Effects of application of NO on plant growth and quality of pakchoi(Brassica chinensis L.)

Objectives Effect of different concentrations of nitric oxide (NO) on biomass, nutritional and antioxidant quality of pakchoi were studied to provide a theoretical basis for atmospheric NO-associated plant ecological responses and agricultural production.

Methods A pot experiment was conducted using pakchoi (Brassica chinensis L.) as tested material in a closed growth chambers. The exogenous NO was applied in rate of 0 (control), 100, 200, and 400 nL/L in each chamber. The plant biomass was weighed, and the contents of nitrate, soluble sugar and soluble protein were determined, and the total phenolics, total flavonoids and ascorbic acid were analyzed.

Results Compared with the no NO addition control, the application of 100, 200, and 400 nL/L exogenous NO caused considerable increases by 64%, 42% and 10% respectively in fresh weight and by 88, 61 and 49% respectively in dry weight of pakchoi. The best NO concentration was 100 nL/L. Compared with the control, 100 nL/L, 200 nL/L, and 400 nL/L gaseous NO decreased the nitrate concentrations in pakchoi by 59%, 76%, and 94%, respectively. The NO treatments also induced accumulation of soluble sugar and protein in pakchoi, and the most effective concentration for this effect was 100 nL/L. The exogenous gaseous NO application also significantly elevated the levels of several antioxidant compounds including total phenols, flavonoids, and ascorbate.

Conclusions Atmospheric application of trace amount of gaseous nitric oxide could be an effective strategy for improving both biomass production and quality of pakchoi. In general, NO 100 nL/L has the best effect on the growth and quality of pakchoi in greenhouse production.