Performance of hydroponic pak choi (Brassica rapa subsp. chinensis) under elevated sodium conditions

A.W. Svyantek, Z. Wang, B. Rana, I. Tatar, C. Auwarter, H. Hatterman-Valenti
In North Dakota, soils and irrigation water sources frequently have elevated sodium (Na+) cation content leading to decay of clayey soil structure, reduced water drainage, and decreased crop yield potential. To meet the growing demand for local fruits and vegetables as well as to overcome the brevity of the state’s growing season, regional farmers utilize controlled environment production in hoop houses, high-tunnels, and greenhouses. Under persistent irrigation, soil-based crops may not be advisable on account of probable sodium accumulation within the soil matrix. Increasing in use, hydroponic production of vegetables enables cropping in a soilless system. Yet, little is known about production under North Dakota’s irrigation water impediments. To investigate the growth of pak choi (Brassica rapa subsp. chinensis) under elevated sodium concentrations, an experiment was conducted with six rates of sodium (0, 75, 150, 300, 600, and 1200 mg L‑1) applied to three hydroponically grown pak choi genotypes (‘Joi Choi’, ‘Mei Qing Choi’, and ‘Rosie’). Genotypic differences were observed for all harvest traits except for root:shoot ratio. Contrastingly, only plant height and root:shoot ratio were altered by elevated sodium content. Neither linear nor quadratic effects of sodium concentration on yield were detected for these hydroponically grown pak choi genotypes; yet calculated plant physiological stress indices indicated that all plant harvest metrics suffered for ‘Mei Qing Choi’ and ‘Rosie’ under the highest rates of sodium (1200 mg L‑1). From these results, the majority of North Dakota irrigation well water (<300 mg L‑1 Na+) is estimated to be acceptably below threatening levels contributing to sodium toxicity and yield reduction in pak choi. Nevertheless, many of North Dakota’s sodic soils and waters have additional anions and cations present which require further investigation as controlled agriculture in hydroponic systems expands in the region.
Svyantek, A.W., Wang, Z., Rana, B., Tatar, I., Auwarter, C. and Hatterman-Valenti, H. (2021). Performance of hydroponic pak choi (Brassica rapa subsp. chinensis) under elevated sodium conditions. Acta Hortic. 1321, 133-140
DOI: 10.17660/ActaHortic.2021.1321.17
Asian vegetables, marginal water, non-heading Chinese cabbage, salinity, salt tolerance

Acta Horticulturae