The study evaluates the accuracy of two FvCB model sub-models (I and II) in estimating the maximum electron transport rate for CO₂ assimilation (J_A-max) by comparing estimated values with observed maximum electron transport rates (J_f-max) in four C₃ species: Triticum aestivum L., Silphium perfoliatum L., Lolium perenne L., and Trifolium pratense L. Significant discrepancies were found between J_A-max estimates from sub-model I and observed J_f-max values for T. aestivum, S. perfoliatum, and T. pratense (p < 0.05), with sub-model I overestimating J_A-max for T. aestivum. Sub-model II consistently produced higher J_A-max estimates than sub-model I. This study highlights limitations in the FvCB sub-models, particularly their tendency to overestimate J_A-max when accounting for electron consumption by photorespiration (J_O), nitrate reduction (J_Nit), and the Mehler reaction (J_MAP). An alternative empirical model provided more accurate J_f-max estimates, suggesting the need for improved approaches to model photosynthetic electron transport. These findings have important implications for crop yield prediction, ecological modeling, and climate change adaptation strategies, emphasizing the need for more accurate estimation methods in plant physiology research.

Improving crop salinity management requires enhanced understanding of salinity responses of leaf and fine-root traits governing resource acquisition, ideally in relation to ion accumulation at intra- or inter-specific levels. We hypothesized that these responses are coupled towards integrated resource conservation for plants under prolonged salt treatment. We tested the hypothesis with a glasshouse experiment on saplings of six contrasting Prunus hybrids, subjected to either control or salt treatment (reverse osmosis water versus 3.3 dS m^-1 chloride solution containing mixed cations). Sample collections were carried out at 30 and at 60 days after the start of treatments. All six hybrids showed significantly higher lamina chloride concentration in response to salt treatment, with GF677 accumulating a lower concentration than the other five hybrids. There was significantly lower specific leaf area (SLA) in ‘Monegro’ and lower root tissue density (RTD) in ‘Nemaguard’ after 60 days – but not 30 days – of salt treatment. No hybrid showed concurrent significant decrease of SLA and specific root surface area (SRA) under salt treatment. The a priori known salinity-sensitive hybrid ‘Nemaguard’ not only showed decreased RTD and a negative relationship between root biomass and salt treatment duration, but also showed increased SRA without notable change of average root diameter. Lamina chloride accumulation and leaf gas exchange response were closely correlated along a gradient towards resource conservation from control to salt-treated plants in all hybrids, which was orthogonal to another gradient characterized by a hybrid-dependent modification of SLA, SRA, RTD and percentage of root length within the finest diameter class. This study highlighted the intraspecific differential resource investment strategies, reflected by the hybrid-specific salinity-response coordination among leaf and fine-root acquisitive traits.

The invasive aquatic macrophyte Pontederia crassipes (water hyacinth) exhibits exceptional adaptability across a wide range of light environments, yet the mechanistic basis of its photosynthetic plasticity under both high- and low-light stress remains poorly resolved. This study integrated chlorophyll fluorescence and gas-exchange analyses to evaluate three photosynthetic models—rectangular hyperbola (RH), non-rectangular hyperbola (NRH), and the Ye mechanistic model—in capturing light-response dynamics in P. crassipes. The Ye model provided superior accuracy (R² > 0.996) in simulating the net photosynthetic rate (P_n) and electron transport rate (J), outperforming empirical models that overestimated P_nmax by 36–46% and J_max by 1.5–24.7% and failed to predict saturation light intensity. Mechanistic analysis revealed that P. crassipes maintains high photosynthetic efficiency in low light (LUE_max = 0.030 mol mol⁻¹ at 200 µmol photons m⁻² s⁻¹) and robust photoprotection under strong light (NPQ_max = 1.375, PSII efficiency decline), supported by a large photosynthetic pigment pool (9.46 × 10¹⁶ molecules m⁻²) and high eigen-absorption cross-section (1.91 × 10⁻²¹ m²). Unlike terrestrial plants, its floating leaves experience enhanced irradiance due to water-surface reflection and are decoupled from water limitation via submerged root uptake, enabling flexible stomatal and energy regulation. Distinct thresholds for carboxylation efficiency (CE_max = 0.085 mol m⁻² s⁻¹) and water-use efficiency (WUE_i-max = 45.91 μmol mol⁻¹ and WUE_inst = 1.96 μmol mmol⁻¹) highlighted its flexible energy management strategies. These results establish the Ye model as a reliable tool for characterizing aquatic photosynthesis and reveal how P. crassipes balances light harvesting and dissipation to thrive in fluctuating environments. These resulting insights have implications for both understanding invasiveness and managing eutrophic aquatic systems.