Abstract
Drought and higher temperatures caused by climate change are common stress conditions affecting plant growth and development. The reproductive phase is particularly sensitive to stress, but plants also need to allocate their limited resources to produce floral traits and resources to attract pollinators. We investigated the physiological and floral consequences of abiotic stress during the flowering period of Impatiens glandulifera, a bee-pollinated species. Plants were exposed to three temperatures (21, 24, 27 °C) and two watering regimes (well-watered, water stress) for 3 weeks. Not all parameters measured responded in the same manner to drought and/or heat stress. Drought stress induced leaf senescence, decreasing leaf number by 15–30% depending on growth temperature. Drought also reduced photosynthetic output, while temperature rise affected stomatal conductance. The number of flowers produced dropped 40–90% in response to drought stress, while higher temperatures shortened flower life span. Both stresses affected floral traits, but flower resources diminished in response to higher temperatures, with lower nectar volume and pollen protein content. We conclude that increased temperatures and drought stress, which are becoming more frequent with climate change, can negatively affect flowering, even if plants deploy physiological resistance strategies.
Highlights
Climate change is responsible for more frequent and unpredictable variation in daily and seasonal temperatures, as well as drought [1]
Plants were grown over their flowering period under two watering conditions and three temperature regimes (21, 24, 27 ◦ C), resulting in six treatments (21WW, 21 ◦ C water-stressed (21WS), 24 ◦ C well-watered (24WW), 24 ◦ C water-stressed (24WS), 27 ◦ C well-watered (27WW), 27 ◦ C water-stressed (27WS))
Not all parameters responded in the same direction to a rise in temperature or to drought, alone or in combination
Summary
Climate change is responsible for more frequent and unpredictable variation in daily and seasonal temperatures, as well as drought [1]. These consequences of a warming climate are detrimental to plants, especially when they co-occur [1,2,3]. Temperature rise and drought stresses are more likely to affect plants simultaneously during the Spring and Summer seasons, which are crucial periods for plant–pollinator interactions. The plant reproductive stage is sensitive to higher temperatures and drought [6], which may severely disrupt plant–pollinator interactions by negatively affecting floral signals and resources [7,8]
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