Physiological and pollen-based screening of shrub roses for hot and drought environments

Rose plants growing under natural conditions are exposed to unfavorable environmental conditions such as high temperature and drought, particularly around the blooming stage. This can reduce the reproductive potential and aesthetic value of commercial rose cultivars, which are often more sensitive to harsh conditions. Plants adjust to adverse environments by regulating several morpho-physiological and biochemical processes, which are the key to tolerance mechanisms. Thus, to examine genetic potential of 22 roses, we characterized 18 traits: gas exchange, leaf biophysical, pigments, and pollen germination characteristics using field-grown roses at the blooming stage. A broad genetic variability (P < 0.001) in all measured traits suggests that roses comprise heatand drought-adaptive traits. A weak correlation between the pollen viability or germination and the pollen tube length at 38 degrees C signifying the complexity of reproductive processes. However, three rose cultivars, Moje Hammarberg, Carefree Spirit, and Lavender Meidiland had better pollen germination-related traits (25 %) along with high photosynthetic capacity (24 %) and pigment traits (22 %) compared with sensitive cultivars. The generated phenotypic data, along with reliable phenotyping methods and identified candidate cultivars, would help develop roses with enhanced resilience to stress for dry and hotter climates.

Automated summary

Research has shown that different rose cultivars exhibit genetic variability in response to high temperature and drought, with some cultivars showing better heat and drought resistance, along with higher pollen germination and photosynthetic capacities.