Drought Response of Low and High Maintenance Landscape Roses

Acclimation to drought was studied in the low-maintenance (Rosa hybrida) ‘Ferdy’ and ‘Pink Meidiland’, and the high-maintenance ‘Double Delight’ and ‘Paradise’. All plants were acclimated to drought with five consecutive, 4-day drought cycles, followed by a 2-day irrigation recovery period after the fifth drought cycle. Low-maintenance cultivars experienced less drought stress, as evidenced by higher leaf water potential, whole plant transpiration rate (E), relative water content, and leaf conductance on the final day of drought stress cycles. Morphologically, the low-maintenance cultivars had greater leaf cuticle weight than high-maintenance cultivars. Differences in the density and size of stomata and epidermal cells were not related to drought response. Low-maintenance cultivars had a smaller evaporative surface (smaller total leaf areas, smaller individual leaves, and reduced shoot dry weights). However, root : shoot ratios (root dry weight : top dry weight) and leaf area ratios (total leaf area : total plant dry weight) were comparable. Drought acclimation caused a greater reduction in osmotic potential of low-maintenance roses during the recovery period. Apparently, drought resistance in the low-maintenance roses was associated with increased cuticle thickness, reduced evaporative surface, and smaller individual leaves.