Drought tolerance screening of a Rosa population

Drought stress severely impacts plant production worldwide, and is predicted to increasingly affect crop production due to climate change. One of the main strategies to cope with the changing environment is the development of new cultivars with an improved tolerance against drought stress. A study was initiated to compare mitotically induced tetraploid roses with their diploid counterparts for their drought stress tolerance. The first step in this research is the development of a screening method to evaluate segregation for drought tolerance in a diploid rose population. Therefore, drought tolerance was screened in 69 genotypes selected from the F1 population resulting from a R. wichurana x R. ‘Yesterday’ hybridisation. The plants were subjected to two different irrigation regimes, reducing the amount of water received by the drought stress group to less than 10% of an optimal amount given in the control group. Relative water content (RWC), leaf water potential (?) and effective photochemical quantum yield of photosystem II (Y(II)) were measured, next to stomatal size and density, and leaf morphological characteristics. RWC and ? were good indicators for screening drought sensitivity of the genotypes. However, Y(II) did not prove to be a reliable screening method in this study. This approach allowed the selection of interesting rose genotypes for further characterisation and tetraploidisation, potentially forming the basis of future drought tolerant rose cultivars.