Relative Chlorophyll Content Research Articles

Molecular Insights into Red Palm Weevil Resistance Mechanisms of Coconut (Cocos nucifera) Leaves.

Red palm weevil (RPW) (Rhynchophorus ferrugineus) threatens most palm species worldwide. This study investigated the molecular responses of coconut (Cocos nucifera) leaves to RPW infestation through metabolomics and transcriptomics analysis. An RPW insect attack model was developed by placing different RPW larval densitiesin coconut plants and measuring the relative chlorophyll content of different leaf positions and physiological indicators of dysfunction after RPW infestation. The metabolomic changes were detected in the leaves of 10, 20, 30, 40, and 50 days after infestation (DAI) using GC-MS. Certain metabolites (glycine, D-pinitol, lauric acid, allylmalonic acid, D-glucaro-1, 4-lactone, protocatechuic acid, alpha, and alpha-trehalose) were found to be possible indicators for distinct stages of infestation using metabolomics analysis. The influence on ABC transporters, glutathione, galactose, and glycolipid metabolism was emphasized by pathway analysis. Differentially expressed genes (DEGs) were identified at 5, 10, 15, and 20 DAI through transcriptomics analysis of infested coconut leaves, with altered expression levels under RPW infestation. The KEGG pathway and GO analysis revealed enrichment in pathways related to metabolism, stress response, and plant-pathogen interactions, shedding light on the intricate mechanisms underlying coconut-RPW interactions. The identified genes may serve as potential markers for tracking RPW infestation progression and could inform strategies for pest control and management.

Sole-source Lighting of Lettuce that Increased Yield Had No Negative Effect on Postharvest Longevity

The effects of sole-source lighting on the growth and yield of hydroponically grown lettuce have been extensively studied, but research of postharvest performance is limited. We grew frill-leaf lettuce (Lactuca sativa) ‘Green Incised’ and ‘Hydroponic Green Sweet Crisp’ hydroponically in an indoor vertical research farm under daily light integrals (DLIs) of 12 or 18 mol⋅m−2⋅d−1 and the following three ratios of blue (B; 400–499 nm) and red (R; 600–699 nm) light from light-emitting diode fixtures: B5:R95, B20:R80, and B35:R65. We postulated that biomass accumulation would increase with the DLI and decrease with the B light fraction, and that postharvest longevity would increase with the DLI and the B light fraction. As expected, shoot fresh weight, leaf length and width, leaf number, and relative chlorophyll content (SPAD; ‘Green Incised’ only) decreased as the proportion of B light increased from 5% to 35%. Decreasing the DLI from 18 to 12 mol⋅m−2⋅d−1 reduced the shoot fresh weight and leaf number of both cultivars. Leaves of ‘Green Incised’ were up to 27% wider under B5:R95 and 60% longer under B5:R95 at 12 mol⋅m−2⋅d−1 than those under treatments with a higher DLI or more B light. The shoot fresh weight of ‘Hydroponic Green Sweet Crisp’ was greatest when grown under B5:R95 at 18 mol⋅m−2⋅d−1 and decreased as B light increased or DLI decreased. At the time of harvest, leaves of each cultivar and treatment were placed in clamshells and stored at 7 °C in darkness and evaluated for decay. ‘Green Incised’ that grew under B35:R65 and a DLI of 18 mol⋅m−2⋅d−1 had the shortest storage life, with 9.5 d and 11.4 d for replications 1 and 2, respectively, which were ∼2.5 to 4.0 d and 1.4 to 3.6 d earlier, respectively, than the storage life of lettuce grown under other treatments. In contrast, ‘Hydroponic Green Sweet Crisp’ was not influenced by light quality or DLI and had a storage life of 12.6 to 13.3 d and 13.5 to 14.3 d for replications 1 and 2, respectively. Therefore, a B light fraction between 5% and 20% and a DLI of 18 mol⋅m−2⋅d−1 produced high-yielding frill-leaf lettuce with a relatively long storage life.

Estimating Leaf Chlorophyll Content of Winter Wheat from UAV Multispectral Images Using Machine Learning Algorithms under Different Species, Growth Stages, and Nitrogen Stress Conditions

The rapid and accurate estimation of leaf chlorophyll content (LCC), an important indicator of crop photosynthetic capacity and nutritional status, is of great significance for precise nitrogen fertilization management. To explore the existence of a versatile regression model that can be successfully used to estimate the LCC for different varieties under different growth stages and nitrogen stress conditions, a study was conducted in 2023 across the growing season for winter wheat with five species and five nitrogen application levels. Two machine learning regression algorithms, support vector machine (SVM) and random forest (RF), were used to establish the bridge between UAV-derived multispectral vegetation indices and ground truth LCC (relative chlorophyll content, SPAD), taking the multivariate linear regression (MLR) algorithm as a reference. The results show that the visible atmospherically resistant index, vegetative index, and normalized difference vegetation index had the highest correlation with ground truth LCC, with a Pearson’s correlation coefficient of 0.95. All three regression algorithms (MLR, RF, and SVM) performed well on the training dataset (R2: 0.932–0.944, RMSE: 3.96 to 4.37), but performed differently on validation datasets with different growth stages, species, and nitrogen application levels. Compared to winter wheat species and nitrogen application levels, the growth stages had the greatest influence on the generalization ability of LCC estimation models, especially for the dough stage. At the dough stage, compared to MLR and RF, SVM performed best, with R2 increasing by 0.27 and 0.10, respectively, and RMSE decreasing by 1.13 and 0.46, respectively. Overall, this study demonstrated that the combination of UAV-derived multispectral VIs and the SVM regression algorithm could be successfully applied to map the LCC of winter wheat for different species, growth stages, and nitrogen stress conditions. Ultimately, this research is significant as it shows the successful application of UAV data for mapping the LCC of winter wheat across diverse conditions, offering valuable insights for precision nitrogen fertilization management.

Alleviation of drought stress damages by melatonin and Bacillus thuringiensis associated with adjusting photosynthetic efficiency, antioxidative system, and anatomical structure of Glycine max (L.)

These experiments were performed to study the effect of exogenous treatment with melatonin at 100 μM and seed treatment with Bacillus thuringiensis (106−8 CFU/cm3) on growth, physio-biochemical characters, antioxidant enzymes, and anatomical features of soybean plants cv. Giza 111 under drought conditions. The findings showed that leaves number, nodules number, branches number, relative water content (RWC), chlorophyll content, and maximum quantum efficiency of PSII (Fv/Fm) were significantly reduced in soybean under drought stress. In addition, anatomical structure of stems and leaves were negatively affected in stressed plants. Moreover, proline, electrolyte leakage (EL%) lipid peroxidation (MDA), superoxide (O2·-), hydrogen peroxide (H2O2), and antioxidant enzymes, such as catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD), were significantly increased under drought stress. However, application of melatonin or Bacillus caused an improvement in growth characters, such as branches number, and increased chlorophyll a and b content, RWC as well as Fv/Fm in drought stressed soybean plants. Furthermore, melatonin and Bacillus treatments showed a significant decrease in EL%, MDA, O2·- and H2O2, besides regulating the activity of antioxidant enzymes under drought stress. The stems and leaves anatomical structure, such as lamina thickness, lower and upper epidermis thickness, number of xylem vessels/bundle, stem diameter, xylem vessels diameter, and phloem thickness, were improved under drought conditions with melatonin and Bacillus treatments. Therefore, the outcomes of this investigation recommended the use of melatonin as foliar spray and Bacillus thuringiensis as seed treatment, which could regulate a number of stress-responsive mechanisms to protect the stressed soybean plants, improve their growth under drought stress.

ENHANCEMENT OF FLOWER INDUCTION IN HARUMANIS MANGO (Mangifera indica L.) WITH ETHEPHON APPLICATION DURING OFF-SEASON

In cultural practice of Harumanis tree, plant growth regulator such as paclobutrazol is applied at late vegetative stage to induce flowering. However, starting from 2020 to 2023, there is a sharp yield reduction due to the unexpected weather condition. Unexpected heavy rain had caused Harumanis flower to drop from the panicle before the pollination occur. Due to this problem, ethephon was identified as an alternative plant growth regulator for flower induction. Ethephon is an ethylene releasing agent that help mediate many aspects in plant growth and development such as shoot development and flower induction. Thus, the objective of this study is to observe the influence of ethephon application during off-season on vegetative growth stage and flower induction of harumanis tree. Total of 32 Harumanis trees (3 years old) in Research Plot, Unit Ladang Universiti Teknologi MARA Perlis were treated with ethephon in September 2023 by foliar spray until run-off on the plant canopy. Treatments were arranged according to Randomized Completely Block Design (RCBD) with three different concentrations of ethephon and being diluted 2 hours before application which are 400 ppm, 600 ppm, and 800 ppm and control (without application). The parameters were recorded 2 weeks interval: number of leaves, number of buds, length of bud, relative chlorophyll content, stomatal density, day to flowering, and number of flower panicles. The vegetative growth stage shows significant difference among concentrations applied where number of leaves is higher with 400 ppm. Meanwhile, the flower formation occurs after 2 months and 4 months of ethephon application at treatment of 800 ppm and 400 ppm respectively. However, there is no significant difference presented on the Harumanis physiological characteristics. As from this study, it can be concluded that the application of ethephon influences the growth of performance and flower formation of Harumanis when applied with specific concentration.

Effects of Cascara Cherry and Other Coffee Litter Mulching on Soil Properties, Photosynthesis, and Water Use Efficiency of Coffea Canephora Pierre ex A. Froehner cv. Reyan No.1 Seedling

Mulching cultivation with agricultural wastes is the main production pattern of coffee at present, but the effect of mulching cultivation on photosynthetic physiological processes of coffee plants is still not clear. Therefore, a randomized block design was adopted to establish a field experiment by one-year-old Coffee Canephora seedlings in this study. There were four types of mulch treatments, including non-mulch coffee waste (C), mulching coffee litter (L), mulching coffee cascara (cherry pericarp, P), and mulching coffee litter and cascara (LP) in this field experiment. Soil properties and microenvironment (e.g., moisture, temperature, pH, bulk density, organic matter content, alkali-hydrolyzed nitrogen content, available potassium content, and available potassium content), agronomic traits (e.g., specific leaf area, leaf area index, plant height, and relative chlorophyll content), and photosynthetic indices (e.g., photosynthesis, transpiration, respiration, stomatal conductance, intercellular CO2 concentration, water use efficiency, and carbon use efficiency) were investigated to determine the effects of different coffee waste mulches on the photosynthetic physiology of coffee seedlings. The results show that coffee litter and cascara mulch significantly reduced soil temperature by 0.42 or 0.33 °C, respectively, and coffee litter rather than cascara mulch significantly increased the soil’s available potassium content by 46.28%, although coffee waste mulch did not affect other soil properties or microenvironment indices; coffee cascara mulching significantly increased the specific leaf area and net and gross photosynthesis of coffee by 45.46%, 78.33%, and 91.72%, respectively, but the mulching treatments did not affect stomatal conductance, transpiration, or carbon use efficiency in this study. Additionally, coffee cascara mulching increased leaf respiration and net and gross water use efficiency by 109.34%, 80.54%, and 104.95%, respectively. The coffee cascara mulching alone had the most significant positive impact on the photosynthetic index, followed by a combination of litter and cascara, litter alone, and the control treatment. The observed variations in the coffee photosynthetic index may be attributed to the reduction of soil temperature caused by mulching treatments rather than the increase in soil nutrients content. These results indicate that coffee cascara mulching could effectively promote photosynthesis and the growth of coffee seedlings by improving the soil microenvironment.

Comparative analysis of red and green lettuce microgreens under different artificial LED lighting conditions

This study investigated how LED light exposure influences the growth and nutrient content of two lettuce microgreens over 10 days in a randomized setup. Lettuce seeds underwent surface sterilization, germination in prepared soil, and exposure to different LED light conditions. Morphological parameters and pigment analysis, including stem length, petiole length, leaf area, plant height, root length, fresh weight, dry matter percentage, were evaluated. Green lettuce outperformed red lettuce in the studied morphological parameters, including stem length (2.74±0.22 cm), plant height (4.54±0.21 cm), and fresh weight (3.79±0.32 g/100 plants) under different LED. White light promoted taller plants with higher fresh weight (4.45±0.43 g/100plants), dry matter (4.84±0.38%), and leaf area (0.76±0.06 cm2) in both lettuce species. In contrast, red light reduced overall growth and development, as evidenced by a 54% decrease in leaf area, despite a 23.36% increase in plant height. Chlorophyll levels varied significantly among LED treatments, with white LED yielding the highest levels in both red and green lettuce. Highest chlorophyll a (146.37±6.27 µg/g FW), chlorophyll b (86.74±2.44 µg/g FW), total chlorophyll (233.11±8.69 µg/g FW) and relative chlorophyll (215.84±8.05 µg/cm²) content was found in green lettuce under white light condition. Similarly, green lettuce grown under white LED had the highest total carotenoid, β-carotene, and lutein. The study concludes that optimizing white LED illumination has the potential to improve the nutritional value of lettuce microgreens by enhancing growth and pigment content, particularly in green varieties. These findings emphasize the crucial role of LED light color in optimizing the nutritional quality of microgreens.

Effect of Split Basal Fertilisation and Top-Dressing on Relative Chlorophyll Content and Yield of Maize Hybrids

Effect of Split Basal Fertilisation and Top-Dressing on Relative Chlorophyll Content and Yield of Maize Hybrids

Functional Characterization of the Soybean Glycine max Actin Depolymerization Factor GmADF13 for Plant Resistance to Drought Stress.

Abiotic stress significantly affects plant growth and has devastating effects on crop production. Drought stress is one of the main abiotic stressors. Actin is a major component of the cytoskeleton, and actin-depolymerizing factors (ADFs) are conserved actin-binding proteins in eukaryotes that play critical roles in plant responses to various stresses. In this study, we found that GmADF13, an ADF gene from the soybean Glycine max, showed drastic upregulation under drought stress. Subcellular localization experiments in tobacco epidermal cells and tobacco protoplasts showed that GmADF13 was localized in the nucleus and cytoplasm. We characterized its biological function in transgenic Arabidopsis and hairy root composite soybean plants. Arabidopsis plants transformed with GmADF13 displayed a more robust drought tolerance than wild-type plants, including having a higher seed germination rate, longer roots, and healthy leaves under drought conditions. Similarly, GmADF13-overexpressing (OE) soybean plants generated via the Agrobacterium rhizogenes-mediated transformation of the hairy roots showed an improved drought tolerance. Leaves from OE plants showed higher relative water, chlorophyll, and proline contents, had a higher antioxidant enzyme activity, and had decreased malondialdehyde, hydrogen peroxide, and superoxide anion levels compared to those of control plants. Furthermore, under drought stress, GmADF13 OE activated the transcription of several drought-stress-related genes, such as GmbZIP1, GmDREB1A, GmDREB2, GmWRKY13, and GmANK114. Thus, GmADF13 is a positive regulator of the drought stress response, and it may play an essential role in plant growth under drought stress conditions. These results provide new insights into the functional elucidation of soybean ADFs. They may be helpful for breeding new soybean cultivars with a strong drought tolerance and further understanding how ADFs help plants adapt to abiotic stress.

Effects of MARDI Nano-Fertilizer Application Frequency on the Growth of Rock Melon

For many years, fertilizers have been utilized in agriculture to increase the fruit yield and quality of various crops, which in turn will increase the nutritive content of products. Recently, MARDI has developed a nano-fertilizer based on nanoemulsions to increase the productivity of rock melon. The development of nanoemulsion-based fertilizer was carried out using the high-energy emulsification method which has significant advantages, such as enhancing the solubilization of active constituents while preserving biological activity. In this work, the effects of the vegetative growth of rock melon on different application frequencies (T1=0, T2=2, T3=4, T4=6, and T5=8 times) of MARDI nano-fertilizer through foliar treatment were studied. The results showed that the vegetative growth of the rock melon including plant height, stem diameter, relative chlorophyll content, and leaf area of rock melon were significantly (p≤0.05) increased by 15.07%, 7.8%, 41.5% and 41.5%, respectively at T3, photosynthetic pigments of Chlorophyll a by 21.1% at T5, Chlorophyll b and carotenoid by 24.99% at T4 treatment. The dry weight biomass did not vary significantly in all treatments but showed an increase in dry biomass over the nano-fertilizers treatment compared to the control. These findings indicate that adding the foliar application of MARDI nano-fertilizer produces optimal growth in rock melon plants.

Phenotypic Dissection of Drought Tolerance in Virginia and Carolinas within a Recombinant Inbred Line Population Involving a Spanish and a Virginia-Type Peanut Lines

Peanut (Arachis hypogaea L.) is a rainfed crop grown in both tropical and subtropical agro-climatic regions of the world where drought causes around 20% yield losses per year. In the United States, annual losses caused by drought are around $50 million. The objective of this research was to (1) identify genetic variation for the normalized difference vegetation index (NDVI), canopy temperature depression (CTD), relative chlorophyll content by SPAD reading (SCMR), CO2 assimilation rate, and wilting among recombinant inbred lines (RILs) derived from two diverse parents N08086olJCT and ICGV 86015, to (2) determine if the physiological traits can be used for expediting selection for drought tolerance, and (3) experimental validation to identify lines with improved yield under water-limited conditions. Initially, 337 lines were phenotyped under rainfed production and a selected subset of 52 RILs were tested under rainout shelters, where drought was imposed for eight weeks during the midseason (July and August). We found that under induced drought, pod yield was negatively correlated with wilting and CTD, i.e., cooler canopy and high yield correlated positively with the NDVI and SPAD. These traits could be used to select genotypes with high yields under drought stress. RILs #73, #56, #60, and #31 performed better in terms of yield under both irrigated and drought conditions compared to check varieties Bailey, a popular high-yielding commercial cultivar, and GP-NC WS 17, a drought-tolerant germplasm.

Sewage sludge compost as an alternative source of phosphorus to rye in acidic sandy soil

Today, the use of chemical fertilisers is significantly determined by their production and purchase costs, which are high. In contrast, phosphorus (P) is present in sewage sludge in a form that is easy for plants to absorb. Good quality sewage sludge compost (SSC) could contain a high quantity of P, together with other macro- and microelements and organic matter. The effect of regular SSC application on soil characteristics as well as plant parameters has been studied since 2003 in Nyíregyháza in a small plot experiment. Focusing on the P in the soil-plant system, our hypothesis was that SSC covers plants’ P demand through enhancing soil P content and its plant availability in the acidic sandy soil. The effect of the SSC was examined at the doses of 0, 9, 18, and 27 t ha-1 on rye as a test crop. Some soil chemical parameters (pH, soil organic matter - SOM, ammonium lactate (AL) extractable P2O5), and the relationship between plant development (green weight, shoot length), physiological parameters (SPAD index), plant shoot P content, and soil available P content were studied. The obtained data indicated that the SOM content, pH, and available P content of the treated plots increased as a result of the long-term applied SSC compared to the control. Measurement of the relative chlorophyll content showed a strong correlation with the available P content of the soil, but surprisingly less correlation with shoot P content was found. The results of plant biomass and soil P content proved that SSC could be used as a low-cost and good source of P for plants.

Cunninghamia lanceolata Canopy Relative Chlorophyll Content Estimation Based on Unmanned Aerial Vehicle Multispectral Imagery and Terrain Suitability Analysis

This study aimed to streamline the determination of chlorophyll content in Cunninghamia lanceolate while achieving precise measurements of canopy chlorophyll content. Relative chlorophyll content (SPAD) in the Cunninghamia lanceolate canopy were assessed in the study area using the SPAD-502 portable chlorophyll meter, alongside spectral data collected via onboard multispectral imaging. And based on the unmanned aerial vehicle (UAV) multispectral collection of spectral values in the study area, 21 vegetation indices with significant correlation with Cunninghamia lanceolata canopy SPAD (CCS) were constructed as independent variables of the model’s various regression techniques, including partial least squares regression (PLSR), random forests (RF), and backpropagation neural networks (BPNN), which were employed to develop a SPAD inversion model. The BPNN-based model emerged as the best choice, exhibiting test dataset coefficients of determination (R2) at 0.812, root mean square error (RSME) at 2.607, and relative percent difference (RPD) at 1.942. While the model demonstrated consistent accuracy across different slope locations, generalization was lower for varying slope directions. By creating separate models for different slope directions, R2 went up to about 0.8, showcasing favorable terrain applicability. Therefore, constructing inverse models with different slope directions samples separately can estimate CCS more accurately.

Bio-nano selenium fertilizer improves the yield, quality, and organic selenium content in rice

To investigate the impact of bio-nano Se on rice yield and quality and Se accumulation, three different forms of Se were applied: Se nanoparticles (SeNPs) synthesized by Proteus penneri LAB-1, a conventional inorganic Se fertilizer (sodium selenite) and an organic Se fertilizer (selenomethionine). The relative chlorophyll content of rice increased in plants treated with the different Se treatments and reached the highest level in the 5 mg/L bio-nano Se treatment. However, the height of rice showed little change. Applying 20 mg/L SeNPs increased rice yield by about 5% compared with organic Se treatment and 6% with inorganic Se treatment. Compared with the control, spraying 20 mg/L bio-nano, organic and inorganic Se on the leaf surface increased the soluble sugar content of rice by about 70%, 59% and 61%, respectively, and the amylose content by 15%, 11% and 10% and decreased soluble protein content by 25%, 18% and 22%, respectively. The Se content of rice increased with the increasing of spraying Se concentration. After spraying 10 mg/L of bio-nano Se, the Se content in the rice reached 271.2–306.5 µg/kg, and the proportion of organic Se was over 85.0%, which met the Se-rich rice and safety standards. This study provides a reference for determining the appropriate bio-nano Se supply level and developing Se-rich rice.

Incorporating canopy radiation enhances the explanation of maize yield change and increases model accuracy under film mulching

Plastic film mulching (PM) has been extensively used to increase crop yields in dryland regions in China. However, the impact of differently colored PM on crop radiation utilization due to the optical properties of the underlying PM surfaces remains unclear. We conducted a two-year field experiment in northwest China to evaluate the dynamics of photosynthetically active radiation interception and absorption (fIPAR and fAPAR), as well as the radiation use efficiency for intercepted and absorbed radiation (RUEi and RUEa) during spring maize (Zea mays L.) growth periods. Two fertilization levels (high and low) and 3 PM treatments (transparent film, black film, and no film) were considered in this study. We also developed empirical regression functions to calculate canopy fAPAR, accounting for both canopy and underlying surface characteristics. Furthermore, we used canopy absorption radiation to drive the Soil-Plant-Atmosphere Continuum System (SPACSYS) model to simulate maize biomass and yield. We found that transparent film mulching (TM) exhibited higher fIPAR and fAPAR than black film mulching and no mulching (CK). TM had an increase of RUEi and RUEa by 10.6% and 9.7%, respectively, relative to CK, resulting in a 9.3–19.2% increase in maize yield and a 25.8–30.2% increase in the partial factor productivity of nitrogen. These increases were mainly attributed to the increased relative chlorophyll content, net photosynthesis rate, and extended grain-filling period under TM. We found that the modified radiation input increased the accuracy of the SPACSYS model in simulating maize biomass and yield. We underscore the importance of using TM in dryland areas to increase crop yields and advocate for incorporating canopy radiation data into crop models, especially in agricultural regions where plastic film mulching is used, to enhance the accuracy of yield simulations.

Rhizophagus irregularis and biochar can synergistically improve the physiological characteristics of saline-alkali resistance of switchgrass.

Inoculation of arbuscular mycorrhizal fungi (AMF) or biochar (BC) application can improve photosynthesis and promote plant growth under saline-alkali stress. However, little is known about the effects of the two combined on growth and physiological characteristics of switchgrass under saline-alkali stress. This study examined the effects of four treatments: (1) no AMF inoculation and no biochar addition (control), (2) biochar (BC) alone, (3) AMF (Rhizophagus irregularis, Ri) alone, and (4) the combination of both (BC+Ri) on the plant biomass, antioxidant enzymes, chlorophyll, and photosynthetic parameters of switchgrass under saline-alkali stress. The results showed that the above-ground, belowground and total biomass of switchgrass in the BC+Ri treatment group was significantly higher (+136.7%, 120.2% and 132.4%, respectively) than in other treatments compared with Control. BC+Ri treatment significantly increased plant leaves' relative chlorophyll content, antioxidant enzyme activity, and photosynthesis parameters. It is worth noting that the transpiration rate, stomatal conductance, net photosynthetic rate, PSII efficiency and other photosynthetic-related indexes of the BC+Ri treatment group were the highest (38% to 54% higher than other treatments). The fitting results of light response and CO2 response curves showed that the light saturation point, light compensation point, maximum carboxylation rate and maximum electron transfer rate of switchgrass in the Ri+BC treatment group were the highest. In conclusion, biochar combined with Ri has potential beneficial effects on promoting switchgrass growth under saline-alkali stress and improving the activity of antioxidant enzymes and photosynthetic characteristics of plants.

Impact of Photosynthetic Efficiency on Watermelon Cultivation in the Face of Drought

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.

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.

Cadmium(II) adsorption by recyclable Zeolite-Loaded Hydrogel: Extension to the removal of Cadmium(II) from contaminated soil

Excessive cadmium(II) (Cd(II)) in soil has gravely jeopardized global ecosystem stability and human health. The removal of Cd(II) is a permanent cure to remediate Cd(II)-contaminated soil. Herein, a recyclable removal material, zeolite@cellulose-poly(acrylamide) hydrogel (Z@CA) was developed. Batch adsorption experiments and characterisations (SEM-EDS, FTIR, XRD, and XPS) were conducted to explore the adsorption capacity and mechanism of Z@CA. A pot experiment was established to evaluate the effect of Z@CA on soil Cd(II) remediation and Cd(II) toxicity in water spinach. The results showed that in aqueous solutions, the maximum adsorption capacity of Cd(II) by Z@CA was 84.4 mg·g−1. Electrostatic attraction, ion exchange, and surface complexation collectively facilitated Cd(II) capture by Z@CA. Even after five adsorption–desorption cycles, Z@CA maintained a Cd(II) removal efficiency of 89.88%. The results of the pot experiment showed that after applying Z@CA (2.5 w/w) in soil for 21 days, the content of bioavailable Cd(II) and total Cd(II) significantly decreased by 59.38% and 1.75%, respectively. The recovery rate of Z@CA reached 94.77% and maintained its original intact structure. In addition, the Cd(II) content of water spinach was reduced by 91.43% compared to the treatment without Z@CA, the weight, height, and relative chlorophyll content reaching 1.34, 1.73, and 1.49 times that of the treatment without Z@CA. The ideal application of Z@CA provides novel approaches and insights into the remediation of Cd(II)-contaminated soils.

Effect of ethyl methane sulphonate on growth, yield and some physiological parameters of Bambara groundnut (Vigna subterranea (L.) verdc) in non - water stressed and water stressed conditions

Bambara groundnut (Vigna subterranea (L.) Verdc.) is a legume cultivatd majorly for it’s seeds and commonly grown by subsistence farmers in sub-Saharan Africa. In order to determine the effect of ethyl methane sulphonate (EMS) mutagen on the growth, yield and some physiological parameters of non-water stressed (NWS) and water stressed (WS) bambara groundnut. It’s seeds were treated with five concentrations (0.00 (control), 0.25, 0.50, 0.75 and 1.00% v/v) Ethyl methane sulphonate and were grown under two conditions: non-water stressed and water stressed. Analysis of variance (ANOVA) revealed significant differences (P ≤ 0.50) in the emergence percentage (6 DAS), germination percentage (7 DAS), plant height (PH), number of leaves per plant (NL), leaf length (LL), leaf width, (LW), relative water content (RWC), chlorophyll a, b and total chlorophyll contents in the non-water stressed and water stressed plants. After rewatering at 8 WAS, highest number of leaves in NWS and WS conditions were observed in 0.75% EMS concentration (229, 189), highest leaf length in NWS and WS plants were observed in 0.50% EMS concentration (9.47cm, 9.13cm). Highest leaf width in NWS and WS plants was observed in 0.25% EMS concentration (4cm, 3.63cm). Highest number of pods per plant (NP) and weight of pods per plant (WP) were observed in 0.75% EMS concentration only in NWS plants. Highest chlorophyll a, b and total chlorophyll content was observed in 1.00% EMS concentration. The result form this study showed that Ethyl methane sulphonate (EMS) mutagen concentration increased the growth, yield and physiological parameters of Bambara groundnut in non-water stressed condition at different doses, however there was no positive effect of EMS on yield in the water stressed plants.