Chlorophyll Content Research Articles

Integration of UAV Multispectral Remote Sensing and Random Forest for Full-Growth Stage Monitoring of Wheat Dynamics

Wheat is a key staple crop globally, essential for food security and sustainable agricultural development. The results of this study highlight how innovative monitoring techniques, such as UAV-based multispectral imaging, can significantly improve agricultural practices by providing precise, real-time data on crop growth. This study utilized unmanned aerial vehicle (UAV)-based remote sensing technology at the wheat experimental field of the Hebei Academy of Agriculture and Forestry Sciences to capture the dynamic growth characteristics of wheat using multispectral data, aiming to explore efficient and precise monitoring and management strategies for wheat. A UAV equipped with multispectral sensors was employed to collect high-resolution imagery at five critical growth stages of wheat: tillering, jointing, booting, flowering, and ripening. The data covered four key spectral bands: green (560 nm), red (650 nm), red-edge (730 nm), and near-infrared (840 nm). Combined with ground-truth measurements, such as chlorophyll content and plant height, 21 vegetation indices were analyzed for their nonlinear relationships with wheat growth parameters. Statistical analyses, including Pearson’s correlation and stepwise regression, were used to identify the most effective indices for monitoring wheat growth. The Normalized Difference Red-Edge Index (NDRE) and the Triangular Vegetation Index (TVI) were selected based on their superior performance in predicting wheat growth parameters, as demonstrated by their high correlation coefficients and predictive accuracy. A random forest model was developed to comprehensively evaluate the application potential of multispectral data in wheat growth monitoring. The results demonstrated that the NDRE and TVI indices were the most effective indices for monitoring wheat growth. The random forest model exhibited superior predictive accuracy, with a mean squared error (MSE) significantly lower than that of traditional regression models, particularly during the flowering and ripening stages, where the prediction error for plant height was less than 1.01 cm. Furthermore, dynamic analyses of UAV imagery effectively identified abnormal field areas, such as regions experiencing water stress or disease, providing a scientific basis for precision agricultural interventions. This study highlights the potential of UAV-based remote sensing technology in monitoring wheat growth, addressing the research gap in systematic full-cycle analysis of wheat. It also offers a novel technological pathway for optimizing agricultural resource management and improving crop yields. These findings are expected to advance intelligent agricultural production and accelerate the implementation of precision agriculture.

Assessment of Tamarix smyrnensis for Phytoremediation Capacity of Laterite Mine Spoils

The phytoremediation potential of the halophytic plant, Tamarix smyrnensis (T. smyrnensis), was examined in toxic metal spoils assisted by biochar and irrigation by air nanobubbles. The substrate (spoil) used in the present study was derived from areas close to laterite (Ni-containing ores) mines. The efficiency of biochar addition in two rates (5 t/ha and 20 t/ha) to improve microbial properties and stabilize soil aggregates was also examined. Furthermore, the effect of irrigation with air-nanobubble-supplemented water was evaluated for the remediation of toxic metal spoils. The physiological condition of the plant species was investigated in terms of biomass, height, chlorophyll content, and antioxidant enzymes. The alkali and heavy metal accumulation and their distribution in the plant parts were assessed to explore whether toxic metals could accumulate in the root and further translocate to the aboveground tissues. The growth of T. smyrnensis was not adversely affected by its cultivation in lateritic spoil, and the highest rate of biochar exhibited a beneficial effect on plant growth in terms of weight (aerial and subterranean biomass). The highest biochar application rate led to significant increases in total chlorophyll content, showing a 97.6% increase when biochar is used alone and a 136% increase when combined with nanobubble irrigation. Remarkably, only when combining irrigation with air nanobubbles and low biochar supplementation did the translocation of the metals from soil to the aboveground tissues occur as the translocation factor was estimated to be greater than unity (TF > 1). The bioconcentration factors remained below 1.0 (BCF < 1) across all treatments, demonstrating limited mobilization from soil to plant tissues despite the application of soil amendments. Finally, the application of nanobubbles increased slightly but not substantially the total uptake of metals, which showed a significant decrease compared to the control groups when the lower dosage of biochar was utilized.

LeafLaminaMap: Exploring Leaf Color Patterns Using RGB Color Indices

The color of the plant leaves is a major concern in many areas of agriculture. Pigmentation and its pattern provide the possibility to distinguish genotypes and a basis for annual crop management practices. For example, the nutrient and water status of plants is reflected in the chlorophyll content of leaves that are strongly linked to the lamina coloration. Pests and diseases (virus or bacterial infections) also cause symptoms on the foliage. These symptoms induced by biotic and abiotic stressors often have a specific pattern, which allows for their prediction based on remote sensing. In this report, an RGB (red, green and blue) image processing system is presented to determine leaf lamina color variability based on RGB-based color indices. LeafLaminaMap was developed in Scilab with the Image Processing and Computer Vision toolbox, and the code is available freely at GitHub. The software uses RGB images to visualize 29 color indices and the R, G and B values on the lamina, as well as to calculate the statistical parameters. In this case study, symptomatic (senescence, fungal infection, etc.) and healthy grapevine (Vitis vinifera L.) leaves were collected, digitalized and analyzed with the LeafLaminaMap software according to the mean, standard deviation, contrast, energy and entropy of each channel (R, G and B) and color index. As an output for each original image in the sample set, the program generates 32 images, where each pixel is constructed using index values calculated from the RGB values of the corresponding pixel in the original image. These generated images can subsequently be used to help the end-user identify locally occurring symptoms that may not be visible in the original RGB image. The statistical evaluation of the samples showed significant differences in the color pattern between the healthy and symptomatic samples. According to the F value of the ANOVA analysis, energy and entropy had the largest difference between the healthy and symptomatic samples. Linear discriminant analysis (LDA) and support vector machine (SVM) analysis provided a perfect recognition in calibration and confirmed that energy and entropy have the strongest discriminative power between the healthy and symptomatic samples. The case study showed that the LeafLaminaMap software is an effective environment for the leaf lamina color pattern analysis; moreover, the results underline that energy and entropy are valuable features and could be more effective than the mean and standard deviation of the color properties.

Impact of Biochar and Hydroretentive Polymers on the Biochemical and Physiological Traits of Satureja rechingeri Jamzad Under Water Deficit Stress

Satureja rechingeri is a valuable medicinal plant, but its growth can be significantly impacted by water deficit stress. To investigate the effects of biochar (BC) and hydroretentive polymers (HPs) on various eco-physiological traits of savory under a water deficit, an experiment was conducted over two consecutive cropping seasons (2017–2019). A randomized complete block design with a split-plot factorial arrangement and three replications was used. The treatments consisted of three levels of irrigation (95 ± 5, 75 ± 5, and 55 ± 5% FC), which were applied to the main plots, and combinations of two levels of biochar and two levels of HPs, which were applied to subplots. The results show that a water deficit reduced the relative water content (RWC), chlorophyll content, and dry matter yield of the shoots. Furthermore, the activity of catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX), and malondialdehyde (MDA) increased in two-year-old plants. The MDA content significantly decreased by 15.6% in the second year compared to in the first year under a water deficit. The application of HPs caused a decrease of 26.4%, 32.5%, and 27.5% in POD, CAT, and APX enzyme activities, respectively, compared to their control levels. In the biochar treatment, there was a significant reduction in the activity of POD, APX, and CAT in the leaves.

Effect of Some Organic Fertilizers on Quality and Yield of Leaf Cuttings of Palak (Beta vulgaris) cv Bengalensis

The present experiment was carried out at the Horticultural Research Farm, Department of Horticulture, Babasaheb Bhimrao Ambedkar University (A Central University), Vidya Vihar, Rae Bareli Road, Lucknow, U.P., India during the year 2019-21. The field experiment was laid out in simple randomized block design comprising of eight treatments combinations with three replication son quality and yield parameters of palak. The experiment finding reveals that all the quality parameters of spinach i.e. chlorophyll content, ascorbic acid, leaf moisture and dry weight were significantly improved by FYM (M3) and application and third time cuttings (C3). Maximum green leaf yield/ha was reported under this treatment has significantly affect treatment (M3) FYM manure applied and three-time cuttings. The maximum chlorophyll content was recorded under the treatment (M3) Azotobacter and first cuttings (M3). The maximum ascorbic acid content was noticed under the treatment(M3) with first time cuttings (C3).

Green remediation of lead (pb) from Pb-toxic soil by combined use of silicon nanomaterials and leguminous Lens culinaris L. plants

Lead (Pb) toxicity is a major issue due to anthropogenic activities that is faced by farmers nowadays which inhibits plant growth and decreases crop yields. From contaminated soils, Pb absorbed by the plants and then ultimately enters into the food chain. Silicon (Si) can reduce Pb availability to plants and can be helpful in Pb immobilization in the soils. Moreover, Si in its nano-form, is expected to augment the beneficial attributes of applied Si. However, very little is known regarding the prospects of nano-Si application and leguminous lentil for alleviating the effects of Pb stress. To assess the effectiveness of bulk Si and nano-Si for reducing Pb toxicity and improving the yield of lentils, a pot study was conducted. Lentil variety Punjab Masoor 2020 was examined under normal and Pb toxic conditions as affected by applied Si and nano-Si. There were eight treatments comprised of different combinations of Si at 100 and 200 mg Si kg− 1 soil, and nano-Si at 125 mg kg− 1 soil, which were tested against Pb at 500 mg kg− 1 soil. A completely randomized design with factorial arrangements was applied along with three replications each. The result showed that Pb toxicity reduced the plant growth, yield, total chlorophyll contents, membrane stability index, relative water content, shoot fresh weight and dry weights of lentil. Whereas Si and nano-Si lessened the negative effect of Pb toxicity by significantly reducing its concentration in plant roots and shoot, and improved agro-physiological traits of lentil in normal and Pb-toxic soil conditions. In soil spiked with 500 mg kg− 1 Pb, the application of 100 and 200 mg bulk Si per kg of soil and 125 mg kg− 1 nano-Si reduced the Pb concentration in shoot by 31, 62 and 84% respectively over controls. In squat, the application of nano-Si most significantly (p ≤ 0.05) reduced the root and shoot Pb concentration in lentil.

Bacillus velezensis CE 100 controls anthracnose disease in walnut trees (Juglans regia L.) by inhibiting Colletotrichum gloeosporioides and eliciting induced systemic resistance.

Biological control of plant diseases is recognized as an effective and environmental friendly alternative to chemical fungicides. We demonstrated the dual biocontrol strategy of Bacillus velezensis CE 100 through the hydrolytic activity of chitinase and β-1,3-glucanase and the elicitation of induced systemic resistance (ISR) against Colletotrichum gloeosporioides that causes anthracnose disease in walnut trees. B. velezensis CE 100 produced a maximum of 62.1 units mL-1 (132.9 units mL-1) chitinase and 5.2 units mL-1 (9.4 units mL-1) β-1,3-glucanase enzymes in the broth culture (crude enzyme fraction), and inhibited spore germination and mycelial growth of C. gloeosporioides by 81.6% and 22.6%, respectively, at 100µlmL-1 of crude enzyme fraction. The inoculation of B. velezensis CE 100 induced the production of pathogenesis-related (PR) chitinase in walnuts by 2.1-fold, and to a lesser extent PR β-1,3-glucanase, and reduced anthracnose disease severity by 3.0-fold compared to the control group. The bacterium produced a maximum of 11.4µgmL-1 indole-3-acetic acid (IAA) and improved the chlorophyll content, shoot length, and root collar diameter of walnut trees compared to the fungicide treatment and control groups. B. velezensis CE 100 demonstrated the prospect of controlling walnut anthracnose by direct antagonism and ISR against C. gloeosporioides, while simultaneously enhancing walnut growth through IAA production.

Agronomic Efficiency of Compost Extracts and Nitrogen-Fixing Bacteria in Soybean Crops

Regenerative agriculture and the use of bioinputs have been gaining prominence in the global agribusiness sector, driven by the growing demand for healthier foods produced with minimal impact on ecosystems. In this context, compost and its derivatives (compost extracts and teas) are used to provide effective microorganisms to crops, although production processes affect the efficiency of compost extracts, as well as the soil microbiota. Thus, the hypothesis raised was that the organic matter source used for compost formation affects the agronomic efficiency of compost extracts. The objective of this study was to evaluate the effect of compost extracts based on litterfall of angiosperm (AC) and gymnosperm (GC) species, and the use of inoculation with the nitrogen-fixing bacteria Bradyrhizobium japonicum and Azospirillum brasilense (Bra+Azo), on soil quality, crop growth, grain yield, and disease control in soybean (Glycine max L.) crops. Using AC and GC resulted in varying effects on soybean growth and soil microbial biomass carbon (SMBC), confirming the hypothesis that the organic matter source affects the agronomic efficiency of compost extracts. Plants inoculated with Bra+Azo exhibited higher chlorophyll contents, resulting in a higher photochemical yield than for those treated with compost extracts (AC and GC). However, plants inoculated with AC and GC exhibited high plasticity in mitigating photochemical stress, reaching similar photosynthetic and transpiration rates to those observed in plants inoculated with Bra+Azo. Additionally, inoculation with Bra+Azo, overall, improved the photosynthetic efficiency of soybean plants, and the compost extracts (AC and GC) were more effective than the inoculation with Bra+Azo in increasing soybean 1000-grain weight, probably due to improvements in root development. The growth promotion observed with AC and GC is likely attributed to increases in SMBC by these compounds, denoting improvements in soil quality and biocontrol of damage caused by insect attacks.

Effect of Cd–Zn compound contamination on the physiological response of broad bean and aphids

IntroductionThe heavy metal elements cadmium (Cd) and zinc (Zn) often coexist in nature, making the environmental media more prone to compound pollution. However, research on the toxic effect of the Cd–Zn combination is still lacking, and the underlying toxic mechanisms remain unclear.MethodsTherefore, in this experiment, we established four treatment groups with different ratios of Cd–Zn compound stress for the broad bean, Vicia faba L., and aphids, Megoura crassicauda, to explore the growth and physiological adaptation mechanisms under different levels of mixed heavy metal stress.ResultsBy measuring the germination rate, seedling height, and chlorophyll content of broad beans, we found that Cd–Zn-mixed stress has a synergistic inhibitory effect on the growth and development of broad beans. Cd and Zn can be transferred through the food chain, while broad beans can resist complex stress by regulating the content of total soluble sugars and photosynthetic pigments in the body, as well as accumulating proline. In addition, in the first generation of adult aphids, treatment with Cd (12.5 mg/kg) + Zn (100 mg/kg) significantly affected the expression of trehalase (TRE) and trehalose-6-phosphate synthase (TPS) genes and influenced the carbohydrate content and trehalase activity in the aphids.DiscussionThe number of offspring produced by the second-generation aphids was significantly reduced under mixed heavy metal treatment, but it was not caused by changes in the vitellogenin (Vg) content. These related results provide new avenues for further exploration of plant responses to mixed heavy metal stress, pest control, and management of heavy metal pollution.

Environmental selection underlies distinct distribution patterns of closely related European evening primroses

Abstract Understanding of species distribution is becoming a key concern in biogeography, ecology and evolution when to consider the ongoing climate change. This study investigates the distribution patterns of closely related Oenothera species focusing on their adaptations to environmental conditions through morphological traits and photosynthetic adjustments. We documented the three distinct distribution patterns in Europe among the studied species. Oenothera rubricaulis, found at higher latitudes, has the smallest flowers and the highest chlorophyll content, accompanied by anthocyanin accumulation, which maximizes light acquisition under low light conditions. Oenothera suaveolens, observed at lower latitudes, displays the largest flowers, a pure green phenotype, the highest stomatal conductance, and a light avoidance strategy, reflected by rapid photoinhibition and hyponasty. Oenothera biennis, with the widest distribution, exhibits an intermediate phenotype, suggesting high plasticity and adaptability of its photosynthetic apparatus. Given the close relationship of these species, our findings suggest that environmental selection following hybridization events has been crucial for their establishment in Europe.

Effect of Processing Methods on the Micronutrient Profile, Colour, and Anti-nutritive Components of Justicia heterocarpa (mwidu)

Justicia heterocarpa (mwidu) is a popular indigenous leafy vegetable picked wild in rural regions of Morogoro, Tanzania, during the wet seasons. This research examined the impact of processing on micronutrients, total phenols, and anti-nutrient content. The fresh leaves (FL) underwent direct shade drying (UBLDDR), blanched shade drying (BLDR), blanched oven drying (BLDO), fermentation (FFL), and gas and microwave cooking (FLCO5, FLCO10, and FLMCO2). Vitamins, chlorophyll, minerals, phenolic compounds, and anti-nutrients were analyzed. All laboratory experiments adhered to procedures and guidelines. The pH dropped more significantly to <3.5 in a 3% salt-3% sugar brine solution with 1.328 ± 0.006 mg/100 g of lactic acid compared to its counterpart. Blanched leaves dried in 5 days, but unblanched leaves took 15 days. Fermented samples demonstrated a notable reduction in total chlorophyll concentration (0.0964 ± 0.075 mg/g) compared to other processing techniques. The nutritional and anti-nutritional composition of Justicia heterocarpa showed significant change (P < 0.05) depending on processing methods. The results indicated a significant loss of vitamin C in the fermented and ten-minute cooked samples, at 74.57% and 61.64%, respectively.Cooked FLMCO2 (107.4%, 11.29 ± 0.03 mg/100g) and FLCO5 (86.26%, 10.51 ± 0.02 mg/100g) exhibited more than a two-fold increase in beta-carotene compared to fresh leaves (3.67 mg/100g). In comparison to alternative processing procedures, samples cooked for 10 minutes exhibited significant mineral leaching, whereas unblanched direct shade drying preserved the highest mineral concentration. Fermented samples (532.83 ± 14.91 GAE/100 g) exhibited a 64.19% increase in total Phenolic compounds compared to fresh leaves (190.83 ± 14.91 GAE/100 g). Nonetheless, tannins increased by 68.1% (254.44 ± 7.45 GAE/100g) in the fermented samples. Samples exposed to extended cooking (17.8 ± 3.17 mg/100 g) and fermentation (40.28 ± 3.34 mg/100 g) exhibited the lowest levels of phytates. The oxalate concentration was significantly decreased in the cooked samples. Justicia heterocarpa may serve as a sustainable food supply in areas of Tanzania experiencing nutritional deficits.

Impact of Pranic Agriculture on Crop Growth and Yield: A Systematic Review

Pranic Agriculture (PA) is a supplementary approach to plant cultivation, incorporating the deliberate process of channeling prana-a fundamental life force energy-towards soil, seeds and seedlings to foster and enhance plant growth. This deliberate cleansing and revitalization process contributes to a harmonious and flourishing environment, fostering optimal conditions for plant development. This systematic review seeks to evaluate the influence of Pranic Agriculture by examining its impact on key crop parameters such as germination, plant dimensions, leaf characteristics, flowering, crop yield, chlorophyll content and plant polymorphism. By delving into seventeen pertinent studies conducted between 2009 and 2024 and published in reputable English peer-reviewed journals, this review aims to shed light on the potential viability of Pranic Agriculture. The selected studies, sourced from databases such as Web of Science, Scopus, Google Scholar and recognized journals by UGC and NAAS, were identified using keywords such as prana and agriculture, pranic agriculture, supplementary agriculture and complementary treatment in agriculture. Pranic Agriculture emerged from the reviewed studies as a catalyst for significant improvements in diverse growth parameters, spanning germination rates, shoot and root development, leaf morphology, early flowering and enhanced yield. In addition, an increase in chlorophyll content and polymorphism is noticed in plants treated by PA. Implementing Pranic Agriculture holds the promise of not only enhancing crop growth and yield, but potentially increasing farmer income. Continued research in this realm promises to deepen our understanding of the interconnected relationship between Pranic Agriculture and the broader environment, paving the way for sustainable agricultural practices that harmonise with nature.

Pharmacophore Recombination Design, Synthesis, and Bioactivity of Ester-Substituted Pyrazole Purine Derivatives as Herbicide Safeners.

Mesosulfuron-methyl, an acetolactate synthase (ALS) inhibitor primarily applied to wheat and rye, can injure or even kill wheat crops. Herbicide safeners can improve the herbicide resistance of crops without reducing the herbicidal effect on targeted weed species. Herein, we present a series of pyrazole purine derivatives with the primary structure of the natural product cytokinin and commercialized safener mefenpyridyl, designed using the pharmacophore recombination method. The title compounds were synthesized and characterized using infrared spectroscopy, 1H and 13C nuclear magnetic resonance spectroscopy, and high-resolution mass spectrometry. A bioactivity assay proved that most of the target compounds can reduce the wheat phytotoxicity of mesosulfuron-methyl. Measurements of chlorophyll and glutathione contents, along with other enzyme activity assays, confirmed that compounds I-15 and I-13 exhibit higher safety activities compared with the mefenpyr-diethyl safener. Molecular structure comparisons demonstrated that I-15 is more readily absorbed and disseminated through the crop than the commercialized safener mefenpyr-diethyl. Molecular docking models and molecular dynamics simulations elucidated the protective mechanism of safeners; specifically, compound I-15 competitively binds to the ALS active site with mesosulfuron-methyl. The current study reveals the potential of pyrazole purine derivatives in the future discovery of novel herbicide safeners.

Genome-Wide Identification and Expression Divergence of CBF Family in Actinidia arguta and Functional Analysis of AaCBF4 Under Cold Stress

The C-repeat binding factors (CBFs) gene is essential for plants’ cold response, which could not only be induced by the inducer of CBF expression (ICE) genes but also activated the expression of the cold-regulated (COR) gene, thereby participating in the ICE-CBF-COR cold response pathway. However, this gene family and its functions in Actinidia arguta remain unclear. In this study, whole-genome identification and functional analysis of CBF family members in A. arguta were performed. Eighteen CBF genes, which were located on four chromosomes and had five tandem repeats, were identified. The proteins encoded by the genes were predicted to be located in the nucleus and cytoplasm. The results of the promoter cis-acting element analysis revealed light response elements, low-temperature response elements, and hormone (methyl jasmonate, gibberellin, salicylic acid, etc.) response elements. We analyzed collinearity with other kiwifruit genomes, and, interestingly, the number of CBF family members differed across geographic locations of A. arguta. RT-qPCR revealed that the expression of the CBF gene family differed under low-temperature treatment; specifically, we observed differences in the expression of all the genes. Based on phylogenetic relationships and RT-qPCR analysis, the expression of AaCBF4.1 (AaCBF4) was found to be highly upregulated, and the function of this gene in cold resistance was further verified via overexpression in transgenic Arabidopsis. AaCBF4-overexpressing plants showed higher tolerance to cold stress, showing a higher germination rate, higher chlorophyll content and lower relative electrolyte leakage. In addition, compared with the wild-type Arabidopsis, the overexpressing plants exhibited significantly reduced oxidative damage due to the reduction in reactive oxygen species production under cold stress. Therefore, AaCBF4 plays an important role in improving the cold resistance of Actinidia arguta and can be further used to develop kiwifruit germplasm resources with strong cold resistance.

Influence of environmental factors on phytochemical compositions and antioxidant activity of Juniperus communis L

The present study focuses on the phytochemical content of Juniperus communis L. collected from different altitudinal locations in Uttarakhand, India. To the best of our knowledge, this is the first report which analyses the secondary metabolite contents, antioxidant potential, chlorophyll and carotenoid content of J. communis needles and their correlation with the environmental factors. The results showed variation in phytochemical content from different locations, with the highest total phenolic content of 42.80 ± 1.398 mg GAE/g DW estimated from JC3 (3891 m), flavonoid content of 2.47 ± 0.120 mg QE/g DW from JC4 (4065 m), and tannin content of 8.21 ± 1.445 mg TAE/g DW from JC4. The highest antioxidant activity determined by DPPH and ABTS assays were calculated as 36.97 ± 0.030 μg/mL and 518.78 ± 0.123 μg/mL in JC4 respectively while FRAP assay revealed highest antioxidative capacity of samples from JC2 (3507 m). The GC–MS analysis revealed the presence of around 35 compounds with communic acid, beta-Elemene, oplopanone, mome inositol, and spathulenol as the major compounds. In conclusion, elevation significantly influences the extraction yield, chlorophyll content, total polyphenol content, antioxidant activity, and chemical composition of the extracts.Soil properties, such as pH, moisture content, and nutrient availability, also played a role in these variations. Therefore, the findings suggest that environmental factors can significantly impact the bioactive potential of J. communis and highlight the importance of considering these factors in future research and applications.

Effects of Selenium Foliar Spraying on Seedling Growth and Stem Sheath Hardness in Fragrant Rice

Previous studies have shown that selenium (Se) can influence rice growth and yield. However, the Se effect on rice lodging remains unknown. This study aimed to investigate the impact of different Se treatments on seedling growth and stem sheath hardness in fragrant rice. A hydroponic experiment was conducted using two fragrant rice varieties, Yuxiangyouzhan and Xiangyaxiangzhan, as experimental materials. Two forms of selenium fertilizers (amino acid-chelated selenium and sodium selenite) were used. There were five foliar spraying selenium fertilizer treatments (CK: no selenium fertilizer; T1: 4 μmol·L−1 amino acid-chelated selenium; T2: 8 μmol·L−1 amino acid-chelated selenium; T3: 4 μmol·L−1 sodium selenite; and T4: 8 μmol·L−1 sodium selenite), and the effects of the different selenium fertilizer treatments on seedling growth and stem sheath hardness in fragrant rice were studied. Significant Se treatment effects on root fresh weight, seedling dry weight, plant height, stem sheath length, number of leaves, chlorophyll content, stem sheath hardness, peroxidase activity in leaf and stem sheaths, and lignin content in the roots were detected. A significant Se treatment and variety interaction effect on the stem sheath hardness was observed. The different forms/levels of selenium fertilizer affected the seedling growth and the stem sheath hardness differed. The Se treatments improved seedling growth and significantly affected the dry weight, chlorophyll content, stem sheath hardness, and peroxidase activity in leaf and stem sheaths. Compared with the CK treatment, the Se treatments increased the total dry weight of seedlings in Xiangyaxiangzhan and Yuxiangyouzhan by the ranges of 25.43–52.77% and 18.97–30.09%, respectively. The T2–T4 treatments increased the stem sheath hardness values in Xiangyaxiangzhan and Yuxiangyouzhan by the ranges of 21.6–54.7% and 38.3–146.6%, respectively, as compared to the CK treatment. The Se treatments had a promoting effect on physiological indexes such as stem sheath length, lignin content in the stem sheath, and dry matter accumulation in different plant tissues, thereby increasing the total dry weight. The Se treatment had an inhibitory effect on chlorophyll b content and total chlorophyll content, whilst it increased the chlorophyll a content and chlorophyll a/b ratio, which in turn affected the photosynthesis of rice. Therefore, appropriate Se treatments (the application of 8 μmol·L−1 amino acid-chelated selenium, 4 μmol·L−1 sodium selenite, and 8 μmol·L−1 sodium selenite) could improve seedling growth and stem sheath hardness, which was related to the parameter changes, such as the dry weight, photosynthesis pigments, and peroxidase activity. These findings suggest that different Se fertilizers can positively regulate rice resistance to lodging and growth. This study can provide theoretical support for the application of selenium fertilizer.

Mitigation of salinity stress in salt-sensitive rice seedlings via phytohormone synthesis, antioxidant defence enhancement, and ion balance regulation induced by 5-aminolevulinic acid-producing purple non-sulfur bacteria.

Salt stress, intensified by climate change, is a significant threat to rice production, a vital staple for over half the world's population. This makes addressing salt stress in rice cultivation a pressing issue. This study investigates the role of PNSB as a biostimulant in enhancing salinity tolerance of salt-sensitive rice seedlings, addressing existing gaps in knowledge on physiological and biochemical impacts under saline stress. We inoculated salt-sensitive rice seedlings with PNSB under 80 mmol NaCl stress in a controlled environment. After a 5-day treatment, we conducted biochemical and physiological analyses. Salinity stress induced oxidative stress in salt-sensitive rice seedlings. However, application of 5-ALA-producing PNSB mitigated stress, elevated 5-ALA in shoots by 23%, roots by 190.5%, and chlorophyll content by 105.0%. PNSB treatment also reduced superoxide radicals (O2 •-) and H2O2 by 26.7% and 38.7%, respectively, related to increased activity of the antioxidant enzymes, SOD (142.9%) and APX (41.8%). This led to lower electrolyte leakage (25.2%) and MDA (17.4%), indicating reduced ROS. Additionally, proline and soluble sugar content decreased by 29.2% and 72.5%, respectively. PNSB treatment also reduced sodium to potassium ion content in both shoots (31.2%) and roots (27.4%) of salt-stressed rice seedlings. These findings suggest that PNSB may facilitate nutrient solubilization and ion balance, thereby mitigating the adverse effects of salinity, with potential implications for sustainable agricultural practices to improve crop yield in saline environments. Future research should focus on elucidating the specific biochemical pathways involved in PNSB-mediated stress tolerance and exploring their application across diverse crop species and varying stress conditions.

Mitigating drought stress in fenugreek through synergistic effects of alanine and potassium-enriched biochar

Drought stress adversely affects plant growth, development, and yield. It can decrease seed germination, biomass accumulation, root proliferation, chlorophyll contents, and stomatal conductance. To overcome this critical issue, researchers suggest employing environmentally friendly approaches. The exogenous application of alanine (AL) acts as an osmolyte, which helps balance the cellular water under drought stress. It can also improve root architecture, biomass accumulation, and plant fertilizer use efficiency. Applying biochar can improve soil structure, water, and nutrient retention in soil, which are allied factors in enhancing plant growth under drought stress. Furthermore, the enrichment of potassium (K) in biochar also increases its availability to plants, directly regulating the stomatal conductance to alleviate drought stress. That’s why the current study aims to explore the combined effect of AL and potassium-enriched biochar (KBC) on fenugreek cultivated under drought stress. Four levels of AL (control, 2mM, 4mM, and 6mM) were applied with 0%, 1%, and 2% KBC in three replicates. Results showed that 2mM AL + 2%KBC showed significant improvement in plant length (5.24%), plant fresh weight (25.36%), plant dry weight (16.23%), chlorophyll a (7.80%), chlorophyll b (15.83%), total chlorophyll (10.65%) over the control under drought stress. A significant increase in shoot N, P, and K concentration compared to control under drought stress also validated the effectiveness of 2mM AL + 2%KBC. In conclusion, 2mM AL + 2%KBC is an effective amendment for alleviating drought stress in fenugreeks. Under drought stress, growers are recommended to apply 2mM AL + 2%KBC to achieve better fenugreek growth.

Unprecedented Summer Phytoplankton Bloom in the Ross Sea

AbstractHigh‐resolution glider sampling in the southwestern Ross Sea revealed an extensive phytoplankton bloom in austral summer 2022–2023 that persisted for over one month and extended through the upper 100 m of the water column. The temporal mean euphotic‐zone chlorophyll concentration was 20.38.5 , six to nine times higher than average summer Ross Sea concentrations. The bloom was likely initially dominated by Phaeocystis, favored over diatoms due to low light and high iron availability. Our observations are consistent with an ice‐edge bloom likely fueled by iron supply and enhanced stratification from late sea‐ice melt during an anomalously high ice‐covered summer. Photoacclimation to particularly low light conditions might have enhanced Chl‐a fluorescence. In the Ross Sea, the most productive region in the Southern Ocean, understanding the drivers of this extreme bloom is crucial for predicting potential impacts of the changing climate on primary production rates and carbon sequestration.

Plant growth-promoting microorganisms as natural stimulators of nitrogen uptake in citrus.

Improving nitrogen uptake efficiency by citrus in Mediterranean areas, where this crop predominates, is crucial for reducing ground-water pollution and enhancing environmental sustainability. This aligns with the Farm to Fork Strategy (European Green Deal) objectives, which aim to reduce the use of mineral fertilizers by up to 20% and to eliminate soil contamination from nitrogen entirely. In this context, exploring the potential of plant growth-promoting bacteria application to reduce nutrient inputs is a promising opportunity. The objective of the present study was to evaluate the effect of two Bacillus subtilis strains either individually inoculated or in combination with Saccharomyces cerevisiae on 15N-labeled fertilizer uptake efficiency and physiological parameters. Individual inoculations positively affected tree water potential, leaf chlorophyll concentrations (SPAD-values) and photosynthetic performance, enhancing tree growth. Fertilizer-15N use efficiency increased, as did phosphorus and potassium uptakes. Conversely, no response was observed in the trees co-inoculated with S cerevisiae. Therefore, PGPB can be considered an interesting means to reduce reliance on synthetic fertilizers in citrus orchards, minimizing the environmental impact and promoting sustainable production practices.