Oxidative stress defence responses of wheat (Triticum aestivum L.) and chilli (Capsicum annum L.) cultivars grown under textile effluent fertilization

Unravelling drought and salinity stress responses in barley genotypes: physiological, biochemical, and molecular insights

In the face of escalating environmental challenges, understanding crop responses to abiotic stress is pivotal for sustainable agriculture. The present study meticulously investigates the intricate interplay between drought and salinity stress in barley (Hordeum vulgare L.). Employing three distinct barley genotypes-Traveller, Prunella, and Zahna-we scrutinize their physiological, biochemical, and molecular adaptations under stress conditions. Our findings underscore genotype-specific responses, unravelling the multifaceted mechanisms that govern stress tolerance. Chlorophyll content, a vital indicator of photosynthetic efficiency, exhibits significant variations across genotypes. Salinity stress induces a decline in chlorophyll levels, while drought stress triggers a more nuanced response. Stomatal conductance, a key regulator of water loss, also diverges among the genotypes. Traveller displays remarkable stomatal closure under drought, conserving water, whereas Prunella and Zahna exhibit contrasting patterns. Antioxidant enzyme activities, crucial for combating oxidative stress, fluctuate significantly. Activities of superoxide dismutase (SOD) and catalase (CAT) surge under salinity stress, while drought predominantly impacts SOD. Gene expression profiling reveals genotype-specific signatures, with stress-responsive genes modulating adaptive pathways. Correlation analyses revealed the intricate interplay of the physiological and biochemical parameters. Genotype-specific adaptations, coupled with dynamic physiological and molecular responses, underscore the plasticity of barley's stress tolerance mechanisms. Throughout the study, the Zahna genotype demonstrated notable tolerance in terms of performance. These insights hold promise for breeding resilient cultivars, bolstering food security in an increasingly unpredictable climate. By deciphering the barley stress symphony, we contribute to the harmonious orchestration of sustainable agricultural practices.

Salinity-driven nitrogen removal and bacteria community compositions in microbial fuel cell-integrated constructed wetlands

The effects of salinity gradients (500-4000 mg·L-1 NaCl) on electricity generation, nitrogen removal, and microbial community were investigated in a constructed wetland-microbial fuel cell (CW-MFC) system. The result showed that power density significantly increased from 7.77 mW m-2 to a peak of 34.27 mW m-2 as salinity rose, indicating enhanced electron transfer capabilities under saline conditions. At a moderate salinity level of 2000 mg·L-1 NaCl, the removal efficiencies of NH4+-N and TN reached their maximum at 77.34 ± 7.61% and 48.45 ± 8.14%, respectively. This could be attributed to increased microbial activity and the presence of critical nitrogen-removal organisms, such as Nitrospira and unclassified Betaproteobacteria at the anode, as well as Bacillus, unclassified Rhizobiales, Sphingobium, and Simplicispira at the cathode. Additionally, this salinity corresponded with the highest abundance of Exiguobacterium (3.92%), a potential electrogenic bacterium, particularly at the cathode. Other microorganisms, including Geobacter, unclassified Planctomycetaceae, and Thauera, adapted well to elevated salinity, thereby enhancing both electricity generation and nitrogen removal.

Genetic Regulation, Environmental Cues, and Extraction Methods for Higher Yield of Secondary Metabolites in Capsicum

Capsicum (chili pepper) is a widely popular and highly consumed fruit crop with beneficial secondary metabolites such as capsaicinoids, carotenoids, flavonoids, and polyphenols, among others. Interestingly, the secondary metabolite profile is a dynamic function of biosynthetic enzymes, regulatory transcription factors, developmental stage, abiotic and biotic environment, and extraction methods. We propose active manipulable genetic, environmental, and extraction controls for the modulation of quality and quantity of desired secondary metabolites in Capsicum species. Specific biosynthetic genes such as Pun (AT3) and AMT in the capsaicinoids pathway and PSY, LCY, and CCS in the carotenoid pathway can be genetically engineered for enhanced production of capsaicinoids and carotenoids, respectively. Generally, secondary metabolites increase with the ripening of the fruit; however, transcriptional regulators such as MYB, bHLH, and ERF control the extent of accumulation in specific tissues. The precise tuning of biotic and abiotic factors such as light, temperature, and chemical elicitors can maximize the accumulation and retention of secondary metabolites in pre- and postharvest settings. Finally, optimized extraction methods such as ultrasonication and supercritical fluid method can lead to a higher yield of secondary metabolites. Together, the integrated understanding of the genetic regulation of biosynthesis, elicitation treatments, and optimization of extraction methods can maximize the industrial production of secondary metabolites in Capsicum.

Role of Elevated Ozone on Development and Metabolite Contents of Lemongrass [Cymbopogon flexuosus (Steud.) (Wats.)]

The present study was conducted to assess the effect of elevated ozone stress on the development and metabolite contents of lemongrass, a medicinal plant. The experimental plant was exposed to two elevated ozone concentrations (ambient + 15 ppb, and ambient + 30 ppb) using open-top chambers. Samplings were carried out at 45 and 90 days after transplantation (DAT), for the analysis of different characteristics, while the metabolite contents of leaves and essential oils were analyzed at 110 DAT. Both the doses of elevated ozone had notable negative effects on the carbon fixation efficiency of plants, resulting in a significant reduction in plant biomass. Enzymatic antioxidant activity increased during the second sampling, which suggests that the scavenging of reactive oxygen species was more prominent in lemongrass during the later developmental stage. The results of the present study showed a stimulated diversion of resources towards the phenylpropanoid pathway, which is made evident by the increase in the number and contents of metabolites in foliar extract and essential oils of plants grown at elevated ozone doses, as compared to ambient ozone. Elevated ozone not only upregulated the contents of medicinally important components of lemongrass, it also induced the formation of some pharmaceutically active bio compounds. On the basis of this study, it is expected that increasing ozone concentrations in near future will enhance the medicinal value of lemongrass. However, more experiments are required to validate these findings.

Assessing the Cooling and Air Pollution Tolerance among Urban Tree Species in a Tropical Climate

We present the results of classifying plants at species level that can tolerate air pollution, provide cooling, and simultaneously survive and thrive in urban environments. For this purpose, we estimated the air pollution tolerance index (APTI) and anticipated performance index (API) of several species growing in a park located in central Bangkok, Thailand. The cooling effect was quantified by calculating the reduction in soil and air temperatures. Melaleuca quinquenervia (Cav.) S.T. Blake, Albizia saman (Jacq.) Merr., Chukrasia tabularis A. Juss. had the highest API score and were able to substantially reduce the temperature and were in a group of highly recommended species which also included other species like A. saman, C. tabularis, Tabebuia rosea (Bertol.) Bertero ex A. DC., Dalbergia cochinchinensis Pierre etc. Species from both evergreen and deciduous habitat were able to provide ambient cooling but were vulnerable to air pollution and included Elaeocarpus grandifloras Sm. and Bauhinia purpurea L. However, there were other species which had a high air pollution tolerance but failed to provide adequate cooling, such as Hopea odorata Roxb. and Millingtonia hortensis L.f. The results would be of interest to urban greenspace landscapers in such climates while selecting suitable species that can provide multiple ecosystem services ranging from air pollution tolerance to temperature reduction without reducing plant vitality.

Urban dust pollution tolerance indices of selected plant species for development of urban greenery in Delhi

The rise in urbanization has led to an increase in dust pollution which is hazardous to the health of living beings. The role of roadside plant species in intercepting particulate matter and improving air quality is well reported. Hence, this study was carried out to determine the ability of various plant species to intercept atmospheric dust and withstand the abiotic stress triggered by dust deposition. In the present investigation, three sites (viz., control, commercial, and industrial) differing in anthropogenic activities and vegetation were selected. Sixteen plant species entailing both trees and shrubs that are commonly occurring at all three sites were selected to estimate their dust interception capacity (DIC). The impact of dust pollution on foliage biochemistry and their tolerance in winter and summer seasons were analyzed. Based on biochemical, biological, and socio-economic parameters, air pollution tolerance index (APTI) and anticipated performance index (API) were evaluated. Both dust load and DIC were found to be two times higher in winter than in the summer season. Terminalia arjuna, Ficus benghalensis, and Plumeria alba were the best dust accumulators, while Prosopis juliflora accumulated least. The highest DIC was observed at the industrial site, for Terminalia arjuna (0.025 mg/cm²/d) in winter and Plumeria alba (0.023 mg/cm²/d) in the summer season. Photosynthetic pigments showed a negative correlation with dust load, while pH, ascorbic acid, electrolytic leakage (E.L.), and proline content showed a positive correlation. In the present study, APTI and API values were highest for Ficus religiosa, Ficus benghalensis, Alstonia scholaris, Dalbergia sissoo, and Terminalia arjuna. Such plant species with wide canopy, large and rough leaf surface area with perforated veins are found to be more suitable and, hence, recommended for the development of greenery to improve air quality in urban areas like Delhi.

Evaluation of cytotoxicity and genotoxicity effects of refractory pollutants of untreated and biomethanated distillery effluent using Allium cepa

Environmental pollution caused by the discharge of raw and partly treated distillery effluent has become a serious and threatening problem due to its high pollution load. The aim of the present study was to assess the physicochemical load in alcohol distillery effluent before and after biomethanation treatment and the cyto- and genotoxicity effects of refractory pollutants emanated in raw/untreated and biomethanated distillery effluent on the ultrastructural and biochemical responses of Allium cepa root tip cells. Physicochemical analysis revealed high biochemical oxygen demand (BOD: 47840-36651 mg L^-1), chemical oxygen demand (COD: 93452-84500 mg L^-1) and total dissolved solids (TDS: 64251-74652 mg L^-1) in raw and biomethanated effluent along with metal(loid)s (Fe: 456.152-346.26; Zn: 1.654-1.465; Cu: 0.648-0.562; Ni: 1.012-0.951, and Pb: 0.264 mg L^-1) which were beyond the safe discharge values prescribed by the environmental regulatory agencies. The UV-Visible and Fourier transform infrared spectrophotometry analyses confirmed the high levels of organic, inorganic, and mixed contaminants discharged in raw and biomethanated distillery effluents. Furthermore, GC-MS analysis characterised chemical contaminants, such as hexadecanoic acid, butanedioic acid, bis(trimethylsilyl) ester; hexadecane, 2,6,11,15-tetramethyl, stigmasterol, and β-sitosterol trimethylsilyl ether that have been reported as androgenic-mutagenic, and endocrine disrupting chemicals by the United States Environmental Protection Agency (U.S. EPA). The cytotoxicity measured by A. cepa showed dose depended inhibition root growth inhibition and simultaneous reduction in mitotic index in tested effluents. The chromosomal aberrations studies resulted in laggard chromosomes, sticky chromosomes, vagrant chromosomes, chromosome loss, c-mitosis, chromosome bridge, abnormal metaphase, and disturbed anaphase as found in a dose-dependent manner. Furthermore, dose-dependent enhancement in the levels of malondialdehyde, hydrogen peroxide, and antioxidative enzymes, such as superoxide dismutase, ascorbate peroxidase, and catalase were found to be higher in raw effluents treated root cells compared to biomethanated distillery effluent. Analysis of ultrastructural changes in root tip cells by TEM analysis revealed dramatic changes in the morphology of cell organelles and accumulation of metallic elements in and on the surface tissues. The results concluded that the discharged distillery effluents retained certain toxic pollutants which imposed cytotoxic and genotoxic hazards to A. cepa. Thus, for the sake of environmental protection, the raw as well as the disposed biomethanated effluent must be efficiently treated before its dumping into the terrestrial ecosystem.

Understanding drought response mechanisms in wheat and multi-trait selection

Wheat crop is very sensitive to osmotic stress conditions. As an abiotic stress, drought may exert a considerable effect on the levels of specialized metabolites in plants. These metabolites may exert beneficial biological activities in the prevention or treatment of disorders linked to oxidative stress in plants and humans. Furthermore, osmoprotector accumulation helps wheat to increase the maintenance of osmotic balance. Therefore, identifying wheat genotypes with better drought tolerance is extremely important. In this sense, this research aimed to understand agronomic, physiological and biochemical responses of spring wheat strains and cultivars to drought stress, under field conditions, and jointly select strains via multi-trait index. We evaluated agronomic, physiological and biochemical variables in 18 genotypes under field condition. The results demonstrated that all variables were affected by the drought. Most genotypes were significantly reduced in grain yield, except VI_14774, VI_14668, VI_9007 and TBIO_ATON. The variables related to photosynthesis were also affected. An increase above 800% was observed in proline contents in genotypes under drought. Sodium and potassium also increased, mainly for VI_131313 (Na), while VI_130758 and VI_14774 presented increased K. We evaluated the antioxidant potential of the different strains and the total content of phenolic compounds. The most drought-responsive genotypes were BRS_264, VI_14050 and VI_14426. Reduced grain yield and photosynthetic variables, and increased specialized metabolism compounds are due to plant defense mechanisms against drought conditions. Furthermore, variation in genotypes can be explained by the fact that each plant presents a different defense and tolerance mechanism, which may also occur between genotypes of the same species. Four strains were selected by the multivariate index: VI_14055, VI_14001, VI_14426 and VI_1466. Such results allow us to predict which genotype(s) performed best in semi-arid environments and under climatic fluctuations.

Environmental pollution, toxicity profile, and physico-chemical and biotechnological approaches for treatment of textile wastewater

Textile industries discharges a huge quantity of unused synthetic dyes in wastewater leading to increased environmental pollution and pose a great risk to human health. Thus, a significant improvement in effluent quality is required before it is discharged into the environment. Although, several physicochemical methods have been practiced for the efficient color and dyes removal from textile effluents, these approaches have some drawbacks of greater use of expensive chemicals, low sensitivity, formation of excess sludge which also have secondary disposal problem. Thus, there is still a need for energy efficient, affordable, effective, and environmentally friendly treatment technologies. Bioremediation has been considered as a promising an upcoming active field of research for the treatment of unwanted color and target compounds from the contaminated environment. In order to efficient treatment of textile effluent, the main objective of the present study was to isolate and characterize the indigenous microbial isolates from textile industry effluents and sludge samples and investigate their dye removal and decolorization ability along with the influence of various process parameters on effluents decolorization that draining into the open environment.

The Stimulation of Superoxide Dismutase Enzyme Activity and Its Relation with the Pyrenophora teres f. teres Infection in Different Barley Genotypes

Changes in superoxide dismutase (SOD) enzyme activity were examined in infected barley seedlings of five cultivars with the goal to study the role of SOD in the defense mechanism induced by Pyrenophora teres f. teres (PTT) infection. Our results showed that although there were differences in the responses of the cultivars, all three PTT isolates (H-618, H-774, H-949) had significantly increased SOD activity in all examined barley varieties at the early stages of the infection. The lowest SOD activity was observed in the case of the most resistant cultivar. Our results did not show a clear connection between seedling resistance of genotypes and SOD enzyme activity; however, we were able to find strong significant correlations between the PTT infection scores on the Tekauz scale and the SOD activity. The measurement of the SOD activity could offer a novel perspective to detect the early stress responses induced by PTT. Our results suggest that the resistance of varieties cannot be estimated based on SOD enzyme activity alone, because many antioxidant enzymes play a role in fine-tuning the defense response, but SOD is an important member of this system.

Assessment of ozone toxicity on cotton (Gossypium hirsutum L.) cultivars: Its defensive system and intraspecific sensitivity

Anthropogenic activities help the ozone formation at the troposphere which causes toxic effects on plants and humans. Ozone is a highly reactive gas that enters in plants through stomata and initiates the overproduction of ROS which causes oxidative stress in plants that lead to the destruction of membranal lipids, proteins, impaired the production of sugars and other metabolites and ultimately damage the cell. Presented study was conducted to assess the ozone toxicity on the biomass accumulation of cotton (Gossypium hirsutum L.) cultivars and the role of antioxidative activity in intraspecific sensitivity among the tested cultivars. Results showed that the ozone exposed plants have higher accumulation of H₂O₂ and MDA correspond to the EDU supplementation which increase the membrane permeability and adversely influence the protein, starch, and biomass accumulation and allocation of the experimental cotton cultivars. On the basis of biomass reduction, cotton cultivar ADC1 is the most sensitive cultivar, while cultivars G. Cot.21 > GADC-2 and G. Cot.13 is moderately sensitive and cultivar V-797 is the least sensitive to ozone stress. Activated defense mechanism such as enhanced activity of antioxidative compounds and enzymes detoxify the ROS by scavenging H₂O₂ and protects plants against damage. However, activation of defence is variable among the cultivars and corresponded to the biomass loss. Study concluded that the ozone sensitivity among the cotton cultivars depends on the scavenging of ROS. Further, study recommended cultivar ADC-1 as an assessment tool for ozone and cultivar V-797 for cultivation at ozone prone areas to minimize the agricultural loss.

Role of textile effluent fertilization with biosurfactant to sustain soil quality and nutrient availability

The textile industry is one of the world's most pollution generating industries, and management of its toxic effluent has become a global issue. However, the use of textile effluent as source of nutrients can be a viable option due to the presence of some essential minerals, although the presence of several toxic elements can deteriorate soil health. Therefore, experiments were conducted to identify the potential of textile effluent fertilization together with biosurfactant amendment to increase the soil health and nutrient status for agricultural sustainability. In this study, soil fertilized with different concentrations of textile effluent treatments (i.e. T1A, T2A and T3A) was treated with two different concentrations of biosurfactants to accurately appraise the suitability of a set of soil quality parameters including, physical, chemical, biochemical, and biological activities. A thorough analysis of all soil health parameters was undertaken before sowing the seeds and after cultivation of either Triticum aestivum (cv. LOK-1 and GW-496) or Capsicum annum (cv. GVC-101 and GVC-121). The results indicated that lower concentrations of textile effluent are a good source of nutrients while biosurfactants served as good solubilizers of metals and made it more available at the higher effluent concentration (T2C). Under these conditions, not only did fertilizers significantly increased, but also the microbial population as well as the enzymatic activity of soil was enhanced. Lower concentrations of micronutrients in the soil after crop cultivation is attributed to the higher level of their availability to the plants during their growth and development. This study provides new insight into the biosurfactants application to enhance soil micronutrients availability and increase crop productivity using textile effluents as a source of nutrients.

Role of transitory starch on growth, development and metal accumulation of Triticum aestivum cultivars grown under textile effluent fertilization

Accumulation of transitory starch in leaves is an environment-dependent multifaceted process affected through stress caused by nutrient deficiency or excess of heavy metals in growing medium. On the other hand, textile effluent is one of the major pollution causing industrial waste due to the presence of heavy metal and organic contaminants. Besides the presence of higher pollution load, this effluent also contains some minerals essential for plant growth and metabolism and can serve as source of nutrients to plants. In presented experiment, a mesocosm study was conducted to evaluate the phenotypic, biochemical performance and trace element status of Triticum aestivum (cv. LOK-101 and GW-496) cultivars in response to transitory starch activity grown under textile effluent fertilization. Improved activity of transitory starch under textile effluent fertilization deals with plant growth by providing carbon in the form of soluble sugar. Study also finds a strong correlation of photosynthetic pigments, carbohydrates and plant biomass to transitory starch. As expected, the elemental concentration (Zn, Cu, Mn, Fe, Co, Pb, Cd, and As) in plants increased with increasing dose of textile effluent. The study concluded that the transitory starch is one of the key components in plant leaves that regulate plant growth under stress condition. Furthermore, the study also concluded that the lower dose of textile effluent significantly favours growth and nutrient status of plants without any negative impact. Therefore, the application of lower concentration of textile effluent as basal dose in agriculture may serve as source of nutrient/micronutrient to plants and also can be a sustainable way for effluent management.

Manganese accumulation and plant physiology behavior of Camellia oleifera in response to different levels of potassium fertilization

The effects of potassium (K) fertilization (KCl, analytically pure; 0, 60, 200, and 400 mg kg^-1) on the growth and Mn accumulation of Camellia oleifera in two types of Mn-contaminated soils were investigated. The potential mechanisms underlying the impacts of K fertilization were explored. C. oleifera accumulated high amounts of Mn in both soil conditions. The addition of K fertilizer decreased the soil pH and promoted Mn accumulation in C. oleifera. However, the plant biomass decreased significantly under the high level of K fertilization (400 mg kg^-1), and the oxidative stress was stimulated under Mn contamination. But an appropriate concentration of K fertilizer (200 mg kg^-1) was necessary for the formation of photosynthesis pigments, nonenzymatic antioxidants and antioxidant enzymes, metabolic processes, and nutrient uptake. Furthermore, when plants supplemented with a low level of K fertilization (200 mg kg^-1), the catalase activity in C. oleifera leaves was enhanced to alleviate oxidative stress and protect the plant from Mn contamination. Our study demonstrated that 200 mg kg^-1 of K fertilizer has the potential to further enhance the efficiency of Mn phytoremediation by C. oleifera.

Impact assessment of azulene and chromium on growth and metabolites of wheat and chilli cultivars under biosurfactant augmentation

Dye azulene and heavy metal chromium are two different types of persistent toxic compounds present in textile effluent. These compounds contaminate the soil and harm plant productivity during unchecked disposal of textile effluent to the farm soil. Environmental and safety concerns associated with crops, soil, and human health encourage the exploration of biological tools to control the issue. We hereby propose the application of biosurfactant (lipopeptide) to reduce the toxic effects of azulene and chromium in plants. Results of the study indicated that the augmentation of biosurfactant with azulene and chromium promoted seed germination, plant biomass, specific leaf weight (SLW), chlorophyll content, protein content, soluble sugar and ascorbic acid concentration in cultivars of wheat and chilli. Decreasing the level of proline under biosurfactant augmentation further confirms the reduction of oxidative stress caused by azulene and chromium amendment. The results indicated that lipopeptide biosurfactant could be an effective biological tool to reduce the toxic effect of persistent substances in soil, thus maintaining soil health and sustainable agriculture.