Long-term UV-B and temperature enhancements suggest that females of Salix myrsinifolia plants are more tolerant to UV-B than males

• We studied long-term effect of UV-B and temperature on S. myrsinifolia genders.
• UV-B affected the accumulation of phenolics and temperature improved reproduction.
• Genders differed in UV-B response and females were more tolerant than males.
• We found no apparent trade-off between growth, defense and reproduction.
• Warming decreased the intensity of rust infection.

Males of sexually dimorphic trees and shrubs are hypothesized to have lower reproduction costs, to grow faster and to be less well defended than females. Sex-related differences in sexual reproduction, photosynthesis, growth, phenolic concentrations and rust infection in field-grown Salix myrsinifolia plants were investigated after 3-year exposure to modulated UV and temperature enhancements. UV-B increased leaf hyperin and salicortin, while elevated temperature increased chlorogenic acid concentrations in females only. The UV-induced accumulation of leaf flavonoids, condensed tannins and salicylates was facilitated by warming to a greater degree in females than in males. The UV treatment had only minor effects on shoot biomass, photosynthesis and reproduction, while temperature significantly increased all the variables related to growth and sexual reproduction. Enhanced UV-B tended to decrease biomass and leaf thickness in males, which, along with the UV-induced increase in leaf phenolics in females, suggests that the females have greater tolerance to UV-B compared to males. Irrespective of the UV and temperature treatments, no apparent trade-off between growth, reproduction and allocation to defense was detected. Consequently, in the long-term, the genders of S. myrsinifolia might respond differently to future climate change which, in turn, might affect the sex ratio and spatial distribution of willow species.