Intercellular CO2 Concentration Research Articles

Stomatal response to VPD in C4 plants with different biochemical sub-pathways.

C4 NAD-malic enzyme (NAD-ME) species occurs in drier regions and exhibit different drought responses compared to C4 NADP-malic enzyme (NADP-ME) species. However, a physiological mechanism explaining the geographical discrepancies remains uncertain. This study examined gas exchange patterns that might explain different distributions observed between two subtypes of C4 photosynthesis. We measured the response of leaf gas exchange to vapour pressure deficit (VPD) and CO2 in plants from six distinct C4 clades having closely related NAD-ME and NADP-ME species using a Li-Cor 6400 gas exchange system. We found that NAD-ME species exhibited greater relative reductions in stomatal conductance with increases in VPD than NADP-ME species but observed no consistent subtype differences in C4 cycle activity as indicated by the initial slope of the A response to intercellular CO2 concentration. Based on these results, we hypothesise the greater response of gs to increasing VPD may enable NAD-ME plants to outperform NADP-ME plants in hot, dry environments where VPD is normally high.

Multicontamination Toxicity Evaluation in the Model Plant Lactuca sativa L.

Many contaminated soils contain several toxic elements (TEs) in elevated contents, and plant-TE interactions can differ from single TE contamination. Therefore, this study investigated the impact of combined contamination (As, Cd, Pb, Zn) on the physiological and metabolic processes of lettuce. After 45 days of exposure, TE excess in soil resulted in the inhibition of root and leaf biomass by 40 and 48%, respectively. Oxidative stress by TE accumulation was indicated by markers-malondialdehyde and 5-methylcytosine-and visible symptoms of toxicity (leaf chlorosis, root browning) and morpho-anatomical changes, which were related to the change in water regime (water potential decrease). An analysis of free amino acids (AAs) indicated that TEs disturbed N and C metabolism, especially in leaves, increasing the total content of free AAs and their families. Stress-induced senescence by TEs suggested changes in gas exchange parameters (increase in transpiration rate, stomatal conductance, and intercellular CO2 concentration), photosynthetic pigments (decrease in chlorophylls and carotenoids), a decrease in water use efficiency, and the maximum quantum yield of photosystem II. These results confirmed that the toxicity of combined contamination significantly affected the processes of lettuce by damaging the antioxidant system and expressing higher leaf sensitivity to TE multicontamination.

Effect of cold stress on photosynthetic physiological characteristics and molecular mechanism analysis in cold-resistant cotton (ZM36) seedlings.

Low temperature and cold damage seriously hinder the growth, development, and morphogenesis of cotton seedlings. However, the response mechanism of cotton seedlings under cold stress still lacks research. In this study, transcriptome sequencing, gas exchange parameters, and rapid chlorophyll fluorescence parameters were analyzed in leaves of cold-tolerant upland cotton variety "ZM36" under different temperature stress [25°C (T25, CK), 15°C (T15), 10°C (T10), and 4°C (T4)]. The results showed that the net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), PSII potential maximum photochemical efficiency (Fv/Fm), and performance index (PIabs) of cotton leaves significantly decreased, and the intercellular CO2 concentration (Ci) and Fo/Fm significantly increased under cold stress. The transcriptome sequencing analysis showed that a total of 13,183 DEGs were involved in the response of cotton seedlings at each temperature point (T25, T15, T10, and T4), mainly involving five metabolic pathways-the phosphatidylinositol signaling system, photosynthesis, photosynthesis antenna protein, carbon fixation in photosynthetic organisms, and carotenoid synthesis. The 1,119 transcription factors were discovered among all the DEGs. These transcription factors involve 59 families, of which 15.8% of genes in the NAC family are upregulated. Through network regulatory analysis, the five candidate genes GhUVR8 (GH_A05G3668), GhPLATZ (GH_A09G2161), GhFAD4-1 (GH_A01G0758), GhNFYA1 (GH_A02G1336), and GhFAD4-2 (GH_D01G0766) were identified in response to cold stress. Furthermore, suppressing the expression level of GhPLATZ by virus-induced gene silencing led to the reduction of low temperature resistance, implying GhPLATZ as a positive regulator of low temperature tolerance. The findings of the study revealed a piece of the complex response mechanism of the cold-tolerant variety "ZM36" to different cold stresses and excavated key candidate genes for low temperature response, which provided support for accelerating the selection and breeding of cotton varieties with low temperature tolerance.

Field Examinations on the Application of Novel Biochar-Based Microbial Fertilizer on Degraded Soils and Growth Response of Flue-Cured Tobacco (Nicotiana tabacum L.).

Southwestern China is receiving excessive chemical fertilizers to meet the challenges of continuous cropping. These practices are deteriorating the soil environment and affecting tobacco (Nicotiana tabacum L.) yield and quality adversely. A novel microbially enriched biochar-based fertilizer was synthesized using effective microorganisms, tobacco stalk biochar and basal fertilizer. A field-scale study was conducted to evaluate the yield response of tobacco grown on degraded soil amended with our novel biochar-based microbial fertilizer (BF). Four treatments of BF (0%, 1.5%, 2.5% and 5%) were applied in the contaminated field to grow tobacco. The application of BF1.5, BF2.5 and BF5.0 increased the available water contents by 9.47%, 1.18% and 2.19% compared to that with BF0 respectively. Maximum growth of tobacco in terms of plant height and leaf area was recorded for BF1.5 compared to BF0. BF1.5, BF2.5 and BF5.0 increased SPAD by 13.18-40.53%, net photosynthetic rate by 5.44-60.42%, stomatal conductance by 8.33-44.44%, instantaneous water use efficiency by 55.41-93.24% and intrinsic water use efficiency by 0.09-24.11%, while they decreased the intercellular CO2 concentration and transpiration rate by 3.85-6.84% and 0.29-47.18% relative to BF0, respectively (p < 0.05). The maximum increase in tobacco yield was recorded with BF1.5 (23.81%) compared to that with BF0. The present study concludes that the application of BF1.5 improves and restores the degraded soil by improving the hydraulic conductivity and by increasing the tobacco yield.

Effects of different light conditions on morphological, anatomical, photosynthetic and biochemical parameters of Cypripedium macranthos Sw.

In this study, the morphological (plant height, leaf length and width, stem diameter and leaf number), anatomical (epidermal cell density and thickness, Stomatal length and width), photosynthetic (net photosynthetic rate, transpiration rate, stomatal conductance, intercellular CO2 concentration, relative humidity, leaf temperature and chlorophyll fluorescence parameters) and biochemical parameters (the content of soluble sugar, soluble protein, proline, malondialdehyde and electrical conductivity) of Cypripedium macranthos Sw. in Changbai Mountain were determined under different light conditions (L10, L30, L50, L100). The results showed that morphological values including plant height, leaf area, stem diameter and leaf number of C. macranthos were smaller under the condition of full light at L100. The epidermal cell density and epidermal thickness of C. macranthos were the highest under L30 and L50 treatments, respectively. It had the highest net photosynthetic rate (Pn) and chlorophyll content under L50 treatment. Meanwhile, correlation analysis indicated that photosynthetically active radiation (PAR) and water use efficiency (WUE) were the main factors influencing Pn. C. macranthos accumulated more soluble sugars and soluble proteins under L100 treatment, while the degree of membrane peroxidation was the highest and the plant was severely damaged. In summary, the adaptability of C. macranthos to light conditions is ranked as follows L50 > L30 > L10 > L100. Appropriate light conditions for C. macranthos are 30%-50% of full light, which should be taken into account in protection and cultivation.

A comprehensive evaluation of different responses of supplementary light qualities on physiological and biochemical mechanisms of ‘Kyoho’ grape

Grape is an economically important fruit crop worldwide, for which light qualities play a diverse role in vineyard growth and development. However, the regulatory mechanisms between different light qualities and the quality of plant growth at the morphophysiological and pomological levels remain unknown. Therefore, in the current study, we studied plant physiological, biochemical and genetical analysis to investigate the response of all seven light qualities, including red (R), blue (B), white (W), 1-red, 1 blue (1R1B), 2-red, 1-blue (2R1B), 1-red, 2-blue (1R2B), and natural (N, was used as control group) to evaluate ‘Kyoho'grape (Vitis labrusca L. × V. vinifera) morphophysiological, pomological traits at light responsive transcriptional pathway, which revealed the possible networking metabolism controlling fruit quality and quantity of grape plant. Our results showed that photosynthetic indicators such as leaf stomata, number of stomata, and longitudinal and transverse diameter of stomata improved under red and blue light qualities as compared to white light. Leaf gas exchange indicators showed that net photosynthetic rate, transpiration rate, intercellular CO2 concentration rate, total conductance to CO2, stomatal conductance, conductance to water vapor, maximal quantum yield of PS (II), actual photochemical quantum efficiency, electron transfer chain, and non-photochemical quantum efficiency improve under blue and red light. Photosynthetic pigments showed that chlorophyll a and b, carotenoid, and total pigment contents improved under blue and red light. Nutrient elements showed that potassium, phosphorous, magnesium, calcium, iron, and zinc contents improved under blue and red light. Morphological and organic acid indicators such as the appearance of fruit shape, firmness, and titratable acidity improved under blue and light. However, there was a notable increment in the total soluble sugar under blue and red light as compared to natural light. The composition of sugar including (sucrose, fructose, glucose) and organic acids (tartaric acid, citric acid, and malic acid) improved under blue and red light (fruits) and showed notable reductions for tartaric acid under blue and red light (leaves) as compared to natural light. Aromatic compounds showed that esters, aldehydes, acetaldehyde, 2-hexenal, ethyl acetate, n-propyl acetate, butanoic acid, ethyl ester, 1-hexanol, 2-ethyl, 2-propanone, and 1‑hydroxyl, improved under blue and red light. Further, changes in enhanced expression of light-responsive genes including VvCRYI, VvCRY2, VvPHYA, VvPHYB, VvCOP1, VvHY5, VvHYH, and VvPIF4 upregulated under blue and red light, while VvPIF3.1 down-regulated as compared to natural light. Also, chlorophyll synthesis-related genes including VvSGR, VvPAO, and VvCHLH upregulated under blue and red light, while VvNYC1, VvPPH, and VvPOR showed noticeable changes under blue and red light as compared to natural light. Interestingly, most of the relative genes were highly expressed in fruits as compared to leaves. Finally, we have established correlation and principal component analysis for indicators in grapes. Current findings provide novel mechanisms by which different responses of supplementary light control the plant fruit quality of grapes.

Study on the photosynthetic growth characters in Cimicifuga dahurica (Turcz.) Maxim under different supplemental light environments

Cimicifuga dahurica (C. dahurica) is an important medicinal plant in the northern region of China. The best supplemental light environment helps plant growth, development, and metabolism. In this study, we used two-year-old seedlings as experimental materials. The white light as the control (CK). The different ratios of red (R) and blue (B) combined light were supplemented (T1, 2R: 1B, 255.37 μmol m−2·s−1; T2, 3R: 1B, 279.69 μmol m−2·s−1; T3, 7R: 1B, 211.16 μmol m−2·s−1). The growth characteristics, photosynthetic pigment content, photosynthesis and chlorophyll fluorescence parameters, and primary metabolite content were studied in seedlings. The results showed that: 1) The fresh weight from shoot, root, and total fresh weight were significantly (P < 0.05) increased under T2 and T3 treatment. 2) The contents of chlorophyll a (Chl a), chlorophyll b (Chl b), and total chlorophyll (Chl) were significantly (P < 0.05) increased under T2 treatment, and carotenoid (car) content was reduced. 3) The photochemical quenching (qP), the actual photosynthetic efficiency of PSII (Y(II)), and the photosynthetic electron transfer rate (ETR) from leaves were significantly (P < 0.05) increased under T1 treatment. The Net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), and transpiration rate (Tr) were significantly (P < 0.05) increased under T2 and T3 treatments. 4) A total of 52 primary metabolites were detected in C. dahurica leaves. Compared with CK, 14, 15, and 18 differential metabolites were screened under T1, T2, and T3 treatments. In addition, D-xylose, D-glucose, glycerol, glycolic acid, and succinic acid were significantly (P < 0.05) accumulated under the T2 treatment, which could regulate the TCA cycle metabolism pathway. The correlation analysis suggested that plant growth was promoted by regulating the change of D-mannose content in galactinol metabolism and amino sugar and nucleotide sugar metabolism. In summary, the growth of C. dahurica was improved under T2 treatment.

Impact of exogenous melatonin foliar application on physiology and fruit quality of wine grapes (Vitis vinifera) under salt stress.

Soil salinisation is an important abiotic stress faced in grape cultivating, leading to weakened plant vigour and reduced fruit quality. Melatonin as a novel hormone has shown positive exogenous application value. Therefore, this study used wine grape (Vitis vinifera ) 'Pinot Noir' as a test material to investigate the changes of foliar spraying with different concentrations of melatonin on the physiology and fruit quality of wine grapes in a field under simulated salt stress (200mmolL-1 NaCl). The results showed that foliar spraying of melatonin significantly increased the intercellular CO2 concentration, maximum photochemical quantum yield of PSII, relative chlorophyll and ascorbic acid content of the leaves, as well as the single spike weight, 100-grain weight, transverse and longitudinal diameters, malic acid, α-amino nitrogen and ammonia content of fruits, and decreased the initial fluorescence value of leaves, ascorbate peroxidase activity, glutathione content, fruit transverse to longitudinal ratio and tartaric acid content of plants under salt stress. Results of the comprehensive evaluation of the affiliation function indicated that 100μmolL-1 melatonin treatment had the best effect on reducing salt stress in grapes. In summary, melatonin application could enhance the salt tolerance of grapes by improving the photosynthetic capacity of grape plants under salt stress and promoting fruit development and quality formation, and these results provide new insights into the involvement of melatonin in the improvement of salt tolerance in crop, as well as some theoretical basis for the development and industrialisation of stress-resistant cultivation techniques for wine grapes.

Effects of Different N Fertilizer Doses on Phenology, Photosynthetic Fluorescence, and Yield of Quinoa

Quinoa (Chenopodium quinoa Willd.) is gaining recognition as a pseudocereal due to its nutritional attributes and adaptability to challenging conditions and marginal soils. However, understanding the optimal fertilization for quinoa growth remains a challenge. This study investigates the effects of nitrogen fertilization (0, 90, 120, and 150 kg using urea) on quinoa phenology, growth, and photosynthesis in the Loess Plateau region of China, a critical area facing soil erosion and ecological degradation. The results showed that nitrogen fertilization significantly influenced quinoa phenology, prompting early flowering and shorter growth at an optimum rate of 120 kg ha−1. Nitrogen application enhanced growth traits such as plant height, stem diameter, and chlorophyll content, particularly at the heading and flowering stages. Photosynthesis-related parameters, including net photosynthesis rate, transpiration rate, stomatal conductance, and intercellular CO2 concentration, were affected by nitrogen application, with higher values observed at 120 kg ha−1. Non-photochemical quenching was significantly increased by nitrogen application, indicating the efficient dissipation of excess energy. The study demonstrated a positive correlation between grain yield and growth traits, photosynthesis-related traits, and chlorophyll content. In conclusion, quinoa yield could be significantly improved at the Loess Plateau region under rainfed conditions by an optimal nitrogen fertilizer rate of 120 kg ha−1, which reduces the growth duration while increasing photosynthesis traits.

Potassium humate supplementation improves photosynthesis and agronomic and yield traits of foxtail millet

Foxtail millet is a highly nutritious crop, which is widely cultivated in arid and semi-arid areas worldwide. Humic acid (HA), as a common plant growth regulator, is used as an organic fertilizer and feed additive in agricultural production. However, the impact of potassium humate KH on the photosynthetic rate and yield of foxtail millet has not yet been studied. We explored the effects of KH application on the morphology, photosynthetic ability, carbon and nitrogen metabolism, and yield of foxtail millet. A field experiment was performed using six concentrations of KH (0, 20, 40, 80, 160, and 320 kg ha−1) supplied foliarly at the booting stage in Zhangza 10 cultivar (a widely grown high-yield variety). The results showed that KH treatment increased growth, chlorophyll content (SPAD), photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs). In addition, soluble protein content, sugar content, and nitrate reductase activity increased in KH-treated plants. With increased KH concentration, the effects became more evident and the peak values of each factor were achieved at 80 kg ha−1. Photosynthetic rate showed significant correlation with SPAD, Tr, Gs, and soluble protein content, but was negatively correlated with intercellular CO2 concentration. Compared to that of the control, the yield of foxtail millet under the T2, T3, T4, and T5 (40, 80, 160, and 320 kg ha−1 of KH) treatments significantly increased by 6.0%, 12.7%, 10.5%, and 8.6%, respectively. Yield exhibited a significant positive correlation with Tr, Pn, and Gs. Overall, KH enhances photosynthetic rate and yield of foxtail millet, therefore it may be conducive to stable millet production. These findings may provide a theoretical basis for the green and efficient production of millet fields.

Effects of Progressive Drought Stress on the Growth, Ornamental Values, and Physiological Properties of Begonia semperflorens

Water is one of the most important elements affecting the growth of ornamental plants. To investigate the effects of drought stress on the growth, ornamental values, and physiological properties of Begonia semperflorens, watering treatments with 250 mL (control check, CK), 200 mL (extremely light drought, ELD), 150 mL (light drought, LD), 100 mL (moderate drought, MD), 50 mL (severe drought, SD), and 25 mL (extremely severe drought, ESD) on the B. semperflorens variety “Chao Ao” were performed in this study. As a result, compared to the control (CK), the number of flowers, leaves, and branches, leaf size, plant height, crown diameter, as well as water content, transpiration rate, net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, and chlorophyll content in leaves decreased, followed by an increased amount of drought stress. The contents of the osmotic adjustment substances, such as soluble sugar, soluble protein, proline, and betaine, were increased under drought stress. Indicators related to antioxidant activities, such as SOD activity, increased and then decreased. The POD activity, CAT activity, MDA content, and plasma membrane permeability of B. semperflorens were higher under increased drought stress than in the control condition. The APX activity decreased and then increased under drought stress. In conclusion, B. semperflorens responds to drought stress by increasing osmotic adjustment substances and antioxidant activities and reducing the water loss, growth potential, and photosynthetic rate. The correlation analysis showed that, except for APX, the drought resistance coefficients of 23 other indexes were correlated in different degrees. Therefore, this study suggests that B. semperflorens has a strong drought resistance ability, retaining high ornamental values in conditions of moderate drought stress, and can still survive under extremely high drought stress.

System of wheat intensification (SWI): Effects on lodging resistance, photosynthetic efficiency, soil biomes, and water productivity.

Intense cultivation with narrow row spacing in wheat, a common practice in the Indo-Gangetic plains of South Asia, renders the crop more susceptible to lodging during physiological maturity. This susceptibility, compounded by the use of traditional crop cultivars, has led to a substantial decline in overall crop productivity. In response to these challenges, a two-year field study on the system of wheat intensification (SWI) was conducted. The study involved three different cultivation methods in horizontal plots and four wheat genotypes in vertical plots, organized in a strip plot design. Our results exhibited that adoption of SWI at 20 cm × 20 cm resulted in significantly higher intercellular CO2 concentration (5.9-6.3%), transpiration rate (13.2-15.8%), stomatal conductance (55-59%), net photosynthetic rate (126-160%), and photosynthetically active radiation (PAR) interception (1.6-25.2%) over the existing conventional method (plant geometry 22.5 cm × continuous plant to plant spacing) of wheat cultivation. The lodging resistance capacity of both the lower and upper 3rd nodes was significantly higher in the SWI compared to other cultivation methods. Among different genotypes, HD 2967 demonstrated the highest recorded value for lodging resistance capacity, followed by HD 2851, HD 3086, and HD 2894. In addition, adoption of the SWI at 20 cm × 20 cm enhanced crop grain yield by 36.9-41.6%, and biological yield by 27.5-29.8%. Significantly higher soil dehydrogenase activity (12.06 μg TPF g-1 soil hr-1), arylsulfatase activity (82.8 μg p-nitro phenol g-1 soil hr-1), alkaline phosphatase activity (3.11 n moles ethylene g-1 soil hr-1), total polysaccharides, soil microbial biomass carbon, and soil chlorophyll content were also noted under SWI over conventional method of the production. Further, increased root volumes, surface root density and higher NPK uptake were recorded under SWI at 20×20 cm in comparison to rest of the treatments. Among the tested wheat genotypes, HD-2967 and HD-3086 had demonstrated notable increases in grain and biological yields, as well as improvements in the photosynthetically active radiation (PAR) and chlorophyll content. Therefore, adoption of SWI at 20 cm ×20 cm (square planting) with cultivars HD 2967 might be the best strategy for enhancing crop productivity and resource-use efficiency under the similar wheat growing conditions of India and similar agro-ecotypes of the globe.

Deficit Irrigation with Silicon Application as Strategy to Increase Yield, Photosynthesis and Water Productivity in Lettuce Crops.

In regions where water is a limited resource, lettuce production can be challenging. To address this, water management strategies like deficit irrigation are used to improve water-use efficiency in agriculture. Associating this strategy with silicon (Si) application could help maintain adequate levels of agricultural production even with limited water availability. Two lettuce crop cycles were conducted in a completely randomized design, with a factorial scheme (2 × 3), with three irrigation levels (60%, 80% and 100%) of crop evapotranspiration (ETc), and with and without Si application. To explore their combined effects, morphological, productive, physiological and nutritional parameters were evaluated in the crops. The results showed that deficit irrigation and Si application had a positive interaction: lettuce yield of the treatment with 80% ETc + Si was statistically similar to 100% ETc without Si in the first cycle, and the treatment with 60% ETc + Si was similar to 100% ETc without Si in the second cycle. Photosynthetic rate, stomatal conductance, intercellular CO2 concentration, transpiration rate and total chlorophyll content increased under water-stress conditions with Si application; in the first cycle, the treatment with 80% ETc + Si increased by 30.1%, 31.3%, 7.8%, 28.46% and 50.3% compared to the same treatment without Si, respectively. Si application in conditions of water deficit was also beneficial to obtain a cooler canopy temperature and leaves with higher relative water content. In conclusion, we found that Si applications attenuate water deficit effects and provide a strategy to ameliorate the yield and water productivity in lettuce crops, contributing to more sustainable practices in agriculture.

Transcriptome-metabolome and anatomy conjoint analysis of vital component change of photosynthesis of Foxtail millet under different drought conditions

Drought caused by extreme climate change has become more severe and unpredictable, causing imperceptible effects on leaf photosynthesis in foxtail millet. To investigate the damage, we performed light drought (LD) and heavy drought (HD) treatments at both the elongation (Y) and booting stages to obtain a comprehensive understanding of the morphological, anatomical, physiological, transcriptome, and metabolome levels. Under drought stress, the length and area of leaves decreased, especially during the HD treatment at the booting stage. The number of mesophyll cells and the area of large vascular bundles were both decreased under LD and HD treatments at the booting stage, as well as with more blurring vascular bundle structure and Kranz anatomy. However, these numbers decreased but with no significance under Y-LD and Y-HD treatments at the elongation stage. The net photosynthetic rate, stomatal conductivity, transpiration rate, and intercellular CO2 concentration significantly decreased at the booting stage. In addition, the efficiency of electron transfers in photosystem II (PS II) decreased. Conjunction analyses of the transcriptome and metabolome were utilized to uncover the underlying mechanism at the booting stage. The results showed that there was no common differentially enriched pathway in the transcriptome and metabolome under LD treatment but thirty-two pathways were enriched in both the transcript and metabolome under HD treatment. Among these, three pathways arginine, proline metabolism, tyrosine metabolism, ubiquinone, and other terpenoid-quinone biosynthesis pathways were differentially enriched in both the transcript and metabolome. The accumulation of Homogentisate, Salidroside, Homoprotocatechuate, L-DOPA, Tyramine, and L-Tyrosine increased under drought stress. Although genes related to PSII and the Calvin cycle were slightly up-regulated under LD conditions, they were down-regulated under HD condition. The metabolites of Ribose-5P, Glycerate-3P, D-Fructosel 1,6P2, and D-Fructose-6P were all decreased in both the LD and HD treatments, especially D-Fructose-6P, confirming that drought stress had a negative effect on the Calvin cycle. The results revealed that regardless of the severity of drought, photosynthetic function was compromised not only at the morphological and anatomical levels but also in terms of impaired ATP synthase and inhibited photosynthetic CO2 assimilation.

Contribution of Photosynthetic, Root and Phenotypic Traits to Soybean Plant Height

Breeding new high-yield and high-quality forage soybean cultivars is an effective approach to addressing the shortage of feed protein and sustainable agricultural development. Plant height is a key indicator of forage soybean genotypes and is closely related to forage yield. However, the determinants affecting soybean plant height remain highly uncertain. In order to analyze the factors contributing to plant height differences among soybean cultivars, two tall-stemmed soybean cultivars (“Neinong S001” and “Neinong S002”) and two short-stemmed soybean cultivars (“Neinong 0004” and “Neinong 0005”) were used in this study as test materials for examining aboveground phenotypic characteristics, root traits, and photosynthetic characteristics. The test materials were planted in 2018 at Chakintai Ranch (122°15′ E, 43°38′ N) using the potting method, and the indicators were measured in June. The results showed that the leaf area, root volume, and root surface area of high-stemmed soybean cultivars were significantly (p &lt; 0.05) lower than those of short-stemmed soybean cultivars. Additionally, the dry weight of a single plant and transpiration rate were significantly (p &lt; 0.05) higher in high-stemmed soybean cultivars compared to short-stemmed soybean cultivars. It was found that soybean plant height was significantly (p &lt; 0.05) correlated with leaf area, leaf shape index, intercellular CO2 concentration, transpiration rate, SPAD, root weight, root length, root surface area, and root volume. Further path analyses revealed that intercellular CO2 concentration and root surface area had a direct impact on plant height, with direct effect coefficients of 0.22 and −0.91, respectively. These results provide new insights into the sustainability development and genetic enhancement of plant height characteristics in forage soybean.

Effects of Penoxsulam on Photosynthetic Characteristics and Safety Evaluation of Foxtail Millet

Foxtail millet planting has a long history and profound role in agricultural civilization. However, weeds have become one of the obstacles restricting the development of the foxtail millet industry. Penoxsulam, as an early post-emergence herbicide for controlling gramineous weeds in paddy fields, is effective for some broadleaf weeds. In this study, six different doses (CK, 0.5X, 1X, 2X, 3X, 4X) of penoxsulam were sprayed at the 3–5 leaf stage of the conventional variety Jingu 21 to study its effect on the growth and development of foxtail millet, in order to screen out the appropriate spraying concentration. The main results are as follows: Within 15 days after spraying penoxsulam, the plant height and leaf area of foxtail millet decreased with the increase in spraying dose, and gradually recovered 15–25 days after spraying, but there were still significant differences compared with CK. The photosynthetic pigment content, net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), the maximum photochemical efficiency (Fv/Fm), photosynthetic system II actual photochemical efficiency (Y(II)), and photochemical quenching coefficient (qP) of foxtail millet decreased with an increase in the penoxsulam spraying dose, while the intercellular CO2 concentration (Ci) and non-photochemical quenching coefficient (NPQ) showed an upward trend. There was almost no significant difference in each index between the spraying dose of 0.5X and 1X and CK, but the photosynthesis of foxtail millet leaves was still significantly inhibited under a spraying dose of 3X and 4X. Penoxsulam had certain growth-inhibiting effects on Echinochloa crus-galli (L.) Beauv. (E. crus-galli), Digitaria sanguinalis (L.) Scop. (D. sanguinalis), Chenopodium album L. (C. album), and Amaranthus retroflexus L. (A. retroflexus) which increased as the spraying dosage increased. Our study found that spraying dose groups of 0.5X and 1X penoxsulam were safe for foxtail millet growth and could be used to control gramineous weeds in fields. Other spraying doses are not recommended in the field due to their serious phytotoxicity to foxtail millet, which provides a new measure for weed control in foxtail millet fields.

Effects of Cu2O nanoparticles on the kinetic characteristics of rapid chlorophyll fluorescence induction and related genes in wheat seedlings.

Metal nanoparticles could be accumulated in soils, which threatens the ecological stability of crops. Investigating the effects of cuprous oxide nanoparticles (Cu2O-NPs) on photosystem Ⅱ (PSⅡ) of wheat seedling leaves holds considerable importance in comprehending the implications of Cu2O-NPs on crop photosynthesis. Following the hydroponic method, we investigated the effects of 0, 10, 50, 100, and 200 mg·L-1 Cu2O-NPs on chlorophyll fluorescence induction kinetics and photosynthetic-related genes in wheat seedlings of "Zhoumai 18". The results showed that, with the increases of Cu2O-NPs concentrations, chlorophyll contents in wheat leaves decreased, and the standardization of the OJIP curve showed a clearly K-phase (ΔK＞0). Cu2O-NPs stress increased the parameters of active PSⅡ reaction centers, including the absorption flux per active RC (ABS/RC), the trapping flux per active RC (TRo/RC), the electron transport flux per active RC (ETo/RC), and the dissipation flux per active RC (DIo/RC). Cu2O-NPs stress decreased the parameters of PSⅡ energy distribution ratio including the maximum quantum yield of PSⅡ (φPo), the quantum yield of electron transport from QA (φEo), and the probability that a trapped exciton moved an electron further than QA (Ψo), while increased the quantum ratio for heat dissipation (φDo). Moreover, there was a decrease in photosynthetic quantum yield Y(Ⅱ), photochemical quenching coefficient (qP), net photosynthetic rate (Pn), stomatal conductance (gs), intercellular CO2 concentration (Ci), and transpiration rate (Tr) of leaves with the increases of Cu2O-NPs concentration. Under Cu2O-NPs stress, the expression levels of genes which included PSⅡ genes (PsbD, PsbP, Lhcb1), Rubisco large subunit genes (RbcL), cytochrome b6/f complex genes (PetD, Rieske), and ATP synthase genes (AtpA, AtpB, AtpE, AtpI) were downregulated. These results indicated that Cu2O-NPs stress altered the activity and structure of PSⅡ in wheat seedlings, affected the activity of PSⅡ reaction centers, performance parameters of PSⅡ donor and acceptor sides. PSⅡ related genes were downregulated and exhibited significant concentration effects.

Multi-trait selection for nutritional and physiological quality of cacao genotypes in irrigated and non-irrigated environments

Water is a scarce, strategic resource and the most important input for economic development, especially in agricultural countries such as Brazil. Cocoa production is directly related to water availability, and, as climate changes, selecting drought-tolerant genotypes is vital to keep cacao crops sustainable. Here, we evaluated cacao genotypes under irrigated and water-stressed conditions and selected drought-tolerant ones based on nutritional and physiological traits. Thirty-nine genotypes were monitored for three years for agronomic traits and higher fruit yield. After this evaluation, the 18 most promising genotypes were evaluated in a randomized block design, under a 2 (with and without irrigation) ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes$$\\end{document} 18 (genotypes) factorial arrangement, with three replicates and five plants per plot. We evaluated seven physiological and 11 nutritional traits, selecting genotypes based on the Genotype-by-Trait Biplot approach. Significant effects (p < 0.05) were observed for the nutritional traits N, P, Mg, S, Zn, Cu, Mn and for the physiological traits CO2 assimilation rate (A), stomatal conductance (gs), transpiration (E), intercellular and atmospheric CO2 concentrations (Ci/Ca), intrinsic water use efficiency (A/gs), instantaneous water use efficiency (A/E), and instantaneous carboxylation efficiency (A/Ci), as determined by analysis of variance. The genotype ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes$$\\end{document} irrigation treatment interaction was significant (p < 0.05) for the traits A, gs, and E. Genotypes CP 41, CP 43, and CCN 51 exhibited superior performance for both nutritional and physiological traits (A, gs, and E). In the irrigated environment, CP 41 showed superiority in traits such as P, A/E, A/gs, Mn, S, and Zn. Conversely, under non-irrigated conditions, CP 43 exhibited better performance in nutritional properties, specifically Mn, Mg, and Zn. Notably, in both irrigated and non-irrigated environments, CCN 51 excelled in key physiological traits, including A/Ci, A/E, and A/gs. This robust performance across diverse conditions suggests that these three genotypes possess physiological mechanisms to endure water-stressed conditions. Our research can generate valuable insights into these genotypes informing suitable choices for cocoa cultivation, especially in the context of global climate change.

Water use efficiency and its influencing factors following plantations restoration with Caragana korshinskii and Robinia pseudoacacia in the loess hilly region

Water use efficiency (WUE) as an indicator reflecting plant drought resistance, is crucial for plant survival adaptation and forestland sustainability especially in water scarce areas during revegetation. The understanding of WUE characteristics of major tree species at different ages and the key factors influencing WUE in the loess hilly region is currently lacking. The study selected Caragana korshinskii (CK) and Robinia pseudoacacia (RP) plantations, two species widely planted in different plantation ages (16, 30, and 47 years), in the loess hilly region. The instantaneous water use efficiency (WUEt) and short-term water use efficiency (WUEs) of these plantations were calculated to investigate the factors influencing both WUEt and WUEs. The results showed that the WUEt and WUEs of CK plantations showed an increasing trend with increasing plantation age, while the RP plantations was lowest at 30 years. The soil water content (SWC) in CK and RP plantations demonstrated an upward trend as the age of the plantations increased, while the pH showed a decreasing trend. Older CK plantations had high porosity of soil (Ps) and saturated hydraulic conductivity (Ks), coupled with a low bulk density (BD). Unlike CK plantations, the maximum value of Ps in RP plantations was observed at 30 years. The soil organic carbon (SOC), dissolved organic carbon (DOC), total nitrogen (TN), and dissolved organic nitrogen (DON) contents of RP and CK plantations increased with the increase of restoration years. Except for net photosynthetic rate (An), the 16-year RP and CK showed strong photosynthesis. During the revegetation process, soil and leaf factors explained 85.31% and 90.52% of the differences in WUEt and WUEs under plantations at different stand ages. Among them, DON and intercellular CO2 concentration (Ci) were the most sensitive factors to WUE in soil physicochemical and leaf physiological properties, respectively. The interaction between soil physicochemical and leaf physiological properties significantly influences variations in WUEt and WUEs. These variations were primarily constrained by the synergistic effects of DON, SWC and, Ci. In conclusion, our study underscores the importance of soil and leaf factors in affecting WUE, contributing to improved understanding of water utilization capacity and stand growth strategies during vegetation restoration.

Morphological and Physiological Characteristics os African Mahogany (Khaya Senegalensis) Seedlings in Substrate with Poultry Manure

Purpose: Evaluate the morphophysiological characteristics of Khaya senegalensis seedlings, after being cultivated in substrates with poultry manure. Method/design/approach: The experiment was conducted in a greenhouse for 90 days. During this period, the seedlings were subjected to doses of 0, 5, 10, 15, 20 and 25 grams of poultry manure. At the end, they were evaluated for net photosynthetic rate, transpiration rate, transpiration rate, vapor pressure deficit, stomatal conductance and intercellular CO2 concentration. Then, measurements of height, diameter and biomass were performed. Results and conclusion: The dose of 25 grams provided the best conditions when analysing the physiological characteristics, which resulted in greater growth and greater dry mass production of K. senegalensis seedlings. Research implications: These results show that, for the seedlings to grow in a substrate containing poultry manure, firstly, there are improvements in the physiological conditions of the plants, which are reflected in faster growth. Therefore, there is a need to study the type of manure and the dose that is applied, before recommending a type of substrate. Originality/value: Use of organic waste for seedlings production, which is an environmentally correct destination.