Germination and growth of spinach under potassium deficiency and irrigation with high-salinity water

WOS:000603106200001PubMed ID:33317110Information is scarce on the interaction of mineral deficiency and salinity. We evaluated two salt-tolerant spinach cultivars under potassium (K) doses (0.07, 0.15, 0.3, and 3.0 mmolc L?1) and saline irrigation (5, 30, 60, 120, and 160 mmolc L?1 NaCl) during germination and growth. There was no interaction between salinity and K. Salinity decreased germination percent (GP), not always significantly, and drastically reduced seedling biomass. ‘Raccoon’ significantly increased GP at 60 mmolc L?1 while ‘Gazelle’ maintained GP up to 60 or 120 mmolc L?1. After 50 days under saline irrigation, shoot biomass increased significantly at 30 and 60 mmolc L?1 at the lowest K dose but, in general, neither salinity nor K dose affected shoot biomass, suggesting that salinity supported plant growth at the most K-deficient dose. Salinity did not affect shoot N, P, or K but significantly reduced Ca, Mg, and S, although plants had no symptoms of salt toxicity or mineral deficiency. Although spinach seedlings are more sensitive to salt stress, plants adjusted to salinity with time. Potassium requirement for spinach growth was less than the current crop recommendation, allowing its cultivation with waters of moderate to high salinity without considerable reduction in yield, appearance, or mineral composition. © 2020 by the authors.U.S. Department of Agriculture, USDA CRIS 2036–13210-006–00DFunding: This research was funded by the United States Department of Agriculture (USDA-ARS) as part of the internal project: CRIS 2036–13210-006–00D; Enhancing Special Crop Tolerance to Saline Irrigation Waters.Acknowledgments: We acknowledge the financial support of a grant provided by TUBITAK (2219 International Postdoctoral Research Scholarship Program) for Kadir Uçgun’s work on this project at the US Salinity Laboratory (USDA-ARS), Riverside, USA. We also acknowledge the help of Alysia Soria, Kimberly Wilkerson, and Noah Gangoso for their assistance with harvest, saline solutions and sample preparation and Pangki Xiong for the analyses of macro/micronutrients and of Na and Cl in tissues of spinach. We also acknowledge the help of Ray Anderson and Dennise Jenkins for the confirmation of greenhouse light intensity