SALINITY STRESS Saponin seed priming improves salt tolerance in quinoa A. Yang 1,2 | S. S. Akhtar 2,3 | S. Iqbal 4 | Z. Qi 1 | G. Alandia 2 | M. S. Saddiq 4 | S.-E. Jacobsen 2 1 School of Water Conservancy and Civil Engineering, Northeast Agriculture University, Harbin, China 2 Faculty of Science, Department of Plant and Environmental Sciences, University of Copenhagen, T  astrup, Denmark 3 Dansk Agro, T  astrup, Denmark 4 Department of Agronomy, University of Agriculture Faisalabad, Faisalabad, Pakistan Correspondence S.-E. Jacobsen, Faculty of Science, Department of Plant and Environmental Sciences, University of Copenhagen, T  astrup, Denmark. Emails: seja@plen.ku.dk and aizheng.yang@neau.edu.cn Abstract Quinoa (Chenopodium quinoa Willd.) is a facultative halophyte of great value, and World Health Organization has selected this crop, which may assure future food and nutritional security under changing climate scenarios. However, germination is the main critical stage of quinoa plant phenology affected by salinity. Therefore, two experiments were conducted to improve its performance under salinity by use of saponin seed priming. Seeds of cv. Titicaca were primed in seven different solu- tions with varying saponin concentrations (i.e. 0%, 0.5%, 2%, 5%, 10%, 15%, 25% and 35%), and then, performances of primed seeds were evaluated based on mean germination time and final germination percentage in germination assays (0 and 400 mM NaCl stress). Saponin solutions of 10%, 15% and 25% concentration were found most effective priming tools for alleviating adverse effects of salt stress dur- ing seed germination. Performances of these primed seeds were further evaluated in pot study. At six-leaf stage, plants were irrigated with saline water having either 0 or 400 mM NaCl. The results indicated that saline irrigation significantly decreased the growth, physiology and yield of quinoa, whereas saponin priming found operative in mitigating the negative effects of salt stress. Improved growth, physiology and yield performance were linked with low ABA concentration, better plant water (osmotic and water potential) and gas relations (leaf photosynthetic rate, stomatal conductance), low Na + and high K + contents in leaves. Our results suggest that saponin priming could be used as an easy-operated and cost-effective technol- ogy for sustaining quinoa crop growth on salt-affected soils. KEYWORDS Chenopodium quinoa, halophyte, priming, salinity, saponin 1 | INTRODUCTION Salinity is one of the major threats to crop production, especially in arid and semi-arid regions of the world (Schleiff, 2008). According to an estimate, 1,128 Mha land of the world is affected by salinity or sodicity (Wicke, et al., 2011), including 100 Mha has turned to saline due to use of brackish irrigations (FAO, 2008). Different approaches have been used to cope with salinity stress, but the easiest and most sustainable option to counter salinity stress is to cultivate halophytic crops like quinoa (Chenopodium quinoa Willd.) in such conditions. Halophytes grow optimally even at high salt concentrations (100–200 mM NaCl for dicots and 50 mM for monocots) (Flowers & Colmer, 2008). Quinoa is gaining increased attention by scientists to feed the world’s burgeoning population because of its high potential as a human food source, caused by its high tolerance to abiotic stresses (salinity, drought and frost) and its nutritional quality (Jacobsen, Mujica, & Jensen, 2003; Adolf, Jacob- sen, & Shabala, 2013). Halophytes are tolerant to excess salts but high concentrations of salts affect germination in both glycophytes and halophytes Accepted: 15 June 2017 DOI: 10.1111/jac.12229 J Agro Crop Sci. 2017;1–9. wileyonlinelibrary.com/journal/jac © 2017 Blackwell Verlag GmbH | 1