Salt Tolerance of Hydrangea Plants Varied among Species and Cultivar within a Species

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 dS·m−1, and nutrient solution-based saline solutions at an EC of 5.0 dS·m−1 (EC 5) or 10 dS·m−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.

Salinity Tolerance of Four Hardy Ferns from the Genus Dryopteris Adans. Grown under Different Light Conditions

“…During their growth and development plants are exposed to different environmental stresses, the effects of which are often synergistic, and their combined outcome is considerably more powerful than that of individual stress factors [28,29]. Understanding the response of individual genotypes to adverse environmental conditions allows for proper selection of tolerant and resistant plants [7,10,30]. Most studies on the effects of stressful conditions have been carried out on flower ornamentals, while the group of leaf ornamental plants has so far received very little attention.…”

“…The negative effects of salinity are due to toxicity of sodium ions that accumulate in plant tissues and disturb plant ionic balance [9]. The assessment of ion content in plants grown under salt stress is important from a cognitive and practical perspective, as the ion level might be a marker for selecting species and cultivars tolerant to elevated salinity [10,11].…”

Growth, Gas Exchange, and Mineral Nutrients of Hydrangea Hybrids Irrigated with Saline Water

“…There was 36% and 68% reduction in leaf area for YW × Nigra, 77% and 91% for YW × Oakhill, and 39% and 72% for YH × Hamburg, compared with control, when irrigated with saline solution at an EC of 5.0 or 10.0 dS•m À1 , respectively. Similarly, Niu et al (2020) reported that elevated salinity stress reduced leaf area of H. macrophylla, H. paniculata, H. quercifolia, H. serrata, and H. serrata ×macrophylla cultivars by 20% to 58% and 42% to 89%, respectively, when irrigated with saline solution at an EC of 5.0 or 10.0 dS•m À1 . H. macrophylla 'Smhmtau' and 'Smnhmsigma' also had reduced leaf area when irrigated with saline solution at an EC of 5.0 or 10.0 dS•m À1 (Liu et al, 2017).…”

“…Liu et al (2017) reported that H. macrophylla 'Smhmtau' and 'Smnhmsigma' irrigated with saline solution at an EC of 10.0 dS•m À1 experienced foliar salt damage with visual scores of 3 on the same scale described in this paper, but when they were irrigated with saline solution at an EC of 5.0 dS•m À1 , the visual scores were %4. Niu et al (2020) reported that H. macrophylla 'Ayesha', 'Mathilda Gutges', and 'Merritt's Supreme', H. serrata ×macrophylla 'Sabrina' and 'Selina' exhibited much better visual scores than H. paniculata 'Interhydia' and 'Bulk', H. quercifolia 'Snow Flake', and H. serrata 'Preciosa', especially when they were irrigated with saline solution at an EC of 10.0 dS•m À1 . With respect to the visual score only, YW × Nigra and YH × Hamburg exhibited more tolerance to salinity stress than those cultivars of H. macrophylla, H. paniculata, H. quercifolia, H. serrata, and H. serrata ×macrophylla that were evaluated in different experiments with the same saline solutions and experimental duration, but different growing seasons (Niu et al, 2020), but the salinity tolerance of YW × Oakhill was similar to those cultivars.…”

“…Among 10 woody ornamental taxa evaluated in an 8-week study with saline water irrigation at EC levels of 5.0 or 10.0 dS•m À1 , H. macrophylla 'Smhmtau' and 'Smnhmsigma' were the most salt-tolerant taxa with minor foliar damage and with the highest leaf sodium and chloride concentrations (Liu et al, 2017). Niu et al (2020) evaluated 11 hydrangea cultivars with a nutrient solution at an EC of 1.0 dS•m À1 and saline solution at an EC of 5.0 or 10.0 dS•m À1 . They found that H. macrophylla 'Ayesha' and H. serrata ×macrophylla 'Sabrina' and 'Selina' were relatively salt-tolerant; H. macrophylla 'Merritt's Supreme' and 'Mathilda' were moderately tolerant, Hydrangea quercifolia 'Snowflake' and H. macrophylla 'Emotion' were moderately salt sensitive; and H. paniculata 'Bulk', H. paniculata 'Interhydia', H. serrata 'Preciosa', and H. macrophylla 'Passion' were salt sensitive.…”