Plant Chlorophyll Research Articles

Biochar derived from olive oil pomace mitigates salt stress on seedling growth of forage pea.

Studies are being conducted to develop strategies to reduce the adverse effects of salinity stress. In the present study, it was aimed to determine the interactive effects of salinity stress with biochar on plant growth-the physiological and biochemical attributes of forage peas (Pisum sativum ssp. arvense L.). Salt applications were carried out with irrigation water at concentrations of 0, 25, 50, 75, and 100 mM NaCl. The experiment was conducted using a randomized complete block design with three applications [control: 0 (B0), 2.5% biochar (B1), and 5% biochar (B2)], five salt doses [0 (S0), 25 (S1), 50 (S2), 75 (S3), and 100 (S4) mM NaCl], and three replications, arranged in a 3 × 5 factorial arrangement. In the salt-stressed environment, the highest plant height (18.75 cm) and stem diameter (1.71 mm) in forage pea seedlings were obtained with the application of B1. The root fresh (0.59 g/plant) and dry weight (0.36 g/plant) were determined to be the highest in the B1 application, both in non-saline and saline environments. A decrease in plant chlorophyll content in forage pea plants was observed parallel to the increasing salt levels. Specifically, lower H2O2, MDA, and proline content were determined at all salt levels with biochar applications, while in the B0 application these values were recorded at the highest levels. Furthermore, in the study, it was observed that the CAT, POD, and SOD enzyme activities were at their lowest levels at all salt levels with the biochar application, while in the B0 application, these values were determined to be at the highest levels. There was a significant decrease in plant mineral content, excluding Cl and Na, parallel to the increasing salt levels. The findings of the study indicate that biochar amendment can enhance forage peas' growth by modulating the plant physiology and biochemistry under salt stress. Considering the plant growth parameters, no significant difference was detected between 2.5% and 5% biochar application. Therefore, application of 2.5 biochar may be recommended.

Pengaruh Aplikasi Nanobiostimulan Rumput Laut (Padina minor Yamada) terhadap Kadar Klorofil Kedelai (Glycine max (L.) Merr.)

Chlorophyll is a green pigment in plants which is important for the process of photosynthesis. The photosynthesis process affects plant growth. Seaweed extract has been proven to be a source of biostimulants that can increase plant growth, one of which is Padina minor. Concentration and frequency are important factors that influence the work of biostimulants. One effort to increase the effectiveness of biostimulants is by changing the crude extract into the form of nanoparticles. This research aims to analyze the effect of concentration, frequency, and interaction between concentration and frequency of crude extract and Padina minor nano extract on chlorophyll levels in soybean plants. The method used was a completely randomized design (CRD) in factorial consisting of 2 factors and 4 replications. Factor A concentration of Padina minor extract, namely control, crude extract 0.4%, nano extract 0.2%, 0.3%, 0.4%, 0.5% and 0.6%. Factor B is the frequency of administration of Padina minor extract, namely 1, 2, and 3 times administration. Based on research that has been carried out, the results showed that administration of 0.4% crude extract increased the average chlorophyll a level by 6.6% and a total of 11%. Meanwhile, chlorophyll b gave the same results as 0.3% nano extract, namely an increase of 14% compared to the control. The total frequency of administration of Padina minor extract was 3 times, and the same as the other treatments, increasing chlorophyll a levels by 4.6%, b by 5.2%, and a total of 4.9% compared to the control. The interaction between concentration and frequency of administration of Padina minor nano extract gives the same results as the crude extract, with lower concentration and less frequency of application in increasing levels of chlorophyll a, chlorophyll b, and total chlorophyll in soybean plants.

Three-Dimensional Quantification and Visualization of Leaf Chlorophyll Content in Poplar Saplings under Drought Using SFM-MVS

As global temperatures warm, drought reduces plant yields and is one of the most serious abiotic stresses causing plant losses. The early identification of plant drought is of great significance for making improvement decisions in advance. Chlorophyll is closely related to plant photosynthesis and nutritional status. By tracking the changes in chlorophyll between plant strains, we can identify the impact of drought on a plant’s physiological status, efficiently adjust the plant’s ecosystem adaptability, and achieve optimization of planting management strategies and resource utilization efficiency. Plant three-dimensional reconstruction and three-dimensional character description are current research hot spots in the development of phenomics, which can three-dimensionally reveal the impact of drought on plant structure and physiological phenotypes. This article obtains visible light multi-view images of four poplar varieties before and after drought. Machine learning algorithms were used to establish the regression models between color vegetation indices and chlorophyll content. The model, based on the partial least squares regression (PLSR), reached the best performance, with an R2 of 0.711. The SFM-MVS algorithm was used to reconstruct the plant’s three-dimensional point cloud and perform color correction, point cloud noise reduction, and morphological calibration. The trained PLSR chlorophyll prediction model was combined with the point cloud color information, and the point cloud color was re-rendered to achieve three-dimensional digitization of plant chlorophyll content. Experimental research found that under natural growth conditions, the chlorophyll content of poplar trees showed a gradient distribution state with gradually increasing values from top to bottom; after being given a short period of mild drought stress, the chlorophyll content accumulated. Compared with the value before stress, it has improved, but no longer presents a gradient distribution state. At the same time, after severe drought stress, the chlorophyll value decreased as a whole, and the lower leaves began to turn yellow, wilt and fall off; when the stress intensity was consistent with the duration, the effect of drought on the chlorophyll value was 895 < SY-1 < 110 < 3804. This research provides an effective tool for in-depth understanding of the mechanisms and physiological responses of plants to environmental stress. It is of great significance for improving agricultural and forestry production and protecting the ecological environment. It also provides decision-making for solving plant drought problems caused by global climate change.

Effects of hypobaria, hyperoxia, and nitrogen form on the growth and nutritional quality of lettuce

The objectives of this research were to investigate the impact of hypobaria, hyperoxia, and nitrogen form on the growth and nutritional quality of plants. Pre-culture 20-day-old lettuce (Lactuca sativa L. var. Rome) seedlings grew for 25 days under three levels of total atmospheric pressure (101, 54, and 30 kPa), two levels of oxygen partial pressure (21 and 28 kPa), and two forms of nitrogen (NO3N and NH4N). The ratios of NO3N to NH4N included 3: 1, 4: 0, 2: 2, and 0: 4. The nitrogen quantity included two levels, i.e. N1, 0.1 g N kg−1 dry matrix and N2, 0.2 g N kg−1 dry matrix. The growth status of lettuce plants in different treatments differentiated markedly. Regardless of the nitrogen factor, the growth status of lettuce plants treated with total atmospheric pressure/oxygen partial pressure at 54/21 was equivalent to the treatment of 101/21. Under the hypobaric condition (54 kPa), compared with 21 kPa oxygen partial pressure, hyperoxia (28 kPa) significantly inhibited the growth of lettuce plants and the biomass (fresh weight) decreased by 60.9%-69.9% compared with that under 101/21 treatment. At the N1 level, the sequence of the biomass of lettuce plants supplied with different ratios of NO3N to NH4N was 3: 1 > 4: 0 > 2: 2 > 0: 4, and there were higher concentrations of chlorophyll and carotenoid of lettuce plants supplied with the higher ratio of NO3 to NH4. At the N2 level, the effects of different ratios of NO3N to NH4N on lettuce plants were similar to those at the N1 level. The high nitrogen (N2) promoted the growth of lettuce plants such as 54/21/N2 treatments. Both form and nitrogen level did not affect the stress resistance of lettuce plants. Hypobaria (54 kPa) increased the contents of N, P, and K and hyperoxia (28 kPa) decreased the content of organic carbon in lettuce plants. The high nitrogen (N2) improved the content of total N and the N uptake. The ratios of NO3N to NH4N were 4: 0 and 3: 1, lettuce could absorb and utilize N effectively. This study demonstrated that hyperoxia (28 kPa) inhibited the growth of lettuce plants under the hypobaric condition (54 kPa), and high level of nitrogen (0.2 g N kg−1 dry matrix) and NO3N: NH4N at 3: 1 markedly enhanced the growth, the contents of mineral elements and the nutritional quality of lettuce plants.

Comparative Study of Traditional and Environmentally Friendly Zinc Sources Applied in Alkaline Fluvisol Soil: Lettuce Biofortification and Soil Zinc Status

The use of highly effective sources of zinc (Zn) in alkaline agricultural soils is essential to achieve crop biofortification, maintain crop quality, and avoid potential environmental risks. This research examines the efficacy of environmentally friendly Zn complexes (citric acid, CIT and glycine, GLY) compared to a traditional source (ZnSO4) for the lettuce cultivation in alkaline soil. The effectiveness of Zn sources was assessed based on the concentration of total and soluble Zn, plant biomass, and contents of photosynthetic pigments. The soil Zn status was also evaluated. While all Zn sources (Zn-GLY, Zn-CIT, and ZnSO4) showed positive effects on lettuce growth, Zn-GLY exhibited the highest efficacy. This source exhibited increases of 230%, 502%, 296%, and 409% over the control in Zn concentration in young and mature leaves, soluble Zn, and Zn uptake, respectively. Zn-GLY also resulted in a 371% increase in soil exchangeable Zn concentration, compared to the control treatment. Our findings indicate that Zn-GLY could replace the traditional ZnSO4 treatment, as it achieved high Zn biofortification of lettuce and a high concentration of Zn available in the medium-long term in the soil. The beneficial effect of the chelating agent GLY on plant chlorophyll and carotenoid contents is also remarkable.

The content of dry matter and chlorophylls in paulownia plants of different ages in the Right Bank Forest Steppe of Ukraine

Purpose. To determine the influence of the main fertilization, the application of cryoprotectant and foliar feeding on the formation of the content of dry matter and chlorophylls a and b in paulownia plantations of different ages. Methods. The research was carried out in 2021–2023 at the experimental plot of the Bila Tserkva National Agrarian University located in the forest plantations in the Right Bank Forest Steppe of Ukraine (Kyiv region). Design of the experiment: factor A – fertilization: 1) without fertilizers, 2) application of organic fertilizer Vermykompost (400 kg/ha) before planting; factor B – application of cryoprotectant: 1) without cryoprotectant, 2) cryoprotectant Mars-EL (0.5 l/ha) applied at the beginning of leaf growth; factor B – foliar application of fertilizers: 1) no treatment, 2) Quantum-AmiNoFrost (1.5 l/ha), 3) SmartGrow Recovery (2.0 l/ha). Results. In the first year of vegetation in the flowering phase, the average content of dry matter of paulownia plants was 44.8%, chlorophylls a and b – 2.6 and 1.5 mg/kg, and in the control treatment – 43.6%, 2.14 and 1.43 mg/kg, respectively. According to the experiment, the highest indicators were obtained in the treatment of fertilizing plantations with organic fertilizer Vermykompost, as well as cryoprotectant Mars-EL and foliar application of anti-stressors Quantum-AminoFrost or SmartGrow Recovery: dry matter content – 46.4 and 46.9%, chlorophyll a – 2.80 and 2.89 mg/kg, chlorophyll b – 1.59 and 1.65 mg/kg, respectively. In the 2-year-old plantations, the average content of dry matter in the treatments was 45.7%, chlorophylls a and b – 2.74 and 1.54 mg/kg, while in the control treatment these indicators were significantly lower: 45.2%, 2.24 and 1.24 mg/kg, respectively. As in the previous year, the maximum contents of dry matter (46.2–46.3%) and photosynthetic pigments (chlorophyll a: 2.89–3.01 mg/kg, chlorophyll b: 1.66–1.70 mg/kg) obtained for combinations of all three factors of the experiment. In the third year of vegetation of paulownia plantations in the flowering phase, on the average, the stems contained 51.2% of dry matter; the content of chlorophyll a in the leaves was 3.95 mg/kg, chlorophyll b – 2.84 mg/kg, in the control variant – 49.7%, 3.71 and 2.51 mg/kg, respectively. The highest results according to the experiment, as in the previous two years, were recorded in the treatment with the complex application of organic fertilizer Vermykompost, cryoprotectant Mars-EL and Quantum-AminoFrost or SmartGrow Recovery: the content of dry matter was 52.5–52.7%, chlorophyll a 4.05–4.07 mg/kg, and chlorophyll b 2.84–2.89 mg/kg. Conclusions. The parameters of the formation of indicators of the content of dry matter and photosynthetic pigments in paulownia plants were largely determined by the agrotechnical measures applied in the experiment, namely, the introduction of the main fertilizer and the treatment of plants during the growing season with cryoprotectant and anti-stress formulations, as well as the age of the plants. In particular, in the first two years of vegetation, the contents of dry matter and chlorophylls a and b were approximately at the same level in the experimental treatments, while in the third year, as the plants developed, they increased significantly. Throughout all the years of the study, the highest indicators of the content of dry matter and photosynthetic pigments were recorded in the treatments with the complex application of all three studied factors: fertilizer, cryoprotectant and foliar feeding.

Effects of Rootstock on Water Stress, Physiological Parameters, and Growth of the Pistachio Tree

In Spain, almost all pistachios are grown under water-stress conditions. Pistachio plants have sophisticated mechanisms to avoid or tolerate stress. It is known that the rootstock affects responses to water stress in the cultivar grafted onto it. The traditional belief is that Pistacia terebinthus L. is the rootstock best adapted to rainfed conditions. This study examined the effect of rootstock on stress traits, photosynthetic rate, transpiration, stomatal conductance, chlorophyll, polyphenol concentrations, and growth in plants of Pistacia vera L. cv. Kerman grafted onto P. terebinthus, P. atlantica, and UCB-1. These responses were classified into constituent traits and characteristics of the plant’s adaptation to water stress. The latter was induced by adding PEG 6000 to the nutrient solution. Plants grafted onto P. terebinthus showed more constituent traits, while plants grafted onto UCB-1 showed a greater number of drought-responsive traits. Plants grafted onto P. atlantica showed similar adaptative traits to those observed in UCB-1 but lower values of transpiration and net photosynthesis. Although it is likely that plants grafted onto P. terebinthus survive longer under extreme drought conditions, under moderate stress conditions, their yield is probably lower than that of plants grafted onto UCB-1 under the same moderate stress conditions.

Impact of pharmaceutical industry wastewater on stress physiological responses of Spirodela polyrhiza (L.) Schleiden.

Impact of pharmaceutical wastewater collected from aeration tank on aquatic macrophyte Spirodela polyrhiza (L.) Schleiden was studied in the present study. Various plant parameters such as chlorophyll, protein, and proline content of wastewater-exposed plants were examined to determine the toxic impacts of pharmaceutical wastewater. In addition to these parameters, electrolyte leakage (EL) and catalase (CAT) activities in S. polyrhiza were assessed for each day of exposure to the wastewater. S. polyrhiza was exposed to four different wastewater concentrations (25%, 50%, 75%, and 100%) under laboratory conditions for 7 days. The plants experienced severe toxicity as revealed by the reduction in photosynthetic pigments, increase in electrolyte leakage, and enhancement of antioxidant enzyme (CAT) activity in S. polyrhiza with an increase in concentration and time of exposure to pharmaceutical effluent.

Calcium ammonium nitrate applications for improved leaf growth and photosynthetic responses in the CAM orchid Phalaenopsis under elevated CO2 in a greenhouse

Phalaenopsis Queen Beer ‘Mantefon’ is an orchid species that absorbs CO2 at nighttime due to its crassulacean acid metabolism. These orchids originated from nutrient–poor environments in tropical forest understories. However, elevated CO2 at nighttime influences plant nitrogen utilization for growth. This study investigated the leaf growth and photosynthetic responses in Phalaenopsis Queen Beer ‘Mantefon’ to varying ambient and elevated CO2 (400 and 800 μmol⋅mol−1, respectively) and four nitrogen−based calcium ammonium nitrate (CAN) levels over 20 weeks: calcium, ammonium, and nitrate levels by 0.00, 0.00, and 0.00 mmol⋅L−1 (CAN0, control), 0.90, 0.55, and 2.97 mmol⋅L−1 (CAN1), 6.73, 1.11, and 6.05 mmol⋅L−1 (CAN2), and 12.80, 1.72, and 9.13 mmol⋅L−1 (CAN3), respectively. The phosphate and potassium levels were consistent across all CAN levels at 2.74 and 4.37 mmol⋅L−1, respectively. Elevated CO2 levels showed no significant impact on the number of leaves in CAN1−3 plants yet increased with those with CAN0. Leaf area significantly increased with elevated CO2 levels by 44 % (CAN0) and 26 % (CAN1). Strong correlations emerged between the number of leaves and leaf area, as well as between leaf area and root−to−shoot dry biomass ratio (R/S). Increasing CO2 levels heightened SPAD chlorophyll in CAN0 plants, and SPAD and F0 showed a strong correlation with elevated CO2 and increasing CAN levels. The total dry biomass decreased in plants with high CAN (CAN and CAN3) compared to those with CAN0, regardless of CO2 levels, and Fv/Fm dropped below 0.616 with high CAN under elevated CO2. Phalaenopsis Queen Beer ‘Mantefon’ demonstrated augmented leaf growth and R/S under limited CAN (CAN0) and elevated CO2 conditions, indicating improved resource allocation potential. The results suggest that supplying CO2 in a greenhouse can effectively improve Phalaenopsis vegetative growth with limited nutrient conditions, which differs from growth aspects under ambient CO2 levels.

Molecular insights into the salt stress response of Pearl millet (Pennisetum glaucum): Pathways, differentially expressed genes and transcription factors

AbstractIntroductionPearl millet (Pennisetum glaucum) plays a crucial role as a cereal crop in arid and semi‐arid regions, where it confronts the formidable challenge of salt stress.Materials and MethodsTo unravel the underlying molecular mechanisms that underpin its salt stress resilience, we subjected 14‐day‐old seedlings to three distinct groups: Control, 75 mM NaCl and 150 mM NaCl. These pots received daily irrigation with their respective treatment solutions for a duration of 7 days. Following this week‐long treatment, we measured plant chlorophyll content, as well as the fresh and dry weights of shoots and roots. It became evident that the saline treatment, particularly in the 150 mM NaCl group, had a more pronounced impact on both weight and chlorophyll content in comparison to the control group, surpassing the effects observed in the 75 mM NaCl group. Subsequently, we conducted RNA sequence analysis on the leaves of Pearl millet from both the control and 150 mM NaCl‐treated groups.ResultsThe results revealed that 27.6% of Pennisetum glaucum genes exhibited differential expression, with 3246 genes being upregulated and 7408 genes downregulated when compared to the control group. Principal component analysis underscored distinct variations in gene expression patterns between the control and salt‐stressed groups. Pathway analysis sheds light on the upregulated differentially expressed genes (DEGs), highlighting their involvement in crucial pathways such as phytyl‐PP biosynthesis, lysine degradation, glutamate biosynthesis, nitrate assimilation and DLO biosynthesis. Conversely, the downregulated DEGs were associated with pathways like coumarins biosynthesis, pinobanksin biosynthesis, UDP‐ d‐glucuronate biosynthesis and cholesterol biosynthesis, among others. Furthermore, our transcription factor analysis unveiled specific families associated with the salt stress response, including bHLH, ERF, NAC, WRKY, bZIP, MYB and HD‐ZIP.ConclusionsThese findings represent a significant advancement in our comprehension of Pearl millet's capacity to withstand salt stress and provide potential targets for the development of salt‐resistant crops, contributing to the advancement of sustainable agriculture in regions affected by salinity.

A newly isolated Bacillus pumilus strain SH-9 modulates response to drought stress in soybean via endogenous phytohormones and gene expression (Daegu, South Korea)

Drought stress hampers plant growth and productivity. Some microorganisms mitigate stress in plants; however, the molecular mechanism by which they interact with plants in mitigating stress remains unknown. This study aimed to determine the mechanism by which plant growth–promoting rhizobacteria modulate drought stress in soybean. Results indicated that B. pumilus SH-9 (SH-9) produced indole acetic acid and siderophore, and had capacity for phosphate solubilization. The test for polyethylene glycol 6000 (PEG) tolerance, showed that SH-9 could withstand high PEG concentration (up to 30 %). The isolate was identified a B. pumilus strain using a 16 s ribosomal DNA gene sequence. Inoculation of soybeans with SH-9 enhanced soybean plant growth and biomass by 20 %, even under high drought stress. This was due to a reduction of the endogenous phytohormone (abscisic acid) and upregulation of the antioxidant defense system (SOD, POD, APX, and GSH) by SH-9. Furthermore, the transcription factors GmDREB2, GmbZIP1, and GmNCED3 were involved. Inoculation with SH-9 also improved physio-morphological characteristics such as biomass, chlorophyll, seedling length, and relative water contents in the stressed plant. Overall, the findings of this study indicated that SH-9 enhances plant growth by promoting phosphate solubilization, siderophore, and exopolysaccharides. We, therefore, conclude that SH-9 is a drought-tolerant variant that can improve plant growth even under drought stress via modulation of expression of the phytohormone gene, and antioxidant profile.

Plant growth regulators affecting canola (Brasica Napus L.) biochemistry including oil yield under drought stress.

The objective was to test the effects of PGR on canola (Brassica napus L.) biochemistry including oil yield under drought stress. A two-year (Y1 and Y2) split plot field experiment on the basis of a randomized complete block design with three replications was conducted. The main factor was, drought stress levels, including irrigation after areduction of 40 (D1), 60 (D2) and 80% (D3) of field capacity (FC) moisture, and the sub-factor was PGR including control (S1), soil application of humic acid (S2), foliar applications of amino acid (S3), fulvic acid (S4) or seaweed extract (S5), and the combination of all PGR (S6). Although drought stress significantly decreased plant chlorophyll contents (a, b and total), oil percentage and oil yield, PGR significantly increased them. The D3 treatment, compared with control, decreased crop oil yield by 48.67 and 35.29% in the first and second year, respectively. However, treatment Y2D3S6 significantly increased oil percentage (43.10%) compared with control (40.97%). The PGR increased seed oil yield, in D3, by a maximum of 254kg ha-1. The PGR numerically (p ≤ 0.0886) increased proline to 6.14 mg g-1 LFW (Y1D3S6) compared with control (4.79 mg g-1 LFW). The PGR also significantly increased sugar content to 17.05 mg g-1 LFW, significantly different from thecontrol (12.95 mg g-1 LFW). In conclusion, the tested PGR can improve the biochemical properties (quality) including oil yield of canola in drought stress conditions, which is of economic and health significance.

Effect of light intensity on growth and chlorophyll content of Horenso (Spinacia oleracea) plants

Horenso plant or Japanese spinach (Spinacia oleracea) is a vegetable plant that is often used for consumption because it contains precursor, vitamins and minerals that are beneficial to health. Plant productivity can be increased by environmental engineering through the use of shade because sunlight influences directly through photosynthesis and indirectly in plant growth and development due to direct metabolic responses. This study aims to determine the effect of light intensity on plant growth and plant chlorophyll content and to see the correlation between chlorophyll content and plant growth of Spinacia oleracea. The research was conducted by experimental method with 3 differences in light intensity namely A = 6000 lux, B = 3000 lux, and C = 2000 lux and 3 differences in shade namely A = clear plastic shade, B = opaque plastic shade and C = white plastic shade. Chlorophyll measurement is used by using the spectrophotometer method. Horenso plant growth is measured by the increase in plant height and the width of the leaf diameter. Data analysis used the ANOVA test to identify significant differences in each treatment.The experimental results showed the value of P = 0.728 while the value of α= 0.05, that there is no effect of light intensity on the growth of Horenso plants and The results of the correlation test showed that the value of P>α. The value of P = 0.704 while the value of α = 0.05, there is no significant relationship between the growth of horenso plants and plant chlorophyll content.

Modeling of The Nitrogen Requirement of Winter Wheat for Protein Content Using Optical Sensor in Central Anatolia Region of Türkiye

Chlorophyll meters manage both the amount and duration of nitrogen fertilizer application based on the principle that the chlorophyll or nitrogen content of plants should be maintained throughout their development. For smallholders in developing countries, the use of a hand-held meter to manage nitrogen fertilizer in rice and wheat is the most popular method. The adoption of nitrogen management strategies based on close sensing using chlorophyll meters and optical sensors will largely depend on the inclusion of specific economic analysis in future research. The importance of using sensors and chlorophyll meters for nitrogen fertilizer management depends on how successful current practices have been. In this study, five different nitrogen rates (0, 80, 120, 160, 200 kg N ha-1) were applied to two different wheat varieties, and the effect of these different nitrogen rates on wheat protein content was investigated in a randomized block design. A quadratic polynomial model described the relationship between protein content and nitrogen rates.

Exposure to TiO2 nanoparticles improves the physiological characteristics of drought‐challenged chickpeas (Cicer arietinum L.)

AbstractDrought stress markedly affects plant growth and crop production. In turn, treatment with some metal‐based nanoparticles (NPs) such as TiO2‐NPs could improve the plant tolerance against drought stress. In the present study, the effects of different levels of moisture regime (40%, 60%, and 90% field capacity [FC]) in conjunction with various concentrations of TiO2‐NPs (0, 5, 10, 20, and 40 mg. L−1) on chickpea were studied. Exposure of drought‐challenged chickpea plants to TiO2‐NPs raised antioxidant enzyme activity compared with plants grown under drought without TiO2‐NP treatment. The highest activity of ascorbate peroxidase (APX) was observed at 40% FC and application of 40 mg. L−1 TiO2‐NPs. Moreover, peroxidase (POX) activity has increased with the enhancing concentration of TiO2‐NPs to 20 mg. L−1 at 90% FC. In comparison, the application of 40 mg. L−1 TiO2‐NPs and decreasing levels of FC caused a rise in the activity of superoxide dismutase (SOD). Exposure to TiO2‐NPs raised the amount of total phenols and 2,2‐diphenyl‐1‐picryl‐hydrazyl‐hydrate (DPPH) at different levels of moisture regime. The content of malondialdehyde (MDA) at 60% FC has decreased by 22% after treatment with 20 mg. L−1 TiO2‐NPs compared with control plants. Also, treatment with TiO2‐NPs heightened the proline content, and the highest amount of proline was obtained at 40% FC by applying 20 mg. L−1 NPs. The treatment with TiO2‐NPs in the moisture regimes led to higher chlorophyll and carotenoid production in chickpea plants. Taken together, the application of TiO2‐NPs could raise the defense potential of chickpea plants against oxidative stress caused by the generation of reactive oxygen species.

A Leaf-Patchable Reflectance Meter for In Situ Continuous Monitoring of Chlorophyll Content.

Plant wearable sensors facilitate the real-time monitoring of plant physiological status. In situ monitoring of the plant chlorophyll content over days can provide valuable information on the photosynthetic capacity, nitrogen content, and general plant health. However, it cannot be achieved by current chlorophyll measuring methods. Here, a miniaturized and plant-wearable chlorophyll meter for rapid, non-destructive, in situ, and long-term chlorophyll monitoring is developed. The reflectance-based chlorophyll sensor with 1.5mm thickness and 0.2g weight (1000 times lighter than the commercial chlorophyll meter), includes a light emitting diode (LED) and two symmetric photodetectors (PDs) on a flexible substrate, and is patched onto the leaf upper epidermis with a conformal light guiding layer. A chlorophyll content index (CCI) calculated based on the sensor shows a better linear relationship with the leaf chlorophyll content (r2 > 0.9) than the traditional chlorophyll meter. This meter can wirelessly communicate with a smartphone to monitor the leaf chlorophyll change under various stresses and indicate the unhealthy status of plants for long-term application of plants under various stresses earlier than chlorophyll meter and naked-eye observation. This wearable chlorophyll sensing patch is promising in smart and precision agriculture.

Combined toxic effects of polypropylene and perfluorooctanoic acid on duckweed and periphytic microorganisms.

Microplastics and perfluorooctanoic acid coexist in the aquatic environment. Duckweed was exposed to a range of concentrations (0.1-1000 μg L-1) of solutions containing polypropylene (PP) and perfluorooctanoic acid (PFOA) for 14 days to measure their toxicity. The result showed the single and combined PP and PFOA treatments did not significantly influence the growth of duckweed. The greatest PP and PFOA concentrations of combined pollution affect plant chlorophyll. Moreover, the combined treatment of duckweed consistently resulted in increased malondialdehyde (MDA) levels, indicating oxidative damage. As an antioxidant stress response, the combination-treated plants were encouraged to produce superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). Meanwhile, 3519 Operational Taxonomic Units (OTUs) were identified in the duckweed rhizosphere. Proteobacteria was the most predominant microbial community. Shannon, Simpson, and Chao1 discovered that microbial communities changed in response to single and combination PP and PFOA treatments, with decreased diversity and increased abundance. In addition, SEM analysis also revealed that the combined treatment significantly phyllosphere microorganisms. The findings of this investigation add to our knowledge of how PP and PFOA affect duckweed and the rhizospheric microorganisms, expanding the theoretical basis for employing duckweed in complex contamination.

Pseudomonas stutzeri improves the tolerance of Lemna minor to Cu(OH)2 nanopesticide by regulating the uptake of copper, antioxidant defense mechanisms, and the expression of metacaspase-1, chlorophyllase, and stress-responsive genes

This study investigated the effect of Pseudomonas stutzeri inoculation on Lemna minor treated with Cu(OH)2 nanopesticide (NP). The results showed that P. stutzeri inoculation increased the relative growth rate (RGR) in NP-treated plants. Although chlorophyll and carotenoid contents decreased significantly in NP-treated plants, P. stutzeri inoculation led to an increase in chlorophyll and carotenoid contents in NP-treated plants. Copper (Cu) content increased with increasing NP concentration, but it decreased significantly in the presence of P. stutzeri. NP treatment caused increased H2O2 and TBARS levels, as well as proline levels. However, P. stutzeri inoculation led to decreased H2O2 and TBARS levels and increased SOD, POX, GST, GR, GPX, and DHAR activities. The expression of genes encoding SOD, GST, metacaspase-1, and chlorophyllase was upregulated by NP treatment alone. Additionally, when plants were inoculated with P. stutzeri, the expression of these genes was further enhanced. In conclusion, P. stutzeri inoculation had a positive effect on the growth and antioxidant system of L. minor treated with NP as it enhanced RGR, increased chlorophyll and carotenoid contents, and decreased Cu content and oxidative stress. These findings suggested that P. stutzeri has the potential to promote aquatic plant growth and counteract the negative impacts of NP on these plants.

Combined Effect of PGPR Strains <i>Pseudomonas plecoglossicidA</i> 2,4-D and Humic Substances on the Growth, Content of Photosynthetic Pigments and Phytohormones in Wheat Plants in Drought Conditions

The aim of the study was to study the effect of bacteria that stimulate plant growth and humic substances on the content of chlorophyll, nitrogen balance index, cytokinin concentration, abscisic acid in wheat plants grown in drought conditions. The accumulation of the raw mass of wheat plants during treatment with a strain of Pseudomonas plecoglossicida 2,4-D bacteria and humic substances with a deficiency of soil moisture is shown. Stimulation of plant growth is associated with the activation of root growth, which led to an increase in the nitrogen balance index and chlorophyll concentration in the treated plants. The detected increase in the concentration of chlorophyll in plants treated with P. plecoglossicida 2,4-D correlated with a decrease in the content of abscisic acid in shoots, and in plants treated with humates – with an increase in cytokinins in shoots. A higher efficiency of plant treatment with a combination of bacteria and humic substances than any of them individually may be associated with the additive effect of these treatments on hormonal balance.

The identification of pests and diseases of rice plants using sentinel-2 satellite imagery data at the end of the vegetative stage

One of the factors that affect production yield of cultivation crops, including rice plants, is pest/disease attacks. Various types of pests/diseases are often found in rice cultivation such as rats, stem borers and rice leaf folders. The damage caused by these pests/diseases can lead to production decreases and crop failure. To prevent an increase in pest infestation, monitoring can be carried out by employing remote sensing technologies such as Sentinel 2 satellite imagery. The identification of rice plant pests/diseases can be done using Vegetation Indices such as NDVI and NDRE, due to their sensitivity to plant chlorophyll. The purpose of this study was to identify infected pest and disease of rice plants in paddy fields by using Sentinel-2 satellite imagery. The methods of this study were spatial analysis and simple linear regression analysis, by looking at the relation between Vegetation Indices and rice productivity. The research results showed that based on the low value of NDVI and NDRE at the end of vegetative stage, some of rice fields were infected with pests and diseases. From field observation, it was found that the pests and diseases included rats, rice leaf folders, borers and blasts. Pests/diseases infestation in paddy fields lead to a low Vegetation Index value which results in low rice production. Comparing the NDVI and NDRE, NDRE was better in detecting pests and diseases due to its sensitivity to the plants’ chlorophyll.