was weak, the surface was dull, the taste was poor, and the sensory score was 12 points. Exogenous melatonin increased the carbohydrate content (starch, sucrose, glucose, and fructose) and improved the yield and quality of soybeans under drought. The natto produced by soybeans under drought stress with exogenous melatonin had high nattokinase content (756 U/mL) and long wire drawing. The surface of the product was rich in mucus and had a natto aroma. Its comprehensive sensory score was 20 points. Natto from soybeans under drought stress that were treated with exogenous melatonin showed significantly higher yield, nutrient content, and quality, than those under drought stress without treatment. This study provides theoretical data that can facilitate the development of new methods to improve the quality of soybeans grown under drought conditions.
Highlights
Drought reduces the water content of soybean leaves and the integrity of cell membrane, which limits the orderly progress of physiological [1] and biochemical reactions, such as carbon and nitrogen assimilation, transfer, and distribution during soybean growth, and thereby leads to slow crop growth and development [2, 3]
We explored whether the application of melatonin would improve drought resistance and quality of soybean and its products under drought stress, while aiming at utilizing the findings to improve the quality of soybean products in the future
Test Materials. e drought-sensitive soybean variety Suinong 26 was provided by the National Engineering Technology Research Center for Coarse Cereals, China; Bacillus subtilis var. natto strains were purified from commercially available natto starter cultures (MG) bought from Miyagino natto Production Research Institute, Japan; beef extract peptone (NA) agar medium, daidzin, glycerin, genistin, genistein, urokinase standards, fibrin tablets, and daidzein were purchased from Beijing Obosing Biotechnology Co., Ltd., China
Summary
Drought reduces the water content of soybean leaves and the integrity of cell membrane, which limits the orderly progress of physiological [1] and biochemical reactions, such as carbon and nitrogen assimilation, transfer, and distribution during soybean growth, and thereby leads to slow crop growth and development [2, 3]. Melatonin regulates the levels of growth hormones and improves the activities of carbon and nitrogen metabolismrelated enzymes and photosynthetic rate [15, 16], promoting carbon and nitrogen metabolism and improving yield and quality of soybean. Nattokinase, one of the most important active substances in natto, dissolves thrombus, reduces blood viscosity, improves blood circulation, and softens and increases blood-vessel elasticity. It can reduce the risk of death due to cardiovascular diseases in both men and women. There are studies on melatonin application and the improvement of antioxidant and drought resistance properties of crops, there is a lack of data on the influence of melatonin treatment on the nutritional composition and quality of soybean and its products. We explored whether the application of melatonin would improve drought resistance and quality of soybean and its products (such as natto) under drought stress, while aiming at utilizing the findings to improve the quality of soybean products in the future
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
