Photosynthetica最新文献

Many studies have been conducted on maize to study the effect of drought on yield at the flowering stage, but understanding biochemical and photosynthetic response against drought at the seedling stage needs to be well established. Thus, to understand differential changes and interaction of biochemical and photosynthetic parameters at the seedling stage under drought, a greenhouse experiment with twelve maize genotypes under severe drought (30% field capacity) and irrigated (90-100% field capacity) conditions were performed. Drought differentially altered biochemical and photosynthetic parameters in all genotypes. A sharp increase in hydrogen peroxide, malondialdehyde (MDA), and total antioxidant capacity (TAOC) were seen and a positive association between H₂O₂ and TAOC, and MDA and transpiration rate (E) was observed under drought. Nonphotochemical quenching increased under drought to avoid the photosystem damage. PCA biplot analysis showed that reducing E and increasing photosynthetic efficiency would be a better drought adaptation mechanism in maize at the seedling stage.

Quinoa has been identified as a climate-resilient crop that can overcome unfavorable conditions. This study explores the photochemical efficiency of quinoa compared to maize subjected to drought stress. The JIP-test was used to assess the photochemical efficiency of both crops. Proline content, leaf water potential, and membrane leakage were also determined. The maximum photochemical efficiency (F_v/F_m) did not change for quinoa and maize under moderate stress. However, severe drought conditions resulted in a decline in F_v/F_m in maize but not quinoa. Furthermore, the PSII performance index (PI_ABS,total) declined steadily in maize soon after the onset of drought stress. The decline in the PI_ABS,total values for quinoa was only observed after a period of severe drought stress. Membrane leakage was also more prevalent in the maize plants, while quinoa had higher proline contents. This study concluded that both quinoa and maize maintained PSII structure and function under moderate drought conditions. However, only quinoa maintained PSII structure and function under severe drought conditions.

The study proposes to evaluate the photosynthetic plasticity of Rhizophora mangle L. in four mangrove sites distributed along with the Great Vitória Estuarine System. The variation in organic matter content, which implies the higher essential nutrient availability, contributed to better energy flux performance related to electron transport. Furthermore, salinity damaged the reaction centers (RC), since the site with the highest salinity showed changes in the number and size of active photosynthetic RC and in the specific energy flows per active RC (absorption flux, trapped energy flux, and dissipated energy flux), but the plasticity of the species in response to salt stress was confirmed by the increase of performance index for energy conservation (PI_Total), net photosynthetic rate (P _N), and the water-use efficiency (WUE). Also, the results showed that the luminous intensity available compromises the functionality of PSII, in turn, it increases WUE. The results indicate the effect of the chlorophyll a content, which provides more substrate for light absorption, on the electron flow and PI_Total is related to P _N and WUE. The study indicates the ecological plasticity of R. mangle to the conditions of the evaluated area.

In nature, plants are often confronted with wide variations in light intensity, which may cause a massive carbon loss and water waste. Here, we investigated the response of photosynthetic rate and stomatal conductance to fluctuating light among ten rice genotypes and their influence on plant acclimation and intrinsic water-use efficiency (WUE_i). Significant differences were observed in photosynthetic induction and stomatal kinetics across rice genotypes. However, no significant correlation was observed between steady-state and non-steady-state gas exchange. Genotypes with a greater range of steady-state and faster response rate of the gas exchange showed stronger adaptability to fluctuating light. Higher stomatal conductance during the initial phase of induction had little effect on the photosynthetic rate but markedly decreased the plant WUE_i. Clarification of the mechanism influencing the dynamic gas exchange and synchronization between photosynthesis and stomatal conductance under fluctuating light may contribute to the improvement of photosynthesis and water-use efficiency in the future.

Oaks may contribute to the stabilization of European forests under climate change. We utilized two common gardens established in contrasting growth regimes, in Greece (Olympiada) and Germany (Schwanheim), to compare the diurnal photosynthetic performance of a Greek and an Italian provenance of two Mediterranean oaks (Quercus pubescens and Q. frainetto) during the 2019 growing season. Although the higher radiation in the southern common garden led to a strong midday depression of chlorophyll a fluorescence parameters (maximum quantum efficiency of PSII, performance index on absorption basis), comparable light-saturated net photosynthetic rates were achieved in both study areas. Moreover, both species and provenances exhibited analogous responses. Q. pubescens had enhanced chlorophyll a fluorescence traits but similar photosynthetic rates compared to Q. frainetto, whereas the provenances did not differ. These findings indicate the high photosynthetic efficiency of both oaks under the current climate in Central Europe and their suitability for assisted migration schemes.

Clusia is a widely distributed neotropical genus with 321 currently described species. This remarkable genus is the only one known to contain trees sensu stricto with CAM photosynthesis. To survey the occurrence of CAM in Clusia species from Colombia, we determined the leaf stable carbon isotope composition (δ¹³C) of 568 specimens from 114 species deposited in 12 Colombian herbaria. In the vast majority of specimens, δ¹³C values indicated that C₃ photosynthesis was the principal contributor to carbon gain. δ¹³C values typical of strong CAM (less negative than -20‰) were observed in only five species, in four of them for the first time. All samples with CAM-type isotopic signatures were collected below 1,000 m a.s.l., whereas species with predominantly C₃ occurred from sea level to 3,500 m a.s.l. Together with information already available in the literature, we conclude that CAM is present in 22% (35/156) of the species of Clusia investigated thus far.

The sustainable production of upland cotton, an economically important fiber crop, is threatened by changing environmental factors including high temperatures and low-soil water content. Both high heat and low-soil water can reduce net photosynthesis resulting in low fiber yields or poor fiber quality. Leaf chlorophyll content has a direct relationship with photosynthetic rate. Understanding how high heat and low-soil water affect chlorophyll content can identify opportunities for breeding improvement that will lead to sustainable fiber yields. A two-year field trial located in Maricopa Arizona measured leaf chlorophyll content, available soil water, ambient air temperatures, and cotton growth measurements collected by a high-clearance tractor equipped with proximal sensors. The results showed that low-soil water significantly increased leaf chlorophyll content, while high temperatures significantly reduced content. Structured equation modeling revealed that cotton may divert available resources to leaf area and chlorophyll content for the production of photosynthates during periods of high temperatures.