Zhang, Yong-JiangSack, LawrenCao, Kun-FangWei, Xue-MeiLi, Nan2017-03-282017Zhang, Yong-Jiang, Lawren Sack, Kun-Fang Cao, Xue-Mei Wei, and Nan Li. 2017. “Speed versus endurance tradeoff in plants: Leaves with higher photosynthetic rates show stronger seasonal declines.” Scientific Reports 7 (1): 42085. doi:10.1038/srep42085. http://dx.doi.org/10.1038/srep42085.http://nrs.harvard.edu/urn-3:HUL.InstRepos:31731860We tested for a tradeoff across species between plant maximum photosynthetic rate and the ability to maintain photosynthesis under adverse conditions in the unfavorable season. Such a trade-off would be consistent with the observed trade-off between maximum speed and endurance in athletes and some animals that has been explained by cost-benefit theory. This trend would have importance for the general understanding of leaf design, and would simplify models of annual leaf carbon relations. We tested for such a trade-off using a database analysis across vascular plants and using an experimental approach for 29 cycad species, representing an ancient plant lineage with diversified evergreen leaves. In both tests, a higher photosynthetic rate per mass or per area in the favorable season was associated with a stronger absolute or percent decline in the unfavorable season. We resolved a possible mechanism based on biomechanics and nitrogen allocation; cycads with high leaf toughness (leaf mass per area) and higher investment in leaf construction than in physiological function (C/N ratio) tended to have lower warm season photosynthesis but less depression in the cool season. We propose that this trade-off, consistent with cost-benefit theory, represents a significant physio-phenological constraint on the diversity and seasonal dynamics of photosynthetic rate.en-USJournal Article2017-03-2810.1038/srep42085