Photosynthetica最新文献

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.

Rice (Oryza sativa L.) research has rarely focused on the response to low-nitrogen stress in different subtypes previously and lacked a low-nitrogen tolerance evaluation system. Here, we investigated the physiological characteristics under moderate and low-nitrogen stress conditions in two japonica cultivars (NG46 and NG9108) and two indica cultivars (LYP9 and 9311). Using subordinate function analysis and principal component analysis, the low-nitrogen tolerance of four rice varieties was comprehensively evaluated; stomatal conductance, total carotenoid content, and nitrate reductase NR activity were taken as the low-nitrogen tolerance evaluation system. Among the four rice cultivars, NG46 and LYP9 had significant advantages in photosynthetic gas-exchange capacity, optimizing the balance between light-harvesting capacity, the ratio of reaction center inactivation, the magnitude of decrease in heat dissipation, and nitrogen-metabolism enzyme activities. The results investigated the physiological mechanisms of rice adaptation to low-nitrogen stress and offered a reliable method for assessing low-nitrogen tolerance in rice.

Winter oilseed rape (Brassica napus L.), the principal oilseed crop in Europe, is notably vulnerable to spring frosts that can drastically reduce yields in ways that are challenging to predict with standard techniques. Our research focused on evaluating the efficacy of photosynthetic efficiency analysis in this crop and identifying specific chlorophyll fluorescence parameters severely impacted by frost, which could serve as noninvasive biomarkers for yield decline. The experiments were carried out in semi-controlled conditions with several treatments: a control, one day at -3°C, three days at -3°C, one day at -6°C, and three days at -6°C. We employed continuous-excitation and pulse-amplitude-modulation chlorophyll fluorescence measurements to assess plant sensitivity to frost. Also, plant gas exchange and chlorophyll content index measurements were performed. Certain parameters strongly correlated with final yield losses, thereby establishing a basis for developing new agricultural protocols to predict and mitigate frost damage in rapeseed crops accurately.

Cadmium stress (CS) induced the peroxide damage and inhibited wheat photosynthetic capacity and growth. Compared to CS, selenium (Se) application plus CS bolstered chlorophyll and carotenoid contents, photosynthetic rate, the maximum photochemical efficiency of PSII, the quantum yield of PSII photochemistry, and photochemical quenching, superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, L-galactono-1,4-lactone dehydrogenase, and gamma-glutamylcysteine synthetase activities, ascorbic acid and glutathione contents, AsA/dehydroascorbic acid and GSH/oxidized glutathione, and decreased nonphotochemical quenching (q_N), antioxidant biomarkers malondialdehyde and hydrogen peroxide contents, and electrolyte leakage (EL). At the same time, Se alone declined antioxidant biomarkers contents, q_N and EL, and augmented the rest of the aforementioned indexes. Our research implied that Se upregulated wheat's antioxidant capacity. In this way, Se improved wheat photosynthetic performance and growth, especially for 10 μM sodium selenite (Na₂SeO₃). Consequently, 10 μM Na₂SeO₃ may be considered a useful exogenous substance to reinforce wheat cadmium tolerance.

Desert biocrusts play an important role in the control of desertification and artificial inoculation can promote the formation and development of biocrusts. Physiological and growth responses of biocrusts inoculated on desert surfaces were investigated to assess the effect of mixture ratio, inoculation times, and water supply under laboratory conditions. The application of biological sand-fixing material prepared by cultivated algae crust and polymeric composites in a 1:1 ratio accelerated the most accumulation of chlorophyll a in 0.55 mg kg^-1, thickness in 3.06 mm, and fresh mass in 0.69 g cm^-1, was the most beneficial to formation and development of artificial biocrust. The water supply and cultivation time always significantly promoted the growth and accumulation of chlorophyll a and biomass under artificial cultivation and inoculation treatments. Artificial inoculation of biological sand-fixing material can lead to the formation of desert biocrust, which provides an engineering application method for desertification control.

This study aimed to evaluate the impact of four biochar concentrations (0, 2, 5, and 8%) on single and interactive effects of salinity and drought stresses on the morphological, physiological, and photosynthetic parameters of faba bean plants. PCA analysis showed that plants displayed different behavior under non-stressed and stressed conditions. The most discriminating quantitative characters were related to plant biomass production and photosynthesis, especially shoot dry mass, root dry mass, plant fresh mass, internal CO₂ concentration, net CO₂ assimilation rate, and relative water content. The obtained results confirm the biochar's important role in promoting plant growth under normal or stressed conditions. Thus, a better understanding of the impact of biochar on plant growth under drought and salinity stresses will be beneficial for sustainable agriculture.

The present paper aims to open discussion on the information content, physical mechanism(s), and measuring protocols to determine the partitioning of the absorbed light energy in oxygenic photosynthetic organisms. Revisiting these questions is incited by recent findings discovering that PSII, in addition to its open and closed state, assumes a light-adapted charge-separated state and that chlorophyll a fluorescence induction (ChlF), besides the photochemical activity of PSII, reflects the structural dynamics of its reaction center complex. Thus, the photochemical quantum yield of PSII cannot be determined from the conventional ChlF-based protocol. Consequently, the codependent quantity - the quantum yield of the so-called nonregulatory constitutive nonphotochemical quenching (npq) - loses its physical meaning. Processes beyond photochemistry and regulatory npq should be identified and characterized by multifaceted studies, including ChlF. Such investigations may shed light on the putative roles of dissipation and other energy-consuming events in the stress physiology of photosynthetic machinery.