Changes In Chlorophyll Content Research Articles

Effects of Drought Stress on Photosynthesis and Chlorophyll Fluorescence in Blue Honeysuckle

Blue honeysuckle (Lonicera caerulea L.) is a deciduous shrub with perennial rootstock found in China. The objectives of this study were to explore the drought tolerance of blue honeysuckle, determine the effect of drought stress on two photosystems, and examine the mechanism of acquired drought tolerance. In this study, blue honeysuckle under four levels of simulated field capacity (100%, 85%, 75%, and 65% RH) was grown in split-root pots for drought stress treatment, for measuring the changes in chlorophyll content, photosynthetic characteristics, and leaf chlorophyll fluorescence parameters. The chlorophyll content of each increased under mild stress and decreased under moderate and severe stress. The net photosynthetic rate, transpiration rate, intercellular carbon dioxide concentration, and stomatal conductance of blue honeysuckle decreased with the increase in water stress. However, the water utilization rate and stomatal limit system increased under mild and moderate stress and decreased under severe stress. The maximum fluorescence (Fm), maximum photochemical efficiency, and quantum efficiency of photosystem II decreased with the decrease in soil water content, and the initial fluorescence increased significantly (p < 0.01). With the decrease in soil water content, the energy allocation ratio parameters decreased under severe drought stress. The main activity of the unit reaction center parameters first increased and then decreased. ABS/CSm, TRo/CSm, ETo/CSm, and REo/CSm gradually declined. After a comprehensive analysis, the highest scores were obtained under adequate irrigation (CK). Overall, we concluded that the water irrigation system of blue honeysuckle should be considered adequate.

Overexpression of RpKTI2 from Robinia pseudoacacia Affects the Photosynthetic Physiology and Endogenous Hormones of Tobacco.

Kunitz trypsin inhibitor genes play important roles in stress resistance. In this study, we investigated RpKTI2 cloned from Robinia pseudoacacia and its effect on tobacco. RpKTI2 was introduced into the tobacco cultivar NC89 using Agrobacterium-mediated transformation. Six RpKTI2-overexpressing lines were obtained. Transgenic and wild-type tobacco plants were then compared for photosynthetic characteristics and endogenous hormone levels. Transgenic tobacco showed minor changes in chlorophyll content, fluorescence, and photosynthetic functions. However, the maximum photochemical efficiency (Fv/Fm) increased significantly while intercellular CO2 concentration (Ci) decreased significantly. Stomatal size and hormone content (indole-3-acetic acid, zeatin riboside, gibberellin, and indole-3-propionic acid) were reduced, while brassinosteroid content increased. Random forest regression revealed that RpKTI2 overexpression had the biggest impact on carotenoid content, initial fluorescence, Ci, stomatal area, and indole-3-acetic acid. Overall, RpKTI2 overexpression minimally affected chlorophyll synthesis and photosynthetic system characteristics but influenced stomatal development and likely enhanced the antioxidant capacity of tobacco. These findings provide a basis for future in-depth research on RpKTI2.

Application and progress of water colour remote sensing technology in monitoring chlorophyll concentration changes in seawater

This paper provides an in-depth discussion on the application and progress of water colour remote sensing technology in monitoring changes in chlorophyll concentration in seawater. The hydrochromatic remote sensing technique uses spectral data acquired by remote sensing satellites and airborne platforms to monitor and analyse the distribution of marine chlorophyll, which is of great significance for understanding and protecting marine ecosystems. The article first introduces the basic principles and development history of this technology, and then discusses in detail its applications in global ocean monitoring, including resource management, environmental assessment, and ecological protection. In the discussion, we highlight the advantages of water colour remote sensing technology in providing large-scale and efficient ocean monitoring, while also pointing out the challenges it faces in terms of data accuracy, atmospheric disturbance handling and algorithm development. In particular, these challenges are gradually being overcome with the application of advanced computational techniques, such as machine learning and artificial intelligence, resulting in significant improvements in monitoring accuracy and efficiency. Finally, this paper looks at the future direction of water colour remote sensing technology, including technological innovation, data integration and interdisciplinary collaboration, highlighting the potential value of this technology in addressing global climate change and marine environmental protection. Through this comprehensive analysis, we have gained a deeper understanding and appreciation of the important role of water colour remote sensing technology in global ocean monitoring and management.

Foliar application of selenium promotes starch content accumulation and quality enhancement in foxtail millet grains

ContextThe northern regions of China are the core production areas for foxtail millet. However, the lack of selenium in the soil constrains local agricultural development. Foliar application of selenium is a significant method to improve selenium levels, yet few studies have systematically analyzed the effects of selenium on the quality of millet, especially its starch content. ObjectiveThis study aims to assess the effects of selenium foliar spray on the starch composition and overall content within millet grains, specifically by elucidating the mechanisms through examining changes in chlorophyll content in the flag leaves during the grain-filling stage and the activity of enzymes related to starch synthesis in the grains. Additionally, this research seeks to determine the optimal rate of selenium application that would maximize the quantity and quality of starch in millet grains. MethodsA two-year field experiment on foxtail millet was conducted with five selenium treatments (Se rates of 0, 20, 40, 60, and 100 g Se/ha, defined as T0, T1, T2, T3, T4 in this study, respectively). Grain starch content, activities of starch synthesis-related enzymes, flag leaves chlorophyll content, and antioxidant status of the flag leaves were measured at seven time points during grain filling. ResultsThe starch content in foxtail millet grains increased quadratically with the application of selenium, reaching a maximum under the T3 treatment, which enhanced the content by 15.27 % and 11.97 % over two years, respectively. The addition of selenium at low concentrations (T1-T3 treatments) not only enhanced the activities of the three starch synthesis-related enzymes, AGPase, SuSy, and SSS, but also delayed the senescence of the flag leaves, thereby promoting grain starch synthesis. In contrast, excessive selenium application (T4 treatment) expedited the aging of the flag leaves, grain starch synthesis was inhibited compared to the T3 treatment. Moreover, foliar application of selenium led to an increase in the SSS activity in the grains, which in turn reduced the content of straight-chain starch. Under the T3 treatment, the grain straight-chain starch content decreased by 22.30 % and 28.35 % over two years, respectively. ConclusionsFoliar application of selenium enhanced the activities of enzymes related to grain starch synthesis and had a dual effect on the senescence process of flag leaves, regulating the content and composition of starch in foxtail millet grains. The spraying concentration of 60 g Se/ha was most favorable for the accumulation and quality improvement of grain starch. ImplicationsThe results of this study will aid in enhancing the value-added potential of foxtail millet starch products through precise fertilization, improving the yield and quality of foxtail millet in northern China.

Variability of Primary Productivity as an Initial Link in Carbon Flux Under the Influence of Hydrological Conditions in the Baltic Sea

Investigating variability in phytoplankton primary productivity as a key component of the “biological pump” is critical to quantifying flux in the marine environment. We hypothesized that under certain hydrological conditions, changes in phytoplankton productivity are greater with changes in photosynthetic efficiency (the ratio of primary production (P P ) to the rate of electron transport in the phytoplankton photosystem, P P /ETR) than with changes in chlorophyll content. This study showed that increase of P P during sharp changes in hydrological parameters in the temporary frontal South-East Baltic (SEB) is achieved by increasing the efficiency of photosynthesis, i.e., the degree of use of light energy captured by chlorophyll a (Chl a). In the Gulf of Finland (GF), an increase in P P followed an increase in salinity from the Neva mouth to the sea and controls chlorophyll contents with low variability in photosynthetic efficiency. For SEB and GF, measurements of parameters of phytoplankton productivity and chlorophyll a content in late autumn (November) are carried out. The first stage of carbon flow (in biological pump), expressed in terms of primary production, was higher in the SEB than in the GF

Research on the evolutionary of spectral features of the initial damaged parts of 'Red Delicious' apples

It is crucial for early detection of mechanical damage to improve the quality of commodity fruit. For the problem of low identification accuracy of damage detection models due to the small degree of damage and unclear damage features in the initial damage of fruit and vegetables, this research analyzed the evolution process of spectral information in the initial damage of (0–3 h) of 'Red Delicious' apples. Three sensitive bands of 650–734 nm, 850–970 nm, and 1255–1314 nm, were extracted, and the average spectral reflectance and spectral curve shape features tanθ of the sensitive bands were analyzed. The conclusion is as follows: (1) In the 650–734 nm band, spectral reflectance decreasing and then stabilizing, reflecting enzymatic browning development. More severe damage led to lower reflectance. Over time, tanθ decreased, with more severe damage showing faster reduction, reflecting changes in chlorophyll content in the peel. (2) In the 850–970 nm band, reflectance showed a decreasing-then-increasing trend, reflecting moisture content changes in the damaged area. More severe damage resulted in lower reflectance. Over time, tanθ initially rose, then decreased and stabilized. More severe damage led to greater tanθ. (3) In the 1255–1314 nm band, reflectance initially increased, then decreased and stabilized, reflecting temperature changes in the damaged area. More severe damage led to higher reflectance. Over time, tanθ first increased, then decreased, with more severe damage showing smaller tanθ. The study on the evolutionary pattern of the spectral features after the impact of 'Red Delicious' apples provides theoretical basis for more reliable detection of the initial minor damage of apples in the future.

Avicennia germinans leaf traits in degraded, restored, and natural mangrove ecosystems of Guyana

AbstractMangrove leaves have unique features that enable them to cope with shifting environmental conditions while preserving their general functionality and efficiency. We examined the morphological characteristics and chlorophyll content (spectroscopically) of 600 mature Avicennia germinans leaves selected from 30 trees located in one degraded, one restored, and one natural mangrove ecosystem along Guyana's coastline. Systematic sampling was carried out using the closest individual sampling method in the wet and dry seasons. We hypothesized that both habitat type and seasonality influence the leaf traits and chlorophyll content of A. germinans. Our findings showed that A. germinans leaves are mesophyllous, and traits such as leaf perimeter, area, length, width, dry mass, wet mass, turgid mass, leaf‐specific area, and relative water content showed fluctuations in ecosystems (one‐way ANOVA, p < .05) as well as seasonally (paired t‐test, p < .05). Substantial, positive correlations (p < .05, R > .75) were also established for over 10 leaf parameters in both seasons while PCA and multiple regression analyses further confirmed the strong relationships between leaf morphological features and their respective locations. Changes in chlorophyll concentration were most noticeable in the degraded ecosystem while variations in leaf traits were more pronounced in the restored mangrove area. This may be due to the various disturbances found in each ecosystem coupled with fluctuations in the seasons. Our results demonstrate that mangroves, to some extent, alter their plant structures to cope with environmental stressors present in the various ecosystems they thrive in to maintain their survival.

Rapid and Nondestructive Evaluation of Wheat Chlorophyll under Drought Stress Using Hyperspectral Imaging.

Chlorophyll drives plant photosynthesis. Under stress conditions, leaf chlorophyll content changes dramatically, which could provide insight into plant photosynthesis and drought resistance. Compared to traditional methods of evaluating chlorophyll content, hyperspectral imaging is more efficient and accurate and benefits from being a nondestructive technique. However, the relationships between chlorophyll content and hyperspectral characteristics of wheat leaves with wide genetic diversity and different treatments have rarely been reported. In this study, using 335 wheat varieties, we analyzed the hyperspectral characteristics of flag leaves and the relationships thereof with SPAD values at the grain-filling stage under control and drought stress. The hyperspectral information of wheat flag leaves significantly differed between control and drought stress conditions in the 550-700 nm region. Hyperspectral reflectance at 549 nm (r = -0.64) and the first derivative at 735 nm (r = 0.68) exhibited the strongest correlations with SPAD values. Hyperspectral reflectance at 536, 596, and 674 nm, and the first derivatives bands at 756 and 778 nm, were useful for estimating SPAD values. The combination of spectrum and image characteristics (L*, a*, and b*) can improve the estimation accuracy of SPAD values (optimal performance of RFR, relative error, 7.35%; root mean square error, 4.439; R2, 0.61). The models established in this study are efficient for evaluating chlorophyll content and provide insight into photosynthesis and drought resistance. This study can provide a reference for high-throughput phenotypic analysis and genetic breeding of wheat and other crops.

Development of an accurate low cost NDVI imaging system for assessing plant health

BackgroundSpectral imaging is a key method for high throughput phenotyping that can be related to a large variety of biological parameters. The Normalised Difference Vegetation Index (NDVI), uses specific wavelengths to compare crop health and performance. Increasing the accessibility of spectral imaging systems through the development of small, low cost, and easy to use platforms will generalise its use for precision agriculture. We describe a method for using a dual camera system connected to a Raspberry Pi to produce NDVI imagery, referred to as NDVIpi. Spectral reference targets were used to calibrate images into values of reflectance, that are then used to calculated NDVI with improved accuracy compared with systems that use single references/standards.ResultsNDVIpi imagery showed strong performance against standard spectrometry, as an accurate measurement of leaf NDVI. The NDVIpi was also compared to a relatively more expensive commercial camera (Micasense RedEdge), with both cameras having a comparable performance in measuring NDVI. There were differences between the NDVI values of the NDVIpi and the RedEdge, which could be attributed to the measurement of different wavelengths for use in the NDVI calculation by each camera. Subsequently, the wavelengths used by the NDVIpi show greater sensitivity to changes in chlorophyll content than the RedEdge.ConclusionWe present a methodology for a Raspberry Pi based NDVI imaging system that utilizes low cost, off-the-shelf components, and a robust multi-reference calibration protocols that provides accurate NDVI measurements. When compared with a commercial system, comparable NDVI values were obtained, despite the fact that our system was a fraction of the cost. Our results also highlight the importance of the choice of red wavelengths in the calculation of NDVI, which resulted in differences in sensitivity between camera systems.

Trends in Changes in Primary Phytoplankton Production According to Remote Sensing Data in the Deep-Sea Region of the Black Sea for 1998–2015

The analysis of long-term seasonal changes in the concentration of chlorophyll, the maximum rate of phytoplankton photosynthesis and water temperature in the surface layer of the open waters Black Sea from 1998 to 2015 has been carried out. The trends of these indicators were assessed. For the research, we used the data of satellite observations SeaWiFS and MODIS-Aqua, MODIS-Terra. Typical positive temperature trends of 4 % in the deep-water western part of the sea. An annual temperature rise in deep-water areas was noted in the western cyclonic circulation by 0.038 °C. According to average annual data in other areas, no increase was found. The increase was mainly due to the winter season. Negative trends of primary phytoplankton production within 16.4–18.6 % of the initial level according to average annual values throughout the deep-water area. Significance level — p < 0.1. A decrease in primary production was observed in the summer. There were no statistically significant directional changes in chlorophyll concentration based on averaged data over 18 years. In different parts of the deep-sea area, the direction of interannual and seasonal changes in all indicators was similar. The emerging trend towards a decrease in phytoplankton productivity in recent years may lead to a restructuring of the phytoplankton community.

Copper exposure leads to changes in chlorophyll content and secondary metabolite profile in Lantana fucata leaves.

Cultivation of plants in environments polluted by metals at toxic levels can affect the biosynthesis of secondary metabolites. Here, we analysed the effect caused by excess copper on the concentration of chlorophylls a and b and the profile of secondary metabolites of Lantana fucata leaves. Five copper (Cu) treatments (mg Cukg-1 soil) were tested: T0, 0; T1, 210; T2, 420; T3, 630; and T4, 840. We found that the concentrations of chlorophylls in the plants decreased when compared to the control. However, this did not lead to a significant reduction in its growth, possibly due to the low translocation of the metal to shoots and the activation of plant defence systems to tolerate the environment in which they are exposed, increasing the emission of lateral roots and activating pathways for the production of secondary metabolites. Therefore, we found a decrease in the concentration of two key compounds in secondary metabolism, p -coumaric and cinnamic acids in treatments with higher copper concentrations. We also found an increase in phenolics. Decreases in p -coumaric and cinnamic acids may have occurred because these are precursors in the synthesis of phenolic compounds, which are increased in the high Cu treatments. Six secondary metabolites were characterised, described for the first time for this plant species. Thus, the presence of excess Cu in the soil may have triggered an increase in the amount of reactive oxygen species in the plants, which that led to the synthesis of antioxidant compounds, as a defence strategy.

Fast, Cheap and Reliable Monitoring of Microalgae-Based Paracetamol Removal from Aquatic Environment Using Electrochemical Sensor Technology

Paracetamol (PRL) is an analgesic and antipyretic drug, and its consumption has increased all across the world during the COVID-19 pandemic era. However, its excessive consumption makes it an endocrine-disrupting factor, and it is toxic for the liver. It easily contaminates water resources due to its high solubility, and has substantial potential to access both aquatic life and humans. Therefore, its removal by sustainable methods is a highlighted issue for today’s world that has experienced increasing scarcity of water. Herein, microalgae-based PRL removal and its electrochemical monitoring were performed. The removal performed with Scenedesmus sp. was monitored by disposable pencil graphite electrodes and cyclic voltammetry. The removal was achieved without the requirement of complex procedures, and the monitoring of this removal finished in less than 1 min. Application of the system in real life was tested in the presence of tap water. The biosorption kinetics, isoterms, and changes in chlorophyll content of the microalgae were calculated, and the microscopic characterizations of the biosorption were performed. The selectivity of the system was studied against other water contaminants. This is the first study about the removal of PRL using Scenedesmus sp. and the monitoring of the removal using disposable electrochemical sensor technology.

Estimating chlorophyll content of Zizania latifolia with hyperspectral data and random forest

The amount of chlorophyll in a plant useful to indicate its physiological activity and then changes in chlorophyll content have been used as a good indicator of disease as well as nutritional and environmental stresses on plants. Chlorophyll content estimation is one of the most applications of hyperspectral remote sensing data. The aim of this study is to evaluate dimensionality reduction for estimating chlorophyll contents from hyperspectral reflectance. Random Forest (RF) has been applied to assess biochemical properties such as chlorophyll content from remote sensing data; however, an approach integrating with dimensionality reduction techniques has not been fully evaluated. A total of 200 Zizania latifolia leaves with 5 treatments from Shizuoka University field were measured for reflectance and chlorophyll content. then, the regression models were generated based on RF with three dimensionality reduction methods including principal component analysis, kernel principal component analysis and independent component analysis. This research clarified that PCA is the best method for dimensionality reduction for estimating chlorophyll content in Zizania Latifolia with a RMSE value of 5.65 ± 0.58 μg cm-2.

Identification and function analysis of yellow-leaf mutant (YX-yl) of broomcorn millet

BackgroundBroomcorn millet is highly tolerant to drought and barren soil. Changes in chlorophyll content directly affect leaf color, which subsequently leadsleading to poor photosynthetic performance and reduced crop yield. Herein, we isolated a yellow leaf mutant (YX-yl) using a forward genetics approach and evaluated its agronomic traits, photosynthetic pigment content, chloroplast ultrastructure, and chlorophyll precursors. Furthermore, the molecular mechanism of yellowing was explored using transcriptome sequencing.ResultsThe YX-yl mutant showed significantly decreased plant height and low yield. The leaves exhibited a yellow-green phenotype and poor photosynthetic capacity during the entire growth period. The content of chlorophyll a, chlorophyll b, and carotenoids in YX-yl leaves was lower than that in wild-type leaves. Chlorophyll precursor analysis results showed that chlorophyll biosynthesis in YX-yl was hindered by the conversion of porphobilinogen to protoporphyrin IX. Examination of chloroplast ultrastructure in the leaves revealed that the chloroplasts of YX-yl accumulated on one side of the cell. Moreover, the chloroplast structure of YX-yl was degraded. The inner and outer membranes of the chloroplasts could not be distinguished well. The numbers of grana and grana thylakoids in the chloroplasts were low. The transcriptome of the yellowing mutant YX-yl was sequenced and compared with that of the wild type. Nine chlorophyll-related genes with significantly different expression profiles were identified: PmUROD, PmCPO, PmGSAM, PmPBDG, PmLHCP, PmCAO, PmVDE, PmGluTR, and PmPNPT. The proteins encoded by these genes were located in the chloroplast, chloroplast membrane, chloroplast thylakoid membrane, and chloroplast matrix and were mainly involved in chlorophyll biosynthesis and redox-related enzyme regulation.ConclusionsYX-yl is an ideal material for studying pigment metabolism mechanisms. Changes in the expression patterns of some genes between YX-yl and the wild type led to differences in chloroplast structures and enzyme activities in the chlorophyll biosynthesis pathway, ultimately resulting in a yellowing phenotype in the YX-yl mutant. Our findings provide an insight to the molecular mechanisms of leaf color formation and chloroplast development in broomcorn millet.

Interactive effects of temperature and nitrogen source on the elemental stoichiometry of a polar diatom

AbstractA recent study hypothesized that the near‐zero temperatures that generally prevail in Arctic waters negate the influence that different nitrogen (N) sources can otherwise have on the growth and elemental stoichiometry of marine micro‐algae. Here we test this hypothesis experimentally by evaluating how temperature (0–9°C) affects the growth and elemental stoichiometry of an ecologically relevant Arctic diatom Chaetoceros gelidus growing on different N sources (ammonium, nitrate, urea) at saturating irradiance. Following an initial acclimation period in which steady growth rates were achieved under each experimental treatment, changes in cellular concentrations of chlorophyll a and particulate carbon (C), nitrogen (N), phosphorus (P), and biogenic silica (Si) were monitored. While N source effects on growth rate became manifest as temperature rose above 0°C, the estimated optimal growth temperature was similar in all cases (Topt = 8.3°C). A positive effect of temperature on the N : P ratio occurred only at 6°C. Above this temperature, the N : P ratio decreased to values close to those observed at 0°C and 3°C. By contrast, the C : N ratio remained nearly invariant between 0°C and 6°C but increased substantially at 9°C. Overall, the results suggest that the presently widespread and successful diatom C. gelidus possesses the ability to remain competitive despite ongoing environmental changes and that its responses to warming and the availability of different N sources may impact elemental fluxes in the future.

The Change of Chlorophyll Content and Chlorophyll Efficiency in Epipremnum aureum by Water and pH

Epipremnum aureum (pothos) is an herbaceous species and is originated to tropical or subtropical South East Asia and Solomon islands. This study investigated the effect of excessive moisture on chlorophyll content and photosynthesis efficiency on E. aureum. The chlorophyll a, b, and total (chlorophyll a + b) contents were measured by using spectrophotometer. Fluorescence analysis for chlorophyll efficiency was measured with the PAM Chlorophyll Fluorometer. The chlorophyll content increases when moisture increases to 30%, but gradually decreases when it exceeds 40%. When the soil moisture was 80%, the values of chlorophyll a and b were 0.317 mg/g and 0.126 mg/g, respectively. This decreased the chlorophyll a, b, and total contents by 38.1%, 46.6%, and 36.8%, respectively, compared to 30% in 80% moisture. The chlorophyll content was highest at pH 6.5 of the soil. The content for chlorophylls a, b, and total were 0.471, 0.219, and 0.446 mg/g at pH 6.5, respectively. The correlation coefficients were subjected of the chlorophyll efficiency as a function of moistures. The change of chlorophyll efficiency in the quenched state (Fv) was also increased at 30% of moisture and then decreased steeply. The maximal possible value for fluorescence (Fm) was varied from 4310 (40% moisture) to 4220 (80% moisture). The Fm was varied from 4098 (pH 4.0) to 4356 (pH 6.5). The maximum quantum yield of photosynthesis (Fv/Fm) was varied from 0.798 (30% moisture) to 0.810 (60% moisture). The slope factors of Fo, Fm, Fv, and Fv/Fm for chlorophyll efficient indicators were 0.938, -0.806, 0.013, and 0.846, respectively. Excess watering decreased chlorophyll a, chl b, and chl (a + b) contents, and the chl a/b ratio in the E. aureum. The growth of this species was not as sensitive to pH compared to moisture.

Consequences of Drought Stress Encountered During Seedling Stage on Physiology and Yield of Cultivated Cotton.

Survival of living organisms depends on the availability of water resources required for agriculture. In the current scenario of limited water resources, it is our priority to maximise the yield potential of crops with a minimum supply of available water. In this study, we evaluated seven cultivated varieties of Gossypium hirsutum (FH-114, FH-152, FH-326, FH-492, FH-942, VH-327 and FH-NOOR) for their tolerance, yield potential and fibre quality under water shortages. We also studied the effect of drought stress on osmoregulation, chlorophyll content, antioxidant (peroxidase and catalase) activity, lipid peroxidation and secondary metabolite accumulation in the varieties under study. It was revealed that three varieties (FH-114, FH-152 and VH-327) exhibited a lower stress susceptibility index and more tolerance to drought stress. All the varieties demonstrated enhanced proline and malondialdehyde content, but no significant change in chlorophyll content was observed under limited water supply. Antioxidant activity offered by catalase and phenolic content was enhanced in FH-492 whilst peroxidase activity increased in FH-114 and FH-326. Phenolic content was highest in FH-942 and decreased significantly in the remaining varieties. Ginning outturn of the cotton varieties increased in VH-327 (19.8%) and FH-326 (3.7%), was not affected in FH-114 and FH-492 and was reduced in FH-152, FH-942 and FH-NOOR. All cotton varieties tested showed an increase in micronaire thickness when exposed to drought stress as early as the seedling stage. This study highlights the evaluation and screening of cotton varieties for their response to drought stress in terms of yield and fibre quality when exposed to water shortages during plant development and can help in devising irrigation plans.

Remediation of Pear Iron Deficiency Chlorosis by Nanocellulose-iron Chelation and the Underlying Mechanism

Nanocrystal cellulose possesses a strong capability to chelate Fe due to its adsorptive properties. Iron deficiency chlorosis (IDC) is a mineral disorder that remarkably weakens pear photosynthesis, causing declines in plant yields and quality. Conventional methods for controlling IDC generally lack efficiency and overuse chemicals. Foliar application of nanocellulose (NC)-Fe chelate (NCFe) provides a new approach to remediate IDC in pear (Pyrus betulifolia). In this study, NC was prepared by acidic hydrolysis using 64 wt% H2SO4 at 45 °C for 45 minutes. NCFe was formulated based on the net charge density of NC and ferrous sulfate (FeSO4) solution. The nanoparticle properties were characterized by transmission electron microscopy (TEM), dynamic light scattering, and conductometry. Pyrus betulifolia seedlings were pre-etiolated in an improved Hoagland’s nutrient solution and treated with bicarbonate. Changes in chlorophyll content, active Fe content, and photosynthesis rate in NCFe-treated leaves were determined by SPAD values, spectrophotometry, and photosynthetic apparatus, respectively. Ferritin genes (PbFER) and pectin methylesterase genes (PbPME) were extracted from leaf tissue, and gene expression profiles were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). The results showed that NCFe particles maintained a whisker-like morphology; the Z-average hydrodynamic diameter and zeta potential of NCFe measured by dynamic light scattering were 107.4 ± 3.0 nm and −9.7 ± 0.4 mV, respectively. When NCFe was prepared at a mixing ratio of 1:3000, the total chlorophyll content, active Fe content, and net photosynthetic rate of plant leaves were significantly enhanced by 23.8%, 65.9%, and 40.4% after 72 hours of treatment, respectively, compared with FeSO4 spraying. Importantly, NCFe treatment also significantly downregulated the expression of PbPME and upregulated the expression of PbFER, which are key genes regulating the active Fe content.

A New Polarization-Based Vegetation Index to Improve the Accuracy of Vegetation Health Detection by Eliminating Specular Reflection of Vegetation

Monitoring chlorophyll content changes in the plant via remote sensing is of great significance for understanding plant growth, monitoring vegetation pests and diseases, which is an important method to study the global climate change. However, the monitored information is often interfered by leaf specular reflection, resulting in reduced accuracy of chlorophyll content inversion. In this article, to eliminate the interference of specular reflection in vegetation remote sensing, a polarized multispectral imaging system (PMSIS) used in the different-light-level situation to observe vegetation was developed, and a new specular reflection removal vegetation index (NSRVI) was proposed to better detect the vegetation health condition under specular reflection interference. Based on previous studies, several vegetation indices (Simple ratio index (SR), Normalized difference vegetation index (NDVI); mSR, mNDVI (ref. [41]); pSR, pNDVI (ref. [46]); and NSRVI) were established, and the impact of specular reflection on vegetation health detection was evaluated. Correlation analysis was done on Relative Chlorophyll content (SPAD), SR, NDVI, mSR, mNDVI, pSR, pNDVI and NSRVI to understand their potential ability to eliminate specular interference. The results show that SR and NDVI have the highest sensitivity to specular reflection, and the other three methods can alleviate the adverse effects of specular reflection to varying degrees. It was observed that NSRVI was well correlated with SPAD (coefficient of determination (R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) = 0.899, RMSE=6.16), highlighting the potential of NRSVI in eliminating specular reflection interference and identifying vegetation health condition. In summary, this method can effectively eliminate specular interference and improve the detection accuracy of vegetation health condition.

Possibilities of using RGB-based image analysis to estimate the chlorophyll content of micropropagated strawberry plants

An image analysis method based on RGB features for rapid estimation of the chlorophyll content of leaves of micropropagated strawberry plants (2 cultivars) was presented in the study. An algorithm describing the relationship between the absolute values of chlorophyll content and the colour components of a leaf image captured with a conventional scanner was developed and tested. The accuracy of the proposed method was compared with that of an optical greenness meters designed for assessing leaf chlorophyll content. The chlorophyll content in the strawberry leaves was correlated with the results of measurements recorded by the two optical meters (SPAD-502, CCM-200) and with RGB values of scans of these leaves. The highest values of correlation coefficients were obtained between the chemical analysis results and mean values of the red colour (R) of the scans. However, varietal differences were evident here, which indicates the need for individual calibrations. In the case of the green colour (G), the accuracy was slightly lower; however, no varietal differences were found, thus one calibration can be used for both cultivars. Three formulas: (R-G)/(R+G), (R-G)/(R+G+B), and R/(R+G+B) were selected and their relationship with the changes in chlorophyll content was tested. These variables did not explain the changes in chlorophyll content better than the variable R. The study confirmed the possibility of using the image capture method for the detection of chlorophyll status in strawberry plantlets cultured in vitro.