Salt tolerance of hydrangea plants varied among species and cultivar within a species

Authors: NIU, GENHUA - Texas A&M University; SUN, YOUPING - Utah State University; HOOKS, TRISTON - Texas A&M University; Altland, James; DOU, HAIJIE - Texas A&M University; PEREZ, CHRISTINA - Texas A&M University

Submitted to: Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2020
Publication Date: 9/4/2020
Citation: Niu, G., Sun, Y., Hooks, T., Altland, J.E., Dou, H., Perez, C. 2020. Salt tolerance of hydrangea plants varied among species and cultivar within a species. Horticulturae. 6(3). Article 54. https://doi.org/10.3390/horticulturae6030054.
DOI: https://doi.org/10.3390/horticulturae6030054

Interpretive Summary: Intense competition for high-quality water among agriculture, industry and other users is promoting the use of alternative water sources for irrigating crops. Alternative waters include treated municipal reclaimed (recycled) water, runoff from greenhouse and nursery operations, agricultural drainage water, and naturally-occurring saline groundwater. The primary challenges of using water from these alternative sources are the high salt levels and undesirable specific ions, particularly sodium (Na+) and chloride (Cl-). Hydrangea, native to Asia and the Americas, is one of the most popular and widely grown and marketed plants in the nursery and floriculture industry. Limited information is available on the salt tolerance of hydrangea, particularly among different species and cultivars. The purpose of this study was to evaluate the relative salt tolerance of 11 popular commercial hydrangea cultivars based on their responses to elevated salinity levels in their growth, visual quality and leaf mineral contents, particularly the uptake of Na+ and Cl- in leaves. Salt tolerance varied with species and cultivars within the species H. macrophylla. ‘Ayesha’ (H. macrophylla), and the two hybrids ‘Sabrina’ and ‘Selina’, were the most tolerant, and a second tolerant group included ‘Mathilda Gutges’ and ‘Merritt’s Supreme’ (H. macrophylla). The next most salt-tolerant cultivars included ‘Preciosa’ (H. serrata) and ‘Passion’ (H. macrophylla), followed by ‘Snowflake’ (H. quercifolia) and ‘Emotion’ (H. macrophyalla). ‘Bulk’ of H. paniculata was the least salt-tolerant, followed by ‘Interhydia’ (H. paniculata). The salt-sensitive cultivars ‘Bulk’, ‘Interhydia’ and ‘Snowflake’ had inherently low leaf Na+ and Cl- concentrations.

Technical Abstract: A greenhouse study was conducted to assess the relative salt tolerance of 11 cultivars of hydrangea: Hydrangea macrophylla 'Ayesha’, ‘Emotion’, ‘Mathilda Gutges’, ‘Merritt’s Supreme’ and ‘Passion’; H. paniculata ‘Interhydia’ and ‘Bulk’; H. quercifolia ‘Snowflake’; H. serrata ‘Preciosa’; and H. serrata macrophylla ‘Sabrina’ and ‘Selina’. Plants were treated with a nutrient solution at an electrical conductivity (EC) of 1.0 dSm''1, and nutrient solution-based saline solutions at an EC of 5.0 dSm''1 (EC 5) or 10 dSm''1 (EC 10). The study was repeated in time Experiments 1 and 2). In both experiments, by the fourth week after treatment, ‘Bulk’ plants in EC 10 exhibited severe salt damage with most of them dead. ‘Interhydia’ was also sensitive, showing severe salt damage in EC 10 with a high mortality rate by the end of the experiment. The leaf area and total shoot dry weight (DW) of all cultivars in EC 5 and EC 10 treatments were significantly reduced compared to the control. Leaf sodium (Na+) and chloride (Cl'') concentrations were negatively correlated with visual quality, leaf area and shoot DW. The salt-sensitive cultivars ‘Bulk’, ‘Interhydia’ and ‘Snowflake’ had inherently low leaf Na+ and Cl'' concentrations in both control and salt-treated plants compared to other cultivars. Salt tolerance varied among species and cultivars within H. macrophylla. Among the 11 cultivars, H.macrophylla ‘Ayesha’ and two hybrids, ‘Sabrina’ and ‘Selina’, were relatively salt-tolerant. H. macrophylla ‘Merritt’s Supreme’ and ‘Mathilda’ were moderately tolerant. H. paniculata ‘Bulk’ was the most sensitive, followed by H. paniculata ‘Interhydia’, and then by H. serrata ‘Preciosa’ and H. macrophylla ‘Passion’, as evidenced by high mortality and severe salt damage symptoms. H. quercifolia ‘Snowflake’ and H. macrophylla ‘Emotion’ were moderately salt-sensitive.