Underlying plant trait strategies for understanding the carbon sequestration in Banj oak Forest of Himalaya.

Plant functional attributes are subjected to environmental adjustments, which lead to modulations in forest processes under environmental changes. However, a comprehensive assessment of the relationships between plant traits and carbon stock remains subtle. The present study attempted to accomplish the gap of knowledge by examining the linkages between forest carbon with plant traits within the Banj Oak forest in the Garhwal Himalaya. Twelve individuals from three major species in the Banj Oak forest were randomly selected for trait measurements, and soil samples were collected randomly across the area for evaluation of soil nutrients and carbon. Forest biomass and soil carbon were estimated following standard protocols. A Structural Equation Model (SEM) was applied to establish the relationship between above ground carbon (AGC) and soil organic carbon (SOC) with leaf and stem traits, and soil nutrients. Stem traits were tree height and tree diameter; whereas leaf morphological traits were leaf area, specific leaf area, leaf dry matter content; leaf physiological traits were photosynthesis rate, stomatal conductance, and transpiration rate; and leaf biochemical traits were leaf carbon concentration, leaf nitrogen concentration, and leaf phosphorus concentration. Soil nutrients were available nitrogen, available phosphorus, and exchangeable potassium. Based on SEM results, AGC of the forest was positively correlated with stem traits and leaf physiological traits, while negatively correlated with leaf morphological traits. SOC was positively correlated with soil nutrients and leaf biochemical traits, whereas negatively correlated with stem traits. These findings may support for precise quantification of forest carbon and modeling of forest carbon stocks besides providing inputs to forest managers for devising effective forest management strategies.

Foliar application of methyl jasmonate affects impatiens walleriana growth and leaf physiology under drought stress.

In this study, the effects of foliar applied methyl jasmonate (MeJA) on drought-stressed Impatiens walleriana growth and leaf physiology parameters: stomatal conductance, chlorophyll, flavonoid, anthocyanin, and nitrogen balance index (NBI), were evaluated. These parameters could serve as indicators of drought tolerance of I. walleriana, a popular horticultural plant worldwide that is very sensitive to drought. The experiment included four treatments: control, drought-stressed plants sprayed with distilled water, drought-stressed plants sprayed with 5 µM MeJA, and drought-stressed plants sprayed with 50 µM MeJA. Foliar spraying with MeJA was performed twice: seven days before and on the day of drought induction. The stressed plant groups were non-irrigated to achieve soil water contents (SWC) of 15 and 5%, while control plants were well-watered throughout the experiment (35-37% SWC). The results of this study showed that drought significantly reduced I. walleriana fresh and dry shoot weight, as well as total leaf area, but did not impact on dry matter content. The foliar application of MeJA improved growth parameters of I. walleriana, depending on the elicitor concentration and drought intensity. Stomatal conductance was slightly reduced at 5% SWC, and foliar applied MeJA at both concentrations. The flavonoid index was slightly reduced at 15 and 5% SWC when 50 µM MeJA was foliar applied, while there were no observed changes in the anthocyanin index in any treatments. The foliar application of 50 µM MeJA increased the chlorophyll index and NBI of I. walleriana at 5% SWC, indicating a contribution of the elicitor to plant drought tolerance at the physiological level.

Consistent physiological, ecological and evolutionary effects of fire regime on conservative leaf economics strategies in plant communities.

The functional response of plant communities to disturbance is hypothesised to be controlled by changes in environmental conditions and evolutionary history of species within the community. However, separating these influences using direct manipulations of repeated disturbances within ecosystems is rare. We evaluated how 41 years of manipulated fire affected plant leaf economics by sampling 89 plant species across a savanna-forest ecotone. Greater fire frequencies created a high-light and low-nitrogen environment, with more diverse communities that contained denser leaves and lower foliar nitrogen content. Strong trait-fire coupling resulted from the combination of significant intraspecific trait-fire correlations being in the same direction as interspecific trait differences arising through the turnover in functional composition along the fire-frequency gradient. Turnover among specific clades helped explain trait-fire trends, but traits were relatively labile. Overall, repeated burning led to reinforcing selective pressures that produced diverse plant communities dominated by conservative resource-use strategies and slow soil nitrogen cycling.

Grapevine leaf physiology and morphological characteristics to elevated CO2 in the VineyardFACE (Free air Carbon dioxide Enrichment) experiment.

Atmospheric carbon dioxide (CO2) concentration has continuously increased since pre-industrial times and has currently reached an average growth rate of 2.3 ppm per year. For the majority of plant species elevated CO2 (eCO2) improves photosynthesis and thus plant biomass production. To investigate the effects of eCO2 on leaf physiology and morphological leaf characteristics two Vitis vinifera L. cultivars, Riesling and Cabernet Sauvignon, grown in the VineyardFACE (Free Air Carbon dioxide Enrichment) system were used. The VineyardFACE is located at Geisenheim, Rheingau comparing future atmospheric CO2-concentrations (eCO2, predicted for the mid-21st century) with current ambient CO2-conditions (aCO2). Experiments were operated under rain-fed conditions for two consecutive years (2015 and 2016). For both varieties and CO2 treatments, leaf gas exchange measurements were performed as well as measures of epidermal flavonoid (Flav) and leaf chlorophyll (Chl) indices by using a portable leaf clip. Furthermore, leaves were sampled for spectrophotometric analysis of the leaf pigments chlorophyll a (Chl a), chlorophyll b (Chl b) and carotenoid (Car). Additionally, leaf cross-sections were produced as permanent preparations to investigate morphological characteristics of the leaf structure. Both cultivars did not differ in leaf chlorophyll meter readings or leaf pigments between the two CO2 treatments while net assimilation was highly stimulated under elevated CO2 for both seasons. Differences found in leaf cross-sections were detected in palisade parenchyma and epidermal thickness of Cabernet Sauvignon under eCO2, whereas Riesling net assimilation increased by 40% under a 20% CO2 enrichment while remaining unaffected in different leaf layer thickness. The observed results within grapevine leaf tissues provide insights to seasonal adaptation strategies of grapevines under elevated CO2 concentrations predicted in future.

Monitoring of Indoor Farming of Lettuce Leaves for 16 Hours Using Electrical Impedance Spectroscopy (EIS) and Double-Shell Model (DSM).

An electrical impedance spectroscopy (EIS) experiment was performed using a double-shell electrical model to investigate the feasibility of detecting physiological changes in lettuce leaves over 16 h. Four lettuce plants were used, and the impedance spectra of the leaves were measured five times per plant every hour at frequencies of 500 Hz and 300 kHz. Estimated R-C parameters were computed, and the results show that the lettuce leaves closely fit the double-shell model (DSM). The average resistance ratios of R1 = 10.66R4 and R1 = 3.34R2 show high resistance in the extracellular fluid (ECF). A rapid increase in resistance (R1, R2, and R4) and a decrease in capacitance (C3 and C5) during water uptake were observed. In contrast, a gradual decrease in resistance and an increase in capacitance were observed while the LED light was on. Comparative studies of leaf physiology and electrical value changes support the idea that EIS is a great technique for the early monitoring of plant growth for crop production.

Aridity and cold temperatures drive divergent adjustments of European beech xylem anatomy, hydraulics and leaf physiological traits.

Understanding plant trait coordination and variance across climatic gradients is critical for assessing forests' adaptive potential to climate change. We measured 11 hydraulic, anatomical and leaf-level physiological traits in European beech (Fagus sylvatica L.) along a moisture and temperature gradient in the French Alps. We assessed how traits covaried, and how their population-level variances shifted along the gradient. The intrapopulation variances of vessel size and xylem-specific conductivity reduced in colder locations as narrow vessels were observed in response to low temperature. This decreased individual-level water transport capacity compared with the warmer and more xeric sites. Conversely, the maximum stomatal conductance and Huber value variances were constrained in the arid and warm locations, where trees showed restricted gas exchange and higher xylem-specific conductivity. The populations growing under drier and warmer conditions presented wide variance for the xylem anatomical and hydraulic traits. Our results suggest that short-term physiological acclimation to raising aridity and heat in southern beech populations may occur mainly at the leaf level. Furthermore, the wide variance of the xylem anatomical and hydraulic traits at these sites may be advantageous since more heterogeneous hydraulic conductivity could imply populations' greater tree-tree complementarity and resilience against climatic variability. Our study highlights that both intrapopulation trait variance and trait network analysis are key approaches for understanding species adaptation and the acclimation potential to a shifting environment.

Effects of Siliceous Natural Nanomaterials Applied in Combination with Foliar Fertilizers on Physiology, Yield and Fruit Quality of the Apricot and Peach Trees.

Siliceous natural nanomaterials (SNNMs), i.e., diatomaceous earth and natural zeolites, have a nanoporous structure with large active surfaces that adsorb cations or polarized molecules. Such nanoporous feature determines the effects related to SNNM utilization as low-risk plant protectants and soil improvers. This work used SNNMs from Romanian quarries as carriers for foliar fertilizers applied to stone-fruit trees, apricot and peach. We determined the effects of SNNMs on the physiology, yield and fruit quality of the treated stone-fruit trees. SNNM application determined impacts specific to the formation of particle films on leaves: reduced leaf temperature (up to 4.5 °C) and enhanced water use efficiency (up to 30%). Foliar fertilizers' effects on yield are amplified by their application with SNNMs. Yield is increased up to 8.1% by the utilization of SNNMs with foliar fertilizers, compared to applying foliar fertilizer alone. Diatomaceous earth and natural zeolites promote the accumulation of polyphenols in apricot and peach fruits. The combined application of SNNMs and foliar fertilizer enhance the performance of peach and apricot trees.

Spatio-temporal differences in leaf physiology are associated with fire, not drought, in a clonally integrated shrub.

In highly disturbed environments, clonality facilitates plant survival via resprouting after disturbance, resource sharing among interconnected stems and vegetative reproduction. These traits likely contribute to the encroachment of deep-rooted clonal shrubs in tallgrass prairie. Clonal shrubs have access to deep soil water and are typically thought of as relatively insensitive to environmental variability. However, how leaf physiological traits differ among stems within individual clonal shrubs (hereafter 'intra-clonal') in response to extreme environmental variation (i.e. drought or fire) is unclear. Accounting for intra-clonal differences among stems in response to disturbance is needed to more accurately parameterize models that predict the effects of shrub encroachment on ecosystem processes. We assessed intra-clonal leaf-level physiology of the most dominant encroaching shrub in Kansas tallgrass prairie, Cornus drummondii, in response to precipitation and fire. We compared leaf gas exchange rates from the periphery to centre within shrub clones during a wet (2015) and extremely dry (2018) year. We also compared leaf physiology between recently burned shrubs (resprouts) with unburned shrubs in 2018. Resprouts had higher gas exchange rates and leaf nitrogen content than unburned shrubs, suggesting increased rates of carbon gain can contribute to recovery after fire. In areas recently burned, resprouts had higher gas exchange rates in the centre of the shrub than the periphery. In unburned areas, leaf physiology remained constant across the growing season within clonal shrubs (2015 and 2018). Results suggest single measurements within a shrub are likely sufficient to parameterize models to understand the effects of shrub encroachment on ecosystem carbon and water cycles, but model parameterization may require additional complexity in the context of fire.

Quantitative trait locus mapping reveals an independent genetic basis for joint divergence in leaf function, life-history, and floral traits between scarlet monkeyflower (Mimulus cardinalis) populations.

PREMISE: Across taxa, vegetative and floral traits that vary along a fast-slow life-history axis are often correlated with leaf functional traits arrayed along the leaf economics spectrum, suggesting a constrained set of adaptive trait combinations. Such broad-scale convergence may arise from genetic constraints imposed by pleiotropy (or tight linkage) within species, or from natural selection alone. Understanding the genetic basis of trait syndromes and their components is key to distinguishing these alternatives and predicting evolution in novel environments. METHODS: We used a line-cross approach and quantitative trait locus (QTL) mapping to characterize the genetic basis of twenty leaf functional/physiological, life history, and floral traits in hybrids between annualized and perennial populations of scarlet monkeyflower (Mimulus cardinalis). RESULTS: We mapped both single and multi-trait QTLs for life history, leaf function and reproductive traits, but found no evidence of genetic co-ordination across categories. A major QTL for three leaf functional traits (thickness, photosynthetic rate, and stomatal resistance) suggests that a simple shift in leaf anatomy may be key to adaptation to seasonally dry habitats. CONCLUSIONS: Our results suggest that the co-ordination of resource-acquisitive leaf physiological traits with a fast life-history and more selfing mating system results from environmental selection rather than functional or genetic constraint. Independent assortment of distinct trait modules, as well as a simple genetic basis to leaf physiological traits associated with drought escape, may facilitate adaptation to changing climates.

Drought and heat wave impacts on grassland carbon cycling across hierarchical levels.

Droughts and heat waves are increasing in magnitude and frequency, altering the carbon cycle. However, understanding of the underlying response mechanisms remains poor, especially for the combination (hot drought). We conducted a 4-year field experiment to examine both individual and interactive effects of drought and heat wave on carbon cycling of a semiarid grassland across individual, functional group, community and ecosystem levels. Drought did not change below-ground biomass (BGB) or above-ground biomass (AGB) due to compensation effects between grass and non-grass functional groups. However, consistently decreased BGB under heat waves limited such compensation effects, resulting in reduced AGB. Ecosystem CO2 fluxes were suppressed by droughts, attributed to stomatal closure-induced reductions in leaf photosynthesis and decreased AGB of grasses, while CO2 fluxes were little affected by heat waves. Overall the hot drought produced the lowest leaf photosynthesis, AGB and ecosystem CO2 fluxes although the interactions between heat wave and drought were usually not significant. Our results highlight that the functional group compensatory effects that maintain community-level AGB rely on feedback of root system responses, and that plant adjustments at the individual level, together with shifts in composition at the functional group level, co-regulate ecosystem carbon sink strength under climate extremes.

Transcriptome analysis and association mapping reveal the genetic regulatory network response to cadmium stress in Populus tomentosa.

Long non-coding RNAs (lncRNAs) play essential roles in plant abiotic stress responses, but the response of lncRNA-mediated genetic networks to cadmium (Cd) treatment remain elusive in trees, the promising candidates for phytoremediation of Cd contamination. We identified 172 Cd-responsive lncRNAs and 295 differentially expressed target genes in the leaves of Cd-treated Populus tomentosa. Functional annotation revealed that these lncRNAs were involved in various processes, including photosynthesis, hormone regulation, and phenylalanine metabolism. Association studies identified 78 significant associations, representing 14 Cd-responsive lncRNAs and 28 target genes for photosynthetic and leaf physiological traits. Epistasis uncovered 83 pairwise interactions among these traits, revealing Cd-responsive lncRNA-mediated genetic networks for photosynthesis and leaf physiology in P. tomentosa. We focused on the roles of two Cd-responsive lncRNA-gene pairs, MSTRG.22608.1-PtoMYB73 and MSTRG.5634.1-PtoMYB27, in Cd tolerance of Populus, and detected insertions/deletions within lncRNAs as polymorphisms driving target gene expression. Genotype analysis of lncRNAs and heterologous overexpression of PtoMYB73 and PtoMYB27 in Arabidopsis indicated their effects on enhancing Cd tolerance, photosynthetic rate, and leaf growth, and the potential interaction mechanisms of PtoMYB73 with abiotic stresses. Our study identifies the genetic basis for the response of Populus to Cd treatment, facilitating genetic improvement of Cd tolerance in trees.

Root anatomical traits determined leaf-level physiology and responses to precipitation change of herbaceous species in a temperate steppe.

Root anatomy plays important roles in the control of leaf water relations. However, few studies have evaluated whether and how anatomical traits of absorptive roots influence leaf physiology of herbaceous species in a temperate grassland. We measured absorptive root anatomical traits and leaf physiological traits of 15 herbaceous species in a temperate steppe and monitored their responses to increased precipitation in a field stimulating experiment. Root anatomical and leaf physiological traits differed among monocotyledonous grasses, monocotyledonous liliaceous species and dicotyledonous forbs. The species with higher stele: root diameter, lower root diameter and cortex thickness exhibited higher transpiration rates and stomatal conductance, but lower intrinsic water-use efficiency. Increased precipitation enhanced transpiration and stomatal conductance of forbs and lilies, but it enhanced photosynthesis in lilies exclusively. The sensitive response of lilies to precipitation may be related to their large root diameter and cortex thickness. In summary, we observed distinct differences in anatomical traits of absorptive roots among plant groups in temperate steppes. These differences drove variations in leaf physiological traits and their diverse responses to precipitation change. These findings highlight the important roles of root anatomical traits in driving leaf-level physiological processes in temperate grasslands.

Seasonal variations in the relationship between sun-induced chlorophyll fluorescence and photosynthetic capacity from the leaf to canopy level in a rice crop.

Photosynthetic capacity (leaf maximum carboxylation rate, Vcmax) is a critical parameter for accurately assessing carbon assimilation by plant canopies. Recent studies of sun-induced chlorophyll fluorescence (SIF) have shown potential for estimating Vcmax at the ecosystem level. However, the relationship between SIF and Vcmax at the leaf and canopy levels is still poorly understood. In this study, we investigated the dynamic relationship between SIF and Vcmax and its controlling factors using SIF and CO2 response measurements in a rice paddy. We found that SIF and its yield (SIFy) were strongly correlated with Vcmax during the growing season, although the relationship varied with plant growth stages. After flowering, SIFy showed a stronger relationship with Vcmax than SIF flux at both the leaf and canopy levels. Further analysis suggested that the divergence of the link between SIF and Vcmax from leaf to canopy are the result of changes in canopy structure and leaf physiology, highlighting that these need to be considered when interpreting the SIF signal across spatial scales. Our results provide evidence that remotely sensed SIF observations can be used to track seasonal variations in Vcmax at the leaf and canopy levels.

Single and combined effects of heat and water stress and recovery on cotton (Gossypium hirsutum L.) leaf physiology and sucrose metabolism.

High temperatures and water-deficit stress limit cotton production around the world. Their individual effects on plant physiology and metabolism have been extensively studied, however, their combination has received considerably less attention. To that end, growth chamber experiments were conducted using cotton (Gossypium hirsutum L.) cultivar ST5288B2F and the objectives were to discern physiological and metabolic alterations after heat and water stress application (single or combined) and recovery, during cotton's vegetative stage. Under water stress conditions, leaf physiological parameters were suppressed and changes in carbohydrate levels, due to alterations in sucrose-metabolizing enzymes activities, were observed. Heat stress alone increased carbohydrate content, and activities of sucrose-degrading enzymes, while leaf physiology remained unaffected. The combined stress did exacerbate decreases in leaf water potential and soluble acid invertase activity, but the rest of the responses were similar to those of water stress. After stress alleviation, leaf physiological parameters of water-stressed plants did not manage to recover and substantial decreases were observed in leaf starch levels and activities of sucrose-cleaving enzymes, while the majority of parameters of heat-shocked plants returned to control levels. Recovery of the plants subjected to the combined stress was comparable to that of water-stressed plants, but significant differences were observed in carbohydrate levels and sucrose synthase activity. Our study demonstrated that under combined stress and post-stress conditions, water stress was the dominant factor affecting cotton leaf physiology and sucrose metabolism, highlighting however, the unique responses of some traits that could not be deduced from the additive effects of the single stresses.

Effect of Different Rates of Nitrogen Fertilization on Crop Yield, Soil Properties and Leaf Physiological Attributes in Banana Under Subtropical Regions of China.

Excessive nitrogen (N) application is widespread in Southern China. The effects of N fertilization on soil properties and crop physiology are poorly understood in tropical red loam soil. We conducted a field experiment to evaluate the effect of nitrogen fertilization rates on physiological attributes (chlorophyll, plant metabolic enzymes, soluble matters) on banana leaves, soil properties (soil enzymes, soil organic matter (SOM), soil available nutrients) as well as banana crop yield in a subtropical region of southern China. The N rates tested were 0 (N0), 145 (N145), 248 (N248), 352 (N352), 414 (NFT), and 455 (N455) g N per plant. The correlations among soil factors, leaf physiological factors and crop yield were evaluated. The results indiated that the high rates of N fertilization (NFT and N455) significantly decreased soil available potassium (K) content, available phosphorus (P) content, glutamine synthetase (GS) activity, and soluble protein and sugar contents compared with lower N rates. The N352 treatment had the highest crop yields compared with higher N rates treatments, followed by the N455 treatment. However, there were no significant differences in crop yields among N fertilization treatments. Factor analysis showed that the N352 treatment had the highest integrated score for soil and leaf physiological factors among all treatments. Moreover, the N352 treatment was the most effective in improving carbon and nitrogen metabolism in banana. Crop yield was significantly and positively linearly correlated with the integrated score (r = 0.823, p < 0.05). Path analysis revealed that invertase, SOM and sucrose synthase (SS) had a strong positive effect on banana yield. Canonical correspondence analysis (CCA) suggested that available K, invertase, acid phosphatase and available P were the most important factors impacting leaf physiological attributes. Cluster analysis demonstrated distinct differences in N application treatment related to variations in soil and leaf factors. This study suggested that excessive N fertilization had a negative effect on soil fertility, crop physiology and yield. The lower N rates were more effective in improving crop yield than higher rates of N fertilization. The N rate of 352 g N per plant (N352) was recommended to reduce excess N input while maintaining the higher yield for local farmers' banana planting.

Leaf age effects on the spectral predictability of leaf traits in Amazonian canopy trees.

Recent work has shown that leaf traits and spectral properties change through time and/or seasonally as leaves age. Current field and hyperspectral methods used to estimate canopy leaf traits could, therefore, be significantly biased by variation in leaf age. To explore the magnitude of this effect, we used a phenological dataset comprised of leaves of different leaf age groups -developmental, mature, senescent and mixed-age- from canopy and emergent tropical trees in southern Peru. We tested the performance of partial least squares regression models developed from these different age groups when predicting traits for leaves of different ages on both a mass and area basis. Overall, area-based models outperformed mass-based models with a striking improvement in prediction observed for area-based leaf carbon (Carea) estimates. We observed trait-specific age effects in all mass-based models while area-based models displayed age effects in mixed-age leaf groups for Parea and Narea. Spectral coefficients and variable importance in projection (VIPs) also reflected age effects. Both mass- and area-based models for all five leaf traits displayed age/temporal sensitivity when we tested their ability to predict the traits of leaves of other age groups. Importantly, mass-based mature models displayed the worst overall performance when predicting the traits of leaves from other age groups. These results indicate that the widely adopted approach of using fully expanded mature leaves to calibrate models that estimate remotely-sensed tree canopy traits introduces error that can bias results depending on the phenological stage of canopy leaves. To achieve temporally stable models, spectroscopic studies should consider producing area-based estimates as well as calibrating models with leaves of different age groups as they present themselves through the growing season. We discuss the implications of this for surveys of canopies with synchronised and unsynchronised leaf phenology.

Coping with drought: stress and adaptive mechanisms, and management through cultural and molecular alternatives in cotton as vital constituents for plant stress resilience and fitness.

Increased levels of greenhouse gases in the atmosphere and associated climatic variability is primarily responsible for inducing heat waves, flooding and drought stress. Among these, water scarcity is a major limitation to crop productivity. Water stress can severely reduce crop yield and both the severity and duration of the stress are critical. Water availability is a key driver for sustainable cotton production and its limitations can adversely affect physiological and biochemical processes of plants, leading towards lint yield reduction. Adaptation of crop husbandry techniques suitable for cotton crop requires a sound understanding of environmental factors, influencing cotton lint yield and fiber quality. Various defense mechanisms e.g. maintenance of membrane stability, carbon fixation rate, hormone regulation, generation of antioxidants and induction of stress proteins have been found play a vital role in plant survival under moisture stress. Plant molecular breeding plays a functional role to ascertain superior genes for important traits and can offer breeder ready markers for developing ideotypes. This review highlights drought-induced damage to cotton plants at structural, physiological and molecular levels. It also discusses the opportunities for increasing drought tolerance in cotton either through modern gene editing technology like clustered regularly interspaced short palindromic repeat (CRISPR/Cas9), zinc finger nuclease, molecular breeding as well as through crop management, such as use of appropriate fertilization, growth regulator application and soil amendments.

Impact assessment of leaf pigments in selected landscape plants exposed to roadside dust.

Continuous addition of undesired effluents to the environment affects foliar surface of leaf, changes their morphology, stomata, photosynthetic pigments, and biochemical constituents which result in massive damage due to persistent nature of the pollutant. In persistent hostile environment, plants fail to grow and develop, and the effects are often extensive. In current study, landscape plants were exposed to different levels of road dust to analyze the effect on various photosynthetic pigments. Dry roadside sediments were collected through a vacuum pump and passed through filters to get fine particles less than 100 µm and sprinkled on Euphorbia milii (EM), Gardenia jasminoides (GJ), and Hibiscus rosa-sinensis (HRs) by using a hand pump, twice daily at T1 (control), T2, T3, and T4 (0, 2, 4, and 6 g/plant, respectively) for a period of 3 months in green house. Road sediment significantly reduces leaf pigments in landscape plants population and the effects were more severe in high level of dust deposition. Individual response of EM, GJ, and HRs to different levels of road dust was variable; however, road sediment significantly reduces leaf pigments at high dose of roadside dust deposition. EM plants exposed to 2 g/plant roadside dust showed higher chlorophyll-a, chlorophyll-b, total chlorophyll, chlorophyllide-b, and polar carotenoid contents as compared to GJ and HRs. Leaf chlorophyll-a, chlorophyll-b, total chlorophyll, carotenoid, and polar carotenoid contents of EM were higher than GJ and HRs in T3 and T4 treatments. However HRs showed significantly higher protochlorophyllide, chlorophyllide-a, and pheophytin-b contents of leaf in T4 group. EM was found as tolerant landscape plant followed by HRs. GJ was most vulnerable to road dust stress. Present study concludes that the entire biosynthesis of leaf pigments is in chain and interlinked together where effect of road dust on one pigment influences other pigments and their derivatives. Salient features of the present study provide useful evidence to estimate roadside dust as a major risk factor for plant pigments, and plants in green belt along roadside suffer retarded growth and fail to establish and develop.

Coping with drought: stress and adaptive mechanisms, and management through cultural and molecular alternatives in cotton as vital constituents for plant stress resilience and fitness

Increased levels of greenhouse gases in the atmosphere and associated climatic variability is primarily responsible for inducing heat waves, flooding and drought stress. Among these, water scarcity is a major limitation to crop productivity. Water stress can severely reduce crop yield and both the severity and duration of the stress are critical. Water availability is a key driver for sustainable cotton production and its limitations can adversely affect physiological and biochemical processes of plants, leading towards lint yield reduction. Adaptation of crop husbandry techniques suitable for cotton crop requires a sound understanding of environmental factors, influencing cotton lint yield and fiber quality. Various defense mechanisms e.g. maintenance of membrane stability, carbon fixation rate, hormone regulation, generation of antioxidants and induction of stress proteins have been found play a vital role in plant survival under moisture stress. Plant molecular breeding plays a functional role to ascertain superior genes for important traits and can offer breeder ready markers for developing ideotypes. This review highlights drought-induced damage to cotton plants at structural, physiological and molecular levels. It also discusses the opportunities for increasing drought tolerance in cotton either through modern gene editing technology like clustered regularly interspaced short palindromic repeat (CRISPR/Cas9), zinc finger nuclease, molecular breeding as well as through crop management, such as use of appropriate fertilization, growth regulator application and soil amendments.

Mitigation of salt stress in white clover (Trifolium repens) by Azospirillum brasilense and its inoculation effect.

BACKGROUND: Salinity is one of the increasingly serious environmental problems worldwide for cultivating agricultural crops. The present study was aimed to ascertain the potential of beneficial soil bacterium Azospirillum brasilense to alleviate saline stress in Trifolium repens. Experimental plants (white clover) were grown from seeds and inoculated with or without A. brasilense bacterial strain supplemented with 0, 40, 80, or 120 mM NaCl into soil. RESULTS: The growth attributes including, shoot heights, root lengths, fresh and dry weights, leaf area and chlorophyll content were significantly enhanced in T. repens plants grown in A. brasilense inoculated soil than un-inoculated controls, particularly under elevated salinity conditions (40, 80 and 120 mM NaCl). Malondialdehyde content of leaf was recorded to be declined under saline conditions. Moreover, the K+/Na+ ratio was also improved in bacterium-inoculated plants, since A. brasilense significantly reduced the root and shoot Na+ level under high salty environment. CONCLUSIONS: Results revealed that soil inoculation with A. brasilense could significantly promote T. repens growth under both non-saline and saline environments, and this study might be extended to other vegetables and crops for the germination and growth enhancement.