Seed nano-priming with multiple nanoparticles enhanced the growth parameters of lettuce and mitigated cadmium (Cd) bio-toxicity: An advanced technique for remediation of Cd contaminated environments.

Seed nano-priming can be used as an advanced technology for enhancing seed germination, plant growth, and crop productivity; however, the potential role of seed nano-priming in ameliorative cadmium (Cd) bio-toxicity under Cd stress has not yet been sufficiently investigated. Therefore, in this study we investigated the beneficial impacts of seed priming with low (L) and high (H) concentrations of nanoparticles including nSiO2 (50/100 mg L-1), nTiO2 (20/60 mg L-1), nZnO (50/100 mg L-1), nFe3O4 (100/200 mg L-1), nCuO (50/100 mg L-1), and nCeO2 (50/100 mg L-1) on lettuce growth and antioxidant enzyme activities aiming to assess their efficacy for enhancing plant growth and reducing Cd phytotoxicity. The results showed a significant increase in plant growth, biomass production, antioxidant enzyme activities, and photosynthetic efficiency in lettuce treated with nano-primed nSiH + Cd (100 mg L-1), nTiH + Cd (60 mg L-1), and nZnL + Cd (50 mg L-1) under Cd stress. Moreover, nano-priming effectively reduced the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA) in lettuce shoots. Interestingly, nano-primed nSiH + Cd, nTiH + Cd, and nZnL + Cd demonstrated efficient reduction of Cd uptake, less translocation factor of Cd with high tolerance index, ultimately reducing toxicity by stabilizing the root morphology and superior accumulation of critical nutrients (K, Mg, Ca, Fe, and Zn). Thus, this study provides the first evidence of alleviating Cd toxicity in lettuce by using multiple nanoparticles via priming strategy. The findings highlight the potential of nanoparticles (Si, Zn, and Ti) as stress mitigation agents for improved crop growth and yield in Cd contaminated areas, thereby offering a promising and advanced approach for remediation of Cd contaminated environments.

Biochar and nano-ferric oxide synergistically alleviate cadmium toxicity of muskmelon.

Cadmium is toxic to plants. The accumulation of cadmium in edible plants such as muskmelon may affect the safe production of crops and result in human health problem. Thus effective measures are urgently needed for soil remediation. This work aims to investigate the effects of nano-ferric oxide and biochar alone or mixture on muskmelon under cadmium stress. The results of growth and physiological indexes showed that compared with the application of cadmium alone, the composite treatment (biochar and nano-ferric oxide) decreased malondialdehyde content by 59.12% and ascorbate peroxidase activity increased by 276.6%. Their addition can increase the stress resistance of plants. The results of soil analysis and cadmium content determination in plants showed that the composite treatment was beneficial to reduce the cadmium content in various parts of muskmelon. In the presence of high concentration of cadmium, the Target Hazard Quotient value of peel and flesh of muskmelon in the composite treatment was less than 1, which means the edible risk was greatly reduced. Furthermore, the addition of composite treatment increased the content of effective components; the contents of polyphenols, flavonoids, and saponins in the flesh of the compound treatment were increased by 99.73%, 143.07%, and 18.78% compared with the cadmium treatment. The results provide a technical reference for the further application of biochar combined with nano-ferric oxide in the field of soil heavy metal remediation, and provide a theoretical basis for further research on reducing the toxicity of cadmium to plants and improving the edible quality of crops.

Alleviating Drought Stress in Brassica juncea (L.) Czern & Coss. by Foliar Application of Biostimulants-Orthosilicic Acid and Seaweed Extract.

Agricultural productivity is negatively impacted by drought stress. Brassica is an important oilseed crop, and its productivity is often limited by drought. Biostimulants are known for their role in plant growth promotion, increased yields, and tolerance to environmental stresses. Silicon in its soluble form of orthosilicic acid (OSA) has been established to alleviate deteriorative effects of drought. Seaweed extract (SWE) also positively influence plant survival and provide dehydration tolerance under stressed environments. The present study was conducted to evaluate the efficacy of OSA and SWE on mitigating adverse effects of drought stress on Brassica genotype RH-725. Foliar application of OSA (2 ml/L and 4 ml/L) and SWE of Ascophyllum nodosum (3 ml/L and 4 ml/L) in vegetative stages in Brassica variety RH 725 under irrigated and rainfed condition revealed an increase in photosynthetic rate, stomatal conductance, transpirational rate, relative water content, water potential, osmotic potential, chlorophyll fluorescence, chlorophyll stability index, total soluble sugars, total protein content, and antioxidant enzyme activity; and a decrease in canopy temperature depression, proline, glycine-betaine, H2O2, and MDA content. Application of 2 ml/L OSA and 3 ml/L SWE at vegetative stage presented superior morpho-physiological and biochemical characteristics and higher yields. The findings of the present study will contribute to developing a sustainable cropping system by harnessing the benefits of OSA and seaweed extract as stress mitigators.

Osmoprotection in Salvia hispanica L seeds under water stress attenuators / Osmoproteção em sementes de Salvia hispanica L sob atenuadores do estresse hídrico

Salvia hispanica cultivation is recent in Brazil and occurs in the off-season, when there is lower water availability in the soil. Water deficit is one of the abiotic factors that most limit germination for compromising the sequence of metabolic events that culminate with seedling emergence. Several attenuating substances have been used to mitigate the effects resulting from this stress and give higher tolerance to the species. Thus, the objective of this study was to evaluate the action of different agents as water stress attenuators in the germination and accumulation of organic compounds in S. hispanica seedlings. The treatments consisted of pre-soaking the seeds for 4 hours in salicylic acid (1 mM.L-¹), gibberellic acid (0.4 mM.L-¹), distilled water and control treatment (without soaking). The seeds were germinated at osmotic potentials of 0.0, -0.1, -0.2, -0.3 and -0.4 MPa, using PEG 6000 as an osmotic agent. The variables germination percentage, germination speed index, shoot and primary root lengths, total dry mass, proline, total soluble sugars and total free amino acids were analyzed. Salicylic acid and gibberellic acid led to the best results among the attenuators tested, increasing germination, length, dry mass and biochemical components of S. hispanica seedlings under water deficit. Therefore, salicylic and gibberellic acids are efficient in mitigating water stress in S. hispanica seeds up to the potential of -0.4 MPa.

O cultivo da Salvia hispanica é recente no Brasil e se dá no período de entressafra, quando há menor disponibilidade hídrica no solo. O déficit hídrico é um dos fatores abióticos que mais limitam a germinação por comprometer a sequência de eventos metabólicos que culminam com a emergência da plântula. Diversas substâncias atenuadoras têm sido empregadas com a finalidade de mitigar os efeitos resultantes desse estresse e conferir maior tolerância às espécies. Desse modo, objetivou-se avaliar a ação de diferentes agentes como atenuadores do estresse hídrico na germinação e acúmulo de compostos orgânicos em plântulas de S. hispanica. Os tratamentos consistiram na pré-embebição das sementes durante 4 horas em ácido salicílico (1 mM.L-¹), ácido giberélico (0,4 mM.L-¹), água destilada e o tratamento controle (sem embebição). As sementes foram germinadas sob os potenciais osmóticos 0,0, -0,1, -0,2, -0,3 e -0,4 MPa, utilizando PEG 6000 como agente osmótico. Analisaram-se as variáveis porcentagem de germinação, índice de velocidade de germinação, comprimento da parte aérea e da raiz primária, massa seca total, prolina, açúcares solúveis totais e aminoácidos livres totais. O ácido salicílico e o ácido giberélico apresentaram os melhores resultados, dentre os atenuadores testados, incrementando a germinação, o comprimento, a massa seca e os componentes bioquímicos de plântulas de S. hispanica sob déficit hídrico. Logo, os ácidos salicílico e giberélico são eficientes na mitigação do estresse hídrico em sementes de S. hispanica até o potencial -0,4 MPa.

Osmoprotection in Salvia hispanica L. seeds under water stress attenuators

Abstract Salvia hispanica cultivation is recent in Brazil and occurs in the off-season, when there is lower water availability in the soil. Water deficit is one of the abiotic factors that most limit germination for compromising the sequence of metabolic events that culminate with seedling emergence. Several attenuating substances have been used to mitigate the effects resulting from this stress and give higher tolerance to the species. Thus, the objective of this study was to evaluate the action of different agents as water stress attenuators in the germination and accumulation of organic compounds in S. hispanica seedlings. The treatments consisted of pre-soaking the seeds for 4 hours in salicylic acid (1 mM.L-1), gibberellic acid (0.4 mM.L-1), distilled water and control treatment (without soaking). The seeds were germinated at osmotic potentials of 0.0, -0.1, -0.2, -0.3 and -0.4 MPa, using PEG 6000 as an osmotic agent. The variables germination percentage, germination speed index, shoot and primary root lengths, total dry mass, proline, total soluble sugars and total free amino acids were analyzed. Salicylic acid and gibberellic acid led to the best results among the attenuators tested, increasing germination, length, dry mass and biochemical components of S. hispanica seedlings under water deficit. Therefore, salicylic and gibberellic acids are efficient in mitigating water stress in S. hispanica seeds up to the potential of -0.4 MPa.

Resumo O cultivo da Salvia hispanica é recente no Brasil e se dá no período de entressafra, quando há menor disponibilidade hídrica no solo. O déficit hídrico é um dos fatores abióticos que mais limitam a germinação por comprometer a sequência de eventos metabólicos que culminam com a emergência da plântula. Diversas substâncias atenuadoras têm sido empregadas com a finalidade de mitigar os efeitos resultantes desse estresse e conferir maior tolerância às espécies. Desse modo, objetivou-se avaliar a ação de diferentes agentes como atenuadores do estresse hídrico na germinação e acúmulo de compostos orgânicos em plântulas de S. hispanica. Os tratamentos consistiram na pré-embebição das sementes durante 4 horas em ácido salicílico (1 mM.L-1), ácido giberélico (0,4 mM.L-1), água destilada e o tratamento controle (sem embebição). As sementes foram germinadas sob os potenciais osmóticos 0,0, -0,1, -0,2, -0,3 e -0,4 MPa, utilizando PEG 6000 como agente osmótico. Analisaram-se as variáveis porcentagem de germinação, índice de velocidade de germinação, comprimento da parte aérea e da raiz primária, massa seca total, prolina, açúcares solúveis totais e aminoácidos livres totais. O ácido salicílico e o ácido giberélico apresentaram os melhores resultados, dentre os atenuadores testados, incrementando a germinação, o comprimento, a massa seca e os componentes bioquímicos de plântulas de S. hispanica sob déficit hídrico. Logo, os ácidos salicílico e giberélico são eficientes na mitigação do estresse hídrico em sementes de S. hispanica até o potencial -0,4 MPa.

Osmoprotection in Salvia hispanica L. seeds under water stress attenuators / Osmoproteção em sementes de Salvia hispanica L. sob atenuadores do estresse hídrico

Salvia hispanica cultivation is recent in Brazil and occurs in the off-season, when there is lower water availability in the soil. Water deficit is one of the abiotic factors that most limit germination for compromising the sequence of metabolic events that culminate with seedling emergence. Several attenuating substances have been used to mitigate the effects resulting from this stress and give higher tolerance to the species. Thus, the objective of this study was to evaluate the action of different agents as water stress attenuators in the germination and accumulation of organic compounds in S. hispanica seedlings. The treatments consisted of pre-soaking the seeds for 4 hours in salicylic acid (1 mM.L-1), gibberellic acid (0.4 mM.L-1), distilled water and control treatment (without soaking). The seeds were germinated at osmotic potentials of 0.0, -0.1, -0.2, -0.3 and -0.4 MPa, using PEG 6000 as an osmotic agent. The variables germination percentage, germination speed index, shoot and primary root lengths, total dry mass, proline, total soluble sugars and total free amino acids were analyzed. Salicylic acid and gibberellic acid led to the best results among the attenuators tested, increasing germination, length, dry mass and biochemical components of S. hispanica seedlings under water deficit. Therefore, salicylic and gibberellic acids are efficient in mitigating water stress in S. hispanica seeds up to the potential of -0.4 MPa.

O cultivo da Salvia hispanica é recente no Brasil e se dá no período de entressafra, quando há menor disponibilidade hídrica no solo. O déficit hídrico é um dos fatores abióticos que mais limitam a germinação por comprometer a sequência de eventos metabólicos que culminam com a emergência da plântula. Diversas substâncias atenuadoras têm sido empregadas com a finalidade de mitigar os efeitos resultantes desse estresse e conferir maior tolerância às espécies. Desse modo, objetivou-se avaliar a ação de diferentes agentes como atenuadores do estresse hídrico na germinação e acúmulo de compostos orgânicos em plântulas de S. hispanica. Os tratamentos consistiram na pré-embebição das sementes durante 4 horas em ácido salicílico (1 mM.L-1), ácido giberélico (0,4 mM.L-1), água destilada e o tratamento controle (sem embebição). As sementes foram germinadas sob os potenciais osmóticos 0,0, -0,1, -0,2, -0,3 e -0,4 MPa, utilizando PEG 6000 como agente osmótico. Analisaram-se as variáveis porcentagem de germinação, índice de velocidade de germinação, comprimento da parte aérea e da raiz primária, massa seca total, prolina, açúcares solúveis totais e aminoácidos livres totais. O ácido salicílico e o ácido giberélico apresentaram os melhores resultados, dentre os atenuadores testados, incrementando a germinação, o comprimento, a massa seca e os componentes bioquímicos de plântulas de S. hispanica sob déficit hídrico. Logo, os ácidos salicílico e giberélico são eficientes na mitigação do estresse hídrico em sementes de S. hispanica até o potencial -0,4 MPa.

Antioxidant defence system based oxidative stress mitigation through dietary jamun tree leaf in experimentally infected snubnose pompano, Trachinotus blochii.

A 45-day feeding trial was conducted to evaluate the effect of dietary jamun tree leaf (JL) on the antioxidant defence system-based disease resistance in juveniles of Trachinotus blochii. The juveniles of snubnose pompano were distributed into four treatment groups in triplicates. Each treatment was fed with a diet containing either 0 (0JL), 0.5 (0.5JL), 1 (1JL) and 1.5% JL (1.5JL) in the feed. After feeding trial, the fishes were experimentally infected with Vibrio parahaemolyticus. The activities of oxidative stress enzymes such as superoxide dismutase and catalase were found to be increasing with increasing level of dietary JL incorporation, and the lower value was witnessed in control group in pre- and post-challenge. After challenge, the alanine and aspartate aminotransferase activities in all the treatments were significantly increased (P < 0.05) than the pre-challenge condition and exhibited reverse trend with the antioxidant enzymes. The alkaline and acid phosphatase activities were found higher in 1.5JL group and showed significant difference (P < 0.05) among the treatments. The respiratory burst activity and liver glycogen content showed an increasing trend as the level of inclusion of JL increased in the diet. The acetylcholinesterase activity was significantly plunged (P < 0.05) after experimental infection, and JL diet fed groups showed better activity. After experimental infection with V. parahaemolyticus, the highest relative percentage of survival was observed in 1JL and 1.5JL groups. Hence, dietary supplementation of jamun tree leaf at the level of 1% is adequate to reduce the oxidative stress and improved the innate immune status through antioxidant defence system.

Effects of Gellan Oligosaccharide and NaCl Stress on Growth, Photosynthetic Pigments, Mineral Composition, Antioxidant Capacity and Antimicrobial Activity in Red Perilla.

The growing market demand for plant raw materials with improved biological value promotes the extensive search for new elicitors and biostimulants. Gellan gum derivatives may enhance plant growth and development, but have never been used under stress conditions. Perilla (Perilla frutescens, Lamiaceae) is a source of valuable bioproducts for the pharmaceutical, cosmetic, and food industries. However, there is not much information on the use of biostimulators in perilla cultivation. In this work we investigated the effects of oligo-gellan and salt (100 mM NaCl) on the yield and quality of red perilla (P. frutescens var. crispa f. purpurea) leaves. Plants grown under stress showed inhibited growth, smaller biomass, their leaves contained less nitrogen, phosphorus, potassium, total polyphenol and total anthocyanins, and accumulated considerably more sodium than control plants. Treatment with oligo-gellan under non-saline conditions stimulated plant growth and the fresh weight content of the above-ground parts, enhanced the accumulation of nitrogen, potassium, magnesium and total polyphenols, and increased antioxidant activity as assessed by DPPH and ABTS assays. Oligo-gellan applied under saline conditions clearly alleviated the stress effects by limiting the loss of biomass, macronutrients, and total polyphenols. Additionally, plants pretreated with oligo-gellan and then exposed to 100 mM NaCl accumulated less sodium, produced greater amounts of photosynthetic pigments, and had greater antioxidant activity than NaCl-stressed plants. Irrespective of the experimental treatment, 50% extract effectively inhibited growth of Escherichia coli and Staphylococcus aureus. Both microorganisms were the least affected by 25% extract obtained from plants untreated with either NaCl or oligo-gellan. In conclusion, oligo-gellan promoted plant growth and enhanced the quality of red perilla leaves and efficiently alleviated the negative effects of salt stress.

Micronutrient Status and Selected Physiological Parameters of Roots in Nickel-Exposed Sinapis alba L. Affected by Different Sulphur Levels.

An efficient method of improving the micronutrient status of Ni-treated white mustard (Sinapis alba L.) using intensive S-SO4 nutrition was developed. Twelve variants of Hoagland's nutrient solution differing in the concentration of S-SO4 (standard: 2 mM S, and elevated level: 6 or 9 mM S) and Ni (0, 0.0004, 0.04, or 0.08 mM Ni) were tested. The beneficial effect of intensive S nutrition on Ni-stressed plants was manifested by a significant rise in the content of Fe, Mn, and Zn, especially in the shoots. An increase was also found in the shoot B, Cu, and Mo content, whilst there were no changes in their root concentrations. Simultaneously, the shoot Cl concentrations dropped. The elevated level of S in the nutrient solution in general enhanced the translocation of Fe, Cu, Mo, and B in Ni-exposed plants. The beneficial effect of intensive S nutrition on the growth and micronutrient balance of Ni-exposed plants can be at least partially related to the positive changes in root surface properties, especially in cation exchange capacity (CEC). Meanwhile both reduced glutathione (GSH) and phytochelatins (PCs) probably do not significantly contribute to Ni resistance of white mustard under intensive S nutrition.

Future Climate CO2 Levels Mitigate Stress Impact on Plants: Increased Defense or Decreased Challenge?

Elevated atmospheric CO2 can stimulate plant growth by providing additional C (fertilization effect), and is observed to mitigate abiotic stress impact. Although, the mechanisms underlying the stress mitigating effect are not yet clear, increased antioxidant defenses, have been held primarily responsible (antioxidant hypothesis). A systematic literature analysis, including "all" papers [Web of Science (WoS)-cited], addressing elevated CO2 effects on abiotic stress responses and antioxidants (105 papers), confirms the frequent occurrence of the stress mitigation effect. However, it also demonstrates that, in stress conditions, elevated CO2 is reported to increase antioxidants, only in about 22% of the observations (e.g., for polyphenols, peroxidases, superoxide dismutase, monodehydroascorbate reductase). In most observations, under stress and elevated CO2 the levels of key antioxidants and antioxidant enzymes are reported to remain unchanged (50%, e.g., ascorbate peroxidase, catalase, ascorbate), or even decreased (28%, e.g., glutathione peroxidase). Moreover, increases in antioxidants are not specific for a species group, growth facility, or stress type. It seems therefore unlikely that increased antioxidant defense is the major mechanism underlying CO2-mediated stress impact mitigation. Alternative processes, probably decreasing the oxidative challenge by reducing ROS production (e.g., photorespiration), are therefore likely to play important roles in elevated CO2 (relaxation hypothesis). Such parameters are however rarely investigated in connection with abiotic stress relief. Understanding the effect of elevated CO2 on plant growth and stress responses is imperative to understand the impact of climate changes on plant productivity.