Photosynthetic Capacity Research Articles

Adzuki bean ( Vigna angularis L.) is a characteristic economic crop with ecological adaptability and industrial potential. During crop production and cultivation, regulating light quality through photo-selective nets or films has become an important environmental control strategy for optimizing their yield and quality. This experiment studied the effects of different color photo-selective nets (red photo-selective net, RN; blue, BN; yellow, YN; green, GN; natural light, CK) on the yield, quality, agronomic traits, photosynthetic characteristics and antioxidant capacity of adzuki beans. The results demonstrate that, compared with CK, RN treatment significantly increased plant height (12.23%) and total dry weight (18.04%), while BN treatment significantly enhanced stem diameter (8.15%), root dry weight (21.62%) and root-shoot ratio (23.53%). RN and BN treatments both optimized the anatomical structure of leaves, showing that palisade tissue and spongy tissue increased significantly by 8.68%, 49.74% and 21.01%, 66.96% respectively compared with CK. This is possibly related to the increased net photosynthetic rate (RN: 23.18% and BN: 14.44% higher than CK) and stomatal conductance (RN: 15.82% and BN: 21.65% higher than CK) to minimize photosynthetic “noon break” depression, and ultimately enhancing the light energy conversion efficiency and actual light energy capture efficiency of the PSII reaction center. Under both RN and BN treatments, the activities of antioxidant enzymes (SOD, POD, CAT) were enhanced to suppress reactive oxygen species (ROS) accumulation; Meanwhile, the malondialdehyde (MDA) content was correspondingly reduced by 11.62% and 39.08% compared to CK. Crucially, RN treatment significantly enhanced the yield of adzuki beans (15.05%), starch content (4.69%), and total phenol content (20.00%) compared to CK. BN treatment substantially increased yield (10.63%), soluble protein content (7.69%), amino acid content (9.55%), and total flavonoid content (38.05%). Under GN treatment, although the yield of adzuki beans decreased (8.56%) and the net photosynthetic rate reduced (2.25%), the total flavonoid content of adzuki beans significantly increased by 51.21%. In conclusion, the red and blue light treatments enhance both photosynthetic capacity and yield and improve quality traits in adzuki beans, offering novel insights into optimizing light environments in cultivating specialized legume varieties.

Microalga Haematococcus lacustris is known for its ability to produce high-value product astaxanthin. The abrupt shift from weak-light in the vegetative phase to high-light in the astaxanthin induction phase triggers severe photodamage during the large-scale cultivation of H. lacustris for astaxanthin production in two phases, causing photobleaching with resultant biomass loss. Current mitigation relies primarily on physical shading. This study found that glutamate/glutamine supplementation before phase shift mitigated the photodamage caused by sudden high-light stress in H. lacustris. Glutamate rapidly enhanced CO2 fixation while simultaneously inducing various photoprotective pathways, including non-photochemical quenching, cyclic electron flow, chlororespiration and photorespiration. This maintained the balance between light absorption and energy utilization in H. lacustris during abrupt environmental shifts, thereby preventing damage on both the donor and acceptor sides in photosystem II. Pre-incubation with glutamate in the dark pre-activated these photoprotective pathways, thus enabling seamless acclimation to high-light stress following abrupt shifts. Meanwhile, glutamine exhibited equivalent efficacy in inducing multiple photoprotective pathways. These findings establish a novel strategy based on dark pretreatment for enhancing photosynthetic capacity under high light and protecting algal cells against photobleaching. The study provides fundamental insights into photoprotective acclimation mechanisms in microalgae and higher plants facing rapid environmental shifts.

Growth-stage-dependent relationship between photosynthetic capacity and leaf biochemical traits in cotton

Limited microbial community responses of marine macroalgae to artificial light at night and moderate warming conditions.

Microbial volatile organic compounds (mVOCs) offer significant benefits to plants, such as promoting growth and activating immune responses, positioning them as promising tools for crop productivity. However, the mechanisms driving mVOCs-mediated plant growth promotion (PGP) and immunity remain unclear. Here, we demonstrated that VOCs produced by the rapeseed (Brassica napus)-derived endophyte Bacillus velezensis CanL-30 (BvVOCs) simultaneously stimulate PGP and immunity in both Arabidopsis thaliana and rapeseed under controlled and field conditions. Gas chromatography-mass spectrometry analysis revealed that 2-heptanone and 2-nonanone in BvVOCs exhibit plant-growth-promoting activity, whereas decane and undecane possess disease resistance-inducing activity in plants. Using metabolomics and transcriptomics, along with genetic and chemical methodologies, we reveal that BvVOCs enhance photosynthetic capacity to promote growth, while jasmonic acid-dependent signalling underpins immunity activation. Furthermore, light intensity significantly influenced BvVOCs effects on PGP and immunity. Crucially, BvVOCs upregulate expression of the GOLDEN2-LIKE (GLK) transcription factors GLK1 and GLK2, and BvVOCs-driven PGP and immunity were lost in glk1glk2 double mutant plants. These findings clarify the molecular basis of Bacillus-based VOCs in boosting growth and disease resistance, underscoring their potential for sustainable pest management in agriculture.

Lipids and amino acids inhibitory herbicides impaired the leaf structure and photosynthetic capacity of wheat seedlings under elevated temperature.

Decoding the Chemodiversity blueprint: Chromosome-scale genome assembly unveils photosynthesis-terpenoid coordination in Cinnamomum burmanni through genomic and miRNA regulatory networks.

Soil contamination by microplastics (MPs) and heavy metals has become a global ecological and environmental issue and poses considerable threats to crop production and human health. In plants, melatonin (MT) functions as a powerful biostimulant, orchestrating vital physiological processes and enhancing stress tolerance. In this study, through controlled pot experiments, how exogenous MT (0.1 mmol L⁻¹) modulates maize responses to low-density polyethylene (LDPE) MPs, cadmium (Cd), and their combination was investigated. Simultaneous exposure to LDPE MPs and Cd exacerbated oxidative damage, inhibited chlorophyll biosynthesis, suppressed photosynthetic capacity, and reduced biomass in maize plants, alongside increasing shoot and root Cd²⁺ levels. Conversely, exogenous MT application reduced the malondialdehyde content by 12.5% under combined stress conditions, indicating a substantial reduction in oxidative damage. Additionally, MT inhibited the absorption and accumulation of Cd²⁺, increased the chlorophyll content, enhanced the photosynthetic efficiency, improved the plant height and stem diameter, thereby increasing maize plant biomass by 5.6%. MT also increased the activity of reactive oxygen species scavenging antioxidant enzymes and promoted the biosynthesis of non-enzymatic antioxidants such as proline and soluble sugars. Metabolomic analysis revealed that exogenous MT treatment significantly affected the levels of 210 metabolites. Notably, key metabolic pathways, including purine metabolism, phenylpropanoid biosynthesis, and tryptophan metabolism, were upregulated, indicating their pivotal role in the stress response mechanism of plants. These results reveal that exogenous MT effectively alleviates the synergistic phytotoxicity of PE MPs and Cd in maize plants, underscoring its promise as a practical strategy for enhancing crop resilience in contaminated environments.

ABSTRACT This study investigated the physiological responses of phytoplankton to reduced light availability, a common feature of turbid coastal ecosystems, focusing on their acclimation and recovery under prolonged light exposure. Three irradiance treatments (low light [LL], medium light [ML] and high light [HL]) were administered for 15 hours, followed by a 3-hour recovery period at 10 μmol photons m−2 s−1. Exposure to prolonged HL significantly reduced the maximal photochemical efficiency of PSII (Fv/Fm) from 0.613 rel. units at initial incubation to 0.302 rel. units after one hour. The HL treatment showed significantly lower non-photochemical quenching (NPQ), indicating an impaired ability to dissipate excess light energy. However, despite this impairment, photoinhibition did not occur. Under HL treatments, a steady increase in photosynthetic capacity (rel.ETRmax) was observed after seven hours of incubation, suggesting that the phytoplankton fully utilized the available light for photosynthesis during the early stages of exposure. LL treatments maintained high photosynthetic efficiency (α) and displayed better overall photosynthetic performance compared to ML and HL treatments. Our findings highlight the significant photophysiological plasticity of turbid water phytoplankton, evidenced by their rapid recovery from light stress, a crucial trait for their survival and productivity in dynamic coastal environments.

Exogenous phosphorus mitigates the negative impact of nitrogen deposition on biocrust nitrogen fixation.

To investigate the photosynthetic characteristics and leaf anatomical structures of seedlings from the endangered plants Ormosia olivacea, Ormosia pachycarpa, and Ormosia sericeolucida, this study aimed to elucidate the influence of leaf structure on photosynthetic traits and light requirements among these three Ormosia species, thereby providing reference for their introduction and cultivation. This study measured the light response curves, CO2 response curves, leaf epidermal and anatomical characteristics, and photosynthetic pigment content of the three Ormosia species. Results indicate: 1. All three species exhibit photophilic tendencies, with Ormosia olivacea demonstrating the highest photosynthetic capacity, achieving a maximum net photosynthetic rate (Pmax) of 1.9062 mol m−2 s−1. Ormosia pachycarpa exhibited the highest potential maximum net photosynthetic rate (Amax), demonstrating superior CO2 utilisation capacity. The Amax values for all three species were significantly higher than their Pmax values. 2. Among the three Ormosia species, Ormosia sericeolucida exhibited the thickest leaf structure, with palisade tissue thickness ordered as follows: Ormosia sericeolucida > Ormosia pachycarpa > Ormosia olivacea. 3. Stomata were present on the lower epidermis of all three species. Ormosia sericeolucida possessed the largest individual stomatal area, while Ormosia olivacea exhibited the highest stomatal density. 4. The chlorophyll a content (Chl a) of all three Ormosia species exceeded their chlorophyll b content (Chl b), indicating they are photophilic plants. Ormosia sericeolucida exhibited higher chlorophyll a (Chl a), chlorophyll b (Chl b), and total chlorophyll (Chl) contents than both Ormosia olivacea and Ormosia pachycarpa. Ormosia olivacea possessed the highest carotenoid content (Car). In summary, Ormosia pachycarpa exhibited the highest potential maximum net photosynthetic rate (Amax), demonstrating the strongest CO2 utilisation capacity, followed by Ormosia olivacea, with Ormosia sericeolucida showing the lowest. Appropriately increasing CO2 levels in cultivation sites would benefit photosynthesis and material accumulation in all three Ormosia species, promoting robust growth.

It is essential to introduce new cultivars to diversify the pomelo industry in China. This paper compared the agronomic and environmental performances of new Tabtim Siam (TS) and Xishi (XS) pomelos with the local cultivars (Red-fleshed Sweet (RS) and Shatian (ST)) in Dabu County. We have generally evaluated the phenological, physiological, fruit quality, stress resistance, and storage characteristics. Findings indicated that TS and XS grew up well, and the phenological stages were adjusted to the local conditions. They had a high pollen viability and equivalent photosynthetic capacity. XS and TS had the highest yield and good fruit quality in terms of higher edible rates, more juice rate, and balanced sugar–acid content. Both the introduced cultivars had greater cold resistance compared with the control with lower semi-lethal temperatures. Polyethylene film at low temperatures to preserve the quality of storage was effective. Compared with RS and ST, TS and XS had a higher price in the market economically. The use of molecular markers (SCoT and SRAP) was able to discriminate all cultivars, which proved genetic uniqueness. In summary, TS and XS have potential to be grown in the Meizhou area and provide high quality, good adaptability, and greater market potential.

There are 5–15 pairs of leaves on the stem of Isodon rubescens. The I. rubescens leaves at different nodes are far apart because the internodes are long. The photosynthetic rates, light response curves and chlorophyll fluorescence characteristics of I. rubescens leaves at different leaf positions were determined in this study to clarify the differences in photosynthetic capacity distinctions of among these leaves. The results showed that the photosynthetic capacity of I. rubescens leaves on the upper part of the stem was slightly lower than that of the leaves on the middle part of the stem. However, the incompletely unfolded tender leaf on the upper part of the I. rubescens stem possessed considerable photosynthetic capacity. The leaves on the middle part of the I. rubescens stem were the main site of photosynthesis for the plant. The I. rubescens leaves at the lower leaf position exhibited a lower photosynthetic capacity. Pruning during the cultivation and management of I. rubescens could prompt the formation of tender leaves and therefore increase the photosynthetic efficiency of plants.

Abstract Eco-Evolutionary Optimality (EEO) theory predicts that plants maximize resource investment in photosynthetic capacity at the lowest costs of acquiring and using such resources. However, current EEO-based models predict photosynthetic capacity based on climate alone, and omit costs for resource acquisition. To explore the link between leaf-level optimality and plant-level nitrogen acquisition costs across different soil environments, we grew two commonly co-occurring species in a greenhouse under three nutrient fertilization levels in sand and two natural soils with matching nutrient availability to the fertilization levels in sand. At the end of the experiment, we measured the maximum rate of Rubisco carboxylation (Vcmax), δ¹³C-derived leaf-to-air CO2 partial pressure ratio (ci/ca), and structural carbon costs for nitrogen acquisition. Increasing nutrient availability increased Vcmax (p < 0.001) and decreased carbon costs for nitrogen acquisition (p < 0.001) similarly in sand and natural soils (p > 0.1 for both). Yet, the leaf ci/ca remained unchanged across treatments in sand (p = 0.426) and natural soils (p = 0.499), consistent with the current EEO-models assumption of climate-dependent optimality. These findings support the general principle that nutrient scarcity increases acquisition costs, while also highlighting a gap in current model formulations that neglect nutrient effects on photosynthetic acclimation.

Increasing planting density is regarded as one of the most effective strategies for enhancing wheat productivity. However, it also increases the risk of yield reduction owing to lodging. Preliminary findings suggest that border effects can improve lodging resistance in drip-irrigated wheat systems. Therefore, to maximize grain yield and lodging resistance, we modified the normal drilling sowing (P1, set as CK1) by expanding the border space (EBS) to 20 cm and obtained the corresponding EBS drilling sowing pattern of P2 (drilling sowing, EBS to 20 cm). We also modified the normal uniform sowing pattern (P3, set as CK2) by EBS to 20 cm and obtained the corresponding EBS uniform sowing pattern of P4 (uniform sowing, EBS to 20 cm). A two-year field experiment was conducted to evaluate the yield performance of four sowing patterns (P1–P4) across four planting densities: 570 × 104 plants ha−1 (D1), 630 × 104 plants ha−1 (D2), 690 × 104 plants ha−1 (D3), and 750 × 104 plants ha−1 (D4). In both years, the grain yield for all patterns initially increased with planting density and then declined. Compared to P1 and P3, the EBS patterns (P2 and P4) exhibited improved tolerance to high planting densities. Among the tested treatments, P4 pattern achieved the highest grain yield (8576–8779 kg ha−1), water use efficiency (15.5–16.0 kg ha−1 mm−1), and economic return (1991–2058 US$ ha−1) at D3. EBS enhanced canopy photosynthesis, optimizing the mobilization of pre-anthesis assimilates stored in vegetative organs toward grains during the filling stage. This redistribution mechanism sustained a high grain weight and spike number under high-density conditions. Furthermore, the improved photosynthetic capacity enhanced stem strength, thereby reducing lodging risk and improving yield stability. Additionally, uniform sowing promoted synchronous development of wheat spikes and reduced harvest losses. Overall, P4 was recommended for high-density drip-irrigated spring wheat systems because of its superior yield performance, stability, water use efficiency, and economic benefits.

The study demonstrates that Macrocoma orthotrichoides employs a poikilochlorophyllous strategy and exhibits rapid photosynthetic recovery, providing novel biochemical and fluorescence-based evidence of desiccation tolerance in this species. Mosses are poikilohydric plants that activate defence mechanisms to protect their tissues and metabolism from dehydration-induced damage, particularly by counteracting the generation/accumulation of reactive oxygen species (ROS). In this study, we evaluate the responses of Macrocoma orthotrichoides gametophytes to dehydration by analysing chlorophyll a fluorescence parameters, metabolite accumulation, and antioxidant enzyme activities in response to ROS production under varying humidity conditions. Fresh gametophyte samples were exposed to controlled moisture regimes, and biochemical analyses revealed that the activity of antioxidant enzymes and proline levels fluctuated in response to dehydration; however, these changes did not fully mitigate oxidative stress and ROS accumulation. Changes in photosynthetic pigment concentrations mirrored enzymatic activity, being consistent with humidity conditions. The decrease in chlorophyll and carotenoid levels during desiccation indicates a poikilochlorophyllous strategy in M. orthotrichoides, with pigments and thylakoid structures being restored upon rehydration. Fluorescence analysis demonstrated that this species tolerates intense dehydration and rapidly regains photosynthetic capacity upon rehydration. Overall, our findings indicate that M. orthotrichoides possesses a suite of biochemical, enzymatic, and physiological adaptations that enable survival and recovery in fluctuating moisture environments, thereby advancing our understanding of desiccation tolerance and photosynthetic resilience in mosses.

IntroductionThe objective of this study was to investigate whether dark septate endophytes (DSEs) can increase plant drought tolerance in the context of vegetation concrete, which is a complex environment.MethodsThis study employed a controlled simulation experiment to investigate the influence of inoculation with diverse DSEs, namely, Paraphoma chrysanthemicola (PC), Alternaria alternata (AA), and Cladosporium cladosporioides (CC), on the growth, photosynthetic characteristics, osmoregulatory substance content, and antioxidant enzyme activities of Cynodon dactylon in vegetation concrete subjected to drought stress.ResultsThese findings demonstrated that DSEs were capable of effectively mitigating the adverse impacts of drought on plant growth. Under moderate drought (MD 55%±5% of the maximum moisture capacity in the field), DSEs increased the dry weight (DB), net photosynthetic rate (Pn), soluble sugar (SS) and peroxidase (POD) of C. dactylon by up to 14.21%, 32.63%, 40.73% and 31.43%, respectively, and reduced the malondialdehyde (MDA) content by 8.02-13.77%. Furthermore, under severe drought (SD, 35%±5% of the maximum moisture capacity in the field), DSE inoculation enhanced the photosynthetic capacity of C. dactylon, stimulated the accumulation of osmoregulatory compounds such as proline (Pro) and soluble protein (SP), and mitigated the water loss associated with drought.ConclusionThe results demonstrate that DSE inoculation enhances the drought resistance of plants used in vegetation concrete by increasing the photosynthetic rate, and contents of antioxidant enzymes and osmoregulatory substances. This study provides reference for the use of DSEs in ecological restoration with vegetation concrete.

ABSTRACTHigh temperatures during the rice panicle initiation stage can easily lead to yield loss. Although exogenous trehalose has been shown to significantly improve plant tolerance to abiotic stresses, its application in rice remains limited. Therefore, in this study, pot experiments were conducted using two rice varieties with differing heat tolerance to investigate whether exogenous trehalose could alleviate heat stress during the panicle initiation stage and to elucidate the underlying physiological mechanisms. The results demonstrated that exogenous trehalose significantly increased rice yield under high‐temperature conditions. In the experiment in 2023, the maximum yield increases for N22 and YR343 were 89.5% and 110.3%, respectively, while in 2024, the increases were 89.2% and 111.6%, respectively. The optimal concentration for exogenous trehalose application was found to be 15 mmol L−1. The yield improvement was primarily attributed to the synergistic effects of exogenous trehalose, which not only enhanced leaf photosynthetic capacity but also improved the activity of key carbohydrate metabolism enzymes, up‐regulated the expression of sucrose transporter genes, and enhanced sucrose utilisation in young panicles. Additionally, it elevated endogenous trehalose levels, increased the accumulation of osmoregulatory compounds, and enhanced antioxidant enzyme activity, while reducing membrane lipid peroxidation. Furthermore, the regulation of hormone metabolism contributed to improved high‐temperature tolerance in rice. In conclusion, the application of trehalose may provide an effective strategy for mitigating high‐temperature damage during the rice panicle initiation stage.

Integrated agronomic optimization can synergistically enhance crop yields and resource use efficiency. This strategy incorporates suitable sowing date, planting density, and fertilization and irrigation management adapted to the local environment. However, there is a dearth of research on how integrated agronomic optimization practices enhance wheat productivity and water use efficiency (WUE) by improving population root distribution and canopy production capacity. Therefore, a two-year field experiment was conducted in the North China Plain. The experiment involved three integrated agronomic practice treatments with four replications: local farmer’s agronomic practice (FP); high-input agronomic practice (HP), which aimed to explore wheat yield potential regardless of resource input costs; and optimized high-input agronomic practice (OP), which was adapted to local conditions to revamp the wheat production system. Compared to FP and HP, OP involved a later sowing date, higher planting density, and lower N fertilizer or irrigation inputs. Results showed that OP significantly improved grain yield, WUE, N fertilizer productivity (NFP), and net profit compared to FP (p < 0.05). Although OP’s yield was 4.25% lower than that of HP, it achieved a 22.99% increase over FP. Compared to HP, OP increased average WUE, NFP, and net profit by 3.08%, 25.68%, and 9.12%, respectively. Over the 2 years, OP promoted deeper roots and higher root length density, which enhanced the uptake of soil water and N. Furthermore, the high transpiration under OP, required for canopy productivity, was sustained by efficient water extraction from deep soil. Additionally, the reduction in unproductive evaporation loss was attributed to increased population density and reduced irrigation. Moreover, OP sustained a higher canopy photosynthetic rate for a longer duration, facilitated by greater post-anthesis N uptake. These improvements in resource acquisition, combined with sustained photosynthetic capacity, ultimately led to more efficient water and N utilization and high grain yield. These indicate that integrated optimization of agronomic practices used under OP can synergistically enhance wheat yield, WUE, and NFP. This was achieved by enlarging and deepening population root distribution while supporting high canopy photosynthesis. Our findings may provide actionable insights into establishing high-yielding, efficient, and profitable wheat production systems in the region.

Root lodging due to wind is common in maize production worldwide, and can reduce photosynthetic capacity as well as nutrient uptake, resulting in significant yield loss and seed quality reduction. Lodging also causes harvesting problems, and ultimately increases production costs. Evaluating maize resistance to lodging is thus important for both breeders and researchers, to optimize agricultural practices, enhance breeding strategies, and ultimately develop new maize varieties with improved resilience. Here, we describe a novel procedure to accurately and quantitatively assess the resistance of maize plants to root lodging in the field. In this approach, users measure mechanical properties of maize root systems and estimate the magnitude of the wind force acting on the maize plants to ultimately derive an antilodging index, a measure that thus considers the balance between internal and external forces acting on the plants in the field. The procedure, which focuses on the plant as a whole and not only on the root system, has been successfully used to evaluate lodging resistance throughout the entire growth period, from the V8 growth stage to plant maturity, in different maize genotypes. We also compare the procedure to others in the literature, and discuss its applicability for assessing crop root lodging resistance in breeding and cultivation programs.