Using the rapid A‐C_i response (RACiR) in the Li‐Cor 6400 to measure developmental gradients of photosynthetic capacity in poplar

Abstract

The rapid A‐Ci response (RACiR) technique alleviates limitations of measuring photosynthetic capacity by reducing the time needed to determine the maximum carboxylation rate (Vcmax) and electron transport rate (Jmax) in leaves. Photosynthetic capacity and its relationships with leaf development are important for understanding ecological and agricultural productivity; however, our current understanding is incomplete. Here, we show that RACiR can be used in previous generation gas exchange systems (i.e., the LI‐6400) and apply this method to rapidly investigate developmental gradients of photosynthetic capacity in poplar. We compared RACiR‐determined Vcmax and Jmax as well as respiration and stomatal conductance (gs) across four stages of leaf expansion in Populus deltoides and the poplar hybrid 717‐1B4 (Populus tremula × Populus alba). These physiological data were paired with leaf traits including nitrogen concentration, chlorophyll concentrations, and specific leaf area. Several traits displayed developmental trends that differed between the poplar species, demonstrating the utility of RACiR approaches to rapidly generate accurate measures of photosynthetic capacity. By using both new and old machines, we have shown how more investigators will be able to incorporate measurements of important photosynthetic traits in future studies and further our understanding of relationships between development and leaf‐level physiology.

Racing against stomatal attenuation: rapid CO2response curves more reliably estimate photosynthetic capacity than steady state curves in a low conductance species

“…Overall, results of A/C i curve fits measured by steady-state or RACiR methods are similar with more precise estimates of C itrans1 for RACiR (Fig. 1), confirming previous studies that the fitted parameters V cmax and J max are statistically equivalent Coursolle et al, 2019;Lawrence et al, 2019;Stinziano et al, 2019b). The single difference was found in the estimation of R d , where the mean was approximately 1.75 ± 0.52 μ mol m -2 s -1 for RACiR and 0.22 ± 0.5 μ mol m -2 s -1 for the steady-state curves.…”

MicroRNA156‐mediated changes in leaf composition lead to altered photosynthetic traits during vegetative phase change

“…Photosynthetic capacity in P. tremula x alba was measured using Rapid AC i Response (RACiR) curves as described in Lawrence, Stinziano, and Hanson (2019). Briefly, A net was measured from reference [CO 2 ] of 300 to 800 µmol m -2 s -1 at 60 µmol mol -1 min -1 CO 2 and a light level of 1500 µmol m -2 s -1 .…”

“…Zea mays A net -C i curves measured A net at reference [CO 2 ] of 400,350,300,250,200,150,100,50,400,500,600,700,800,1000, 1200 ppm, at an air flow rate of 400 µmol s −1 , minimum wait time of 2 min, and light level of 1800 µmol m −2 s −1 . Photosynthetic capacity in P. tremula × alba was measured using rapid A net -C i response (RACiR ™ ) curves as described in Lawrence et al (2019). Briefly, A net was measured from reference [CO 2 ] of 300 to 800 µmol m −2 s −1 at 60 µmol mol −1 min −1 CO 2 and a light level of 1500 µmol m −2 s −1 .…”

Seasonal responses of photosynthetic parameters in maize and sunflower and their relationship with leaf functional traits

“…Given the traditionally time‐intensive nature of measuring P c via leaf‐level gas exchange (although cf. Stinziano et al, , and Lawrence, Stinziano, and Hanson, , for recent advances that substantially curb time requirements), it is appealing to calculate seasonal variations in P c from established relationships between P c and N content (Evans, ; Field & Mooney, ).…”