Water stress responses of five potted Bougainvillea genotypes

The aim of the current work was to evaluate the agronomical and physiological responses of five flowering potted Bougainvillea genotypes: B. glabra var. sanderiana, B. glabra var. sanderiana ‘Variegata’, B. × buttiana ‘Raspberry Ice’, B. × buttiana ‘Rosenka’, and B. ‘Lindleyana’ (=B. ‘Aurantiaca’) widely grown in ornamental industry. Irrigation treatments were based on the daily water use (100, 50, or 25%). The shoot, total biomass, leaf number and total leaf area decreased in response to an increase of water stress, whereas the number of flowers increased. The total biomass reduction in 50 and 25% treatments was 10 and 18%, respectively, indicating that the severity of the water stress must be considered an important aspect. A number of tolerance mechanisms such as increase in stomatal resistance, decrease in leaf water potential, and in leaf osmotic potential have been observed especially under 25% of water use treatment. The five studied genotypes showed major differences in morphological and physiological responses. As far as water stress tolerance is concerned the two genotypes B. glabra var. sanderiana, B. glabra var. sanderiana ‘Variegata’ have a good aptitude for use as potted flowering plants. The adoption of irrigation scheduling, based on 50% of water use could be considered an effective tool to improve commercial quality of Bougainvillea.