Influence of low NaCl concentration on growth, quality and yield of Chinese chive in hydroponic culture

NaCl is always considered as a stress factor and as the main cause of salt stress in plants. However, it has been proved that low concentrations of NaCl have no harmful effect on plant growth. In fact, studies have shown that low concentrations of NaCl actually promote plant growth and quality. As a new mode of cultivation, hydroponic culture has been a suitable solution to control Chinese chive diseases caused by Chinese chive maggot. To explore the effect of low concentrations of NaCl on the growth, quality and production of Chinese chive, 0 mmol·L^-1 (CK), 5 mmol·L^-1, 10 mmol·L^-1, 20 mmol·L^-1 and 30 mmol·L^-1 NaCl were respectively added to nutrient solutions in the experiment. The results showed that plant height, pseudo-stem diameter and leaf length were highest under 20 mmol·L^-1 NaCl treatment. Leaf number of Chinese chive treated with NaCl increased compared with that of CK. However, leaf width decreased with increasing concentration of NaCl. The contents of photosynthetic pigments increased after treated with low concentrations of NaCl. Chlorophyll a, chlorophyll b, carotenoid and chlorophyll a+b contents were highest under 10 mmol·L^-1 NaCl treatment. NaCl treatment decreased nitrate accumulation and nitrate content decreased by 12.42%, 13.17%, 15.16% and 26.76% respectively under 5 mmol·L^-1, 10 mmol·L^-1, 20 mmol·L^-1 and 30 mmol·L^-1 NaCl treatments compared with that under CK. Vitamin C content increased by 12.2%, 12.8% and 5.1% and 15.4% under 5 mmol·L^-1, 10 mmol·L^-1, 20 mmol·L^-1 and 30 mmol·L^-1 NaCl, respectively, compared with that of the control. The contents of soluble sugar, crude fibers and yield of Chinese chive were highest under 10 mmol·L^-1 NaCl. Yield increased respectively by 6.7%, 6.6%, 6.9% and 6.7% in the first harvest, second harvest, third harvest and 3 combined harvests under 10 mmol·L^-1 NaCl over CK. Comprehensive analysis showed that adding 10 mmol·L^-1 NaCl to nutrient solution enhanced growth performance, decreased nitrate content, improved quality and increased production of Chinese chives.