01992nas a2200145   4500008004100000245016200041210006900203300001100272490000800283520141700291100002401708700002301732700002401755856006701779       2016                        eng d00aA safety vs efficiency trade-off identified in the hydraulic pathway of grass leaves is decoupled from photosynthesis, stomatal conductance and precipitation0 asafety vs efficiency tradeoff identified in the hydraulic pathwa  a97-1070 v2103 a<p>A common theme in plant physiological research is the trade-off between stress tolerance and growth; an example of this trade-off at the tissue level is the safety vs efficiency hypothesis, which suggests that plants with the greatest resistance to hydraulic failure should have low maximum hydraulic conductance. Here, we quantified the leaf-level drought tolerance of nine C4 grasses as the leaf water potential at which plants lost 50% (P50 &times; RR ) of maximum leaf hydraulic conductance (Ksat ), and compared this trait with other leaf-level and whole-plant functions. We found a clear trade-off between Ksat and P50 &times; RR when Ksat was normalized by leaf area and mass (P = 0.05 and 0.01, respectively). However, no trade-off existed between P50 &times; RR and gas-exchange rates; rather, there was a positive relationship between P50 &times; RR and photosynthesis (P = 0.08). P50 &times; RR was not correlated with species distributions based on precipitation (P = 0.70), but was correlated with temperature during the wettest quarter of the year (P &lt; 0.01). These results suggest a trade-off between safety and efficiency in the hydraulic system of grass leaves, which can be decoupled from other leaf-level functions. The unique physiology of C4 plants and adaptations to pulse-driven systems may provide mechanisms that could decouple hydraulic conductance from other plant functions.</p>1 aOcheltree, Troy, W.1 aNippert, Jesse, B.1 aPrasad, P., V. Vara  uhttps://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.13781