Leaf Photosynthesis Research Articles

Responses of kecapi (Sandoricum koetjape Merr.) seedlings under different spectrum and intensity of light emitting diode

Kecapi (Sandoricum koetjape Merr.) is a local fruit belonging to the Meliaceae family. The market price of this fruit is unstable due to inconsistent production and fruit quality. Kecapi’s cultivation system can be improved by modifying the environment in which LED (Light Emitting Diode) is used as artificial light. This study aims to determine changes in morphological, physiological, and anatomical responses to LED light’s different spectrum and intensity levels. The research used a two-factor, completely randomized design (CRD) consisting of an LED spectrum (purple and white) and two light intensities. The results showed the changes in morphological and physiological responses in high-intensity treatment with the white spectrum of LED (WH). The low intensity with the white spectrum of LED (WL) increased leaf chlorophyll content and photosynthesis rate. The anatomical response has in the low-intensity purple LED (PL) treatment. Increased leaf width occurred in high intensity with the purple LED spectrum (PH). Glucose content in the leaf decreased in all treatments, and increased fructose content in the leaf only occurred in the low-intensity purple spectrum of LED treatment.

Neofusicoccum parvum: A NOVEL PATHOGEN SPECIES CAUSING WILTED LEAF AND DIEBACK PETIOLES ON LOTUS (Nelumbo nucifera) IN THUA THIEN HUE, VIETNAM

Lotus (Nelumbo nucifera) is an essential species in many countries. In Vietnam, the lotus is a plant with cultural and spiritual significance, representing purity, spiritual growth, and enlightenment. However, petiole dieback and wilted dry leaves are severe diseases that weaken the host and decrease leaf photosynthesis, reducing lotus production. In this study, a new dieback and wilted leaf pathogen were identified via its morphology, phylogeny, and pathogenicity. Four representative Botryosphaeriaceae isolates from lotus fields in Hue, Phong Dien, and Phu Loc were selected for identification and pathogenicity testing. Based on morphological and phylogenetic analyses and by using the ribosomal internal transcribed spacer region (ITS) and β-tubulin (tub-2) gene sequences, we identified four isolates as Neofusicoccum parvum. In the pathogenicity test, typical symptoms appear on the inoculated lotus petioles, including dieback, curving, and wilted leaves. These symptoms are consistent with those observed in the field. In addition to identifying the pathogen species responsible for lotus disease, this study provides valuable insights into the taxonomy and phylogenetic relationships of new fungal pathogens that affect lotus fields. These findings can contribute to effective management strategies to control these diseases and improve lotus production. To the best of our knowledge, this is the first report of characterization and phylogenetic analysis of N. fusicoccum as the causal agent of wilted leaves and dieback disease in Thua Thien Hue, Vietnam.

Dodine as an alternative to chlorothalonil in the control of leaf spot diseases in peanut

AbstractPeanut (Arachis hypogaea L.) is susceptible to leaf spot diseases caused by the fungi Nothopassalora personata and Passalora arachidicola, which can decrease yield substantially. Chlorothalonil is one of the most widely used fungicides to control these diseases but was recently banned in the European Union due to toxicity to amphibians and fish. Dodine is an alternative fungicide with a similar range of activity. However, information about its impact on the peanut physiology is lacking. The objectives of this study were to assess the effect of dodine on leaf photosynthesis, yield, and pod quality of peanut and evaluate the potential of dodine as a replacement of chlorothalonil in the control of leaf spot diseases. A 3‐year field experiment was conducted using Georgia‐06G. Treatments consisted of chlorothalonil at 0.86 kg a.i. ha−1 (high rate), chlorothalonil at 0.43 kg a.i. ha−1 (low rate), dodine at 0.68 kg a.i. ha−1 (high rate), and dodine at 0.34 kg a.i. ha−1 (low rate). Photosynthetic efficiency was altered by fungicide in only a few instances, and a clear trend was not observed. The high rate of dodine resulted in the least defoliation caused by leaf spot of all fungicide treatments. Pod maturity, yield, and grading parameters were not affected by fungicide. Overall, dodine did not impact negatively the photosynthetic activity, pod quality, and yield of peanut. Moreover, this chemistry was efficient in controlling leaf spot diseases under heavy disease pressure; therefore, dodine is a potential replacement of chlorothalonil in the control of leaf spot diseases in peanut.

Effects of elevated carbon dioxide on plant growth and leaf photosynthesis of annual ryegrass along a phosphorus deficiency gradient

IntroductionSoil phosphorus (P) deficiency limits plant growth and productivity in grassland ecosystems and may moderate the growth-promoting effects of “carbon dioxide (CO2) fertilization effect”.MethodsTo evaluate the interactive effects of these two factors on the growth and physiology for annual ryegrass (Lolium multiflorum Lam.), plants were grown in controlled growth chambers with a range of P supply (0.004, 0.012, 0.02, 0.06, 0.1 and 0.5 mM) under two levels of CO2 (400 and 800 μmol mol-1, respectively).ResultsElevated [CO2] dramatically increased the aboveground biomass and net photosynthetic rates of annual ryegrass by 14.5% and 25.3% under sufficient P supply (0.5 mM), respectively, whereas decreased the belowground biomass and net photosynthetic rates under lower P supply of P0.004, P0.02, and P0.06. Two-way ANOVA results showed that CO2 × P (p < 0.001) significantly affected stomatal traits, leaf photosynthesis and biomass. The stimulation of growth and photosynthesis by elevated CO2 concentration (e[CO2]) was reduced or highly suppressed, indicating that the sensitivity of annual ryegrass to P deficiency was enhanced under e[CO2].DiscussionThese results indicated that P limitation may offset the positive effects of e[CO2] on plant growth by altering stomatal traits, leaf photochemical processes and biochemical composition in annual ryegrass.

Nitrogen-potassium balance improves leaf photosynthetic capacity by regulating leaf nitrogen allocation in apple.

Nitrogen (N) and potassium (K) are two important mineral nutrients in regulating leaf photosynthesis. However, the influence of N and K interaction on photosynthesis is still not fully understood. Using a hydroponics approach, we studied the effects of different N and K conditions on the physiological characteristics, N allocation and photosynthetic capacity of apple rootstock M9T337. The results showed that high N and low K conditions significantly reduced K content in roots and leaves, resulting in N/K imbalance, and allocated more N in leaves to non-photosynthetic N. Low K conditions increased biochemical limitation (BL), mesophyll limitation (MCL), and stomatal limitation (SL). By setting different N supplies, lowering N levels under low K conditions increased the proportion of water-soluble protein N (Nw) and sodium dodecyl sulfate-soluble proteins (Ns) by balancing N/K and increased the proportion of carboxylation N and electron transfer N. This increased the maximum carboxylation rate and mesophyll conductance, which reduced MCL and BL and alleviated the low K limitation of photosynthesis in apple rootstocks. In general, our results provide new insights into the regulation of photosynthetic capacity by N/K balance, which is conducive to the coordinated supply of N and K nutrients.

Effects of mepiquat chloride and plant population density on leaf photosynthesis and carbohydrate metabolism in upland cotton

BackgroundMepiquat chloride (MC) application and plant population density (PPD) increasing are required for modern cotton production. However, their interactive effects on leaf physiology and carbohydrate metabolism remain obscure. This study aimed to examine whether and how MC and PPD affect the leaf morpho-physiological characteristics, and thus final cotton yield. PPD of three levels (D1: 2.25 plants·m−2, D2: 4.5 plants·m−2, and D3: 6.75 plants·m−2) and MC dosage of two levels (MC0: 0 g·ha−2, MC1: 82.5 g·ha−2) were combined to create six treatments. The dynamics of nonstructual carbohydrate concentration, carbon metabolism-related enzyme activity, and photosynthetic attributes in cotton leaves were examined during reproductive growth in 2019 and 2020.ResultsAmong six treatments, the high PPD of 6.75 plants·m−2 combined with MC application (MC1D3) exhibited the greatest seed cotton yield and biological yield. The sucrose, hexose, starch, and total nonstructural carbohydrate (TNC) concentrations peaked at the first flowering (FF) stage and then declined to a minimum at the first boll opening (FBO) stage. Compared with other treatments, MC1D3 improved starch and TNC concentration by 5.4% ~ 88.4%, 7.8% ~ 52.0% in 2019, and by 14.6% ~ 55.9%, 13.5% ~ 39.7% in 2020 at the FF stage, respectively. Additionally, MC1D3 produced higher transformation rates of starch and TNC from the FF to FBO stages, indicating greater carbon production and utilization efficiency. MC1D3 displayed the maximal specific leaf weight (SLW) at the FBO stage, and the highest chlorophyll a (Chl a), Chl b, and Chl a + b concentration at the mid-late growth phase in both years. The Rubisco activity with MC1D3 was 2.6% ~ 53.2% higher at the flowering and boll setting stages in both years, and 2.4% ~ 52.7% higher at the FBO stage in 2020 than those in other treatments. These results provided a explanation of higher leaf senescence-resistant ability in MC1D3.ConclusionIncreasing PPD coupled with MC application improves cotton yield by enhancing leaf carbohydrate production and utilization efficiency and delaying leaf senescence.

Photosynthetic and Self-Draining Biohybrid Dressing for Accelerating Healing of Diabetic Wound.

Wound healing is a well-orchestrated progress associated with angiogenesis, epithelialization, inflammatory status, and infection control, whereas these processes are seriously disturbed in diabetic wounds. In this study, a biohybrid dressing integrating the inherent ability of Bromeliad leaf (photosynthesis and self-draining) with the therapeutic effect of artificial materials (glucose-degrading and ROS-scavenging) is presented. The dressing consists of double-layered structures as follows: 1) Outer layer, a Bromeliad leaf substrate full of alginate hydrogel-immobilized glucose oxidase (GOx@Alg@Bromeliad substrate, abbreviated as BGA), can generate oxygen to guarantee the GOx-catalyzed glucose oxidation by photosynthesis, reducing local hyperglycemia to stabilize hypoxia inducible factor-1 alpha (HIF-1α) for angiogenesis and producing hydrogen peroxide for killing bacteria on the surface of wound tissue. The sophisticated structure of the leaf drains excessive exudate away via transpiration-mimicking, preventing skin maceration and impeding bacterial growth. 2) Inner layer, microneedles containing catalase (CAT-HA MNs, abbreviated as CHM), reduces excessive oxidative stress in the tissue to promote the proliferation of fibroblasts and inhibits proinflammatory polarization of macrophages, improving re-epithelialization of diabetic wounds. Together, the biohybrid dressing (BGA-CHM, abbreviated as BCHM) can enhance angiogenesis, strengthen re-epithelialization, alleviate chronic inflammation, and suppress bacterial infection, providing a promising strategy for diabetic wound therapy.

Similar photosynthetic but different yield responses of C3 and C4 crops to elevated O3.

The deleterious effects of ozone (O3) pollution on crop physiology, yield, and productivity are widely acknowledged. It has also been assumed that C4 crops with a carbon concentrating mechanism and greater water use efficiency are less sensitive to O3 pollution than C3 crops. This assumption has not been widely tested. Therefore, we compiled 46 journal articles and unpublished datasets that reported leaf photosynthetic and biochemical traits, plant biomass, and yield in five C3 crops (chickpea, rice, snap bean, soybean, and wheat) and four C4 crops (sorghum, maize, Miscanthus × giganteus, and switchgrass) grown under ambient and elevated O3 concentration ([O3]) in the field at free-air O3 concentration enrichment (O3-FACE) facilities over the past 20 y. When normalized by O3 exposure, C3 and C4 crops showed a similar response of leaf photosynthesis, but the reduction in chlorophyll content, fluorescence, and yield was greater in C3 crops compared with C4 crops. Additionally, inbred and hybrid lines of rice and maize showed different sensitivities to O3 exposure. This study quantitatively demonstrates that C4 crops respond less to elevated [O3] than C3 crops. This understanding could help maintain cropland productivity in an increasingly polluted atmosphere.

Decrease of cytokinin flux from roots enhances degradation of ribulose-1,5-bisphosphate carboxylase/oxygenase: a mechanism of the accelerated decrease of leaf photosynthesis with senescence under soil moisture stress in rice (Oryza sativa L.)

Decrease of cytokinin flux from roots enhances degradation of ribulose-1,5-bisphosphate carboxylase/oxygenase: a mechanism of the accelerated decrease of leaf photosynthesis with senescence under soil moisture stress in rice (Oryza sativa L.)

Evaluation of nano-nitrogen fertilizers and other nitrogen sources on the performance of Guinea grass plants grown in newly reclaimed soil under water deficiency

Water deficiency and chemical fertilizers' pollution are two of many factors causing imbalance in the ecosystem rhythm, which reflects on farm livestock quality and quantity, particularly in arid and semi-arid regions. Limited research is available on the use of different sources of nitrogen fertilizers on pasture crops; hence, an open field research experiment was carried out in newly reclaimed soil to investigate the effect of different sources of nitrogen fertilizers on maximizing protein level and production of Guinea grass (Panicum maximum Jacq.) plant under water deficiency. Present data from two successive seasons revealed that: plants received nitrogen in the form of nano particles recorded significant increases in yield, morphological parameters, leaf anatomy, and chemical composition (macro and micro nutrients, total carbohydrates, plant pigments and crude protein) over control (plants that received the recommended dose of NPK fertilizers) in both growing seasons. In addition, endogenous hormones; gibberellins (GA3) and abscisic acid (ABA) beside enzymes; superoxide dismutase (SOD) and peroxidase (POD) had been affected by different treatments. The lowest amounts of cellulose, hemicellulose and lignin were resulted from nitrogen nano particles treatment, while the rates of leaf photosynthesis, stomatal conductance, intercellular CO2 concentration, and water use efficiency were enhanced also by nitrogen nano particles treatment application. The present findings suggested that increasing crude protein level of Guinea grass plant grown in newly reclaimed soil by addition of the mentioned nanoparticles could be a promising approach to improve crop productivity under water deficiency and reduce environmental pollution.

The high genetic yield of Xinjiang cotton is associated with improvements in boll-leaf system photosynthesis

ContextDespite significant advancements in cotton breeding, there is ongoing debate regarding the mechanism of the yield increase in early-maturing cotton (Gossypium hirsutum L.) through photosynthesis of single leaves in Xinjiang, China. ObjectiveThis study aims to investigate the role of the boll-leaf system (BLS) involving the main-stem leaf, the sympodial leaf, and the boll, in cotton yield formation. Our hypothesis was that genetic breeding enhances cotton yield by improving BLS photosynthesis. MethodsTo examine the relationship between BLS photosynthesis and yield, we conducted a comprehensive literature review spanning 70 years to assess yield changes in the Xinjiang cotton-growing region. We also conducted a series of field experiments in 2020 and 2021 using main cultivars to further investigate the connection between BLS photosynthesis and yield. ResultsLiterature data analysis revealed a consistent increase in boll density, boll weight, and yield of the main cotton cultivars in Xinjiang since the 1950s, particularly after the 1990s. The succession of cultivars showed greater improvements in boll density than boll weight. Our experiments supported these findings by demonstrating that the gradual genetic enhancement in cotton cultivars also led to increased photosynthetic area (PA) and photosynthetic rate (Pn) of the boll-leaf system (BLS). When the BLS was isolated by stem girding, we observed a significant rise in PA, Pn, and boll weight during the genetic improvement. Notably, the boll weight of the cultivars from the 2010s showed the least impact from girdling. These results highlight the prominent enhancement of BLS photosynthesis and subsequent boll growth throughout the succession of Xinjiang cotton cultivars. Further analysis revealed that genetic breeding improved the PA and Pn of both the main-stem leaf and sympodial leaf within the BLS. Specifically, the Pn of the main-stem leaf exhibited a stronger association with boll density than boll weight. Conversely, the Pn of the sympodial leaf showed a significant association with boll weight but not with boll density. ConclusionsThe gradual genetic improvement of cotton cultivars significantly enhanced BLS photosynthesis, resulting to improvements in both boll density and boll weight. The improvement in photosynthesis of the main-stem leaf contributed to enhanced boll density, while the improvement in photosynthesis of the sympodial leaf promoted greater boll weight.

Genome-Wide Association Analysis of Rice Leaf Traits

Yield-related traits have always been a research hotspot in rice breeding, and functional leaves directly affect the photosynthetic efficiency and yield of rice. Therefore, it is of great significance to explore the genes related to rice leaf size and shape to improve rice leaf morphology, photosynthesis efficiency, and yield. This study detected the quantitative trait loci (QTLs) for the length, width, length–width ratio, and area of rice flag leaf and second leaf in 393 accessions from the 3000 Rice Genome Project (3KRGP) by high-density single-nucleotide polymorphism genotyping. As a result, 91 QTLs were detected, among which 5 candidate genes (LOC_Os03g29170, LOC_Os06g17285, LOC_Os04g35060, LOC_Os03g27450, and LOC_Os09g16280) were identified. In addition, the epistatic interactions affecting leaf-related traits were also investigated, resulting in the identification of 134 significant QQIs (QTL by QTL interactions) pairs. The results of this study provide an important genetic basis for mining genes associated with rice leaf shape and valuable genetic information for rice breeding.

Establish an efficient inoculation system of tomato yellow leaf curl virus to assist tomato resistance breeding

Tomato yellow leaf curl virus (TYLCV) endangers the production of tomato in the world, which is largely overcome by cultivating resistant tomato cultivars. Since virus evolves fast and may disrupt the resistance in resistant cultivars, tomato resistance breeding against emerging TYLCV isolates is a long-term task, which requires an efficient inoculation system of TYLCV to screen and identify resistant tomato plants. Previous Agrobacterium-mediated TYLCV infectious clone is to construct the viral genome in the binary vector, and does not have high infection efficiency. In this study, we integrate TYLCV genome in pTRV2GW vector containing partial genome of Tobacco Rattle virus, and generate an Agrobacterium-mediated infectious clone pTRV2GW-TYLCV. Tomato plants are infected by vacuum infiltration with the Agrobacterium culture of infectious clone. PCR analysis with all TYLCV ORFs in infected plants reveals distinct detection of each ORF at different infection stages and a final 100 % infection rate of this inoculation method. Infected tomato plants have typical TYLCV disease symptoms including yellowing, curling, and smaller leaves. Plant growth and leaf photosynthesis are repressed in infected plants compared to non-infected plants. Moreover, the inoculation system is successfully applied for differentiating TYLCV resistant and susceptible cultivars, which can assist tomato resistance breeding.

Effects of microbial fertilizer and irrigation amount on growth, physiology and water use efficiency of tomato in greenhouse

A pot experiment was conducted to investigate the effect of microbial fertilizer and irrigation regime on growth, physiology, water use efficiency (WUE) of tomato plants and soil nutrients. Microbial fertilizers: bacillus subtilis fertilizer (B.s.), bacillus polymyxa fertilizer (B.p.) and combined bacillus species (B.c.) were used as microbial fertilizers in the study, and plants treated without bacillus fertilizer were taken as control (CK). Three irrigation levels were set, i.e., full irrigation (I1) which plants were irrigated to 95 % field capacity (θf), and two deficit irrigations which were 2/3 I1 (I2) and 1/3 I1 (I3), respectively. The result showed that microbial fertilizers enhanced leaf photosynthesis rate (An), transpiration rate (Tr), relative chlorophyll content (CHL), nitrogen index balance (NBI) and leaf water potential (Ψl) in addition to increased plant root length, root surface area, root volume; and promoted plant water consumption, dry matter (DM) and plant water use efficiency (WUE). The content of nitrogen in leaf ([N]leaf), nitrogen use efficiency (NUE), the mineral nitrogen and soil microbial nitrogen content (MBN) were significantly improved by microbial fertilizer. Compared to CK, B.s., B.p. and B.c. increased An by 17.96 %, 11.77 % and 6.83 %, respectively. B.s. fertilizer significantly increased MBN and root length by 21.99 % and 55.08 % than CK. Deficit irrigations decreased An, Tr, stomatal conductance (gs), and improved intrinsic water use efficiency (WUEi) and instantaneous water use efficiency (WUEinst). Deficit irrigation depressed leaf area, Ψl, CHL, NBI, root length, root surface area and root volume, hereby declined plant water consumption, and optimized plant WUE. In this study, microbial fertilizers mitigated negative effects of deficit irrigation on photosynthesis and DM and improved WUE. Compare to CK and other microbial fertilizers, B.s fertilizer treated plants possessed enhanced plant water status, higher leaf gas exchange rates, more developed root system, higher plant nitrogen accumulation and NUE. Hereby, the B.s. fertilizer is an optimal strategy to mitigate water stress in tomato plants and promoted plants growth.

The Impact of Long-Term Dry-Season Irrigation on Eucalyptus Tree Height Growth: Insights from Leaf Photosynthesis and Water Conduction

Tree height is a crucial characteristic of plant ecological strategies and plantation productivity. Investigating the influence of dry-season irrigation on the tree height growth in Eucalyptus plantations contributes to a deeper understanding of precise improvement and sustainable development in such plantations. We conducted a field experiment in a Eucalyptus plantation with three-year fertilization and five-year dry-season irrigation to compare their effects on height growth rate during wet vs. dry seasons. Our findings revealed that long-term dry-season irrigation significantly increased the height growth rate of Eucalyptus urophylla × E. grandis by improving leaf hydraulic conductivity and photosynthetic rate during the dry season. However, in the wet season, the tree height growth rate in the fertilization treatment outperformed the other treatments significantly. Interestingly, we also found that leaf photosynthetic capacity contributed more to accelerating height growth than water conduction within the leaves. By examining the differences in leaf structural and functional traits, our results shed light on the impact of long-term dry-season irrigation on the height growth of E. urophylla × E. grandis plantations. Furthermore, this research provides both theoretical and empirical evidence supporting the application of dry-season irrigation and the potential for further enhancing plantation productivity in seasonally arid areas.

Do mutations modifying the leaf area (nr3) and the number of potential seeds (dfc) influence photosynthetic gas exchange characteristics in common buckwheat Fagopyrum esculentum Moench?

Contemporary buckwheat breeding in Russia is based mainly on a Mendelian mutation det. Some additional mutations are being considered for inclusion in buckwheat breeding programs. Among them are the nr3 (narrow leaf 3) and dfc (determinate floret cluster). We evaluated the effects of the mutations on both the characteristics of photosynthetic gas exchange and the number of seeds per plant. The nr3 reduces the leaf surface area by 1.4 times. The mutant plants show some compensatory increase in photosynthesis rate, which, however, is not enough to reach the level of the source ability as in the wild type since the number of seeds per plant is significantly decreased. The possibility of using this mutation in buckwheat breeding depends on the accumulation of modifiers that increase either leaf size or photosynthesis rate. The reduced number of flowers of the dfs mutation is compensated by an increase in flower fertility, and the number of seeds per plant does not change compared to the wild type. It explains the absence of differences between the dfs and wild type in terms of the photosynthesis rate. This experiment did not reveal any problems for using the dfc mutation in breeding. In general, the results of the work support the photosynthesis rate in buckwheat is regulated based on the source-sink ratio.

Canopy architecture and diurnal CO2 uptake in male and female clones of yerba‐mate cultivated in monoculture and agroforestry

AbstractSecondary sexual dimorphism (SSD) in flowering plants is expressed by sexual differences of characters that are not directly related to gamete production. The leaf C/N ratio, photosynthetic traits or clonal responses have never been studied in relation to SSD in yerba‐mate. It was hypothesized that leaf and plant photosynthesis are higher in female than in male individuals because females must supply photoassimilates to compensate for the additional reproductive investments of SSD in biomass. Here, we investigated how two contrasting light environments (monoculture—MO and agroforestry—AFS) and plant genders change leaf and plant photosynthesis, plant architecture, leaf and branch biomass production and C and N investments of two male and two female clones. To model the 3D yerba‐mate structure, virtual trees were constructed using measurements of plant morphology using VPlant modelling software. The light‐response curves of leaf CO2 assimilation were used to model instantaneous leaf and daily plant photosynthesis. Photosynthetic traits derived from light‐response curves did not differ between MO and AFS. Some architectural traits were segregated sexually only in MO, while some physiological ones only in AFS. Leaf photosynthesis was higher in females than in males in AFS over a large part of the diurnal cycle, but SSD was not expressed in carbon gains at plant or daily scales. Leaf C/N ratio was higher in MO than in AFS, indicating MO as an ecosystem with higher degree of environmental degradation. Female clones had leaves with lower C/N ratio than males in both systems, relating to higher leaf photosynthesis on an area basis in females. SSD expressed in leaf photosynthesis over a large part of the diurnal cycle in AFS was not observed in carbon gains at plant or daily scales, indicating that the integration of physiology and architecture equalized the gender specificities. The insensitivity of photosynthetic traits derived from light‐response curves indicated acclimation of yerba‐mate leaves to a wide range of incoming light.

Photosynthetic machinery and antioxidant enzymes system regulation confers cadmium stress tolerance to tomato seedlings pretreated with melatonin

Cadmium (Cd), a significant heavy metal, is widely distributed in the Earth's crust. However, little is known about its effects on plants and management measured. Melatonin (MEL) is a well-known multifunctional biomolecule; it is a powerful antioxidant molecule that increases a plant's abiotic stress tolerance. MEL enhances nickel, vanadium, and chromium tolerance in plants. This research aimed to examine the impact of Cd-stress on tomato plants and explore the possible contribution of MEL in improving the resistance of tomato plants towards Cd-stress. The current findings exhibited that MEL application significantly enhanced leaf photosynthesis, root structure, osmolytes accumulation, and seedling growth compared with only Cd treatment. MEL application decreased Cd transport from root to shoot, lowering Cd concentrations in leaves. In addition, MEL treatment increased catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR) activity and decreased the level of hydrogen peroxide (H2O2), superoxide ion (O2·−) and malondialdehyde (MDA) in tomato plants. Considering findings, MEL may be used to increase plant growth and Cd stress tolerance while lowering the availability of Cd to plants.

Stem and leaf photosynthesis of seven desert woody species and its influencing factors

Stem photosynthesis widely presents in desert plants, which increases carbon uptake capacity. In this study, we measured the photosynthetic characteristics of leaves and stems in seven desert woody plants (Populus euphratica, Populus alba var. pyramidalis, Populus pruinose, Haloxylon ammodendron, Calligonum rubicundum, Calligonum caput-medusae, Ammopiptanthus mongolicus) in the same habitat, using a portable Li-6400XT photosynthesis system combined with P-Chamber. We analyzed stem photosynthetic rate and its relationship with leaf photosynthetic rate. We measured the stem functional traits, including water content, stem dry matter content, chlorophyll content, water potential, non-structure carbohydrate (NSC), etc., to find out the main affecting factors of stem photosynthesis. The results showed that stem photosynthetic rate of seven species ranged from 0.72 to 1.71 μmol·m-2·s-1, with the largest of P. pruinose and the smallest of H. ammodendron. Stem photosynthetic rate could offset CO2 of stem respiration by 57%-83%. Leaf photosynthetic rate of the seven sepceis ranged from 12.80 to 22.54 μmol·m-2·s-1, with H. ammodendron and A. mongolicus being lower than those of the other five species. There was a significant positive correlation between leaf photosynthetic rate and stem photosynthetic rate. Stem water use efficiency was 2.2-7.7 times of the leaf. Chlorophyll content, NSC, stem respiration rate, and leaf photosynthetic rate were the main factors affecting stem photosynthesis.

Characteristics of Leaf Photosynthesis and Fruit Quality in‘Sweet Gold’Kiwifruit under Adjusted Soil Water Content at the Fruit Maturation Stage

Characteristics of Leaf Photosynthesis and Fruit Quality in‘Sweet Gold’Kiwifruit under Adjusted Soil Water Content at the Fruit Maturation Stage