Photosynthetic responses to water deficit in six Mediterranean sclerophyll species: possible factors explaining the declining distribution of Rhamnus ludovici-salvatoris, an endemic Balearic species.

摘要: We sought to explain the declining distribution in Balearic Islands of endemic shrub Rhamnus ludovici-salvatoris R. Chodat, by comparing its photosynthetic response drought with that several widely distributed, competing Mediterranean species (R. alaternus L., Quercus ilex Pistacia lentiscus Q. humilis Mill. and P. terebinthus L.). All study species, except for two avoided desiccation rapidly adjusting their stomatal conductance at onset drought, maintaining constant leaf relative water content. The showed desiccation-tolerant behavior; i.e., as progressed, predawn content decreased simultaneously closure. four desiccation-avoiding a significant positive correlation between thermal dissipation (estimated fluorescence parameter NPQ (non-photochemical quenching)) de-epoxidation state xanthophyll cycle (DPS). exhibited maximum DPS regardless treatment, but only increased drought. had high ratio photorespiration photosynthesis low intrinsic water-use efficiency; traits are likely be unfavorable plant productivity under arid conditions. It also lowest among six species. conclude account limited ability compete other region.