Photosynthetica最新文献

Melatonin (MT), an indole compound, can boost plant growth under abiotic stress conditions. This experiment aims to elucidate the synergistic effect of MT and ascorbic acid (AsA) in mitigating salinity stress by assessing the photosynthetic and antioxidant capacity of the maize inbred lines H123 and W961. The results indicated that exogenous MT and AsA significantly improved photosynthetic efficiency and biomass of maize under salinity stress. Additionally, exogenous MT and AsA also improved antioxidant enzyme activities, promoted regeneration of AsA and GSH, decreased reactive oxygen species contents, suppressed Na⁺ accumulation, and improved the K⁺/Na⁺ ratio of maize seedlings. Additionally, the AsA inhibitor lycorine decreased the endogenous content of AsA and eliminated the positive effects of MT, while the MT inhibitor p-chlorophenyl alanine (CPA) reduced the endogenous content of MT, which could not eliminate the promoting effects of AsA. The results suggested that AsA may act as a downstream signal involved in the regulatory effects of MT on maize under salinity stress.

The aim was to investigate the morphological, photosynthetic, and hydraulic physiological characteristics of different genotypes of Coffea canephora under controlled cultivation conditions. Growth, conductance, and hydraulic conductivity of the root system of 16 C. canephora genotypes were evaluated in Experiment 1 (November 2013). In Experiment 2 (December 2014), in addition to the previous characteristics, gas exchange, photochemical efficiency, leaf water potential, and leaf hydraulic conductivity were investigated in five genotypes. No significant differences were observed in specific leaf hydraulic conductance, stomatal density, or gas exchange. The correlation between root hydraulic conductance and leaf area and dry mass indicates a physiological balance, reflecting the root system's ability to supply water to the aerial parts and maintain leaf water potential and photosynthetic activity during periods of high atmospheric evapotranspiration. These characteristics are important for genotypes cultivated under low water supply and high evaporative demand, even under irrigation.

This study aims to determine the changes in the photosynthetic performance of leaves at different leaf positions and their correlation and to screen out the basic tillage methods suitable for improving the yield. The decrease in soil salt content significantly improved the PSII performance index and quantum yield for electron transport of the bottom leaf group, synergistically enhanced the photosynthetic performance of summer maize leaves (especially the bottom leaf group), and enhanced the correlation between the bottom, middle (including the ear leaf), and upper leaf groups. Under subsoiling tillage conditions, the bottom leaves could produce more carbohydrates to meet the normal growth of the root system, promote the photosynthesis of the middle leaf group at the ear position, and increase the nutrient output of the upper leaf group to the female ear in the middle and later stages of maize aging.

Rising temperatures can affect stomatal and nonstomatal control over photosynthesis, through stomatal closure in response to increasing vapor pressure deficit (VPD), and biochemical limitations, respectively. To explore the independent effects of temperature and VPD, we conducted leaf-level temperature-response measurements while controlling VPD on three tropical tree species. Photosynthesis and stomatal conductance consistently decreased with increasing VPD, whereas photosynthesis typically responded weakly to changes in temperature when a stable VPD was maintained during measurements, resulting in wide parabolic temperature-response curves. We have shown that the negative effect of temperature on photosynthesis in tropical forests across ecologically important temperature ranges does not stem from direct warming effects on biochemical processes but from the indirect effect of warming, through changes in VPD. Understanding the acclimation potential of tropical trees to elevated VPD will be critical to anticipate the consequences of global warming for tropical forests.

This study aimed to assess variations in leaf gas-exchange characteristics, leaf pigment contents, and some intrinsic traits of photosynthetic pigment molecules in three rice cultivars (cv. JR3015, Wufengyou3015, and Jifengyou3015) using mechanistic models. The findings revealed that chlorophyll content varied significantly among the three cultivars, but not maximum electron transport rate. JR3015 had lower chlorophyll content but the highest eigen-absorption cross-section (σ_ik) and the lowest minimum average life-time of photosynthetic pigment molecules in the excited state (τ_min). Our results suggested that the highest σ_ik and the lowest τ_min in JR3015 facilitated its electron transport rate despite its lower leaf chlorophyll content. Furthermore, compared to Jifengyou3015 and Wufengyou3015, JR3015 had the lowest photosynthetic electron-use efficiency via PSII, which contributed to its lowest maximum net photosynthetic rate. These findings are important in selecting rice cultivars based on their differences in photosynthetic capacity.

This study investigated the effects of recurrent water deficit on drought tolerance traits in black pepper (Piper nigrum L.) 'Bragantina'. Plants were subjected to three cycles of water deficit followed by recovery periods. Water deficit reduced stomatal conductance, photosynthesis, transpiration, and water potential while increasing water-use efficiency. In addition, intercellular CO₂ concentration, leaf temperature, root starch, and adaptive morphological characteristics in leaves and roots increased. Despite these adaptations, plants did not recover vegetative growth after rehydration. The primary tolerance mechanisms observed included increased abaxial epidermis thickness, stomatal density, fine roots, periderm thickness, and starch accumulation in roots. Although gas exchange and leaf water potential were restored, vegetative growth did not fully recover. This study highlights the response of black pepper to recurrent water stress and the underlying mechanisms of its drought tolerance.

We honor here Professor David Mauzerall, a pioneer in the fields of photochemistry and photobiology of porphyrins and chlorophylls in vitro and in vivo, on the occasion of his 95^th birthday. Throughout his career at The Rockefeller University, he refined our understanding of how chlorophyll converts light energy into chemical energy. He exploited top-of-the-line laser technology in developing photoacoustics and a variety of other innovative experimental approaches. His experimental work and conceptual insights contributed greatly to our understanding of photosynthesis and the possible role of photosynthesis in the origin of life. His contributions include many landmark single-authored and collaborative papers, and his legacy includes the training of others who have become authorities themselves. After providing a brief description of his research accomplishments, we include tributes from several of his coworkers and his daughters highlighting their valuable experiences with David Mauzerall on this milestone birthday.