Plant Physiological Status Research Articles

Impact of Structural, Photochemical and Instrumental Effects on Leaf and Canopy Reflectance Variability in the 500–600 nm Range

Current rapid technological improvement in optical radiometric instrumentation provides an opportunity to develop innovative measurements protocols where the remote quantification of the plant physiological status can be determined with higher accuracy. In this study, the leaf and canopy reflectance variability in the PRI spectral region (i.e., 500–600 nm) is quantified using different laboratory protocols that consider both instrumental and experimental set-up aspects, as well as canopy structural effects and vegetation photoprotection dynamics. First, we studied how an incorrect characterization of the at-target incoming radiance translated into an erroneous vegetation reflectance spectrum and consequently in an incorrect quantification of reflectance indices such as PRI. The erroneous characterization of the at-target incoming radiance translated into a 2% overestimation and a 31% underestimation of estimated chlorophyll content and PRI-related vegetation indexes, respectively. Second, we investigated the dynamic xanthophyll pool and intrinsic Chl vs. Car long-term pool changes affecting the entire 500–600 nm spectral region. Consistent spectral behaviors were observed for leaf and canopy experiments. Sun-adapted plants showed a larger optical change in the PRI range and a higher capacity for photoprotection during the light transient time when compared to shade-adapted plants. Outcomes of this work highlight the importance of well-established spectroscopy sampling protocols to detect the subtle photochemical features which need to be disentangled from the structural and biological effects.

A recognition method of multispectral images of soybean canopies based on neural network

Multispectral images of soybean canopies can reflect plant physiological information and growth status effectively, which is of great significance for soybean high-quality breeding, scientific cultivation, and fine management. At present, it is uneven of the gray level difference of the soybean multispectral images occurred in the leaf edge, and is also small of the gray level difference between the target and the background, resulting in inaccurate recognition of the soybean canopies from the multispectral images. Thus, a multispectral images' recognition method of soybean canopies was proposed based on the neural network. First, the method of Gaussian smoothing filter was used to preprocess the raw soybean multispectral images (green light, near-infrared, red light, red edge, and visible light), which maintained the leaf edge details of the soybean multispectral image. Second, the feedforward neural network model was established to extract the canopy region in the soybean multispectral images. In addition, image morphology operation was used to improve the recognition effects of the soybean canopy. Finally, four quantitative indexes were used to evaluate the experimental results. The results showed that the average effective segmentation rate of the proposed method was 91.69%, the under-segmentation rate was reduced by 33.34%, and the over-segmentation rate was reduced by 48.43%. The difference between the pixel average entropy of the proposed method and the standard canopy image was only 0.2295. The research results can provide not only reliable data for further analysis of physiological and ecological indexes of the soybean canopy, but also technical support for multispectral image recognition of other crop canopies.

Substrate-Dependent Effect of Vermicompost on Yield and Physiological Indices of Container-Grown Dracocephalum moldavica Plants

The development of sustainable plant production systems involves a search for different alternatives to chemical fertilizers. The aim of the present study is to compare growth and physiological effects of vermicompost on Dracocephalum moldavica plants in controlled conditions, using two types of commercially available substrates. The intention is to determine whether nondestructively measured photosynthesis-related parameters are useful for monitoring the physiological status of plants. The plants were cultivated in two base substrates without or with the addition of mineral fertilizer, as well as an amendment with vermicompost at a 20% or 30% rate in the conditions of an automated greenhouse. The biomass accumulation for control plants of D. moldavica was identical in peat substrate and commercial garden soil. The average growth increase by mineral fertilizer was 25% for D. moldavica plants grown in peat and 15% for plants grown in soil. Substrate amendment with 20% vermicompost resulted in an 114% average increase in biomass for plants grown in peat and a 98% average increase for plants grown in soil, but for plants at 30% the amendment rate increase was 148% and 68%, for peat and soil, respectively. Consequently, the addition of an identical amount of vermicompost resulted in a poorer growth response of plants in commercial garden soil as a substrate in comparison to peat, but an increase in the amendment rate from 20% to 30% resulted in some growth inhibition for these plants. Chlorophyll concentration was positively affected by the vermicompost amendment in a concentration-dependent manner, but this effect during a cultivation period appeared relatively late. Large differences were found between the three groups of fluorescence-derived parameters, with variable levels of predictability with respect to the differences in plant yield due to the pronounced variation in correlation through time. It is concluded that the incorporation of vermicompost for the cultivation of D. moldavica, even in substrate mixes with relatively high and balanced composition of plant-available nutrients, benefits plant growth, physiological status and biomass yield, but it is necessary to explore interactions between vermicompost and other substrates leading to possible changes in quality-related characteristics of vermicompost in substrate mixes.

Upscaling from leaf to canopy: Improved spectral indices for leaf biochemical traits estimation by minimizing the difference between leaf adaxial and abaxial surfaces

The knowledge of leaf biochemical traits is significant to understand the plant growth and physiological status. Spectral indices have been widely used to assess leaf biochemical traits, while the estimation accuracies at canopy level are frequently lower compared to those at leaf level in part due to the complexity of canopy structures and the variations in optical properties between leaf adaxial and abaxial surfaces. This study thus improved spectral indices with minimizing the effect of the difference between leaf adaxial and abaxial surfaces to assess leaf biochemical traits from leaf to canopy level. The datasets including leaf reflectance and canopy reflectance with corresponding leaf chlorophyll content ( C ab ), water content ( C w ), and dry matter content ( C m ) from a wide range of plant species were used. Results showed that there existed a significant difference between leaf abaxial and abaxial reflectance, causing the variation in the relationship between leaf biochemical traits and spectral indices. The published spectral indices exhibited the strong relationships with C ab , C w , and C m for either leaf adaxial or abaxial data, while the relationships of spectral indices with C ab , C w , and C m from leaf adaxial reflectance were inconsistent with those from leaf abaxial reflectance. The proposed adjusted ratio of difference spectral index (ARDSI) minimized the difference between leaf adaxial and abaxial reflectance for assessing C ab , C w , and C m at leaf level with the root mean square error of 9.32 μg cm -2 , 0.0050 g cm -2 , and 0.0053 g cm -2 , respectively. The application of the proposed ARDSI to the canopy level alleviated the effect of the variations of leaf adaxial and abaxial reflectance difference and canopy structures on the estimation of leaf biochemical traits, which thus improved the assessment of C ab , C w , and C m at canopy level in the simulated and measured datasets. The proposed approach would advance the applicability of spectral indices to monitor the physiological and functional traits of field crops at different scales. • Both leaf sides showed varied surface characteristics and optical properties. • Differences between both leaf sides affected the simulation of canopy reflectance. • Universal spectral indices were developed for leaf adaxial and abaxial surfaces. • The spectral indices well assessed C ab , C w , and C m at leaf and canopy levels.

Assessing Drought and Heat Stress-Induced Changes in the Cotton Leaf Metabolome and Their Relationship With Hyperspectral Reflectance.

The study of phenotypes that reveal mechanisms of adaptation to drought and heat stress is crucial for the development of climate resilient crops in the face of climate uncertainty. The leaf metabolome effectively summarizes stress-driven perturbations of the plant physiological status and represents an intermediate phenotype that bridges the plant genome and phenome. The objective of this study was to analyze the effect of water deficit and heat stress on the leaf metabolome of 22 genetically diverse accessions of upland cotton grown in the Arizona low desert over two consecutive years. Results revealed that membrane lipid remodeling was the main leaf mechanism of adaptation to drought. The magnitude of metabolic adaptations to drought, which had an impact on fiber traits, was found to be quantitatively and qualitatively associated with different stress severity levels during the two years of the field trial. Leaf-level hyperspectral reflectance data were also used to predict the leaf metabolite profiles of the cotton accessions. Multivariate statistical models using hyperspectral data accurately estimated (R2 > 0.7 in ∼34% of the metabolites) and predicted (Q2 > 0.5 in 15–25% of the metabolites) many leaf metabolites. Predicted values of metabolites could efficiently discriminate stressed and non-stressed samples and reveal which regions of the reflectance spectrum were the most informative for predictions. Combined together, these findings suggest that hyperspectral sensors can be used for the rapid, non-destructive estimation of leaf metabolites, which can summarize the plant physiological status.

Contrasting heat tolerance of urban trees to extreme temperatures during heatwaves

Extreme climate conditions, including more frequent and prolonged heatwaves, are increasing in many regions throughout the world. Urban trees can aid in mitigating the adverse impacts of climate extremes; however, their capacity to do so is limited by species differences in ability to maintain function and retain leaves to provide shade under extreme temperatures. To assess tree vulnerability to heatwaves, we used a common garden experiment in Western Sydney, Australia, which included four widely-planted tree species; two native evergreen and two exotic deciduous species. Data were collected during 2019 and 2020, the two hottest summers on local record with maximum air temperatures reaching 45 °C. We monitored plant physiological status as stomatal conductance (gS) and midday leaf water potential (Ψmid). We determined heat tolerance by measuring the leaf critical temperature (Tcrit) for photosynthesis and leaf turgor loss point (πtlp) as thresholds for loss of function and calculated the thermal safety margin. Plant performance was assessed by measuring tree growth and leaf damage after heatwaves. Species responded dynamically with gS decreasing as air temperature and vapor pressure deficit increased during heatwaves. Exotic species had higher gS, Tcrit and πtlp than native species. Leaf damage under heatwave conditions was overall lower in native species. Our results highlight the impact of heatwaves on urban trees and the value of physiological metrics to inform tree species selection to create more resilient urban environments.

Study of resistance of potato varieties to drought in the conditions of the Central Polissya of Ukraine

Objective. To determine and evaluate the indicators of changes in the water regime of the most common varieties of potatoes (on the 60th and 85th day of germination) in the conditions of central Polissya of Ukraine, namely the coefficients of water recovery, water retention, drought resistance and water deficit. Methods. Field and laboratory-based, selection and statistical. Results. The coefficients of water retention, water recovery capacity and drought resistance and water deficit of plant leaves are determined. The highest water content of potato leaves was observed among the following varieties: Tyras, Nahoroda, Serpanok, Slovianka and Chervona Ruta. It is established that the mechanism of water recovery in potato varieties of different maturity groups is different, the highest percentage of this indicator in early-maturing varieties is observed on the 60th day from germination, in the mid ripening group on the 85th day from germination. High value of the integrated indicator of water recovery was demonstrated by the following varieties: Tyras, Vyhoda, Yavir, Lietana, Slovianka Volodarka, Bazaliia and Chervona Ruta. It was found that on the 60th day from germination among the following potato varieties: Chervona Ruta, Serpanok, Avanhard, Mezhyrichka, Nahoroda, Oleksandryt, Radomysl and Bazaliia, the drought resistance coefficient was ≤ 80%. It was found that only in the varieties Tyras and Slovianka, on the 85th day after germination, there is an increase in the numerical expression of the drought resistance coefficient, which indicates an increased degree of adaptation of plants to soil moisture deficiency. In the first and second record the indicator of water deficit of the most of the studied varieties of potatoes was within acceptable limits, indicating a slight negative effect of weather conditions on the physiological state of plants. A slightly increased indicator of water deficit was observed on the 60th day of germination among the following potato varieties: Tyras, Volodarka and Levada, but within two weeks it decreased to a safe level. Conclusions. We recommend growing potato varieties that have shown high values of integrated indicators of water regime in the area of central Polissya and use as a source material for breeding purposes in the creation of new drought-resistant genotypes.

Annual variations of T/ET in a semi-arid region: Implications of plant water use strategies

Understanding the annual variation in the transpiration to evapotranspiration ratio (T/ET) remains a challenge and is essential for a thorough understanding of plant responses to the changing environment. We obtained the annual dynamics of T/ET in a semi-arid area of the southwestern United States based on the medians of monthly T/ET derived from two ET partitioning methods. The variation in monthly T/ET was analysed, and plant water use strategies were discussed based on the water use efficiency evaluated by the transpiration (WUE_T). The results show that physiological changes in plants are vital in the annual dynamics of T/ET. Switches in plant physiological status (growth and dormancy) at the start and end of growing seasons induce two dramatic changes in T/ET. Consequently, there is an annual bimodal dynamic of monthly T/ET, with a maximum of 0.84 in October and a minimum of 0.14 in December. Physiological/biochemical variations of plants indicated by solar-induced chlorophyll fluorescence (SIF) are linearly related to T/ET in growing seasons at a monthly scale (T/ET = 3.40 × SIF + 0.36, R2 = 0.987). Generally, a stable high monthly T/ET occurs under sufficient energy and water conditions and a highly variable monthly T/ET occurs under energy and water deficient conditions. In semi-arid regions, plants can flexibly adjust WUE_T following different water use strategies to survive or gain as much gross primary productivity (GPP) to compete. Saving water by greatly elevating WUE_T is the main strategy by which plants survive the non-growing season when WUE_T is linearly related to SIF (WUE_T = -114.93 × SIF + 3.25, R2 = 0.970). However, GPP and not WUE_T, becomes the goal of plants in growing seasons when they employ a stable and moderate WUE_T (around 2.1 gC kg−1 H2O) despite the abundant energy and precipitation. There are obvious reductions in WUE_T during the transition periods of the plants’ ‘growth-dormancy’ cycle. Our study highlights the importance of studying annual T/ET variations and water-use efficiency dynamics to better understand water use strategies in plants.

Soil conditioners improve rhizodegradation of aged petroleum hydrocarbons and enhance the growth of Lolium multiflorum.

Bioremediation and phytoremediation have demonstrated potential for decontamination of petroleum hydrocarbon-impacted soils. The total petroleum hydrocarbons (TPHs) are known to induce phytotoxicity, reduce water retention in soil, associate hydrophobic nature and contaminants' in situ heterogeneous distribution, limit soil nutrient release and reduce soil aeration and compaction. The ageing of TPHs in contaminated soils further hinders the degradation process. Soil amendments can promote plant growth and enhance the TPH removal from contaminated aged soil. In the present experiment, remediation of TPH-contaminated aged soil was performed by Italian ryegrass, with compost (COM, 5%), biochar (BC, 5%) and immobilized microorganisms' technique (IMT). Results revealed that significantly highest hydrocarbon removal (40%) was noted in mixed amendments (MAA) which contained BC + COM + IMT, followed by COM (36%), compared to vegetative control and other treatments. The higher TPH removal in aged soil corresponds with the stimulated rhizospheric effects, as evidenced by higher root biomass (85-159% increase), and bacterial count compared to NA control. Phyto-stimulants actions of biochar and IMT improved seed germination of Italian ryegrass. The compost co-amendment with other treatments showed improvement in plant physiological status. These results suggested that plant growth and TPH removal from aged, contaminated soils using BC, COM and IMT can improve bioremediation efficiency.

Vitis vinifera and Vitis labrusca’da Sekonder Tomurcukların Donma Noktalarının Belirlenmesi

This study was carried out to determine ability of secondary buds to winter freezing in two Vitis species viz. Vitis vinifera L. and Vitis labrusca L. In 2016 and 2017, one genotype of V. vinifera and one genotype of V. labrusca were sampled at 3 different periods during winter dormant period. The one-year-old shoots obtained from vineyards in winter and the secondary buds on 4th, 5th and 6th nodes on shoots has been used for freezing test. For freezing test, DTA (Differantial Thermal Analyses) methods has been used and test was started at +4 oC and temperature has been decreased and terminated at -30 oC. According to test results, the highest and the lowest temperatures to start freezing of secondary buds of the genotype belongs to V. vinifera was -16.48 oC and -19.49 oC, respectively. For V. labrusca genotype, these values were -15.77 oC and -20.99 oC, respectively. The short period of exotherm has been occurred in deep dormancy period for both species. As a result, freezing points of secondary buds varied among species as well years and physiological status of plants. Determining of freezing points of secondary buds in grapes, it is possible to make better prediction of winter injury.

Metabolic disturbance in lettuce (Lactuca sativa) plants triggered by imidacloprid and fenvalerate

Intensive and indiscriminate use of insecticides in agroecosystems causes phytotoxic disturbances in non-target crops. However, the mechanisms by which plants reprogram cellular metabolites to resist and tolerate such agrochemicals remain unclear. Here, the interaction between lettuce plants with imidacloprid and fenvalerate was investigated by the complementary use of physiological and metabolomic analyses. Neither imidacloprid nor fenvalerate induced overt phytotoxicity in lettuce seedlings. The plant biomass, chlorophyll fluorescence, lipid peroxidation, and membrane integrity were not significantly affected by the selected insecticides. Flavonoid content decreased by 25% in lettuce leaves under fenvalerate exposure, whereas polyphenol and flavonoid contents were not significantly altered by imidacloprid. Although the content of most of the nutrient element in the leaves remained the same following pesticide treatment, iron content decreased by 28.1% under imidacloprid exposure but increased by 22.8% under fenvalerate exposure. Metabolomic analysis revealed that the selected insecticides induced extensive metabolic reprogramming in lettuce roots and shoots. Imidacloprid dramatically increased the metabolism of several amino acids (arginine, cysteine, homoserine, and 4-hydroxyisoleucine), whereas markedly decreased the metabolism of various carbohydrates (glucose, raffinose, maltotetraose, maltopentaose, and stachyose). Fenvalerate did not significantly alter amino acid metabolism but decreased carbohydrate metabolism. Additionally, the relative abundance of most organic acids and polyphenolic compounds decreased significantly after pesticide exposure. These results suggest that plants might program their primary and secondary metabolism to resist and tolerate insecticides. The findings of this study provide important information on how neonicotinoid and pyrethroid insecticides affect the health and physiological state of plants, which are ultimately associated with crop yield and quality.

Biogenic volatile organic compounds in the grapevine response to pathogens, beneficial microorganisms, resistance inducers, and abiotic factors.

The synthesis of volatile organic compounds (VOCs) in plants is triggered in response to external stimuli, and these compounds can migrate to distal tissues and neighbouring receivers. Although grapevine VOCs responsible for wine aroma and plant-insect communications are well characterized, functional properties of VOCs produced in response to phytopathogens, beneficial microorganisms, resistance inducers, and abiotic factors have been less studied. In this review, we focused on the emission patterns and potential biological functions of VOCs produced by grapevines in response to stimuli. Specific grapevine VOCs are emitted in response to the exogenous stimulus, suggesting their precise involvement in plant defence response. VOCs with inhibitory activities against pathogens and responsible for plant resistance induction are reported, and some of them can also be used as biomarkers of grapevine resistance. Likewise, VOCs produced in response to beneficial microorganisms and environmental factors are possible mediators of grapevine-microbe communications and abiotic stress tolerance. Although further functional studies may improve our knowledge, the existing literature suggests that VOCs have an underestimated potential application as pathogen inhibitors, resistance inducers against biotic or abiotic stresses, signalling molecules, membrane stabilizers, and modulators of reactive oxygen species. VOC patterns could also be used to screen for resistant traits or to monitor the plant physiological status.

A new protein hydrolysate-based biostimulant applied by fertigation promotes relief from drought stress in Capsicum annuum L.

Recently, biostimulants have been used in sustainable agriculture as priming agents able to increase crop tolerance to abiotic stressors. Here, a soil application of GHI_16_VHL, a plant protein hydrolysate-based biostimulant, was tested for its capability to mitigate severe water stress effects on Capsicum annuum at flowering time. The biostimulant influence on plant physiological status was monitored upon stress and its relief, by measuring chlorophyll levels, stomatal density, stem water potential, leaf gas exchanges and plant growth. Moreover, leaf osmoregulation and oxidative stress levels were also evaluated by quantifying free proline, total non-structural carbohydrates (NSC), ROS-scavenging activity and H2O2 level.Although biostimulant-primed plants showed a quicker decrease of stem water potential with respect to untreated plants upon drought imposition, they recovered faster probably due to the higher leaf osmolyte accumulation, namely NSC during drought. Moreover, leaf gas exchange recovery was prompted in biostimulant-treated plants, which showed an incremented stomatal density and the same chlorophyll level of well-watered plants at the end of the recovery phase. Hydrogen peroxide level was significantly lower during stress and early recovery in biostimulant primed plants, probably due to the higher catalase activity in treated plants before drought or to the higher level of non-enzymatic antioxidant scavengers in primed stressed plants. Finally, the biostimulant priming increased aboveground relative growth rate and final fruit yield of stressed plants. Taken together, our data suggest that the biostimulant priming treatment promotes a faster and more efficient plant recovery after drought.

Stoichiometric and physiological mechanisms that link hub traits of submerged macrophytes with ecosystem structure and functioning

Eutrophication strongly influences plant stoichiometric characteristics and physiological status by altering nutrient and light availability in the water column. However, the mechanisms linking plant functional traits with ecosystem structure and functioning to clarify the decline of submerged macrophytes have not been fully elucidated to date. Therefore, based on a field investigation of 26 macrophytic shallow lakes on the Yangtze Plain, we first constructed a plant trait network at the whole-plant level to determine the hub traits of submerged macrophytes that play central regulatory roles in plant phenotype. Our results suggested that organ (leaf, stem, and root) phosphorus (P), starch, and total nonstructural carbohydrate (TNC) contents were hub traits. Organ starch and TNC were consistent with those in the experiment-based network obtained from a three-month manipulation experiment. Next, the mechanisms underlying the relationships between the hub traits and vital aspects of ecological performance were carefully investigated using field investigation data. Specifically, stoichiometric homeostasis of P (HP), starch, and TNC were positively associated with dominance and biomass at the species level, and community biomass at the community level. Additionally, structural equation modeling clarified not only a hypothesized pathway from eutrophication to water clarity and community TNC, but also combined effects of community TNC and HP on community biomass. That is, ecosystems dominated by more homeostatic communities tended to have more carbon (C)-rich compounds in relatively oligotrophic conditions, which promoted the primary production of macrophytes. Eutrophication was determined to affect community structure by inhibiting the predominance of more homeostatic species and the production of carbohydrates. Finally, reduced community biomass and increased nutrient contents and nutrient:C ratios in plants induced by eutrophication implied a decrease in the C sink in biomass and may potentially lead to an enhancement of litter decomposition rates and nutrient cycling rates. By adjusting plant responses to eutrophication, stoichiometric and physiological mechanisms linking plant traits with ecosystem structure have important implications for understanding ecosystem processes, and these results may contribute to practical management to achieve the restoration of submerged macrophytes and ecosystem services.

Ionomic differences between tomato introgression line IL8–3 and its parent cultivar M82 with different trends to the incidence of blossom-end rot

Fruit blossom-end rot (BER) is a serious physiological disorder that can cause significant yield losses in tomato (Solanum lycopersicum). Although many studies have suggested that calcium (Ca) deficiency in tomato fruits is a major factor for BER, its onset mechanism has not been fully elucidated. Ionomics is a high-throughput elemental profiling of living organisms that can be applied to understand how differences in plant's physiological status involving inorganic elements. In this study, we examined ionomic differences between the tomato cultivar M82 and its introgression line IL8–3, which contains a short chromosome segment from its wild relative Solanum pennellii on chromosome 8 of M82, and has a low incidence of fruit BER. Among the essential elements, Ca showed marked different behavior between the two lines. IL8–3 showed preferential Ca partitioning to fruits compared with M82. The slow growth rate and high Ca concentration observed in IL8–3 fruit during the early growth stages may also be responsible for the low BER incidence in this line. Although Ca ions bind to cell wall pectin and membrane phospholipids, and contribute to cell structure stability, these components showed no significant differences between fruits of the two lines. The fruit ionome differed considerably between M82 and IL8–3, and was not affected by available Ca status in the field. The M82 fruit had higher concentrations of many elements such as magnesium, potassium, boron, and sulfur than did IL8–3, and this trend was also observed in rotten fruit. This suggests that the influence of the leaf (source), rather than the fruit (sink), could be involved in the onset mechanism of BER.

Nitrogen supply affects cannabinoid and terpenoid profile in medical cannabis (Cannabis sativa L.)

Secondary metabolism in plants is considerably affected by environmental factors including mineral nutrition. Nitrogen is a key plant nutrient, known to affect primary and secondary metabolism in plants, that its effect on the cannabis plants' chemical profile is not known. To evaluate the hypothesis that N supply affects the cannabinoid and terpenoid profile, we studied the impact of N application on chemical and functional-physiology phenotyping in medical cannabis at the flowering stage. The plants were grown under five N treatments of 30, 80, 160, 240, and 320 mg L−1 (ppm) under environmentally controlled conditions. The results revealed that N supply affects cannabinoid and terpenoid metabolism, supporting the hypothesis. The concentrations of most cannabinoids and terpenoids tested were highest under the deficient concentration of 30 mg L−1 N and declined with the elevation of N supply. The concentrations of the two main cannabinoids, tetrahydrocannabinolic acid (THCA) and cannabidiolic acid (CBDA), decreased by 69% and 63%, respectively, with the increase in N supply from 30 to 320 mg L−1 N. Plant development and function were restricted under inputs lower than 160 mg L−1 N, demonstrating N deficiency. The morpho-physiological state of the plants was optimal at supply rates of 160–320 mg L−1 N. Inflorescence yield reflected the plant physiological state, increasing with the increase in N supply up to 160 mg L−1 N, and was unaffected by further increase in N. These results of the functional and chemical characterizations suggest that high N supply has adverse effects on the production of secondary compounds in cannabis, while it promotes growth and biomass production. Hence, N supply may serve for the regulation of the cannabinoid and terpenoid profiles, or for increasing plant yield, according to the desired production scheme. Taken together, the results reveal that the optimal N level for yield quantity, that allows also a relatively high secondary metabolites content, is 160 mg L−1 N. Finally, the present study provides a better understanding of the impact of N on 'drug-type' medical cannabis physiology, and takes us one step closer to the optimization of medical cannabis cultivation.

A Neural Network Method for Classification of Sunlit and Shaded Components of Wheat Canopies in the Field Using High-Resolution Hyperspectral Imagery

(1) Background: Information rich hyperspectral sensing, together with robust image analysis, is providing new research pathways in plant phenotyping. This combination facilitates the acquisition of spectral signatures of individual plant organs as well as providing detailed information about the physiological status of plants. Despite the advances in hyperspectral technology in field-based plant phenotyping, little is known about the characteristic spectral signatures of shaded and sunlit components in wheat canopies. Non-imaging hyperspectral sensors cannot provide spatial information; thus, they are not able to distinguish the spectral reflectance differences between canopy components. On the other hand, the rapid development of high-resolution imaging spectroscopy sensors opens new opportunities to investigate the reflectance spectra of individual plant organs which lead to the understanding of canopy biophysical and chemical characteristics. (2) Method: This study reports the development of a computer vision pipeline to analyze ground-acquired imaging spectrometry with high spatial and spectral resolutions for plant phenotyping. The work focuses on the critical steps in the image analysis pipeline from pre-processing to the classification of hyperspectral images. In this paper, two convolutional neural networks (CNN) are employed to automatically map wheat canopy components in shaded and sunlit regions and to determine their specific spectral signatures. The first method uses pixel vectors of the full spectral features as inputs to the CNN model and the second method integrates the dimension reduction technique known as linear discriminate analysis (LDA) along with the CNN to increase the feature discrimination and improves computational efficiency. (3) Results: The proposed technique alleviates the limitations and lack of separability inherent in existing pre-defined hyperspectral classification methods. It optimizes the use of hyperspectral imaging and ensures that the data provide information about the spectral characteristics of the targeted plant organs, rather than the background. We demonstrated that high-resolution hyperspectral imagery along with the proposed CNN model can be powerful tools for characterizing sunlit and shaded components of wheat canopies in the field. The presented method will provide significant advances in the determination and relevance of spectral properties of shaded and sunlit canopy components under natural light conditions.

Potential of S-containing and P-containing complexones in improving phytoextraction of mercury by Trifolium repens L.

Mercury is a global pollutant in the modern world. There is a large number of areas in the world where mercury is present in soils in significant quantities. Remediation methods which have traditionally been proposed may pose a risk of secondary mercury contamination and/or adverse health effects for cleaners. Phytoextraction of heavy metals from the soil environment is currently considered one of the promising non-invasive methods of remediation. But this approach has limited effectiveness. Chemically induced phytoextraction can increase the efficiency of this process both by converting less bioavailable mercury compounds to bioavailable fractions in the soil and by increasing the rate of transfer of metals in plants. This paper presents the results of a screening study of various chemical amendments to enhance the phytoextraction of mercury by Trifolium repens L. The results showed good potential for the induction of phytoextraction of phosphorus(P) and sulfur (S)-containing chelates. With this study, for the first time for the phytoextraction of mercury, the monoethanolamine salt of 2,2′-(ethylenedithio) diacetic acid was used as the S-containing chelate, and the disubstituted potassium salt of 1-hydroxy ethylidene-1,1-diphosphonic acid was used as the P-containing chelate. Further attention is given to study the effect that exogenous application of phytohormones and plant growth regulators has on the efficiency of mercury absorption and physiological status of plants, which performed well in combination with a P-containing chelate.

Designing of A Sensor and Mobile Application for Identification of Tomato Plant Physiological State

Designing of A Sensor and Mobile Application for Identification of Tomato Plant Physiological State - written by Teuma Mbezi M , Deussom Djomadji E. M , Ambang Zachee published on 2021/01/28 download full article with reference data and citations

Особенности роста робинии псевдоакации в условиях степной зоны

RUSSIAN JOURNAL OF FOREST SCIENCE, 2021, No. 3, P. 240–249 FEATURES OF ROBINIA PSEUDOACACIA GROWTH IN STEPPE ZONE CONDITIONS N. V. Ivanisova, R. G. Sedoy, O. I. Baboshko, L. V. Kurinskaya Novocherkassk engineer-meliorative institute – a branch of the Don State Agrarian University Pushkinskaya st. 111, Novocherkassk 346428, Rostov Oblast, Russia E-mail: lyubov.kurinskay@mail.ru Received 21 January 2020 Robinia pseudoacacia L . is a widespread species in protective plantations in southern Russia. The rapidity of growth and the ease of cultivation made it one of the most popular species in protective forestry. But at the same time there are a number of authors who continue to consider it a low-value and unpromising species due to its short life in the steppe zone. Changes in climatic conditions that have been observed in recent decades are gradually shifting the boundaries of agroclimatic zones. So, for example, the territory where the study objects are located ‑ the arid steppe of the Stavropol Krai, has acquired the features of a very arid zone by now. Changes in climatic conditions entail a change in the adaptive mechanisms of tree and shrub vegetation. As a result of the studies, it was found that the survival rate of robinia in the arid steppe conditions in the first year is affected by the amount of precipitation, and in subsequent years - by the presence of sharp temperature fluctuations in the spring-autumn period and high temperatures in the summer. The extremums of high or low temperatures are not as dangerous for this species as the frequency of their fluctuations from negative to positive. The growth of pseudoacacia robinia stands is determined by a combination of factors, such as precipitation + soil fertility + air temperature. In recent years, there has been a tendency towards a decrease in the amount of precipitation, which significantly affects the survival rate and growth of robinia. Biological resistance is determined not only by the meteorological conditions of the winter period, but also to a large extent by the physiological state of plants in the previous spring-summer season. Analysis of data on the course of robinia growth showed that the development of plantations in the steppe zone of the Stavropol Krai is relatively slow in the first years and gets faster in subsequent years, provided there is enough available soil moisture in summer and there are no sharp temperature fluctuations in the autumn-spring period. Key words: Robinia pseudoacacia, protective plantations, growth, resilience, adaptational mechanisms, steppe zone. 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