Alleviation of drought stress through foliar application of thiamine in two varieties of pea (Pisum sativum L.).

Drought stress poorly impacts many morphological and physio-biochemical processes in plants. Pea (Pisum sativum L.) plants are highly nutritious crops destined for human consumption; however, their productivity is threatened under drought stress. Thiamine (vitamin B1) is well-known essential micronutrient, acting as a cofactor in key metabolic processes. Therefore, this study was designed to examine the protective effect of foliar application of thiamine (0, 250, and 500 ppm) on two varieties of pea plants under drought stress. Here, we conducted the pot experiment at the Government College Women University, Faisalabad, to investigate the physio-biochemical and morphological traits of two pea varieties (sarsabz and metior) grown under drought stress and thiamine treatment. Drought stress was applied to plants after germination period of 1 month. Results showed that root fresh and dry weight, shoot fresh and dry weight, number of pods, leaf area, total soluble sugars, total phenolics, total protein contents, catalase, peroxidase, and mineral ions were reduced against drought stress. However, the application of thiamine (both 250 and 500 ppm) overcome the stress and also enhances these parameters, and significantly increases the antioxidant activities (catalase and peroxidase). Moreover, the performance of sarsabz was better under control and drought stress conditions than metior variety. In conclusion, the exogenous application of thiamine enabled the plants to withstand drought stress conditions by regulating several physiological and biochemical mechanisms. In agriculture, it is a great latent to alleviate the antagonistic impact of drought stress on crops through the foliar application of thiamine.

Zinc oxide nanoparticles as potential hallmarks for enhancing drought stress tolerance in wheat seedlings.

Drought is one of the major abiotic stresses which negatively affects plant growth and development. The current study evaluated the effects of drought on the growth, physiology, and biochemical attributes of wheat seedlings; and examined the role of foliar application of ZnO nanoparticles in alleviating drought-induced effects. Two wheat cultivars i.e., Anaj-2017 and FSD-2018 were grown in soil-filled pots and were subjected to 100% field capacity (FC) (well watered) and 50% of FC (drought stress). Whilst different treatments of ZnO nanoparticles spray included no spray, water spray, and 50, 100, and 150 ppm ZnO. Results demonstrated that drought caused a significant reduction in seedling fresh and dry weights, photosynthetic pigmentation, and antioxidant activities compared with a well-watered treatment. Nevertheless, the application of 100 and 150 ppm of ZnO nanoparticles effectively ameliorated the negative effects of drought and enhanced the performance of both cultivars under drought. Data revealed a significant increase in fresh and dry weight of shoot and root with the application of ZnO nanoparticles. A substantial increase of 73.68% and 28.51% in chlorophyll "a" and 26.15% and 50.02% in chlorophyll "b" was recorded with the application of 100 ppm of ZnO nanoparticles in Anaj-2017 and FSD-2018, respectively over control (0 ppm). The application of these nanoparticles also triggered the antioxidant defense system and protected the crop from oxidative damage. Averaged across different stress treatments, application of 150 and 100 ppm of ZnO nanoparticles increased the peroxidase activity by 60% and 72% in FSD-2018, and 15% and 23% in Anaj-2017, respectively compared with no spray. FSD-2018 outperformed Anaj-2017 regarding its overall performance under ZnO treatments and drought conditions. In a nutshell, it can be concluded that ZnO nanoparticles ameliorated the negative impacts of drought by improving the growth, physiology, and antioxidant defense of both wheat cultivars.

Impact of climate change on wheat grain composition and quality.

Wheat grain quality, an important determinant for human nutrition, is often overlooked when improving crop production for stressed environments. Climate change makes this task more difficult by imposing combined stresses. The scenarios relevant to climate change include elevated CO2 concentrations (eCO2 ) and extreme climatic events such as drought, heat waves, and salinity stresses. However, data on wheat quality in terms of climate change are limited, with no concerted efforts at the global level to provide an equitable and consistent climate risk assessment for wheat grain quality. Climate change induces changes in the quality and composition of wheat grain, a premier staple food crop globally. Climate-change events, such as eCO2 , heat, drought, salinity stress stresses, heat + drought, eCO2 + drought, and eCO2 + heat stresses, alter wheat grain quality in terms of grain weight, nutrient, anti-nutrient, fiber, and protein content and composition, starch granules, and free amino acid composition. Interestingly, in comparison with other stresses, heat stress and drought stress increase phytate content, which restricts the bioavailability of essential mineral elements. All climatic events, except for eCO2 + heat stress, increase grain gliadin content in different wheat varieties. However, grain quality components depend more on inter-varietal difference, stress type, and exposure time and intensity. The climatic events show differential regulation of protein and starch accumulation, and mineral metabolism in wheat grains. Rapid climate shifting impairs wheat productivity and causes grain quality to deteriorate by interrupting the allocation of essential nutrients and photoassimilates. © 2022 Society of Chemical Industry.

Diverse Physiological Roles of Flavonoids in Plant Environmental Stress Responses and Tolerance.

Flavonoids are characterized as the low molecular weight polyphenolic compounds universally distributed in planta. They are a chemically varied group of secondary metabolites with a broad range of biological activity. The increasing amount of evidence has demonstrated the various physiological functions of flavonoids in stress response. In this paper, we provide a brief introduction to flavonoids' biochemistry and biosynthesis. Then, we review the recent findings on the alternation of flavonoid content under different stress conditions to come up with an overall picture of the mechanism of involvement of flavonoids in plants' response to various abiotic stresses. The participation of flavonoids in antioxidant systems, flavonoid-mediated response to different abiotic stresses, the involvement of flavonoids in stress signaling networks, and the physiological response of plants under stress conditions are discussed in this review. Moreover, molecular and genetic approaches to tailoring flavonoid biosynthesis and regulation under abiotic stress are addressed in this review.

Effect of Salinity and Plant Growth Promoters on Secondary Metabolism and Growth of Milk Thistle Ecotypes.

Milk thistle (Silybum marianum (L.)) is a wild medicinal herbal plant that is widely used in folk medicine due to its high content of secondary metabolites (SMs) and silymarin; however, the data regarding the response of milk thistle to salinity are still scarce and scanty. The present study evaluated the effect of salinity on a geographically diverse population of milk thistle and on the role of medium supplementation (MS) with ascorbic acid, thiourea, and moringa leaf extract in improving the SMs and growth-related attributes under salinity stress (SS). For germination, a 120 mM level of salinity was applied in the soil during the seedling stage. After salinity development, predetermined levels of the following compounds were used for MS: thiourea (250 µM), moringa leaf extract (3%), and ascorbic acid (500 µM). The data regarding growth attributes showed that SS impaired plant growth and development and increased SM production, including alkaloids, anthocyanin, and saponins. Moreover, ascorbic acid, followed by moringa leaf extract, was the most effective in improving growth by virtue of increased SMs, especially under salt stress conditions. The present study demonstrated that milk thistle could withstand moderate doses of SS, while MS improved all the growth parameters by increasing the accumulation of SMs.

Appraisal of foliar spray of iron and salicylic acid under artificial magnetism on morpho-physiological attributes of pea (Pisum sativum L.) plants.

The appraisal of foliar treatment of iron (Fe) and salicylic acid (SA) on plant under artificial magnetism is very crucial in understanding its impact on growth and development of plants. The present study was designed to document the potential role of Fe and SA on pea (Pisum sativum L.) Matore variety exposed to different magnetism treatments (geomagnetism and artificial magnetism). Thus a pot experiment was conducted using Completely Randomized Design under factorial with three replicates. Various artificial magnetic treatment were applied in pots prior to sowing. Further, 15 days germinated pea seedlings were foliarly supplemented with 250 ppm Fe and 250µM SA, moreover after 20 days of foliar fertilization plants were harvested to analyze and record various morpho-physiological attributes. Data elucidate significant variations in pea plants among different treatments. Artificial magnetism treatments in combination with foliar application of Fe and SA significantly improved various growth attributes (root and shoot length, fresh and dry weights of root and shoot, leaf area), photosynthetic pigments (Chl a, b and carotenoids) and the contents of soluble sugars. However, oxidative stress (H2O2 and MDA) enhanced under different magnetism treatment but foliar application of Fe and SA hampered the production of reactive oxygen species thereby limiting the concentration of H2O2 and MDA in plant tissues. Furthermore the accumulation of nutrients (iron, potassium and nitrate) profoundly increased under artificial magnetism treatment specifically under Fe and SA foliar treatment excluding nitrate where Fe foliar treatment tend to limit nitrate in plant. Consequently, the present research interestingly highlights progressive role of Fe and SA foliar treatment on pea plants under artificial magnetism. Thus, foliar supplementation may be suggested for better growth and development of plants combined with magnetic treatments.

Assessment of Phenotypic Diversity in the USDA Collection of Quinoa Links Genotypic Adaptation to Germplasm Origin.

Quinoa's germplasm evaluation is the first step towards determining its suitability under new environmental conditions. The aim of this study was to introduce suitable germplasm to the lowland areas of the Faisalabad Plain that could then be used to introduce quinoa more effectively to that region. A set of 117 quinoa genotypes belonging to the USDA quinoa collection was evaluated for 11 phenotypic quantitative traits (grain yield (Y), its biological and numerical components plus phenological variables) in a RCBD during two consecutive growing seasons at the University of Agriculture, Faisalabad, Pakistan under mid-autumn sowings. Genotypic performance changed across the years, however most phenotypic traits showed high heritability, from 0.75 for Harvest Index (HI) to 0.97 for aerial biomass (B) and Y. Ordination and cluster analyses differentiated four groups dominated by genotypes from: Peru and the Bolivian Highlands (G1); the Bolivian Highlands (G2); the Ballón collection (regarded as a cross between Bolivian and Sea Level (Chilean) genotypes) plus Bolivian Highlands (G3); and Ballón plus Sea Level (G4), this latter group being the most differentiated one. This genetic structure shared similarities with previous groups identified using SSR markers and G×E data from an international quinoa test. G4 genotypes showed the highest Y associated with higher B and seed numbers (SN), while HI made a significant contribution to yield determination in G2 and seed weight (SW) in G3. G1 and G2 showed the lowest Y associated with a lower B and SN. Moreover, SW showed a strongly negative association with SN in G2. Accordingly, G4 followed by G3 are better suited to the lowland areas of Faisalabad plain and the physiological traits underlying yield determination among genotypic groups should be considered in future breeding programs.

Regulation of photosynthesis under salt stress and associated tolerance mechanisms.

Photosynthesis is crucial for the survival of all living biota, playing a key role in plant productivity by generating the carbon skeleton that is the primary component of all biomolecules. Salinity stress is a major threat to agricultural productivity and sustainability as it can cause irreversible damage to photosynthetic apparatus at any developmental stage. However, the capacity of plants to become photosynthetically active under adverse saline conditions remains largely untapped. This study addresses this discrepancy by exploring the current knowledge on the impact of salinity on chloroplast operation, metabolism, chloroplast ultrastructure, and leaf anatomy, and highlights the dire consequences for photosynthetic machinery and stomatal conductance. We also discuss enhancing photosynthetic capacity by modifying and redistributing electron transport between photosystems and improving photosystem stability using genetic approaches, beneficial microbial inoculations, and root architecture changes to improve salt stress tolerance under field conditions. Understanding chloroplast operations and molecular engineering of photosynthetic genes under salinity stress will pave the way for developing salt-tolerant germplasm to ensure future sustainability by rehabilitating saline areas.

Phytoremediation of nickel by quinoa: Morphological and physiological response.

The amount of soil contaminated with heavy metal increases due to urbanization, industrialization, and anthropogenic activities. Quinoa is considered a useful candidate in the remediation of such soil. In this pot experiment, the phytoextraction capacity of quinoa lines (A1, A2, A7, and A9) against different nickel (Ni) concentrations (0, 50, and 100 mg kg-1) were investigated. Required Ni concentrations were developed in polythene bags filled with sandy loam soil using nickel nitrate salt prior to two months of sowing and kept sealed up to sowing. Results showed that translocation of Ni increased from roots to shoots with an increase in soil Ni concentration in all lines. A2 line accumulated high Ni in leaf compared to the root as depicted by translocation factor 3.09 and 3.21 when grown at soil having 50 and 100 Ni mg kg-1, respectively. While, in the case of root, A7 accumulated high Ni followed by A9, A1, and A2, respectively. There was a 5-7% increased seed yield by 50 mg kg-1 Ni in all except A1 compared to control. However, growth and yield declined with a further increase in Ni level. The maximum reduction in yield was noticed in A9, which was strongly linked with poor physiological performance, e.g., chlorophyll a, b, and phenolic contents. Ni concentrations in the seed of all lines were within the permissible value set (67 ppm) by FAO/WHO. The result of the present study suggests that quinoa is a better accumulator of Ni. This species can provide the scope of decontamination of heavy metal polluted soil. The screened line can be used for future quinoa breeding programs for bioremediation and phytoextraction purpose.

Application of Zinc and Iron-Based Fertilizers Improves the Growth Attributes, Productivity, and Grain Quality of Two Wheat (Triticum aestivum) Cultivars.

Field-based experiments were conducted during wheat cultivation seasons of 2017-2018 and 2018-2019 to minimize the impact of hidden hunger (micronutrient deficiencies) through agronomic biofortification of two wheat cultivars with zinc and iron. Two spring-planted bread wheat cultivars: Zincol-16 (Zn-efficient) and Anaj-17 (Zn-inefficient with high-yield potential) were treated with either zinc (10 kg/ha), iron (12 kg/ha), or their combination to study their effect on some growth attributes (plant height, tillers, and spike length, etc.,), productivity, and quality. No application of zinc and iron or their combinations served as the control. Maximum Zn and Fe contents of grains were improved by sole application of Zn and Fe, respectively. A higher concentration of Ca in grains was observed by the combined application of Zn and Fe. Starch contents were found maximum by sole application of Fe. Sole or combined application of Zn and Fe reduced wet gluten contents. Maximum proteins were recorded in Anaj-17 under control treatments. Zincol-16 produced maximum ionic concentration, starch contents, and wet gluten as compared to Anaj-17. Yield and growth attributes were also significantly (p < 0.05) improved by combined application as compared to the sole application of Zn or Fe. The combined application also produced the highest biological and grain yield with a maximum harvest index. Cultivar Anaj-17 was found more responsive regarding growth and yield attributes comparatively. The findings of the present study showed that the combined application of Zn and Fe produced good quality grains (more Zn, Fe, Ca, starch, and less gluten concentrations) with a maximum productivity of bread wheat cultivars.

Plant growth promoters mediated quality and yield attributes of milk thistle (Silybum marianum L.) ecotypes under salinity stress.

Silybum marianum (L.) Gaertn (Astraceae) is a well-reputed medicinal plant mostly utilized for silymarin (Sily) content and oil production, however, the information about Sily contents in achene part is still fragmented under different climatic conditions. In this study four milk thistle ecotypes from Faisalabad (FSD), Gujranwala (GUJ), Quetta (QTA), and Kallar kahar (KK) having an altered achene color were analyzed under salt stress. Application of plant growth promoters (PGPs) is one of the solution for ameliorating the effect of salinity and increasing the quantity and quality traits of milk thistle, so ascorbic acid (AsA), thiourea (TU), and moringa leaf extract (MLE) were soil supplied after developing salinity stress (120 mM with irrigation) at germination stage. Predetermined levels were selected for PGPs such as AsA (500 µM), MLE (3%), and TU (250 µM). Results revealed that all yield related attributes were significantly decreased, while secondary metabolites, pericarp epidermis, pericarp parenchyma, and pericarp seed integument increased under salinity stress. Data suggested that PGPs treatment was helpful to alleviate the deleterious effects of salinity stress and enhance the milk thistle quality and quantity parameters. The ecotypic variations with altered achene color patterns represent an advantage for QTA ecotypes for higher Sily extraction under salt stressed conditions.

Oxidative stress tolerance potential of milk thistle ecotypes after supplementation of different plant growth-promoting agents under salinity.

The aim of the present work was to evaluate the effect of different plant growth promoters (PGPs) such as ascorbic acid (500 µM), thiourea (250 µM) and moringa leaf extract (3%) to mitigate salinity stress (120 mM NaCl) in four different milk thistle [Silybum marianum (L.) Gaertn.] ecotypes from Faisalabad (FSD), Gujranwala (GUJ), Kallar Kahar (KK), and Quetta (QTA) under field conditions for two years (2017-2018). In the present study, oxidative stress indicators such as malondialdehyde (MDA) and hydrogen peroxide (H2O2) and activities of different antioxidant enzymes and levels of non-enzymatic antioxidants were significantly differed among ecotypes, salinity, and PGPs. Supplementation with ascorbic acid and moringa leaf extract improved antioxidant defense machinery during the acclimation process against salinity, and milk thistle ecotypes represent their background of ecological zones and inherent tendency to face and confronting stress with improving antioxidant levels to a significant extent in varying ways. Ecotypic variations showed that QTA ecotype Followed by FSD, GUJ, and KK had more antioxidant capacity, with minimum reactive oxygen species production. Interestingly, the correlation data revealed that MDA and H2O2 had a positive correlation with each other and showed a negative correlation with all the enzymatic and non-enzymatic antioxidants.

Seed Priming with Sorghum Water Extract Improves the Performance of Camelina (Camelina sativa (L.) Crantz.) under Salt Stress.

Seed priming with sorghum water extract (SWE) enhances crop tolerance to salinity stress; however, the application of SWE under salinity for camelina crop has not been documented so far. This study evaluated the potential role of seed priming with SWE in improving salt stress tolerance in camelina. Primed (with 5% SWE and distilled water-hydropriming) and nonprimed seeds were sown under control (no salt) and salt stress (10 dS m-1) conditions. Salinity reduced camelina's emergence and growth, while seed priming with SWE improved growth under control and stress conditions. Under salt stress, seed priming with SWE enhanced emergence percentage (96.98%), increased root length (82%), shoot length (32%), root dry weight (75%), shoot dry weight (33%), α-amylase activity (66.43%), chlorophyll content (60-92%), antioxidant enzymes activity (38-171%) and shoot K+ ion (60%) compared with nontreated plants. Similarly, under stress conditions, hydrogen peroxide, malondialdehyde (MDA) content, and shoot Na+ ion were reduced by 60, 31, and 40% by seed priming with SWE, respectively, over the nonprimed seeds. Therefore, seed priming with SWE may be used to enhance the tolerance against salt stress in camelina.

Fe toxicity in plants: Impacts and remediation.

Fe is the fourth abundant element in the earth crust. Fe toxicity is not often discussed in plant science though it causes severe morphological and physiological disorders, including reduced germination percentage, interferes with enzymatic activities, nutritional imbalance, membrane damage, and chloroplast ultrastructure. It also causes severe toxicity to important biomolecules, which leads to ferroptotic cell death and induces structural changes in the photosynthetic apparatus, which results in retardation of carbon metabolism. However, some agronomic practices like soil remediation through chemicals, nutrients, and organic amendments and some breeding and genetic approaches can provide fruitful results in enhancing crop production in Fe-contaminated soils. Some quantitative trait loci have been reported for Fe tolerance in plants but the function of underlying genes is just emerging. Physiological and molecular mechanism of Fe uptake, translocation, toxicity, and remediation techniques are still under experimentation. In this review, the toxic effects of Fe on seed germination, carbon assimilation, water relations, nutrient uptake, oxidative damages, enzymatic activities, and overall plant growth and development have been discussed. The Fe dynamics in soil rhizosphere and role of remediation strategies, that is, biological, physical, and chemical, have also been described. Use of organic amendments, microbe, phytoremediation, and biological strategies is considered to be both cost and environment friendly for the purification of Fe-contaminated soil, while to ensure better crop yield and quality the manipulation of agronomic practices are suggested.

Exogenous Application of Salicylic Acid and Hydrogen Peroxide Ameliorate Cadmium Stress in Milk Thistle by Enhancing Morpho-Physiological Attributes Grown at Two Different Altitudes.

Cadmium (Cd+2) is a potential and widespread toxic environmental pollutant, mainly derived from a rapid industrial process that has inhibitory effects on growth, physiological, and biochemical attributes of various plant species, including medicinal plants such as Silybum marianum L. Gaertn commonly known as milk thistle. Plant signaling molecules, when applied exogenously, help to enhance/activate endogenous biosynthesis of potentially important signaling molecules and antioxidants that boost tolerance against various abiotic stresses, e.g., heavy metal stress. The present study documented the protective role of salicylic acid (SA;0.25 µM) and hydrogen peroxide (H2O2; 10 µM) priming, foliar spray, and combinational treatments in reducing Cd+2 toxicity (500 µM) in milk thistle grown at two diverse ecological zones of Balochistan Province of Pakistan i.e., Quetta (Qta) and Turbat (Tbt). The morpho-physiological and biochemical attributes of milk thistle were significantly affected by Cd+2 toxicity; however, priming and foliar spray of SA and H2O2 significantly improved the growth attributes (root/shoot length, leaf area, and root/shoot fresh and dry weight), photosynthetic pigments (Chl a, b, and carotenoids) and secondary metabolites (Anthocyanin, Soluble phenolics, and Tannins) at both altitudes by suppressing the negative impact of Cd+2. However, the oxidative damage parameters, i.e., MDA and H2O2, decreased astonishingly under the treatment of signaling molecules, thereby protecting membrane integrity under Cd+2 stress. The morphological variations were profound at the low altitude (Tbt) as compared to the high altitude (Qta). Interestingly, the physiological and biochemical attributes at both altitudes improved under SA and H2O2 treatments, thus hampered the toxic effect of Cd+2. These signaling compounds enhanced tolerance of plants under heavy metal stress conditions with the consideration of altitudinal, and ambient temperature variations remain to be the key concerns.

Phytoremediation of Cadmium: Physiological, Biochemical, and Molecular Mechanisms.

Cadmium (Cd) is one of the most toxic metals in the environment, and has noxious effects on plant growth and production. Cd-accumulating plants showed reduced growth and productivity. Therefore, remediation of this non-essential and toxic pollutant is a prerequisite. Plant-based phytoremediation methodology is considered as one a secure, environmentally friendly, and cost-effective approach for toxic metal remediation. Phytoremediating plants transport and accumulate Cd inside their roots, shoots, leaves, and vacuoles. Phytoremediation of Cd-contaminated sites through hyperaccumulator plants proves a ground-breaking and profitable choice to combat the contaminants. Moreover, the efficiency of Cd phytoremediation and Cd bioavailability can be improved by using plant growth-promoting bacteria (PGPB). Emerging modern molecular technologies have augmented our insight into the metabolic processes involved in Cd tolerance in regular cultivated crops and hyperaccumulator plants. Plants' development via genetic engineering tools, like enhanced metal uptake, metal transport, Cd accumulation, and the overall Cd tolerance, unlocks new directions for phytoremediation. In this review, we outline the physiological, biochemical, and molecular mechanisms involved in Cd phytoremediation. Further, a focus on the potential of omics and genetic engineering strategies has been documented for the efficient remediation of a Cd-contaminated environment.

Effect of Salinity Stress on Various Growth and Physiological Attributes of Two Contrasting Maize Genotypes

Abstract The response of two local maize (Zea mays L.) genotypes designated as Sahwal-2002 (salt-tolerant) and Sadaf (salt-sensitive) to salt stress was investigated under controlled growth conditions. The role of phenylalanine and seed priming under salt stress in maize with different morphological parameters were studied. The genotype Sadaf, being salt-tolerant, experienced more oxidative damage than the Sahiwall-2002 genotype under salt stress. The salinity affected both growth and physiological attributes of the maize species whereas the phenylalanine successfully increased the salinity tolerance in maize species at the seedling stage.