Greenhouse rose (Rosa × spp. L.) production is facing the use of poor-quality irrigation waters and regulatory pressures to recycle runoff and drainage effluents. Two experiments (were conducted to evaluate the yield and quality and ion accumulation responses of roses grafted on various rootstocks to increasing salinity stress. In Expt. 1, the scion ‘Bridal White’ grafted on ‘Manetti’, R. odorata (Andr.), ‘Natal Briar’, and ‘Dr. Huey’ were irrigated over four flowering cycles with complete nutrient solutions supplemented with NaCl at 0, 5, and 30 mm. In Expt. 2, plants of ‘Red France’ on ‘Manetti’ and ‘Natal Briar’ were irrigated over six flowering cycles with complete nutrient solutions supplemented with NaCl + CaCl2 (2:1 m ratio) at 0, 1.5, 3, 6, 12, and 24 mm. Salt concentration increases significantly and negatively affected the biomass, cut flower production, and foliage quality of the roses in both experiments, but the responses were modulated by rootstock selection. ‘Manetti’ plants in general sustained better absolute and relative biomass and flower yields, accumulated less Na+ and Cl− in its tissues, and showed less toxicity symptoms with increasing salinity than the others. ‘Natal Briar’ also had similar absolute productivity responses as ‘Manetti’ but were afflicted by a significantly different mineral nutrient profile, including higher accumulations and toxicities with Na+ and Cl− that led to lower foliage visual ratings. Conversely, the relative yields of plants on ‘Dr. Huey’ and R. odorata were similarly reduced by increasing salinity, but the former had lower Na+ and Cl− concentrations in its tissues and better visual scores than the latter, which fared as the worst. A combined analysis of the results suggests that on a productivity basis (biomass and flower yields), greenhouse roses could withstand overall maximum electrical conductivities (i.e., osmotic effects) of applied fertigation solutions of 3.0 ± 0.5 dS·m−1. On the other hand, and considering the aesthetic responses (visual scores) of on-plant and harvested foliage (cut flower shoots), greenhouse rose tolerance to applied Na+ and Cl− concentrations (ion-specific effects) could range up to 10 ± 2 mm.

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Plants of Rosa × spp. L. ‘Happy Hour’ grafted on the rootstocks R. × ‘Manetti’ and R. × ‘Natal Briar’ were salinized with 12 mM NaCl and received supplemental calcium (Ca) applications (as CaSO4) of 0, 2.5, 5.0, 7.5 and 10 mM. Additional plants were salinized with 6 mM Na2SO4 and supplemented with 5 mM CaSO4 and compared to non-salinized, no supplemental Ca control plants. Cumulative flowers harvested, shoot length and leaf chlorophyll index were similar for both rootstocks across salt treatments, but Manetti plants had higher dry weights in flowers and most plant tissues except roots. Productivity and water relations in NaCl-salinized plants were not responsive to supplemental Ca. Conversely, calcium-supplemented plants salinized with Na2SO4 had better productivity and quality than those with NaCl, and were similar to non-stressed control plants. Salt injury symptoms were evident only on NaCl-treated plants, regardless of Ca supplements, and closely associated with chloride, but not sodium, accumulation, in leaf tissues. The extent of the ameliorative properties of supplemental calcium applications on salinized rose plants is influenced by the salinity level, the chemical composition of the salinizing solution (major ions and counter-ions) and the cultivar (scion) and rootstock selection.

Greenhouse rose plants, `Bull's Eye', budded on the rootstocks Rosa manetti and R. × `Natal Briar', were grown in containers filled with a peat-based growing medium. The plants were irrigated with a 0.5× Hoagland solution salinized with a fixed 12-mM Na solution made up of seven ratios of NaCl, Na2SO4, and NaNO3 (100:0, 50:50:0, 0:100:0, 0:50:50, 0:0:100, 50:0:50, and 33:33:33). The results after four flushes of growth and flowering showed higher dry weight productivities in R. manetti plants. Salt composition (i.e., counter-anion ratios) significantly affected the dry weight yield of `Natal Briar' plants, with those irrigated with 100% Na2SO4 and NaNO3 having the highest and lowest values, respectively. While the plants budded on R. manetti did not show significant responses to salt composition, there was a strong tendency for higher dry weight yields in binary salt (anion) compositions. Leachates collected throughout the study showed similar pH (7.5) and electrical conductivities (4.7 dS/m) for all salt treatments. Leachate Cl- concentrations were linearly correlated with Cl- application, whereas leachate Na+ concentrations remained similar among treatments. Plants on R. manetti accumulated less leaf Na+ and Cl- than in R. × `Natal Briar' plants, with lower values observed, in general, in plants irrigated with solutions containing Na2SO4.

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