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The widespread application of nanoparticles (NPs) in agriculture has not only enhanced the efficiency of agrochemical use but also introduced environmental pollution, potentially impacting human health through absorption and accumulation in edible plants. The purpose of this study was to evaluate the toxic effects and ecological risks of Cu2O nanoparticles (nCu2O) in the life cycle of soybean, and to provide a theoretical basis for the safe application of NPs in agriculture. Soybeans were grown in natural soil modified with nCu2O, bulk cuprous oxide (bCu2O) and copper sulfate (CuSO4) at concentrations of 0, 50, 200, and 800 mg/kg. Samples and grains from treated soybeans were collected at the flowering, podding, and seed-filling stages for analysis. The results indicated that treatments with nCu2O, bCu2O, and Cu2+ reduced the chlorophyll content in soybean leaves, thereby affecting photosynthesis. Significant reductions were observed in the net photosynthetic rate (Pn), the transpiration rate (Tr), stomatal conductance (Gs), the quantum yield of photosystem II (Y(II)), photochemical quenching (qP), and the electron transport rate (ETR) at high concentrations. However, the toxicity of nCu2O to photosynthesis recovers as the plant grows. Almost all treatments increased the levels of antioxidant enzymes (SOD, POD, CAT) and reduced oxidative stress. In the nCu2O and bCu2O treatments, grain protein content was significantly reduced, while fat and water content increased. Phosphorus (P) content decreased, whereas sulfur (S), potassium (K), magnesium (Mg) and calcium (Ca) contents increased. The accumulation of copper in plants followed the order nCu2O > bCu2O > Cu2+, with the bCu2O treatment being slightly more toxic than the nCu2O treatment, and both being more toxic than the Cu2+ treatment. The above data indicated that nCu2O had a dose-dependent effect, which significantly inhibited soybean growth and changed grain quality at high concentrations. [ABSTRACT FROM AUTHOR]

Salt stress is a critical abiotic factor that adversely affects plant growth and productivity by impairing photosynthesis. This study explores the impact of exogenous ascorbic acid (AsA) on the photosynthetic performance of tomato seedlings (Solanum lycopersicum L. cv. Ligeer 87-5) under salt stress. Hydroponic experiments were conducted in a solar greenhouse, where tomato seedlings were subjected to the following five treatments: Control, NaCl, NaCl + AsA, NaCl + lycorine (LYC), and NaCl + LYC + AsA. Our findings demonstrate that salt stress significantly reduced chlorophyll and carotenoid contents, levels of chlorophyll synthesis precursors (5-aminolevulinic acid (ALA), porphobilinogen (PBG), uroporphyrinogen III (Urogen III), protoporphyrin IX (Proto IX), magnesium protoporphyrin IX (Mg-Proto IX), protochlorophyllide (Pchl)), and essential elements (Mg, Fe, Mn, Zn, Mo, and P) in both roots and leaves. These reductions led to a substantial decline in net photosynthetic rate (Pn) and compromised photosystem II (PSII). In contrast, exogenous AsA application significantly enhanced the content of photosynthetic pigment precursors and essential elements, improved stomatal aperture and gas exchange efficiency, and boosted the photosynthetic performance of tomato seedlings under salt stress. Furthermore, AsA treatment mitigated the negative effects of salt stress by protecting PSII, increased light energy utilization efficiency, and alleviated both stomatal and non-stomatal limitations. The application of the AsA synthesis inhibitor LYC exacerbated the detrimental effects of salt stress, further reducing chlorophyll content and photosynthetic efficiency. In conclusion, exogenous AsA plays a vital role in enhancing the photosynthetic performance and stress tolerance of tomato seedlings under salt stress by stabilizing chlorophyll biosynthesis, facilitating essential element absorption, and optimizing stomatal function. This study provides a new approach and feasible measures for improving tomato resistance and yield, which is significant for enhancing crop productivity, managing saline soils, and promoting sustainable agricultural practices. [ABSTRACT FROM AUTHOR]

The cultivation of medicinal plants plays a crucial role in promoting human health benefits. However, the production of these plants can be affected by drought conditions. This research aimed to investigate the impact of differing water status (non-drought and drought during the flowering to harvest stage) and various iron treatments on the performance of black cumin. The iron treatments included no iron as the control (nFe), no iron with seed hydro-priming (nFe + P), seed iron priming (pFe), seed iron priming with iron foliar spraying (pFe + sFe), and double iron foliar spraying (sFe + sFe). The purpose of these treatments was to assess the effect of iron application methods on plant response under different water conditions. The findings revealed that drought significantly reduced the levels of Chla (15%) and RWC (5.9%), plant height (7%), follicle number (16.7%), seed number (4.6%), 1000-seed weight (3.2%), and seed yield (30.1%). Additionally, drought increased the proline content (90.9%), electrolyte leakage (9.2%), and MDA levels (23.9%). Interestingly, applying iron amendments reduced electrolyte leakage and increased seed yield under both water conditions. The drought-induced increase in proline content was more pronounced in the nFe treatment than in the other treatments. The amount of MDA in the nFe and nFe + P treatments was significantly higher under drought conditions compared to non-drought conditions. In conclusion, the addition of iron amendments helps black cumin plants recover from the effects of drought and reduces damage to seed growth. This means that using both seed iron priming and iron foliar spraying can significantly improve yields. Alternatively, focusing on either seed iron priming or double iron foliar spraying can also boost black cumin production compared to not using iron amendments. [ABSTRACT FROM AUTHOR]

Rapeseed–rice rotation is a cropping system that improves the land-use rate. The present study conducted a field experiment with winter planting of rapeseed as treatment (WR) and winter fallow as control (CK) to investigate the effects of winter planting of rapeseed on growth, yield formation, and 2-acetyl-1-pyrroline (2-AP) biosynthesis of fragrant rice in the two subsequent cropping seasons. The results show that WR treatment improved alkali-hydro nitrogen and rapidly available phosphorus contents in soil. Compared with CK, WR treatment significantly increased grain yield and effective panicle number per plant by 21.16–27.26% and 7.33–21.24%, respectively. Higher net photosynthetic rate, leaf area index, and dry matter accumulation of fragrant rice plants were recorded in WR treatment and CK. Furthermore, compared with CK, WR treatment significantly increased grain 2-AP content, which could be explained by increased content of pyrroline-5-carboxylic acid, methylglyoxal, 1-pyrroline, and enhanced activity of proline dehydrogenase. In addition, future studies should be conducted at a molecular level to reveal the regulation mechanism in 2-AP biosynthesis of fragrant rice under conditions of winter planting of rapeseed. [ABSTRACT FROM AUTHOR]

Climate change increases the risk of coffee yield due to the genotype-dependent effects of water deficit on coffee physiology. The goal of this research was to evaluate how water deficit altered the physiological and growth characteristics of arabica coffee (Coffea arabica L.). Water status, photosynthetic response to CO2 intercellular concentration (A/Ci curves) and growth parameters were evaluated in seedlings of four genotypes (Catimor ECU 02, Cavimor ECU, red Caturra and Sarchimor 4260). Most of the physiological traits evaluated differed significantly among genotypes. Between control and water deficit plants, significant variations occurred in the A/Ci parameters, showing a wide range of values for net photosynthetic rate, stomatal conductance, and water use efficiency, with decreases ranging from 4 to 74%. Maximum electron transport rate through photosystem II, highest rate of RuBisCO carboxylation, and triose phosphate utilization rate were all strongly decreased by water deficit 61% (red Caturra and Sarchimor 4260), followed by Cavimor ECU (35%) and Catimor ECU 02 (24%). Differences in response to water deficit among genotypes suggest possible genotypic differences in tolerance. The results indicated that Catimor ECU 02 and Cavimor ECU were less sensitive to water deficit, while red Caturra and Sarchimor 4260 were the most susceptible. [ABSTRACT FROM AUTHOR]

Maize is among the most significant crops in the world regarding production and yield, but it is highly sensitive to drought, which reduces the growth, photosynthetic efficiency, grain quality, and yield production of a plant. Quantum yield efficiency of photosystem II is a critical photosynthetic component that is susceptible to drought stress. This study intended to investigate the effects of drought stress on growth and morpho-physiological parameters using three maize hybrids ('P-3011w', 'P-3092' and 'iku20') with contrasting soil moisture contents (100%, 40%) at the pre-flowering stage. The stress treatment (40%) was initiated at stage V7, for a period of 15 days; the experimental units were established in a completely randomized design with split-plot arrangement along with three repetitions in 42 L pots using a substrate of peat moss, black soil and poultry manure (1:2:1). The morphological, growth-related and physiological parameters were assessed, including chlorophyll fluorescence (Fv/Fm), which was measured using a LiCor-6400-40 fluorometer. The results showed that all morphological, growth-related and physiological variables decreased under drought stress during the reproductive stage, with the exception of leaf temperature and intercellular CO2 concentration, which increased by 12% and 54%, respectively. Drought stress significantly reduced the photosynthetic chlorophyll fluorescence (43%), due to damage to photosystem II. The lowest percentage of damage to photosystem II (34%) was observed in the iku20 genotype. In contrast, P-3011w and P-3092 had the highest levels of significantly similar damage (49% and 46%, respectively). The correlation analysis showed a highly positive interaction of chlorophyll fluorescence (Fv/Fm) with net photosynthetic rate and stomatal conductance under drought conditions, and multiple regression analysis revealed that the maximum effect on net photosynthetic rate under drought was due to the damage it caused to photosystem II. Thus, iku20 might have a tendency to be able to withstand drought stress in the dry northeast region of Mexico. Overall, we concluded that the photosystem II was negatively impacted by drought stress thus causing a reduction in all physiological, morphological and growth-related variables. [ABSTRACT FROM AUTHOR]

Mesotrione (MET) belongs to the p-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting class of maize post-emergence herbicides, and it is safe for maize at the recommended doses, but the safety of MET differs among maize varieties in actual field production. In this study, four different maize varieties, ZD958, SN3, ST6 and POP16, were used as experimental materials to analyze their physiological responses to MET by comparing the activities of photosynthesis and antioxidant enzymes as well as the HPPD activity. The results showed that ZD958 was the most resistant to MET, followed by SN3 and ST6, and POP16 was the most sensitive to MET. The primary photosynthetic and antioxidant enzyme indices of all four maize varieties indicated that the resistant variety ZD958 was significantly higher than the sensitive variety POP16. HPPD activity was highest in ZD958 followed by SN3 and ST6 in both treated and control groups. POP16 exhibited the lowest HPPD activity. The results showed that the differences in resistance to MET in different types of maize varieties were closely related to the photosynthetic efficiency of plants and the HPPD activity. MET had minimal impact on common maize but showed a significant effect on popcorn. [ABSTRACT FROM AUTHOR]

Selecting the best oil palm cultivars adapted to specific agro-climatic conditions helps ensure fruit and oil production success. Many biotic and abiotic problems can limit the productivity of the crop, some of which have not yet been described, as well as their symptoms and degree of impact. In oil palm, a disturbance known as leaf-bending occurs, in which the palms present a bending or breakage of the petiole in the leaves, representing a significant challenge for oil palm cultivation. Although leaf-bending in oil palm plantations is known, its effect on the palm's performance and its possible causes are unknown. Thus, the objectives of the present work were to describe and propose a quantitative way to evaluate leaf-bending in different cultivars (Elaeis guineensis Jacq. and the interspecific O×G hybrid) and to evaluate the disturbance effect on the physiology and nutritional balance of the oil palm. The results showed that most leaves from leaf rings three and four of the palm phyllotaxis have the highest affectation, with 74% leaf-bending. The cultivars with a Deli × La Mé and Coarí × La Mé genetic background were the most tolerant; however, the Deli × AVROS and Deli × Yangambi genetic crosses were the most susceptible. The difference in the affectation between the groups was 60% to 70%. Leaf-bending affected physiological parameters such as photosynthesis, transpiration, and stomatal conductance. Thus, below the second ring of leaves, the affected plants' physiological parameters decreased between 40% and 50%. The nutritional diagnosis showed that the most sensitive cultivars to leaf-bending were Deli × AVROS, which presented the highest average index of nutritional balance (IBNm), indicating that this genetic cross had the highest nutritional imbalance. On the contrary, the most tolerant cultivars were Deli × La Mé, which presented the lowest IBNm, associated with a better nutritional condition. [ABSTRACT FROM AUTHOR]

The use of polymer-coated urea (PCU) can improve nitrogen use efficiency (NUE), compared to the application of rapid-release urea (RU). However, the effect of PCU-based nitrogen management on grain yield and the NUE of rice and its underlying mechanism remain unclear. A japonica rice cultivar Jinxiangyu 1 was grown in the field with four treatments including N omission (0N), split application of RU (Control), one-time application of 100% PCU (T1), and one-time application of 70% PCU + 30% RU (T2). Results showed that, compared to the control, the grain yield was significantly increased in the T2 treatment, while it was comparable in the T1 treatment. This was mainly due to increased total spikelets in the T2 treatment. Root oxidation activity (ROA) and root zeatin (Z) + zeatin riboside (ZR) content during booting were the distinct advantages of the T2 treatment, compared to either the control or T1 treatment, exhibiting significant or highly significant correlations with leaf photosynthesis. This process contributed significantly to total spikelets and total N uptake. Additionally, the T2 treatment absorbed more N than the control without reducing the internal N use efficiency (IEN), primarily due to its unchanged harvest index (HI) driven by comparable non-structural carbohydrate remobilization. In conclusion, combining PCU with RU can enhance the coordination of root and shoot traits during booting while maintaining a competitive HI at maturity, thereby significantly improving grain yield and achieving a balance in N uptake and utilization. [ABSTRACT FROM AUTHOR]

Accurately understanding the critical threshold of leaf magnesium (Mg) concentration is crucial for rapid diagnosis of crop Mg status; however, little information is available on critical Mg concentration for different physiological processes in dicots and monocots. Here, we investigated the sensitivity of biomass, chlorophyll (Chl) at different leaf positions/ages, leaf area (LA), and photosynthesis (Pn) to Mg deficiency between rice (Oryza sativa L.) and cucumber (Cucumis sativus L.). Plants were grown hydroponically under twelve Mg concentration gradients. Results showed reducing the external Mg supply to a certain level resulted in significant decline in biomass, Chl, LA, and Pn in both plants. A leaf Mg threshold of 0.97 mg g−1 DM (dry matter) for total biomass was found in rice, which was not identified in cucumber. Critical Mg thresholds for Chl a, b, and carotenoids (Car) showed a decreasing trend with leaf age, suggesting Chl in upper young leaves are more sensitive to Mg deficiency; however, visible Mg-deficiency symptoms were predominantly in mid-aged leaves with a higher rate of Mg remobilization, especially in cucumber. Leaf critical Mg concentrations for Chl a+b, Pn, and LA were 1.22, 1.05, and 1.00 mg g−1 DM in rice, respectively, which were lower than those of cucumber, 4.23, 4.09, and 3.55 mg g−1 DM, implying that cucumber was more susceptible to low Mg stress; Chl a+b was the most sensitive indicator of Mg deficiency. Overall, Chl a+b of upper young mature leaves can be used as an early diagnostic index of Mg nutrition in crops, especially Mg-insensitive crops. [ABSTRACT FROM AUTHOR]

The influence of light downconversion films (red, pink and blue films) on leaf physiological features and fruit bioactive compound accumulation was studied in strawberry plants. Red, pink and blue films were able to convert light less utilised by plants into more efficient light wavebands with various possibilities depending on the film characteristics (blue film shifts UV into blue radiation; red film shifts green into red radiation, pink film shifts UV and green into blue and red radiation but to a lesser extent than red film). Indeed, by enhancing the quality of light available for photosynthesis, the utilization of these films holds the potential to improve agricultural productivity and sustainability. All of these light downconversion films resulted in higher plant fresh weight compared to a control colourless (Cnt) film, with plants grown under blue film (UV-to-blue light conversion) showing the most impressive results in terms of total leaf area (+25%), leaf thickness (+10%) and leaf mass per area (+15%). Simultaneously, during the flowering stage, plants under blue film had a higher net photosynthetic rate due to the increase in photosynthetically efficient wavelengths. Moreover, blue film resulted in the highest total phenolic (+40% and +28% than red and pink films, respectively) and flavonoid content (+54%, +84%, +70% than Cnt, red and pink films, respectively) in fruit, with specific effects on targeted phenols, i.e., quercetin, ellagic acid and its glycoside, ellagitannins, and procyanidins. In conclusion, the use of the UV-to-blue conversion light film tested herein represents an innovative solution to increase strawberry yield and promote fruit nutraceutical features, playing a pivotal role in ensuring food quality and security and sustainable agricultural practices. [ABSTRACT FROM AUTHOR]

Saline-sodic stress induces iron deficiency in rice, reduces leaf photosynthetic performance, and inhibits yield enhancement. In this study, we investigated the effects of exogenous Fe on the photosynthetic performance and transcriptomics of two different tolerant rice cultivars CB9 (Changbai9: saline tolerant cultivar) and TH899 (Tonghe899: saline sensitive cultivar) with 4-week-old Fe-deficient rice seedlings under saline stress, Fe deficiency stress, and both co-stresses. The results showed that under saline and alkaline stress, spraying exogenous iron favored the growth of the two cultivars of rice, with a 32.68% and 39.82 increase in fresh weight, a 2.20-fold and 2.16-fold increase in pigment, respectively, and an 80.28% and 100.00% increase in net photosynthetic rate, respectively, as compared with the iron-deficiency treatment. Transcriptome analysis showed that we found a higher number of differentially expressed genes (7785 differentially expressed genes) in response to exogenous Fe spraying in the soda-salt sensitive variety TH899. The differentially expressed genes that are common to the two cultivars are primarily enriched in metabolic pathways, including plant hormone signal transduction (map04075) and phenylpropanoid biosynthesis (map00940). Specifically, among these genes, 14 are differentially expressed in the carotenoid biosynthetic metabolic pathway. The differentially expressed genes specific to the salinity-tolerant variety CB9 were mainly enriched in the metabolic pathways of glyoxylate and dicarboxylic acid methyl metabolism (map00630), and carbon fixation in photosynthetic organisms (map00710), among which 20 genes were significantly expressed in the pathway for carbon fixation in photosynthetic organisms (map00710). The research results offer specific theoretical support for enhancing the salt tolerance of rice. [ABSTRACT FROM AUTHOR]

Drought stress can impact the physiological and biochemical properties of crops. However, selenium (Se) can effectively alleviate the abiotic stress experienced by plants. This study aims to investigate how applying selenium to tomato leaves affects their antioxidant system and photosynthetic traits when subjected to drought conditions. The experiment used four different foliar selenium concentrations and three different irrigation levels. The investigation scrutinized the effects of foliar spraying employing different selenium concentrations on the antioxidant system, osmotic adjustment substances, photosynthetic performance, and growth indices of tomatoes under drought stress. The findings indicated that drought stress led to cellular oxidative damage, significantly elevating peroxide, MDA, proline, and soluble sugar content (p < 0.001). Under severe drought stress, malondialdehyde (MDA) and proline levels increased by 21.2% and 110.0% respectively, compared to well-watered conditions. Concurrently, the net photosynthetic rate exhibited a reduction of 26.0% and dry matter accumulation decreased by 35.5%. However, after spraying with a low concentration of selenium, selenium reduced oxidative damage and malondialdehyde content by reducing the content of peroxide in leaves, restoring photosynthesis, and promoting the normal growth of tomato. Compared to the control group, spraying with 2.5 mg·L−1 selenium resulted in a 21.5% reduction in MDA content, a 111.8% increase in net photosynthetic rate, and a 29.0% increase in dry matter accumulation. When subjected to drought stress conditions, foliar spraying of low concentrations of selenium (2.5 mg·L−1) can effectively reduce oxidative damage caused by drought stress and alleviate growth constraints in tomatoes. In addition, treatments with high selenium concentrations exhibited specific toxic effects. These findings offer valuable insights into the mechanisms governing selenium-induced drought tolerance in tomatoes, thus advancing our comprehension of standard tomato production practices. [ABSTRACT FROM AUTHOR]

Leymus chinensis is a perennial rhizomatous clone plant. It exhibits strong rhizomatous tillering and clonal growth through asexual reproduction. The root system is interdependent with aboveground growth and root growth can regulate aboveground growth and photosynthesis. Melatonin has been shown to regulate root growth and promote photosynthesis. However, it remains unclear whether melatonin affects aboveground growth and photosynthesis by regulating rhizome growth. To address this gap, we studied nine Leymus chinensis from different geographical locations, all grown under the same conditions. We selected two materials with strong (LC19) and weak (LC2) rhizome growth abilities from nine materials and treated them with exogenous melatonin. We found there were significant positive correlations between stem length, plant height, leaf number and rhizome traits. Additionally, rhizome traits showed significant positive correlations with photosynthetic indices and chlorophyll content. Specifically, for LC2, treatment with 200 μmol/L melatonin significantly increased root length, the number of extravaginal ramets and rhizome clonal growth rate by 88.72%, 43.75% and 43.70%, respectively, resulting in significant increases in aboveground traits. Similarly, for LC19, 200 μmol/L melatonin treatment led to significant increases of 74.66%, 23.02%, 62.71% and 62.72% in four traits, respectively, along with aboveground trait improvements. Furthermore, around 300 μmol/L melatonin treatment promoted photosynthetic efficiency in LC2, while around 100 μmol/L melatonin treatment had the same effect in LC19. In conclusion, our study highlights the relationship between rhizome growth ability, aboveground growth and photosynthesis in Leymus chinensis. Additionally, it suggests that exogenous melatonin can enhance aboveground growth and photosynthesis by regulating rhizome growth. [ABSTRACT FROM AUTHOR]

Cotton photosynthetic efficiency and the root–shoot relationship are two important physiological indexes affecting the final yield, but the interactive effects of plastic film mulching and planting density on the cotton photosynthetic efficiency and root–shoot relationship have rarely been reported. We aimed to investigate the optimal plant density with or without plastic film mulching for improved seed cotton yield in southern Xinjiang. Therefore, a two-year field experiment was conducted to investigate the effects of plastic film mulching (with or without plastic film mulching) and planting density (D1: 9 × 104 plants ha−1; D2: 18 × 104 plants ha−1; D3, 22 × 104 plants ha−1, local conventional planting density; D4, 27 × 104 plants ha−1) on the cotton root–shoot relationship, photosynthetic parameters, and seed cotton yield. Our results showed that the seed cotton yield was improved under plastic film mulching at all planting densities, but economic income was significantly lower in comparison to without plastic film mulching in 2023. Compared with D3, seed cotton yield and economic income at D2 increased by 6.9% and 12.2%, either with or without plastic film mulching, respectively. The highest increase in the seed cotton yield in D2 under plastic film mulching was due to the greatest improvements in the root production capacity and photosynthesis. The boll capacity of the root system (BCR) and boll loading of the root system (BLR) in D2 were the highest among all treatments with film mulching, being 9.0% and 16.9% higher than that in D3 in 2022 and 2023. However, the root–shoot ratio (R/S) was 7.1% and 6.9% lower in D2 than D3, under film mulching, in 2022 and 2023. Moreover, moderate plant density (D2) improved the SPAD value, chlorophyll fluorescence (Fv/Fm and PIabs), and photosynthetic parameter (Pn, Tr, and Gs) and decreased Ci compared with other planting density treatments in both years. Further analyses with correlation analysis showed that the seed cotton yield was highly positive correlated with BLR, BCR, and the photosynthetic parameter. In summary, suitable planting density (18 × 104 plants ha−1) combined with plastic film mulching has the potential to obtain high yields by enhancing the efficiency of photosynthetic assimilates, improving the capacity of cotton root production, providing a reference for suitable planting density under plastic film mulching. [ABSTRACT FROM AUTHOR]

The conducted experiment evaluated the effects of three fungi—Trichoderma atroviride (Ta), Trichoderma harzianum (Th) and Phytium oligandrum (Po)—on the growth of maidens of two apple cultivars, 'Szampion' and 'Topaz', budded on two rootstocks, M.9 and M.26, in the nursery. The evaluation was based on the number of maidens obtained and their height, trunk diameter and number and length of lateral shoots, as well as the fresh weight of the leaves and the whole maiden. For the weaker-growing maidens of the 'Topaz' cultivar, the activity of the photosynthetic apparatus was additionally measured depending on the rootstock and fungal treatments. The number of maidens obtained improved significantly when Th (8.3–9.0%) and Po (8.4–12.8%) were applied, depending on the rootstock and cultivar used. With the best treatment with the Po fungus, on average, for the two cultivars, maiden apple trees budded on the M.9 dwarf rootstock were characterized by a significantly better height of 6% and trunk diameter of 13% compared to the control. In contrast, trees grown on the M.26 rootstock did not have significantly increased growth after the same treatments, with the exception of the Po fungus, which improved the stem diameter by an average of 10%. The use of fungi stimulated an increase in the number and length of the lateral shoots of maidens of the more easily branching 'Szampion' apple tree cultivar. Based on the fluorescence parameters obtained, it can be assumed that the 'Topaz' cultivar on the M.26 rootstock is less susceptible to stress conditions, especially those related to high temperatures and drought. All fungi used had a positive effect on the activity of the photosynthetic apparatus. Significantly worse values of the fluorescence parameters were obtained for the control combination compared to the fungal treatments. [ABSTRACT FROM AUTHOR]

Adaptive characteristics of plants, such as those associated with photosynthesis and resource use efficiency, are usually affected by synthesis costs and resource availability. The impact of extreme climate events such as long-term drought on plant physiological functions needs to be examined, particularly as it concerns the internal management of water and nitrogen (N) resources. In this study, we evaluated the resource management strategies for water and N by xerophytic shrubs, Artemisia ordosica and Salix psammophila, under extreme summer drought. This was carried out by comparing the plants' physiological status during periods of wet and dry summer conditions in 2019 and 2021. Compared with the wet period, A. ordosica and S. psammophila both decreased their light-saturated net carbon (C) assimilation rate (Asat), stomatal conductance (gs), transpiration rate (E), leaf N content per leaf area (Narea), and photosynthetic N use efficiency (PNUE) during the summer drought. Whether in wet or dry summers, the gas-exchange parameters and PNUE of A. ordosica were generally greater than those associated with S. psammophila. The instantaneous water use efficiency (IWUE) response to drought varied with species. As a drought-tolerant species, the A. ordosica shrubs increased their IWUE during drought, whereas the S. psammophila shrubs (less drought-tolerant) decreased theirs. The divergent responses to drought by the two species were largely related to differences in the sensitivity of gs, and as a result, E. Compared with A. ordosica, S. psammophila's inferior plasticity regarding gs response affected its ability to conserve water during drought. Our research illustrates the need for assessing plasticity in gs when addressing plant adaptation to long-term drought. A high dry-season IWUE in xerophytic shrubs can benefit the plants by augmenting their C gain. [ABSTRACT FROM AUTHOR]

Water availability is a limiting factor for plant production, especially in Brazilian semi-arid regions. The main aim of the study was to investigate the physiological effects of drought during the fruiting stage of watermelon cultivation. A completely randomized block design with four replications and six treatments varied by the number of lateral drip tapes (1 or 2) and the duration of drought stress (0, 4, and 8 days) was used. The following parameters were evaluated: relative chlorophyll content, relative leaf water content, electrolyte leakage, CO2 assimilation (A), stomatal conductance (gs), internal CO2 concentration, leaf temperature, transpiration (E), water use efficiency (WUE), carboxylation efficiency (CE), yield, thickness, diameter, length, and fruit °brix, at 4 and 8 days of drought. Drought negatively affected photosynthesis, particularly in treatments with a single dripper and 4 days of drought, resulting in reductions of up to 60% in A, 68% in gs, 44% in E, 58% in WUE, and 59% in CE, but did not have a significant effect on watermelon yield after 4 or 8 days of irrigation. It was concluded that drought influences the physiological responses of watermelon plants, mainly in reducing photosynthesis, but does not drastically affect fruit productivity in short periods of stress. [ABSTRACT FROM AUTHOR]

Leaves are the main site of photosynthesis in plants, and leaf color plays a major role in crop quality, yield, resistance, as well as other aspects. Although the genes related to photosynthesis have been well characterized in plants in general, yellow-green leaf mutants have not yet been fully studied in tomatoes. In the present study, a dark green leaf (GL) mutant was isolated from yellow-leaf tomato (wild-type). The dark GL displays a distinct yellow-green phenotype, and has a greater chlorophyll content and higher photosynthetic rate. Furthermore, the lamellae were clear, and the stroma and grana were orderly, with more stacking and larger starch grains according to the ultrastructure analysis of chloroplasts in GL leaves. Comparative transcriptome analysis of GL and wild-type plants was performed to identify the pathways and genes related to photosynthesis. In this work, a total of 292 differentially expressed genes (DEGs) between GL plants and WT plants were identified, of which 131 genes were upregulated and 161 genes were downregulated. The diterpenoid biosynthesis and photosynthesis antenna proteins were the two most significantly enriched in the first 20 pathways according to KEGG analysis. Most of the DEGs involved in diterpenoid biosynthesis and photosynthesis were antenna proteins. The photosynthesis antenna protein Solyc02g071030 (LHCB1) and the diterpenoid biosynthesis-related genes, Solyc08g005710 and Solyc09g059240, were significantly upregulated in GL leaves compared with WT leaves. The expression patterns of the DEGs were similar to those determined by qRT-PCR. Overall, our research not only revealed the diterpenoid biosynthesis and photosynthesis pathways involving in leaf color variation, but also identified the putative target genes for genetic manipulation in the future. [ABSTRACT FROM AUTHOR]

Plants are often exposed to non-ideal conditions during their growth. The toxicity of heavy metals as abiotic stressors is a significant concern due to their harmful effects on plants. Glycine betaine (GB) is a potent compatible solute that helps plants resist abiotic stresses and plays a crucial role in alleviating them. This study aimed to determine the effective role of glycine betaine (0.5 and 1 mM) as a foliar treatment in sugar beet plants to cope with the toxicity of cadmium (50 mg/kg soil) and lead (100 mg/kg soil). The application of lead (Pb) and cadmium (Cd) in cultivation soil noticeably suppressed morphological growth attributes, such as chlorophylls, carotenoids, sugars, and proteins. At the same time, the aforementioned levels of heavy metals significantly increased the levels of non-enzymatic antioxidants (phenolics and proline) and enzymatic antioxidants (peroxidase, superoxide dismutase, polyphenol oxidase, and catalase) in the root and shoot tissues of sugar beet plants. In contrast, the use of glycine betaine as foliar treatment at 0.5 and 1 mM alleviated the adverse impacts of cadmium and lead by promoting the aforementioned attributes. Furthermore, the application of 1 mM GB was more effective in increasing the contents of phenolics in root by approximately 16% and 29%, phenolics in shoot by about 25% and 10%, peroxidase activity by about 82% and 116%, superoxide dismutase activity by about 56% and 47%, polyphenol oxidase activity by about 9% and 36%, catalase activity by about 19% and 25%, in cadmium- and lead-stressed plants, respectively. Additionally, it reduced the levels of proline in sugar beet tissues. Overall, the application of glycine betaine has the efficacy to counteract the adverse impacts of cadmium and lead toxicity on sugar beet plants by enhancing the metabolic indices as well as the non-enzymatic and enzymatic antioxidant activities. [ABSTRACT FROM AUTHOR]

Sulfur (S) fertilization and rhizobium inoculation are important agronomic practices for improving soybean growth and yield. However, their combined effects on yield components and the resultant impacts on yield need further investigation. Our study aimed to verify the combined effects of S fertilizer and rhizobium inoculant on the yield components and seed yield of soybeans, as well as photosynthesis dynamics during the V5–R6 growth stages. A randomized block design incorporating two factors was employed for field experiments on soybean, involving the application of five rates of sulfur (0, 5.0, 9.8, 14.8, and 19.6 kg S ha−1) with rhizobium inoculation or without. A reduction of 50% in mineral fertilizer according to farmer practice (FP) was applied alongside different rates of sulfur for field experiments on soybeans. The findings indicated that the application of sulfur fertilization significantly enhanced soybean yield by increasing the number of grains per plant (NG) and the number of pods per plant (NP). Maximum grain yield was reached under treatment with an S rate of 19.6 kg S ha−1, which increased NG by 39% more than an S rate of 0 kg S ha−1. Correlation analysis indicated that higher photosynthesis was closely associated with increased yield components. This study demonstrated that applying S fertilizers could improve soybean production by combining the appropriate sulfur concentration and rhizobia inoculation. [ABSTRACT FROM AUTHOR]

Duckweed growing in paddy fields (DGP) has substantially increased because of the effects of climate warming and/or eutrophication in irrigated water. Previous studies have primarily focused on investigating the effects of DGP as a nonchemical agent for enhancing rice productivity on nitrogen utilization in rice paddy fields. However, how DGP impacts rice yield remains poorly understood. Therefore, a field experiment with three representative rice cultivars was conducted to determine the effects of DGP on rice yield, considering ecological factors, photosynthetic capacity, spectral changes, and plant growth. The results showed that DGP significantly reduced the pH value by 0.6 and the daily water temperature by 0.6 °C, accelerated rice heading by 1.6 days and increased the soil and plant analyzer development (SPAD) and photosynthetic rate of leaves by 10.8% and 14.4% on average, respectively. DGP also markedly enhanced the values of various vegetation indices such as RARSc, MTCI, GCI, NDVI705, CI, CIrededge, mND705, SR705, and GM, and the first derivative curve of the rice canopy reflectance spectrum exhibited a 'red shift' phenomenon upon DGP treatment. Changes in the aforementioned factors may lead to average increases of 4.7% in plant height, 15.0% in dry matter weight, 10.6% in panicles m−2, 2.3% in 1000-grain weight, and ultimately a 10.2% increase in grain yield. The correlation observed suggested that the DGP-induced enhancement in grain yield can be achieved by reducing the pH and temperature of the paddy water, thus enhancing the SPAD value and photosynthesis of leaves and stimulating rice plant growth. These results could offer valuable theoretical support for the future sustainable development of agriculture and the environment through the biological synergy between rice and duckweed. [ABSTRACT FROM AUTHOR]

Titanium has been reported to have positive effects on crop growth and production in various species. However, the impact of titanium on the Tartary buckwheat crops has not yet been studied. Therefore, an experiment was conducted to investigate the effect of spraying different concentrations of ionic titanium on the growth, photosynthesis, and uptake of mineral nutrients in Tartary buckwheat. The results showed that the application of titanium significantly improved dry matter accumulation, internode diameter, main stem node, root length, root average diameter, root surface area, root volume, grains per plant, and weight of grains per plant. Additionally, chlorophyll and photosynthetic parameters showed improvement regardless of the concentration of titanium used. The study found that titanium accumulation was mainly in leaves. The content of titanium in leaves showed a significant positive correlation with K, Ca, Mg, Mn, Cu, Zn, and B. This suggests a potential synergistic relationship between titanium and minerals in Tartary buckwheat leaves. Furthermore, the study also observed a significant increase in the total accumulation of P, K, Ca, Mg, Mn, Cu, Zn, and B in Tartary buckwheat plants. Overall, this study provides evidence for the positive effects of titanium on Tartary buckwheat and offers a theoretical foundation for practical production. [ABSTRACT FROM AUTHOR]

Extreme weather events, including drought, have occurred worldwide with increasing frequency and severity in recent years. Drought stress is the main limiting factor for agricultural development in many regions, including tobacco—an important economic crop and a model plant for scientific research. As it is adapted to the tropics, tobacco is highly susceptible to drought stress, with resultant decreases in yield and quality. Glycine betaine (GB) is an osmoregulatory substance that can enhance plant resistance to various abiotic stresses. Here, we investigate the protective mechanism of genetically engineered glycine betaine (GB) on tobacco photosynthesis under drought stress induced by 30% PEG-6000. This study used transgenic tobacco (T) accumulating GB and wild-type tobacco (WT) to investigate the protective effects conferred by the genetic engineering of GB synthesis on tobacco photosynthesis under drought stress (induced by 30% PEG-6000). The results showed that the net photosynthetic rate of the tobacco plants significantly decreased under drought stress, and the degree of decrease was significantly lower in the T line than in the WT line. GB accumulation improved the resistance of photosynthesis to drought stress. Furthermore, under drought stress, the photosynthesis improvement in the T line was related to the accumulation of GB, leading to maintenance of the water status, the promotion of osmotic regulation, and an enhancement in antioxidant enzyme activities, which reduced membrane peroxidation and thereby increased the thylakoid membrane's protein content and function, especially the photosystem II (PSII) function. The results provide a theoretical basis for further research on genetic engineering related to GB synthesis and the field application of exogenous GB. [ABSTRACT FROM AUTHOR]

High temperatures significantly injure the flowering, pollination, fruit growth, and quality of plants. Photosynthesis, the fundamental process supporting plant life, is crucial. Nevertheless, the quantitative evaluation of the physiological activity of the photosynthetic system of Nanfeng tangerine (NT) plants under high-temperature conditions remains a challenge. This research utilized NT plants, a distinctive citrus variety in Jiangxi Province, as the experimental subject. The study investigated the effects of varying degrees of high-temperature stress and duration on 16 photosynthetic physiological parameters of NT plants. The study examined the impact of four varying high-temperature treatment levels (32/22 °C, 35/25 °C, 38/28 °C, and 41/31 °C) for durations of 2, 4, 6, and 8 days, respectively. Principal component analysis was utilized to identify the key indicators of photosynthetic physiological activity in NT plants, with Fv/Fm, Pmax, LCP, H2O2, MDA, and POD being selected as key parameters. The high-temperature stress index model previously constructed was used to calculate the high-temperature stress index value of the NT plants exposed to varying degrees and durations of high temperature, in order to provide a comprehensive assessment of the photosynthetic system of NT plants under high-temperature stress. Subsequently, the high-temperature stress levels were categorized into five levels based on the calculated values: Level 0 for 0 < HSI ≤ 2, Level 1 for 2 < HSI ≤ 4, Level 2 for 4 < HSI ≤ 6, Level 3 for 6 < HSI ≤ 8, and Level 4 for HSI > 8. The research results provide valuable data for agricultural meteorological departments to carry out disaster risk zoning and risk assessment in the future. [ABSTRACT FROM AUTHOR]

Mesotrione is a widely used post-emergence herbicide for maize. The toxicity of mesotrione to maize (especially sweet corn) has been widely reported, and some sweet corn varieties are highly sensitive to mesotrione, which affects subsequent plant growth periods. However, the molecular mechanisms responsible for the differences in susceptibility to mesotrione are not known. By comparing changes in the transcriptome of mesotrione-tolerant line 301 and mesotrione-sensitive line 276 after mesotrione treatment, we found that the genes coding light-harvesting chlorophyll protein complex were induced in 301, and the genes coding loosening cell walls were overrepresented in 276. The net photosynthetic rate, maximum photochemical efficiency of leaf PSII, photochemical quenching of chlorophyll fluorescence, and the electron transport rate were significantly higher in 301 than in 276 after mesotrione treatment, and these effects became more severe as time passed. In addition, oxidative balance was also affected by mesotrione. Compared with 301, SOD, POD, and CAT activities were significantly reduced with longer exposure time in 276. The results suggested that sweet corn can mitigate herbicide mesotrione toxicity by improving photosynthesis, ROS scavenging, and cell wall synthesis. [ABSTRACT FROM AUTHOR]

Due to increasingly frequent unfavorable climate changes, achieving a high grain yield of wheat is a challenge for breeders. The relationships between wheat productivity and photosynthesis traits are not very well understood during the growing season. This study investigated the effect of chlorophyll a fluorescence parameters (maximum quantum yield of primary photochemistry (TRO/ABS) and performance index on absorption basis (PIABS)) on grain yield and the yield-related and technological quality traits of six wheat varieties over two growing seasons. In the first growing season (2021/2022), grain yield was significantly positively correlated with 1000 kernel weight and TRO/ABS at the second measurement point (growth stage 25 (GS 25)). Only the highest-yielding variety Bubnjar (104.0 dt ha−1) showed values of TRO/ABS at the same significance level between the second and third measurement points. Due to elevated virus and disease infections in the second growing season (2022/2023), the grain yield of the investigated varieties decreased between 37.9% (Bubnjar) and 67.6% (Anđelka) relative to the first growing season. The three highest-yielding varieties (Bubnjar, Rujana, and Silvija) in 2022/2023 were the tallest, were later in maturity, escaped yellow rust pressure at the stem elongation stage more efficiently, and also showed the lowest increase in TRO/ABS at this stage (fourth measurement point at GS 47, compared to the third at GS 32). In addition, the highest-yielding variety Bubnjar showed the highest increase in PIABS at the last measurement (seventh) at GS 71 compared to the sixth (GS 69), thus maintaining the vitality of flag leaves at the grain-filling stage, while the other varieties showed a very small increase or even a significant decrease. Therefore, plant photosynthetic activity over the entire growing season contributes to crop productivity. [ABSTRACT FROM AUTHOR]

Climate change has emerged as a challenge for soybean cultivation around the world, stimulating the development of technological alternatives that aim to mitigate the damage caused by water deficit. From this perspective, algae extract-based biostimulants have been tested to reduce water stress in several crops, but little is known about their effects on soybean. Thus, we hypothesize that a commercial biostimulant based on Ascophyllum nodosum can improve the physiological performance and water relations of Glycine max plants subjected to water deficit. To test this hypothesis, we set up an experiment in controlled conditions in a greenhouse, considering five treatments (control; application of biostimulant; water deficit (WD); WD + application of biostimulant; and WD + split application of biostimulant). The experiment was designed in completely randomized blocks with four replications per treatment and conducted in polyethylene pots containing 10 L of soil and three plants per pot. The irrigation was carried out daily; the water deficit was 50% soil moisture at field capacity, starting at the R1 stage (beginning of flowering, where there is at least one flower open at any node on the plant) and maintained for ten days. The biostimulant was applied concurrently with the onset of water deficit. We confirmed the hypothesis that foliar application of 1.0 L ha−1 of the biostimulant reduces the deleterious effects of the common water deficit at the beginning of the reproductive stage of soybean through the reduction of damage from oxidative stress (reduction of malondialdehyde synthesis by 31.2% in relation to the WD plants), maintenance of water potential and cellular homeostasis (10.2% increase in relative water content when compared with WD plants), and conservation of the contents of chlorophyll in leaves and stimulation of photosynthesis and carboxylation (68% increase in net photosynthetic rate and 49.3% increase in carboxylation efficiency in relation to WD plants). However, when applied in installments, the biostimulant was not efficient in reducing soybean water stress. Therefore, we conclude that the application of a biostimulant based on A. nodosum can help reduce the harmful effects of water deficit on soybean plants, opening up perspectives for the mass use of this extract in agricultural crops produced on a large scale. [ABSTRACT FROM AUTHOR]

The agricultural sector faces challenges due to climate change and the growing global population. Alkaline stress could adversely impact plant growth and crop production. This stressor diminishes water quality essential for crop cultivation, consequently impairing plant growth and overall productivity. Gamma-aminobutyric acid (GABA), a non-protein amino acid, may exhibit multifaceted roles in plant responses to adverse environmental conditions. Optimization of crop production in controlled environmental agriculture under artificial light attracted much attention. In the present study, we investigated the effects of different light spectra and GABA concentrations on Lollo Rosso lettuce plants under alkaline stress. Seedlings were placed under different light spectra [red (R), blue (B), white (W), 3R:1B, and 2R:1B:1far red (FR)] and treated with GABA (0 and 50 µmol). Alkaline conditions were instituted by applying NaHCO3 at a concentration of 40 mM. The experiment incorporated a control treatment without NaHCO3. In general, R light exposure caused the highest growth performance of lettuce plants. GABA augmented biomass production in control and alkaline-treated plants across all light spectra. Additionally, it increased the concentrations of photosynthetic and protective pigments under alkaline conditions. GABA also improved the photosynthetic performance under all light spectra. Non-photochemical quenching and pigmentation were enhanced by exposure to B light, especially in plants treated with GABA. Alkaline stress induced an increase in soluble carbohydrate content in the lettuce leaves. These findings highlight the support of GABA application in facilitating coping plants to alkaline stress. [ABSTRACT FROM AUTHOR]

Understanding the spatial heterogeneity of light and photosynthesis distribution within a canopy is crucial for optimizing plant growth and yield, especially in the context of greenhouse structures. In previous studies, we developed a 3D functional-structural plant model (FSPM) of the Chinese solar greenhouse (CSG) and tomato plants, in which the greenhouse was reconstructed as a 3D mockup and implemented in the virtual scene. This model, which accounts for various environmental factors, allows for precise calculations of radiation, temperature, and photosynthesis at the organ level. This study focuses on elucidating optimal canopy configurations for mechanized planting in greenhouses, building upon the commonly used north–south (N–S) orientation by exploring the east–west (E–W) orientation. Investigating sixteen scenarios with varying furrow distance (1 m, 1.2 m, 1.4 m, 1.6 m) and row spacing (0.3 m, 0.4 m, 0.5 m, 0.6 m), corresponding to 16 treatments of plant spacing, four planting patterns (homogeneous row, double row, staggered row, incremental row) and two orientations were investigated. The results show that in Shenyang city, an E–W orientation with the path width = 0.5 (furrow distance + row distance) = 0.8 m (homogeneous row), and a plant distance of 0.32 m, is the optimal solution for mechanized planting at a density of 39,000 plants/ha. Our findings reveal a nuanced understanding of how altering planting configurations impacts the light environment and photosynthesis rate within solar greenhouses. Looking forward, these insights not only contribute to the field of CSG mechanized planting, but also provide a basis for enhanced CSG planting management. Future research could further explore the broader implications of these optimized configurations in diverse geographic and climatic conditions. [ABSTRACT FROM AUTHOR]

Basil (Ocimum basilicum L.) contains abundant nutrients and is considered an economically important edible vegetable. The optimal nutrient levels will increase the productivity and basil quality. However, prominent research on basil regarding the diagnostic nutrient deficiency standard and the corresponding nutrient uptake is still scarce. To this end, the basil plants were hydroponically cultured and subjected to one of 14 nutrient solution treatments, corresponding to the omission of a single nutrient element (designated as -N, -P, -K, -Ca, -Mg, -NH4+, -NO3−, -S, -Fe, -Mn, -B, -Zn, -Mo, and -Cu) and a complete nutrient solution (CS) as the control. The most common nutrient deficiency symptoms were chlorosis, stunted roots and growth, and even leaf necrosis and abscission, in particular of -N, -P, -NO3−, and -Fe. We also found that basil is a NH4+-sensitive species. The photosynthetic capacity (photosynthesis pigments, Fv/Fm ratio, and greenness index) was disturbed to varying degrees when a single nutrient was omitted from the nutrient solution. Additionally, the omission of a specific single nutrient confers significant differences in the tissue nutrients, regardless of the macronutrients and micronutrients considered. Concomitantly, multivariate analysis suggested the correlations among certain important nutrients were distinctly different under different treatments (correlation analysis); the influences of different nutrient deficiencies on the tissue nutrient concentrations showed similarity (principal component analysis). Collectively, the growth, physiological, and biochemical changes studied in this trial not only improved our knowledge for diagnosing nutrient deficiency symptoms for practical cultivation but also provided a comprehensive understanding of the internal nutrient associations in basil. [ABSTRACT FROM AUTHOR]

One of the strategies to combat micronutrient malnutrition is by developing biofortified common bean lines (Phaseolus vulgaris L.) capable of tolerating different stress conditions. In this study, the adaptive responses of different biofortified bean lines grown under combined stress of acidic soil and high-temperatures were evaluated in the Colombian Amazon. A total of 247 common bean lines from the Mesoamerican gene pool were used to determine the adaptive response in terms of phenological, physiological, and agronomic behavior under combined stress conditions. The lines tested were obtained from different single crosses, double crosses, and backcrosses between different bean materials, of which 146 were obtained from F4 families with high iron (Fe) content in seed and 99 common bean lines from F5 families. Different bean lines had grain yields (GY) higher than 1400 kg ha−1 from the F5 (lines: 859, 805, 865, and 657) and F4 (lines: 2853 and 2796) families. The superior performance of these lines was related to a higher photosynthate partitioning that has allowed an increase in pod formation (pod partitioning index, PPI) from the canopy biomass (CB) and grain filling (pod harvest index, PHI; harvest index, HI), resulting in higher values of GY. Values of GY were correlated with CB (r = 0.36), PPI (r = 0.6), PHI (r = 0.68), and HI (r = 0.8, p < 0.001). This increase in agronomic performance is due to a greater allocation of energy to the photosynthetic machinery (ΦII) and its dissipation in the form of heat (ΦNPQ), with increases in the leaf temperature difference (LTD). Based on the results obtained, six biofortified lines of common bean (lines F5: 859, 805, 865, and 657; lines F4: 2853 and 2796) showed traits of tolerance to combined stress and can serve as progenitors to increase Fe and Zn concentration in the seeds of lines that tolerate the combined stress from acidic soil and high temperature in the Colombian Amazon region. [ABSTRACT FROM AUTHOR]

Water stress can trigger acclimation responses and damage plants. The aim of this study was to evaluate the integrative responses of cotton hydraulic conductance, leaf photosynthesis, and carbon metabolism to short-term drought and subsequent rewatering. A water-controlled pot experiment was conducted in 2020, with soil water drying continuing for one day (D1), two days (D2), and three days (D3) after it reached 40% ± 5% of the soil water holding capacity at the blooming stage of cotton, and the soil was then rewatered to the soil water holding capacity. We investigated how the stem hydraulic conductance, gas exchange, and biochemical traits of cotton were affected by imposed drought stress and subsequent rewatering. The hydraulic characteristics of cotton in the D2 and D3 treatments evolved with damage, complete closure of stomatal conductance, and complete deterioration of photosynthesis, in addition to severe floating changes in the carbon metabolism affected by drought. The leaves' functional characteristics after rewatering cannot be completely recovered to full-irrigation levels, and the recovery extent was strongly linked to the duration. Consequently, it is considered desirable to maintain normal physiological activity during the cotton reproductive period, and the drought episode can be sustained for 1 day in a long-term perspective when the soil water content is depleted to 40% ± 5% of the soil water holding capacity. These results can provide in-depth ideas for better understanding the hydraulic and physiological responses of cotton to drought episodes and rewatering, and they can help drought-affected cotton to cope with future climate change. [ABSTRACT FROM AUTHOR]

One-time fertilization with controlled-release urea (CRU) is a research hotspot for its lower labor cost and stability of nitrogen (N) supply for rice growth. Yet the fertilizer formulation needs to be further improved to better adjust the N supplement to meet the demand of rice plants and obtain a higher grain yield. Therefore, the effects of novel fertilizer formulations composed of CRU, urease inhibitor (UI) and nitrification inhibitor (NI) on the rice growth and photosynthetic characteristics as well as high-yield formation were tested through a two-year field experiment. The result indicated that the combined use of CRU and UI treatment can achieve higher yields than with CRU at the same N application level. Meanwhile, with a 20% reduction of N use, one-time application of CRU + UI can obtain the same high yield as the conventional split application of urea. Compared with conventional fertilization and CRU treatment, the CRU + UI treatment had suitable leaf area and biomass accumulation at the vegetative growth stage and high effective stem tiller rate. More post-anthesis dry matter accumulation, higher net photosynthesis rate and low senescence rate were guaranteed for its high yield and nitrogen agronomic efficiency. [ABSTRACT FROM AUTHOR]

Maize is among the most significant crops in the world regarding production and yield, but it is highly sensitive to drought, which reduces the growth, photosynthetic efficiency, grain quality, and yield production of a plant. Quantum yield efficiency of photosystem II is a critical photosynthetic component that is susceptible to drought stress. This study intended to investigate the effects of drought stress on growth and morpho-physiological parameters using three maize hybrids (‘P-3011w’, ‘P-3092’ and ‘iku20’) with contrasting soil moisture contents (100%, 40%) at the pre-flowering stage. The stress treatment (40%) was initiated at stage V7, for a period of 15 days; the experimental units were established in a completely randomized design with split-plot arrangement along with three repetitions in 42 L pots using a substrate of peat moss, black soil and poultry manure (1:2:1). The morphological, growth-related and physiological parameters were assessed, including chlorophyll fluorescence (Fv/Fm), which was measured using a LiCor-6400-40 fluorometer. The results showed that all morphological, growth-related and physiological variables decreased under drought stress during the reproductive stage, with the exception of leaf temperature and intercellular CO2 concentration, which increased by 12% and 54%, respectively. Drought stress significantly reduced the photosynthetic chlorophyll fluorescence (43%), due to damage to photosystem II. The lowest percentage of damage to photosystem II (34%) was observed in the iku20 genotype. In contrast, P-3011w and P-3092 had the highest levels of significantly similar damage (49% and 46%, respectively). The correlation analysis showed a highly positive interaction of chlorophyll fluorescence (Fv/Fm) with net photosynthetic rate and stomatal conductance under drought conditions, and multiple regression analysis revealed that the maximum effect on net photosynthetic rate under drought was due to the damage it caused to photosystem II. Thus, iku20 might have a tendency to be able to withstand drought stress in the dry northeast region of Mexico. Overall, we concluded that the photosystem II was negatively impacted by drought stress thus causing a reduction in all physiological, morphological and growth-related variables.

Climate change increases the risk of coffee yield due to the genotype-dependent effects of water deficit on coffee physiology. The goal of this research was to evaluate how water deficit altered the physiological and growth characteristics of arabica coffee (Coffea arabica L.). Water status, photosynthetic response to CO2 intercellular concentration (A/Ci curves) and growth parameters were evaluated in seedlings of four genotypes (Catimor ECU 02, Cavimor ECU, red Caturra and Sarchimor 4260). Most of the physiological traits evaluated differed significantly among genotypes. Between control and water deficit plants, significant variations occurred in the A/Ci parameters, showing a wide range of values for net photosynthetic rate, stomatal conductance, and water use efficiency, with decreases ranging from 4 to 74%. Maximum electron transport rate through photosystem II, highest rate of RuBisCO carboxylation, and triose phosphate utilization rate were all strongly decreased by water deficit 61% (red Caturra and Sarchimor 4260), followed by Cavimor ECU (35%) and Catimor ECU 02 (24%). Differences in response to water deficit among genotypes suggest possible genotypic differences in tolerance. The results indicated that Catimor ECU 02 and Cavimor ECU were less sensitive to water deficit, while red Caturra and Sarchimor 4260 were the most susceptible.

Rapeseed–rice rotation is a cropping system that improves the land-use rate. The present study conducted a field experiment with winter planting of rapeseed as treatment (WR) and winter fallow as control (CK) to investigate the effects of winter planting of rapeseed on growth, yield formation, and 2-acetyl-1-pyrroline (2-AP) biosynthesis of fragrant rice in the two subsequent cropping seasons. The results show that WR treatment improved alkali-hydro nitrogen and rapidly available phosphorus contents in soil. Compared with CK, WR treatment significantly increased grain yield and effective panicle number per plant by 21.16–27.26% and 7.33–21.24%, respectively. Higher net photosynthetic rate, leaf area index, and dry matter accumulation of fragrant rice plants were recorded in WR treatment and CK. Furthermore, compared with CK, WR treatment significantly increased grain 2-AP content, which could be explained by increased content of pyrroline-5-carboxylic acid, methylglyoxal, 1-pyrroline, and enhanced activity of proline dehydrogenase. In addition, future studies should be conducted at a molecular level to reveal the regulation mechanism in 2-AP biosynthesis of fragrant rice under conditions of winter planting of rapeseed.

Salt stress is a critical abiotic factor that adversely affects plant growth and productivity by impairing photosynthesis. This study explores the impact of exogenous ascorbic acid (AsA) on the photosynthetic performance of tomato seedlings (Solanum lycopersicum L. cv. Ligeer 87-5) under salt stress. Hydroponic experiments were conducted in a solar greenhouse, where tomato seedlings were subjected to the following five treatments: Control, NaCl, NaCl + AsA, NaCl + lycorine (LYC), and NaCl + LYC + AsA. Our findings demonstrate that salt stress significantly reduced chlorophyll and carotenoid contents, levels of chlorophyll synthesis precursors (5-aminolevulinic acid (ALA), porphobilinogen (PBG), uroporphyrinogen III (Urogen III), protoporphyrin IX (Proto IX), magnesium protoporphyrin IX (Mg-Proto IX), protochlorophyllide (Pchl)), and essential elements (Mg, Fe, Mn, Zn, Mo, and P) in both roots and leaves. These reductions led to a substantial decline in net photosynthetic rate (Pn) and compromised photosystem II (PSII). In contrast, exogenous AsA application significantly enhanced the content of photosynthetic pigment precursors and essential elements, improved stomatal aperture and gas exchange efficiency, and boosted the photosynthetic performance of tomato seedlings under salt stress. Furthermore, AsA treatment mitigated the negative effects of salt stress by protecting PSII, increased light energy utilization efficiency, and alleviated both stomatal and non-stomatal limitations. The application of the AsA synthesis inhibitor LYC exacerbated the detrimental effects of salt stress, further reducing chlorophyll content and photosynthetic efficiency. In conclusion, exogenous AsA plays a vital role in enhancing the photosynthetic performance and stress tolerance of tomato seedlings under salt stress by stabilizing chlorophyll biosynthesis, facilitating essential element absorption, and optimizing stomatal function. This study provides a new approach and feasible measures for improving tomato resistance and yield, which is significant for enhancing crop productivity, managing saline soils, and promoting sustainable agricultural practices.

The cultivation of medicinal plants plays a crucial role in promoting human health benefits. However, the production of these plants can be affected by drought conditions. This research aimed to investigate the impact of differing water status (non-drought and drought during the flowering to harvest stage) and various iron treatments on the performance of black cumin. The iron treatments included no iron as the control (nFe), no iron with seed hydro-priming (nFe + P), seed iron priming (pFe), seed iron priming with iron foliar spraying (pFe + sFe), and double iron foliar spraying (sFe + sFe). The purpose of these treatments was to assess the effect of iron application methods on plant response under different water conditions. The findings revealed that drought significantly reduced the levels of Chla (15%) and RWC (5.9%), plant height (7%), follicle number (16.7%), seed number (4.6%), 1000-seed weight (3.2%), and seed yield (30.1%). Additionally, drought increased the proline content (90.9%), electrolyte leakage (9.2%), and MDA levels (23.9%). Interestingly, applying iron amendments reduced electrolyte leakage and increased seed yield under both water conditions. The drought-induced increase in proline content was more pronounced in the nFe treatment than in the other treatments. The amount of MDA in the nFe and nFe + P treatments was significantly higher under drought conditions compared to non-drought conditions. In conclusion, the addition of iron amendments helps black cumin plants recover from the effects of drought and reduces damage to seed growth. This means that using both seed iron priming and iron foliar spraying can significantly improve yields. Alternatively, focusing on either seed iron priming or double iron foliar spraying can also boost black cumin production compared to not using iron amendments.

The widespread application of nanoparticles (NPs) in agriculture has not only enhanced the efficiency of agrochemical use but also introduced environmental pollution, potentially impacting human health through absorption and accumulation in edible plants. The purpose of this study was to evaluate the toxic effects and ecological risks of Cu2O nanoparticles (nCu2O) in the life cycle of soybean, and to provide a theoretical basis for the safe application of NPs in agriculture. Soybeans were grown in natural soil modified with nCu2O, bulk cuprous oxide (bCu2O) and copper sulfate (CuSO4) at concentrations of 0, 50, 200, and 800 mg/kg. Samples and grains from treated soybeans were collected at the flowering, podding, and seed-filling stages for analysis. The results indicated that treatments with nCu2O, bCu2O, and Cu2+ reduced the chlorophyll content in soybean leaves, thereby affecting photosynthesis. Significant reductions were observed in the net photosynthetic rate (Pn), the transpiration rate (Tr), stomatal conductance (Gs), the quantum yield of photosystem II (Y(II)), photochemical quenching (qP), and the electron transport rate (ETR) at high concentrations. However, the toxicity of nCu2O to photosynthesis recovers as the plant grows. Almost all treatments increased the levels of antioxidant enzymes (SOD, POD, CAT) and reduced oxidative stress. In the nCu2O and bCu2O treatments, grain protein content was significantly reduced, while fat and water content increased. Phosphorus (P) content decreased, whereas sulfur (S), potassium (K), magnesium (Mg) and calcium (Ca) contents increased. The accumulation of copper in plants followed the order nCu2O > bCu2O > Cu2+, with the bCu2O treatment being slightly more toxic than the nCu2O treatment, and both being more toxic than the Cu2+ treatment. The above data indicated that nCu2O had a dose-dependent effect, which significantly inhibited soybean growth and changed grain quality at high concentrations.

Selecting the best oil palm cultivars adapted to specific agro-climatic conditions helps ensure fruit and oil production success. Many biotic and abiotic problems can limit the productivity of the crop, some of which have not yet been described, as well as their symptoms and degree of impact. In oil palm, a disturbance known as leaf-bending occurs, in which the palms present a bending or breakage of the petiole in the leaves, representing a significant challenge for oil palm cultivation. Although leaf-bending in oil palm plantations is known, its effect on the palm’s performance and its possible causes are unknown. Thus, the objectives of the present work were to describe and propose a quantitative way to evaluate leaf-bending in different cultivars (Elaeis guineensis Jacq. and the interspecific O×G hybrid) and to evaluate the disturbance effect on the physiology and nutritional balance of the oil palm. The results showed that most leaves from leaf rings three and four of the palm phyllotaxis have the highest affectation, with 74% leaf-bending. The cultivars with a Deli × La Mé and Coarí × La Mé genetic background were the most tolerant; however, the Deli × AVROS and Deli × Yangambi genetic crosses were the most susceptible. The difference in the affectation between the groups was 60% to 70%. Leaf-bending affected physiological parameters such as photosynthesis, transpiration, and stomatal conductance. Thus, below the second ring of leaves, the affected plants’ physiological parameters decreased between 40% and 50%. The nutritional diagnosis showed that the most sensitive cultivars to leaf-bending were Deli × AVROS, which presented the highest average index of nutritional balance (IBNm), indicating that this genetic cross had the highest nutritional imbalance. On the contrary, the most tolerant cultivars were Deli × La Mé, which presented the lowest IBNm, associated with a better nutritional condition.

The influence of light downconversion films (red, pink and blue films) on leaf physiological features and fruit bioactive compound accumulation was studied in strawberry plants. Red, pink and blue films were able to convert light less utilised by plants into more efficient light wavebands with various possibilities depending on the film characteristics (blue film shifts UV into blue radiation; red film shifts green into red radiation, pink film shifts UV and green into blue and red radiation but to a lesser extent than red film). Indeed, by enhancing the quality of light available for photosynthesis, the utilization of these films holds the potential to improve agricultural productivity and sustainability. All of these light downconversion films resulted in higher plant fresh weight compared to a control colourless (Cnt) film, with plants grown under blue film (UV-to-blue light conversion) showing the most impressive results in terms of total leaf area (+25%), leaf thickness (+10%) and leaf mass per area (+15%). Simultaneously, during the flowering stage, plants under blue film had a higher net photosynthetic rate due to the increase in photosynthetically efficient wavelengths. Moreover, blue film resulted in the highest total phenolic (+40% and +28% than red and pink films, respectively) and flavonoid content (+54%, +84%, +70% than Cnt, red and pink films, respectively) in fruit, with specific effects on targeted phenols, i.e., quercetin, ellagic acid and its glycoside, ellagitannins, and procyanidins. In conclusion, the use of the UV-to-blue conversion light film tested herein represents an innovative solution to increase strawberry yield and promote fruit nutraceutical features, playing a pivotal role in ensuring food quality and security and sustainable agricultural practices.

Accurately understanding the critical threshold of leaf magnesium (Mg) concentration is crucial for rapid diagnosis of crop Mg status; however, little information is available on critical Mg concentration for different physiological processes in dicots and monocots. Here, we investigated the sensitivity of biomass, chlorophyll (Chl) at different leaf positions/ages, leaf area (LA), and photosynthesis (Pn) to Mg deficiency between rice (Oryza sativa L.) and cucumber (Cucumis sativus L.). Plants were grown hydroponically under twelve Mg concentration gradients. Results showed reducing the external Mg supply to a certain level resulted in significant decline in biomass, Chl, LA, and Pn in both plants. A leaf Mg threshold of 0.97 mg g−1 DM (dry matter) for total biomass was found in rice, which was not identified in cucumber. Critical Mg thresholds for Chl a, b, and carotenoids (Car) showed a decreasing trend with leaf age, suggesting Chl in upper young leaves are more sensitive to Mg deficiency; however, visible Mg-deficiency symptoms were predominantly in mid-aged leaves with a higher rate of Mg remobilization, especially in cucumber. Leaf critical Mg concentrations for Chl a+b, Pn, and LA were 1.22, 1.05, and 1.00 mg g−1 DM in rice, respectively, which were lower than those of cucumber, 4.23, 4.09, and 3.55 mg g−1 DM, implying that cucumber was more susceptible to low Mg stress; Chl a+b was the most sensitive indicator of Mg deficiency. Overall, Chl a+b of upper young mature leaves can be used as an early diagnostic index of Mg nutrition in crops, especially Mg-insensitive crops.

Grass species have a range of strategies to tolerate soil water restriction, which are linked to the environmental conditions at their site of origin. Climate change enhances the relevance of the functional role of anatomical attributes and their contribution as water stress tolerance factors. Morpho-anatomical traits and adjustments that contribute to drought resistance in Lolium perenne L. (Lp) and Bromus valdivianus Phil. (Bv), a temperate humid grass species, were analysed. The structure of the leaves and pseudostems (stems only in Lp) grown at 20–25% field capacity (FC) (water restriction) and 80–85% FC (control) were evaluated by making paraffin sections. In both species, water restriction reduced the thickness of the leaves and pseudostems, along with the size of the vasculature. Bv had long and dense leaf hairs, small and numerous stomata, and other significant adaptive traits under water stress, including thicker pseudostems (p ≤ 0.001), a greatly thickened bundle sheath wall (p ≤ 0.001) in the pseudostem to ensure water flow, and a thickened cuticle covering on leaf surfaces (p ≤ 0.01) to avoid water loss. Lp vascular bundles developed throughout the stem, and under water restriction the xylem vessel walls were strengthened and lignified. Lp leaves had individual traits of a ribbed/corrugated-shaped upper surface, and the stomata were positioned to maintain relative humidity outside the leaf surface. Water restriction significantly changed the bulliform cell depth in Lp (p ≤ 0.05) that contributed to water loss reduction via the curling leaf blade. This study demonstrated that the two grass species, through different morphological traits, were able to adjust their individual tissues and cells in aboveground parts to reach similar physiological functions to reduce water loss with increased water restriction. These attributes explain how both species enhance persistence and resilience under soil water restriction. [ABSTRACT FROM AUTHOR]

Soil salinity is a severe threat to agricultural production. Most saline soils turn alkaline, increasing the soil pH and, in turn, hampering the growth and development of crops. In this study, the effects of a foliar spray of melatonin (MT; 100 μmol·L−1) on the pH of the root environment, growth of tomato seedlings, endogenous MT levels, rapid chlorophyll fluorescence induction kinetics, and key enzymes of the Calvin cycle under alkaline (60 mmol·L−1 NaHCO3) stress were studied in Riegel 87-5 tomatoes. The results revealed that the growth and photosynthesis of tomato seedlings were inhibited by increased pH in the root environment under alkali stress; however, the application of exogenous MT reduced the pH of the root environment, alleviated the inhibition of growth of tomato seedlings under alkali stress, increased the content of photosynthetic pigments, alleviated the damage of the donor and acceptor sides of the photosynthetic electron transport chain, increased the activity and efficiency of photosynthetic electron transport, and optimized the share of the light energy allocated to PSII reaction centers. Increased expression levels of Calvin-cycle enzymes, including fructose-1,6-bisphosphate aldolase (FBA), fructose-1,6-bisphosphate esterase (FBP), and phosphoglycerate kinase (PGK), led to enhanced photosynthetic performance in tomato seedlings. Exogenous MT boosted endogenous MT levels and stimulated the production and secretion of organic acids in the root system. This regulation of organic acid content reduced the environmental pH in the inter-root zone, alleviating the damage caused by alkali stress. This study indicated that the exogenous administration of MT may mediate an increase in endogenous MT levels, regulate the efficiency of photosynthesis and root pH levels, and play a crucial role in mitigating injury caused by alkali stress in tomato seedlings. [ABSTRACT FROM AUTHOR]

In this study, we evaluated the impact of brown seaweed extract (Ecklonia maxima) on the morphology and physiology of three different plant species. We conducted experiments using two types of fertilizers: an artificial fertilizer (0.1 g/L) and a biological extract of brown seaweed (Ecklonia maxima) at two concentrations (C1 at 1 mL/L and C2 at 2.5 mL/L). For melon, the application of C1 resulted in significant improvements in photosynthesis parameters, total chlorophyll content, and overall plant growth. When C2 was applied, it further enhanced these parameters, leading to a notable increase in shoot phytomass. In the case of cucumber, C1 led to increased resource allocation towards stems and leaves. Conversely, C2 increased the number of green leaves and contributed to higher shoot phytomass. For tomato plants, the application of C1 resulted in a slight increase in photosynthesis, but it did not significantly impact leaf growth. On the other hand, C2 induced a modest increase in photosynthesis, chlorophyll content, and root growth. In summary, our findings indicate that brown seaweed extract has a discernible influence on the physiology of the studied plants. However, the specific effects on resource allocation largely depend on the plant species and the concentration of the extract applied. [ABSTRACT FROM AUTHOR]

Soil heavy metal pollution caused by human activities has become one of the most critical environmental issues with a global concern. Phytoremediation is widely used due to its low cost and environmental friendliness. However, the impact of heavy metals on plant growth remains unclear. This study investigated the effects on the growth and photosynthetic activity of Picris divaricata Vant. under different cadmium concentrations using a hydroponics cultivation system. The results showed that the growth and photosynthetic processes of P. divaricata exhibited a phenomenon of promotion in low Cd concentrations and inhibition in high Cd concentrations. Under a low to medium Cd concentration (≤25 μM), there was no Cd toxicity in terms of plant growth, but high concentrations of Cd inhibited plant growth. The Fe content of leaves gradually increased as the Cd concentration increased; it reached 201.8 mg kg−1 in 75 μM Cd. However, there was no significant difference in Mn between the 75 μM Cd treatment and the control (p > 0.05). The contents of carotenoid ranged between 3.06 and 3.26 mg/g across the different Cd treatments, showing no significant differences. The treatment with 5–75 μM Cd did not directly affect the photosynthesis of P. divaricata. Higher Cd concentrations reduced the stomatal density on the of P. divaricata leaves, resulting in stomatal and mesophyll conductance limitations, indirectly affecting P. divaricata photosynthesis. These research results provide a reference for evaluating and selecting heavy metal tolerant plants and provide environmentally friendly approaches to remediate heavy metal pollution. [ABSTRACT FROM AUTHOR]

Drought severely limits sugarcane productivity in many regions of the world. This study characterized physiological responses to different drought durations in a diverse set of sugarcane genotypes in two crop cycles (plant and ratoon cane). A split-plot design was used where three drought treatments, namely, no drought (SD0), short-term drought (SD1), and long-term drought (SD2), were assigned to main plots and six diverse sugarcane genotypes to subplots. Drought reduced photosynthesis, leaf area index, and biomass yield. However, the study found significant differences in physiological responses to drought among genotypes in both crops. F03-362 (F1), KK09-0358 (BC1), and KK3 (cultivar) demonstrated greater tolerance to drought by maintaining comparatively higher photosynthetic activity, while KK09-0939 (BC2) and TPJ04-768 (BC1) were more sensitive. KK3 and UT12 (cultivar) consistently maintained comparatively higher levels of photosynthesis under drought in the ratoon crop, although stomatal conductance values were comparable to those of other genotypes. Drought significantly reduced dry matter in all genotypes, but more so in the two cultivars. The study demonstrated variable levels of sensitivity to drought among diverse genotypes with different physiological responses being induced by different drought treatments. This information is useful for sugarcane production management and breeding programs. [ABSTRACT FROM AUTHOR]

Saline-sodic stress induces iron deficiency in rice, reduces leaf photosynthetic performance, and inhibits yield enhancement. In this study, we investigated the effects of exogenous Fe on the photosynthetic performance and transcriptomics of two different tolerant rice cultivars CB9 (Changbai9: saline tolerant cultivar) and TH899 (Tonghe899: saline sensitive cultivar) with 4-week-old Fe-deficient rice seedlings under saline stress, Fe deficiency stress, and both co-stresses. The results showed that under saline and alkaline stress, spraying exogenous iron favored the growth of the two cultivars of rice, with a 32.68% and 39.82 increase in fresh weight, a 2.20-fold and 2.16-fold increase in pigment, respectively, and an 80.28% and 100.00% increase in net photosynthetic rate, respectively, as compared with the iron-deficiency treatment. Transcriptome analysis showed that we found a higher number of differentially expressed genes (7785 differentially expressed genes) in response to exogenous Fe spraying in the soda-salt sensitive variety TH899. The differentially expressed genes that are common to the two cultivars are primarily enriched in metabolic pathways, including plant hormone signal transduction (map04075) and phenylpropanoid biosynthesis (map00940). Specifically, among these genes, 14 are differentially expressed in the carotenoid biosynthetic metabolic pathway. The differentially expressed genes specific to the salinity-tolerant variety CB9 were mainly enriched in the metabolic pathways of glyoxylate and dicarboxylic acid methyl metabolism (map00630), and carbon fixation in photosynthetic organisms (map00710), among which 20 genes were significantly expressed in the pathway for carbon fixation in photosynthetic organisms (map00710). The research results offer specific theoretical support for enhancing the salt tolerance of rice.

Leymus chinensis is a perennial rhizomatous clone plant. It exhibits strong rhizomatous tillering and clonal growth through asexual reproduction. The root system is interdependent with aboveground growth and root growth can regulate aboveground growth and photosynthesis. Melatonin has been shown to regulate root growth and promote photosynthesis. However, it remains unclear whether melatonin affects aboveground growth and photosynthesis by regulating rhizome growth. To address this gap, we studied nine Leymus chinensis from different geographical locations, all grown under the same conditions. We selected two materials with strong (LC19) and weak (LC2) rhizome growth abilities from nine materials and treated them with exogenous melatonin. We found there were significant positive correlations between stem length, plant height, leaf number and rhizome traits. Additionally, rhizome traits showed significant positive correlations with photosynthetic indices and chlorophyll content. Specifically, for LC2, treatment with 200 μmol/L melatonin significantly increased root length, the number of extravaginal ramets and rhizome clonal growth rate by 88.72%, 43.75% and 43.70%, respectively, resulting in significant increases in aboveground traits. Similarly, for LC19, 200 μmol/L melatonin treatment led to significant increases of 74.66%, 23.02%, 62.71% and 62.72% in four traits, respectively, along with aboveground trait improvements. Furthermore, around 300 μmol/L melatonin treatment promoted photosynthetic efficiency in LC2, while around 100 μmol/L melatonin treatment had the same effect in LC19. In conclusion, our study highlights the relationship between rhizome growth ability, aboveground growth and photosynthesis in Leymus chinensis. Additionally, it suggests that exogenous melatonin can enhance aboveground growth and photosynthesis by regulating rhizome growth.