Content Of Seedlings Research Articles

Exogenous plant hormones alleviate As stress by regulating antioxidant defense system in Oryza sativa L.

Plant hormones play essential roles in plant growth regulation and resistance to environmental pressure. A hydroponic experiment was conducted using Zhongjiazao 17 rice to explore the effects of exogenous plant hormones on antioxidant response and As accumulation in rice under As stress. Melatonin (MT), 2,4-epibrassinolide (EBL), and jasmonic acid (JA) reduced the As content in seedlings significantly by 13.4% (MT)-32.5% (EBL) under 5µM As stress. Three hormones increased superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities, and glutathione (GSH) content significantly (2.2%-82.9%) in 5µM As stress condition, whereas the levels of H2O2 and malondialdehyde (MDA) were reduced significantly (32.3%-78.1%). Plant hormone addition reduced the As content in seedlings significantly by 18.2% (JA)-33.3% (MT) under 25µM As stress. SOD, POD, and CAT activities and GSH content in seedlings increased significantly (5.6-90.4%) with three hormones addition in 25µM As stress, whereas the levels of H2O2, O2˙¯, and MDA reduced significantly (20.9-73.0%). Staining with 2',7'-dichlorodihydrofluorescein diacetate and nitroblue tetrazolium showed that green fluorescence and blue spots decreased gradually in hormone-treated seedlings, further confirming that the exogenous addition of hormones weakened the oxidative stress of As to seedlings. Oxidative damage by As stress was reduced more by EBL than by the other hormones MT or JA. Totally, exogenous plant hormone can alleviate As stress in rice by activating enzyme activity of antioxidant defense system and scavenging reactive oxygen species, thus reducing oxidative damage and As accumulation in rice seedlings.

Comparison of ammonium, nitrate, and proton fluxes in mycorrhizal and nonmycorrhizal roots of lodgepole pine in contrasting nitrogen treatments

Relatively few comparative studies exist of nitrogen (N) uptake by ectomycorrhizal (EM) and nonmycorrhizal roots under controlled conditions. Instantaneous and long-term N uptake by EM and nonmycorrhizal roots of lodgepole pine seedlings ( Pinus contorta (Douglas) var. latifolia (Engelm.)) were compared after 9–12 months of preconditioning under high or low N supply, with NH4+ and NO3− in proportions of 90:10 and 10:90. EM roots were inoculated with Amphinema byssoides or Laccaria bicolor. Instantaneous net NH4+, NO3−, and H+ fluxes were measured simultaneously on seedling roots with a microelectrode ion flux measurement system, and seedling organ biomass and N content were measured to infer long-term N uptake. Net NH4+ uptake was observed in EM roots of lodgepole pine but NH4+ efflux was observed in nonmycorrhizal roots. Greater instantaneous N uptake in EM roots was supported by higher root and shoot N contents in seedlings associated with L. bicolor than in noninoculated seedlings. Absence of NH4+ efflux in EM roots suggests that root colonization by EM fungi has the potential to reduce futile cycling of NH4+. EM lodgepole pine appeared to prefer NH4+ over NO3− as an N source and instantaneous NH4+ uptake rates were higher in NH4-starved roots. H+ efflux was observed in most roots. Future work should focus on a greater variety of EM species to explore differences among species in N uptake.

Examination of morphological and molecular changes in tomato (Solanum lycopersicum L.) seedlings with the application of tebuconazole

This study aims to determine the effects of tebuconazole substance used at different doses on the quality of tomato seedlings, retrotransposon mobility caused by this substance in the plants and its genotoxic effects and to determine the optimum dose to be used in practice in seedling production. Tebuconazole applied different concentrations (25, 50, 75, 100, 125 and 150 ppm) were tested. According to the study results, the seedling length and stem length significantly according to the applied doses. The study found out that the stem, leaf and root dry matter contents and leaf chlorophyll content (SPAD values) also statistically significantly changed based on the applied doses. According to the data obtained, the lowest seedling length (12.68 cm) and stem length (4.75 cm) were obtained from a dose of 150 ppm. The highest dry matter content in seedlings was obtained at a dose of 50 ppm in stem (22%) and at 0 ppm (control) in leaves (25.01%) and root. In the study, the highest leaf chlorophyll content (SPAD values) was determined at doses of 150 ppm, 125 ppm and 75 ppm, respectively. This study revealed that various doses of tebuconazole had a positive effect on controlling the height of tomato seedlings and specific quality characteristics of seedlings. In addition, molecular analyzes showed that polymorphism ratios in plants that were applied the substance at different doses varied between 4.70% and 38.09% and the GTS (genomic template stability) value varied between 61.91% and 95.30%. Analyses indicated that the polymorphism ratio increased depending on the increase in dose whereas the GTS value decreased.

PHYSIOLOGICAL AND BIOCHEMICAL CHANGES OF TOMATO PLANTS UNDER BACTERIAL INFLUENCE

Tomato (Lycopersicon esculentum L) is one of the most important vegetable crops widely grown around the world. However, the global economic productivity of this crop is limited to a number of phytopathogens. Bacterial spotting and mild rot of tomatoes caused by Pseudomonas syringae pv. tomato and Pectobacterium carotovorum subsp. carotovorum, are one of the most common bacterial diseases that cause significant losses and reduce both the quality and quantity of fruits and impair the nutritional value of tomatoes. Tomato plants are affected by these pathogens throughout the growing season, the lesion is characterized by chlorosis, necrosis and rot. The aim of the study was to analyze the impact on the physiological and biochemical parameters of tomato sprouts affected by pathogens of P. syringae pv. tomato and P. carotovorum subsp. саrotovorum. It was found that strains of P. syringae pv. tomato IZ202014 and P. carotovorum subsp. carotovorum IZ207 cause a 30-40% decrease in germination energy and seed germination of Black Prince, Northern Queen, Riddle and Liana tomatoes compared to the control. According to the analysis of physiological and biochemical parameters, the most resistant to pathogens P. syringae pv. tomato, P. carotovorum subsp. carotovorum variety Northern Queen. Treatment of tomato plants with a suspension of the studied strains causes a decrease in chlorophyll content in seedlings by 58-93%. According to the chlorophyll a/b ratio, the Northern Queen and Black Prince varieties have the highest resistance to bacterial damage. Under the influence of cell suspensions of P. syringae pv. tomato IZ202014 and P. carotovorum subsp. carotovorum IZ207 showed changes in the activity of enzymes of the antioxidant system in tomato seedlings, which indicates a decrease in the oxidative processes of cells.

Biochemical and Physiological Modifications in Seedlings of Schinus terebinthifolius Raddi. After Hardening with Salicylic Acid

Exogenous application of stress inductors can facilitate and accelerate some biological responses that promote plant defense. The objective of the experiment was to quantify some compounds linked to nitrogen metabolism as a function of the application of salicylic acid in Schinus terebinthifolius seedlings submitted to water deficit. The experiment was constituted of four doses of salicylic acid and three periods of water deficit. Quantifications included levels of nitrate, free ammonium, total soluble amino acids, proteins, proline, glycine-betaine and relative water content. When evaluating the relative water content in seedlings of Schinus terebinthifolius at 8 days, it was observed that the dose of 200 mg L-1. Seedlings showed physiological responses when subjected to doses of salicylic acid of 200 and 300 mg L-1. The increase in concentration of proline and glycine are advantageous, because these substances act as osmoregulators and cell protectors against deficit hydrical.

Potassium and melatonin-mediated regulation of fructose-1,6-bisphosphatase (FBPase) and sedoheptulose-1,7- bisphosphatase (SBPase) activity improve photosynthetic efficiency, carbon assimilation and modulate glyoxalase system accompanying tolerance to cadmium stress in tomato seedlings

The mechanism of the combined action of potassium (K) and melatonin (Mel) in modulating tolerance to cadmium (Cd) stress in plants is not well understood. The present study reveals the synergistic role of K and Mel in enhancing physiological and biochemical mechanisms of Cd stress tolerance in tomato seedlings. The present findings reveal that seedlings subjected to Cd toxicity exhibited disturbed nutrients balance [nitrogen (N) and potassium (K)], chlorophyll (Chl) biosynthesis [reduced δ-aminolevulinic acid (δ-ALA) content and δ-aminolevulinic acid dehydratase (δ-ALAD) activity], pathway of carbon fixation [reduced fructose-1,6-bisphosphatase (FBPase) and sedoheptulose-1,7- bisphosphatase (SBPase) activity] and photosynthesis process in tomato seedlings. However, exogenous application of K and Mel alone as well as together improved physiological and biochemical mechanisms in tomato seedlings, but their combined application proved best by efficiently improving nutrient uptake, photosynthetic pigments biosynthesis (increased Chl a and b, and Total Chl), carbon flow in Calvin cycle, activity of Rubisco, carbonic anhydrase activity, and accumulation of total soluble carbohydrates content in seedlings under Cd toxicity. Furthermore, the combined treatment of K and Mel suppressed overproduction of reactive oxygen species (hydrogen peroxide and superoxide), Chl degradation [reduced chlorophyllase (Chlase) activity] and methylglyoxal content in Cd-stressed tomato seedlings by upregulating glyoxalase (increased glyoxalase I and glyoxalase II activity) and antioxidant systems (increased ascorbate-glutathione metabolism). Thus, the present study provides stronger evidence that the co-application of K and Mel exhibited synergistic roles in mitigating the toxic effect of Cd stress by increasing glyoxalase and antioxidant systems and also by improving photosynthetic efficiency in tomato seedlings.

Mycorrhizal fungi and phosphate fertilization in the production of Euterpe edulis seedlings

The present study evaluated the effect of arbuscular mycorrhizal fungi (AMF) inoculation on growth and nutrition of Euterpe edulis seedlings, supplemented or not with phosphate fertilization. The experiment was conducted in a greenhouse. The randomized block design, consisted of a 3x2 factorial arrangement and 4 replicates, with two phosphorus doses (0 and 50 mg dm-3 of soil), two microbiological treatments (Rhizophagus clarus; laroideoglomus etunicatum; R. clarus + C. etunicatum) and control (without fungus). Sowing and inoculation occurred concurrently in 2 kg plastic bags. Height, collar diameter, leaf area, dry shoot mass, macronutrient content and mycorrhizal colonization percentage were determined after 226 days. Regarding mycorrhizal colonization percentage, R. clarus resulted significantly beneficial for the production of E. edulis seedlings. In the absence of phosphate fertilization, R. clarus and mixed inoculum increased all biometric variables and macronutrient contents in seedlings. Therefore, it is concluded that AMF inoculations provide beneficial effects for growth and nutrition of E. edulis seedlings, resulting in more vigorous plants at a low-cost strategy. Highlights: Rhizophagus clarus resulted significantly beneficial for the production of E. edulis seedlings and in the absence of phosphate fertilization, and mixed inoculum ( clarus + Claroideoglomus etunicatum) increased all biometric variables and macronutrient contents in seedlings. The AMF inoculations provide beneficial effects for growth and nutrition of E. edulis seedlings, resulting in more vigorous plants at a low-cost strategy. The AMF, a biological agent of mutualistic associations with plants, constitutes an innovative approach to sustainable agriculture, contributing to increase plant survival rate, a key-factor for the successful reintroduction and conservation of E. edulis, as well as for its commercial exploitation.

Sepia 200cH at 1:1000 dilution ameliorates salt stress in cowpea seedlings but its medium 90% ethanol proves ineffective at the same dilution

Soil salinity severely affects crop yield all over the world. In a recent study we observed that Natrum mur 200cH, a homeopathic remedy, improved growth in germinating cowpea seeds. In the present study we have tested another remedy Sepia, which is complementary to Natrum mur, on cowpea seedlings under salt stress. Cowpea seedlings grown over moist filter paper in petridishes were divided into 4 groups: (1) control in sterile water, (2) in 50mM NaCl solution, (3) seeds pretreated with 90% ethanol diluted with water 1:100 and then transferred to 50mM NaCl solution, (4) seeds pretreated with Sepia 200cH diluted with water 1:100 and transferred to 50mM NaCl solution. In another experiment the groups were same, but the dilution of 90% ethanol and Sepia 200cH was 1:1000 instead of 1:100. The purpose was to further reduce the ethanol content in both the drug and its vehicle 90% ethanol, so that the alcohol effect is minimized or abolished. The data were analysed by ANOVA followed by t-test. Sepia 200cH at both 1:100 and 1:1000 dilutions significantly increased growth, sugar, chlorophyll, protein and water content in seedlings as compared to the untreated salt-stressed group. The effect with the1000th dilution of Sepia 200cH was more pronounced than with its 100th dilution. The vehicle 90% ethanol at 1:100 dilution produced some positive effect on the seedlings, but the 1000th dilution of the vehicle produced no such effect. It is, therefore, concluded that Sepia 200cH could ameliorate salt stress in cowpea seedlings and that the 1000th dilution is more effective than its 100th dilution. The alcohol effect is totally eliminated with the 1000th dilution of 90% ethanol. Thus the 1000th dilution could retain the drug effect and eliminate the vehicle effect.

The research of changes in biochemical parameters extracts of sprouting soybean and rapeseed seeds

At different periods of swelling and incubation (12, 24, 36, 48, 60 h) soybean seeds were selected: swollen (after reaching the critical humidity of soy 58.6 %; rapeseed 43.6 %); sprouted "spouts"; with sprouts ≥1 cm. It was found that the protein content in seedlings gradually decreases from 37.0-41.3% in dormant seeds, to 18.6-20.3% in sprouts after 48 hours in rapeseed and 60 hours of incubation in soybeans. The developed method of differentiation of germinating seeds by physiological state made it possible to register step-by-step changes in extracts according to pH and buffer capacity (BC). This rapid analysis is applicable in the development of technology for protein complex extraction and preparation of protein preparations from non-traditional sources.

Diethyl Aminoethyl Hexanoate Priming Ameliorates Seed Germination via Involvement in Hormonal Changes, Osmotic Adjustment, and Dehydrins Accumulation in White Clover Under Drought Stress.

Drought is a serious outcome of climate change reducing the productivity of forage species under arid and semi-arid conditions worldwide. Diethyl aminoethyl hexanoate (DA-6), a novel plant growth regulator, has proven to be involved in the amelioration of critical physiological functions in many agricultural crops under various abiotic stresses, but the role of the DA-6 in improving seed germination has never been investigated under drought stress. The present study was carried out to elucidate the impact of the DA-6 priming on seeds germination of white clover under drought stress. Results showed that seed priming with the DA-6 significantly mitigated the drought-induced reduction in germination percentage, germination vigor, germination index, seed vigor index, root length, shoot length, and fresh weight after 7 days of seed germination. The DA-6 significantly increased the endogenous indole-3-acetic acid, gibberellin, and cytokinin content with marked reduction in abscisic acid content in seedlings under drought stress. In addition, the DA-6 significantly accelerated starch catabolism by enhancing the activities of hydrolases contributing toward enhanced soluble sugars, proline content and ameliorated the antioxidant defense system to enhance the ability of reactive oxygen species scavenging under drought stress. Furthermore, exogenous DA-6 application significantly increased dehydrins accumulation and upregulated transcript levels of genes encoding dehydrins (SK2, Y2SK, or DHNb) during seeds germination under water deficient condition. These findings suggested that the DA-6 mediated seeds germination and drought tolerance associated with changes in endogenous phytohormones resulting in increased starch degradation, osmotic adjustment, antioxidants activity, and dehydrins accumulation during seed germination under water deficient condition.

Low temperature tolerance at early growth stage of maize hybrids released in the 1970s–2000s

AbstractEarly freezes in the spring are becoming increasingly common. To protect farmers from low temperatures (LT), crops need improved LT tolerance. The hypothesis of this paper is that maize (Zea mays L.) hybrids released in the 2000s had higher LT tolerances than those released in the 1970s. In the study, eight popular maize released between 1970 and 2010 were subjected to LT in four different trials. Germination time, growth uniformity, recovery ability from LT stress, and leaf productivity at seedling stage are important indicators in evaluating LT tolerance of maize. Hybrids released in the 1970s had a higher gibberellin A3 (GA3) content in seeds, which resulted in faster germination in LT (P = .02). In contrast, plant growth uniformity of the 2000s hybrids were higher than that of the 1970s hybrids in LT (P = .00 at emergence). Upon being returned to warm temperatures, the 2000s hybrids recovered more rapidly than old ones mainly because of the larger root systems, higher GA3, and indole‐3‐acetic acid (IAA) content in seedlings. In addition, the 2000s hybrids had a higher chlorophyll content, Fv/Fm, soluble sugar and starch content, and antioxidant enzyme activity in seedlings than old hybrids in LT, which can also contribute to a fast recovery from LT stress. Based on the growth uniformity and recovery ability from LT stress, new hybrids showed a higher LT tolerance than old hybrids during early growth stage. This study showed the genetic tolerance in LT may exist in hybrids that were released 50 yr ago, and that exporting differences between hybrids possible mechanism of temperature tolerance can be identified.

SiCEP3, a C-terminally encoded peptide from Setaria italica, promotes ABA import and signaling.

C-terminally encoded peptides (CEPs) are small peptides, typically post-translationally modified, and highly conserved in many species. CEPs are known to inhibit plant growth and development, but the mechanisms are not well understood. In this study, 14 CEPs were identified in Setaria italica and divided into two groups. The transcripts of most SiCEPs were more abundant in roots than in other detected tissues. SiCEP3, SiCEP4, and SiCEP5 were also highly expressed in panicles. Moreover, expression of all SiCEPs was induced by abiotic stresses and phytohormones. SiCEP3 overexpression and application of synthetic SiCEP3 both inhibited seedling growth. In the presence of abscisic acid (ABA), growth inhibition and ABA content in seedlings increased with the concentration of SiCEP3. Transcripts encoding eight ABA transporters and six ABA receptors were induced or repressed by synthetic SiCEP3, ABA, and their combination. Further analysis using loss-of-function mutants of Arabidopsis genes functioning as ABA transporters, receptors, and in the biosynthesis and degradation of ABA revealed that SiCEP3 promoted ABA import at least via NRT1.2 (NITRATE TRANSPORTER 1.2) and ABCG40 (ATP-BINDING CASSETTE G40). In addition, SiCEP3, ABA, or their combination inhibited the kinase activities of CEP receptors AtCEPR1/2. Taken together, our results indicated that the CEP-CEPR module mediates ABA signaling by regulating ABA transporters and ABA receptors in planta.

Morphophysiological, Enzymatic, and Elemental Activity in Greenhouse Tomato Saladette Seedlings from the Effect of Plant Growth-Promoting Rhizobacteria

The tomato is a widely cultivated and consumed vegetable globally. Comarca Lagunera is an important tomato-exporting region of Mexico. Salinity is an abiotic factor that reduces productivity and increases production costs. To advance growing period, there is high demand for the sustainable production of seedlings. Plant-growth-promoting rhizobacteria (PGPR) are characterized by improving plant growth through different mechanisms and can be an option for reducing the misuse of chemical fertilizers. The importance of the application of strains, evaluating various inoculation methods (in seed, soil, foliar spraying, and root immersion), should be evaluated to propose biofertilization packages in a specific crop. Thus, the study aimed to determine the effect of PGPR (Bacillus paralicheniformis, Acinetobacter guillouiae, Aeromonas caviae, and Pseudomonas lini) vs. nutrient solution and distilled water in the seedlings stage of saladette-type tomato on morphophysiological variables, nitrate reductase (NR) enzyme activity, and plant minerals via tissue analysis under greenhouse conditions. The four PGPR were inoculated by different methods (inoculation in seed, sprinkling, and both) in saladette-type tomato seedlings under greenhouse conditions and evaluated in vivo 40 days after sowing for morphophysiological variables, such as seedling height; stem diameter; root displaced volume; fresh and dry weight matter of the leaves, stems, and roots; leaf area; and nitrate reductase enzyme activity. The effect of the inoculation of PGPR showed significant results for Pseudomonas lini vs. the control, with 40% higher values, on average, for plant height, stem diameter, displaced root volume, and fresh weight of root, leaf, and stem. The response of enzymatic and mineral content in seedlings was variable with nutrient solution and significant with distilled water. Studies related to the promotion of plants in the subsequent phenological stages of a tomato, considering the selected PGPR, should be considered in future research.

H2S pretreatment mitigates the alkaline salt stress on Malus hupehensis roots by regulating Na+/K+ homeostasis and oxidative stress

Hydrogen sulfide (H2S) plays an important role in the plant salt stress response. The main component of salt stress is neutral salt (NaCl); NaHCO3 and Na2CO3 play a key role in soil alkaline due to the influence of pH. Malus hupehensis Rehd. var. pingyiensis Jiang (Pingyi Tiancha, PYTC) is a salt-sensitive apple rootstock. Seedlings of PYTC pretreated with NaHS (an H2S donor) were exposed to an alkaline salt solution, and then the plant growth, root architecture, oxidative damage, Na+/K+ homeostasis and gene expression of MhSOS1 and MhSKOR were investigated. The results showed that NaHS pretreatment increased the endogenous H2S content in seedlings, significantly alleviated the alkaline salt stress-induced growth inhibition and oxidative damage by inducing antioxidant enzymes activities, and sustained the root activity and root architecture of PYTC in the alkaline salt solution. NaHS pretreatment significantly decreased the root Na+ content and increased K+ content to maintain the homeostasis of Na+/K+, and effect the expression of MhSOS1 and MhSKOR at the transcription level in the presence of the alkaline salt. Our study reveals that application of H2S could mitigate the toxic effect of alkaline salt stress on Malus hupehensis seedlings, thus providing a foundation for improved plant tolerance to alkaline salt stress.

Effect of Fe3O4 nanoparticles on germination of seeds and concentration of elements in Helianthus annuus L. under constant magnetic field

The aim of the study was to investigate the effect of the Fe3O4 nanoparticles (Fe-NPs) on the germination of sunflower seeds, early growth of seedlings and the concentration of selected elements in seedlings. The influence of constant magnetic fields in systems with and without Fe-NPs was investigated. Experiments were done on seeds subjected to germination under constant magnetic field (0 (control), 5, 25 and 120 mT) for 7 days in the presence of solution containing 0, 50 or 500 ppm Fe-NPs. No significant effect of Fe-NPs and the magnetic field on germination of seeds and the growth of seedlings has been demonstrated. In most cases, a decrease in germination parameters was observed. For the majority of samples the relative decrease in the concentrations of elements was demonstrated mainly for samples without Fe-NPs. Interestingly, a significant decrease in the concentrations of trivalent (including iron - Fe) and toxic elements in samples containing Fe-NPs in relation to control samples was observed. The authors suggest that in this case the binding (adsorption) of these elements in the roots and seeds of the sunflower by Fe-NPs took place. This explains the lower iron content in seedlings than in seeds prior to sowing.

Morpho-Physiological Responses of Halophyte Climacoptera crassa to Salinity and Heavy Metal Stresses in In Vitro Condition

Climacoptera crassa is an annual halophyte species with great potential for use in the urban landscape. This study was performed to determine C. crassa tolerance to salinity and heavy metal stresses and to compare the plant associated mechanisms to counteract these stresses. For this purpose, the plant seedlings were exposed separately to various concentrations of NaCl (0–700 mM) or heavy metals cadmium (Cd) and lead (Pb) (0–2 mM). Our results indicated that C. crassa seedlings were able to survive at 700 mM NaCl. However, the optimum growth of seedlings was observed at 500 mM salinity. Plant in non-saline condition also displayed a normal growth. C. crassa seedlings were able to tolerate all levels of Pb, whereas their growth was inhibited at Cd concentrations exceeding 0.1 mM. The results also indicated that the increase in salinity levels in the culture medium was paralleled with the enhancement in proline, peroxide and sugar content in seedlings. A comparatively similar trend was observed when seedlings exposed to heavy metal stresses, although, the plant responses were more intense in this condition. These data suggest that osmolyte adjustment beside antioxidative enzyme activation account for the high salt tolerance of this species. Similarly, it was revealed that C. crassa uses the same mechanisms to cope with the excessive amount of heavy metals in culture medium. Therefore, it can be speculated that C. crassa benefits from its halophytic nature to tackle metal ion stresses. The present study clearly suggests that C. crassa is a highly tolerant taxon to salinity that can also survive the presence of low to moderate amount of Cd and Pb at seedling stage.

Public perception and health implication of loom-dye effluent irrigation on growth of rice (Oryza sativa L.) and red amaranth (Amaranthus tricolor L.) seedlings.

Loom-dye effluent discharge has constituted a major environmental threat to the people of Belkuchi Upazila of Sirajganj District. The present study was conducted to characterize loom-dye effluents and investigate their health implications by the growth analysis of rice and red amaranth seedlings along with a survey study among the individuals associated with loom-dyeing, weaving, and crop farming activities. A total of twenty-eight loom-dye effluent samples were collected for physicochemical characterization; among them, only three loom-dye effluents, i.e. pink, violet, and black dyes, at concentrations of 0, 10, 25, 50, 75, and 100% were applied as irrigation water to rice and red amaranth. The plant growth experiment was laid out following a completely randomized design with three replicas. Chemical analyses of loom-dye effluents showed the presence of a significant amount of plant nutrients and heavy metals. The mean concentrations of Pb, Cd, Cr, Fe, Mn, Zn, and Cu were 0.938, 0.046, 0.212, 7.109, 0.609, 0.351, and 0.191mgL-1, respectively. Among the metals, the concentrations of Pb, Cr, Fe, and Mn were above the recommended limit proposed by the irrigation water guideline value. Application of ≤ 25% pink and violet dye effluent and ≤ 10% black dye effluent had significant (p < 0.05) and positive impacts on growth and yield parameters. Heavy metal content in seedlings increased with increasing effluent application rate and crossed the utmost permissible limit at higher concentration. Survey data discovered a moderate knowledge level among the respondents, which might account for the indiscriminate discharge of loom-dye effluent into the surrounding environment. Attitudes, practices, and protective behaviours of the respondents also reflect the caused for long-term pollution through loom-dye effluents. To reduce its negative effects on the health and crop environment, the loom-dye effluents should not be discharged indiscriminately and used for crop irrigation without proper treatment. Furthermore, training programs ought to be introduced to educate the individuals involved in the discharge and subsequent use of loom-dye effluents.

Physiological and Molecular Responses of the Aboveground Part of Indica–Japonica Intersubspecific Tetraploid Rice Seedlings to Ion Beam Stress

Low-energy ion beam bombardment can induce various biological effects on plants, including stimulation, damage, and mutation. However, the physiological and molecular mechanisms of the biological effects of ion implantation are not fully understood. In this article, ion beam implantation was performed on Indica–Japonica intersubspecific tetraploid rice seeds to explore the responses of their seedlings. The investigation found that the aboveground part development of rice seedlings was inhibited, radiation damage was induced, and the metabolic accumulation and expression of abscisic acid (ABA) was disturbed by implantation with large doses of the low-energy $\text{N}^{+}$ beam. The activities of the antioxidant enzymes and proline (Pro) content were also increased by low-dose ion implantation induction. The malondialdehyde (MDA) content in seedlings under ion implantation was markedly higher than those of controls, and increased with the increase of ion beam irradiation doses. Transcriptional expression analysis of selected genes revealed that partly ABA anabolism genes associated with ABA production were significantly upregulated in seedlings in response to ion implantation. The aforementioned results will be useful for further research on the physiological and molecular mechanisms of Indica–Japonica intersubspecific tetraploid rice to ion beam stress.

Exogenous brassinosteroids increase lead stress tolerance in seed germination and seedling growth of Brassica juncea L.

Lead (Pb) is a highly toxic heavy metal to plants, animals, and human beings. The use of growth regulators has reversed the effects of heavy metal stress on germination and early plant development. The aim of this study was to evaluate the effect of brassinosteroids on seed germination and seedling growth of Brassica juncea (L.) Czern. & Coss. under Pb stress conditions. Two forms of application of 24-epibrassinolide (EBL) were evaluated, application on seeds in pre-soaking and on germination paper, using EBL concentrations of 0, 10-10, 10-8, and 10-6M. Germination and seedling growth parameters were evaluated during the germination test. The activity of the enzymes superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase were determined, as well as the lead content in the seeds and seedlings. The EBL applied at the 10-8M concentration was the most effective in overcoming Pb stress in both forms of application. The antioxidant enzyme defense system was compromised by Pb exposure. However, 10-8M EBL increased the activity of antioxidant enzymes such as catalase and peroxidase to overcome the toxic effects caused by Pb. In addition, EBL at the concentration of 10-8M increased Pb content in seedlings without affecting seedling growth.

Effect of N-acetyl-L-cysteine (NAC) on soluble sugar and polyamine content in wheat seedlings exposed to heavy metal stress (Cd, Hg and Pb)

Heavy metal stress adversely affects plant growth and productivity worldwide. Alleviating the stress effect through the exogenous use of various chemical substances has become an interesting area of study in the field of plant stress tolerance. As a thiol compound, the cysteine derivative N-acetylcysteine (N-acetyl- L-cysteine, NAC) is the precursor of glutathione synthesis and a potent ROS scavenger with powerful antioxidant and free radical scavenging capabilities. This study investigated the effects of heavy metals (Cd, Hg and Pb, 100 ?M) on accumulation of soluble sugars and polyamine content in roots and shoots of wheat seedlings, the water potential and proline content in shoots and the role of NAC in protection against heavy metal toxicity. The addition of 1 mM NAC significantly increased root content of glucose, fructose and sucrose in varying degrees (avg. 1.34-, 1.20- and 1.51-fold, respectively) in comparison with heavy metals alone. The treatments led to a significant reduction of sugar content in shoots. Water potential values were highly correlated with proline and sugar content in wheat seedling shoots. Heavy metal stress significantly reduced polyamine content in both plant parts. The addition of NAC increased polyamine content in seedlings in comparison with heavy metals alone in both roots and shoots. These results suggest that NAC may protect plants from oxidative stress damage in heavy metal stress, and this enhancement of stress tolerance seems to involve soluble sugar and polyamine biosynthesis.