Response of six garden roses (Rosa × hybrida L.) to salt stress

Abstract

A greenhouse study was conducted to evaluate six garden roses (‘Caldwell Pink’, ‘Carefree Delight’, ‘Marie Pavie’, ‘New Dawn’, ‘RADrazz’, and ‘The Fairy’) in response to salt stress. Plants grown in containers were subjected to three salinity levels at electrical conductivity (EC) of 1.5 (control, nutrient solution), 4.0 or 8.0dSm−1 (moderate and high salinity levels). Compared to the control, shoot growth at moderate and high salinity levels decreased in all cultivars except for ‘New Dawn’. ‘Caldwell Pink’, ‘Marie Pavie’, and ‘The Fairy’ had greatest shoot growth reduction (65% to 69%) at 8.0dSm−1 EC, followed by ‘Carefree Delight’ and ‘RADrazz’. Flower numbers decreased at high and moderate salinity levels in all cultivars except ‘New Dawn’ and ‘RADrazz’. In ‘Marie Pavie’, ‘RADrazz’, and ‘The Fairy’, no differences were found in leaf stomatal conductance between 1.5 and 4.0dSm−1 EC, and it was reduced at 8.0dSm−1 EC in all cultivars. ‘Caldwell Pink’ and ‘The Fairy’ had greatest reductions in leaf stomatal conductance at 8.0dSm−1 EC, followed by ‘Carefree Delight’, ‘Marie Pavie’, ‘New Dawn’, and ‘RADrazz’. The maximal photo-chemical efficiency of photosystem II (PSII) decreased as salinity increased to 8.0dSm−1, which was highest in ‘New Dawn’ and lowest in ‘Caldwell Pink’. As salinity increased, leaf sodium (Na+) and chloride (Cl−) concentrations increased in all cultivars, and they were highest in ‘Caldwell Pink’, ‘Marie Pavie’ and ‘The Fairy’. The six rose cultivars responded differently to increasing salt stress. ‘New Dawn’ was considered to be more salt tolerant, while ‘Caldwell Pink’, ‘Marie Pavie’, and ‘The Fairy’ were less tolerant to salt compared to the other cultivars.