Premium
Maximizing leaf carbon gain in varying saline conditions: An optimization model with dynamic mesophyll conductance
Author(s) -
Qiu Rangjian,
Katul Gabriel G.
Publication year - 2020
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.14553
Subject(s) - salinity , stomatal conductance , photosynthesis , transpiration , biology , ecophysiology , carbon dioxide , conductance , water use efficiency , irrigation , botany , horticulture , agronomy , physics , ecology , condensed matter physics
SUMMARY While the adverse effects of elevated salinity levels on leaf gas exchange in many crops are not in dispute, representing such effects on leaf photosynthetic rates ( A ) continues to draw research attention. Here, an optimization model for stomatal conductance ( g c ) that maximizes A while accounting for mesophyll conductance ( g m ) was used to interpret new leaf gas exchange measurements collected for five irrigation water salinity levels. A function between chloroplastic CO 2 concentration ( c c ) and intercellular CO 2 concentration ( c i ) modified by salinity stress to estimate g m was proposed. Results showed that with increased salinity, the estimated g m and maximum photosynthetic capacity were both reduced, whereas the marginal water use efficiency λ increased linearly. Adjustments of g m , λ and photosynthetic capacity were shown to be consistent with a large corpus of drought‐stress experiments. The inferred model parameters were then used to evaluate the combined effects of elevated salinity and atmospheric CO 2 concentration ( c a ) on leaf gas exchange. For a given salinity level, increasing c a increased A linearly, but these increases were accompanied by mild reductions in g c and transpiration. The c a level needed to ameliorate A reductions due to increased salinity is also discussed using the aforementioned model calculations.