Applications of humic and fulvic acid under saline soil conditions to improve growth and yield in barley.

BACKGROUND: Enriching the soil with organic matter such as humic and fulvic acid to increase its content available nutrients, improves the chemical properties of the soil and increases plant growth as well as grain yield. In this study, we conducted a field experiment using humic acid (HA), fulvic acid (FA) and recommended dose (RDP) of phosphorus fertilizer to treat Hordeum vulgare seedling, in which four concentrations from HA, FA and RDP (0.0 %, 50 %, 75 % and 100%) under saline soil conditions . Moreover, some agronomic traits (e.g. grain yield, straw yield, spikes weight, plant height, spike length and spike weight) in barley seedling after treated with different concentrations from HA, FA and RDP were determined. As such the beneficial effects of these combinations to improve plant growth, N, P, and K uptake, grain yield, and its components under salinity stress were assessed. RESULTS: The findings showed that the treatments HA + 100% RDP (T1), HA + 75% RDP (T2), FA + 100% RDP (T5), HA + 50% RDP (T3), and FA + 75% RDP (T6), improved number of spikes/plant, 1000-grain weight, grain yield/ha, harvest index, the amount of uptake of nitrogen (N), phosphorous (P) and potassium (K) in straw and grain. The increase for grain yield over the control was 64.69, 56.77, 49.83, 49.17, and 44.22% in the first season, and 64.08, 56.63, 49.19, 48.87, and 43.69% in the second season,. Meanwhile, the increase for grain yield when compared to the recommended dose was 22.30, 16.42, 11.27, 10.78, and 7.11% in the first season, and 22.17, 16.63, 11.08, 10.84, and 6.99% in the second season. Therefore, under salinity conditions the best results were obtained when, in addition to phosphate fertilizer, the soil was treated with humic acid or foliar application the plants with fulvic acid under one of the following treatments: HA + 100% RDP (T1), HA + 75% RDP (T2), FA + 100% RDP (T5), HA + 50% RDP (T3), and FA + 75% RDP (T6). CONCLUSIONS: The result of the use of organic amendments was an increase in the tolerance of barley plant to salinity stress, which was evident from the improvement in the different traits that occurred after the treatment using treatments that included organic amendments (humic acid or fulvic acid).

Co-application of titanium nanoparticles and melatonin effectively lowered chromium toxicity in lemon balm (Melissa officinalis L.) through modifying biochemical characteristics.

Chromium (Cr) toxicity can negatively affect plant growth and development, impacting agricultural productivity and posing risks to human health. Metallic nanoparticles (MNPs) such as titanium dioxide (TiO2) and natural growth regulators such as melatonin (MT) become a promising technology to manage heavy metal-contaminated soils and promote safe food production. The present work was conducted to find the effect of foliar application of TiO2 NPs (15 mg L-1) and MT (100 µM) on growth, biochemical attributes, and Cr accumulation in plant tissues of Melissa officinalis L. under Cr toxicity (50 and 100 mg Cr kg-1 soil). The results showed that Cr toxicity led to decreased plant performance, where 100 mg Cr kg-1 soil led to notable decreases in shoot weight (28%), root weight (27%), essential oil (EO) yield (34%), chlorophyll (Chl) a + b (33%), while increased malondialdehyde (MDA, 30%), superoxide dismutase (SOD) activity (51%), and catalase (CAT) activity (122%). The use of TiO2 NPs and MT, particularly their co-application, remarkably reduced Cr toxicity by enhancing plant weight, Chl content, and lowered MDA and antioxidant activity. Total phenolic content (TPC), total flavonoid content (TFC), EO percentage, and rosmarinic acid in plants treated with Cr at 50 mg Cr kg-1 soil and co-application of TiO2 NPs and MT were relatively higher than in other treatments. Under 100 mg Cr kg-1 soil, the synergic effect of TiO2 NPs and MT-enhanced rosmarinic acid content (22%) but lowered Cr accumulation in roots (51%) and shoots (72%). Heat map analysis showed that CAT, SOD, MDA, and EO yield had the maximum variability under Cr, TiO2 NPs, and MT. Exogenous TiO2 NPs and MT can be recommended to modulate Cr toxicity in lemon balm under soil Cr toxicity.

Zinc oxide nanoparticles mitigated the arsenic induced oxidative stress through modulation of physio-biochemical aspects and nutritional ions homeostasis in rice (Oryza sativa L.).

Zinc oxide nanoparticles (nZn) have emerged as vital agents in combating arsenic (As) stress in plants. However, their role in mitigation of As induced oxidative stress is less studied. Therefore, this study aimed to assess the comparative role of nZn and ZnO in alleviating As toxicity in rice genotype "9311". The results of this study revealed that nZn demonstrated superior efficacy compared to ZnO in mitigating As toxicity. This superiority can be attributed to the unique size and structure of nZn, which enhances its ability to alleviate As toxicity. Exposure to As at a concentration of 25 µM L-1 led to significant reductions in shoot length, root length, shoot dry weight, and root dry weight by 39%, 51%, 30%, and 46%, respectively, while the accumulation of essential nutrients such as magnesium (Mg), potassium (K), iron (Fe), manganese (Mn), and zinc (Zn) decreased by 25%-47% compared to the control plants. Additionally, As exposure resulted in stomatal closure and structural damage to vital cellular components such as grana thylakoids (GT), starch granules (SG), and the nucleolus. However, the application of nZn at a concentration of 30 mg L-1 exhibited significant alleviation of As toxicity, resulting in a reduction of As accumulation by 54% in shoots and 62% in roots of rice seedlings. Furthermore, nZn demonstrated the ability to scavenge reactive oxygen species (ROS) like hydrogen peroxide (H2O2) and superoxide anion (O2.-), while significantly promoted the gas exchange parameters, chlorophyll content (SPAD value), fluorescence efficiency (Fv/m) and antioxidant enzyme activities under As-induced stress. These findings highlight the potential of nZn in mitigating the adverse impacts of As contamination in rice plants. However, further research is necessary to fully comprehend the underlying mechanisms responsible for the protective effects of nZn and to determine the optimal conditions for their application in real-world agricultural settings.

The effect of gibberellic acid on wheat growth and nutrient uptake under combined stress of cerium, zinc and titanium dioxide nanoparticles.

Nanoparticles (NPs) are released and dispersed in the environment because of increased manufacturing and use of nano products. NPs disturb the growth of plants depending upon types, exposure duration and plant species. The purpose of this research was to explore the role of gibberellic acid (GA) exposure through foliar route on wheat growth under alone or combined soil application of cerium oxide (CeO2), zinc oxide (ZnO), and titanium dioxide (TiO2) NPs. GA was foliar-applied (200 mg/L) on the wheat plants treated with individual and in all possible combination of the selected NPs. Explorations have revealed that the combination of NPs and GA worked well to enhance the plant growth and selected nutrient status than NPs alone. Furthermore, GA decreased the boosted antioxidant enzyme activities under the combination and individual NPs compared to the alone NPs treated plants, lowered the oxidative stress in wheat plants which provided the additional proof that GA decreased oxidative damage in plants. Combined NPs showed differential effects than individual NPs application irrespective of GA exposure which varied with NPs combination and studied parameters of plants. GA + NPs differentially affected the potassium, phosphorus, iron and manganese concentrations in wheat tissues than NPs alone treatments. Overall, GA can be applied when there is excess of NPs (either alone or in combination) in the growth medium to ensure the growth of crops. However, further studied are needed with other plant species and alone or combined use of different NPs under GA treatment before any final recommendation.

Green synthesis and characterization of silver and copper nanoparticles and their use as an effective adsorbent for chromium removal and recovery from wastewater.

Chromium (Cr) is one of the hazardous heavy metals that is naturally carcinogenic and causes various health problems. Metallic nanoparticles such as silver and copper nanoparticles (Ag NPs and Cu NPs) have gained great attention because of their unique chemical, physical, and biological attributes, serving diverse and significant role in various useful and sustainable applications. In the present study, both of these NPs were synthesized by green method in which Azadirachta indica plant extract was used. These nanoparticles were characterized by using advanced instrumental techniques such as Fourier transmission infrared (FTIR), X-ray diffraction (XRD), scanning electron microscope attached with energy-dispersive spectroscopy (SEM-EDS), and elemental mapping. These environmentally friendly nanoparticles were utilized for the batch removal of Cr from the wastewater. For analysis of adsorption behaviour, a range of kinetic isotherm models (Freundlich, Temkin, Dubinin, and Langmuir) and kinetic models (pseudo-first-order and pseudo-second-order) were used for the Cu-NPs and Ag-NPs. Cu NPs exhibited the highest Cr removal efficiency (96%) within a contact time of 10-15 min, closely followed by Ag NPs which achieved a removal efficiency of 94% under the similar conditions. These optimal outcomes were observed at a sorbent dose of 0.5 g/L for Ag NPs and 0.7 g/L for Cu NPs. After effectively capturing Cr using these nanoparticles, the sorbates were examined through SEM-EDX analysis to observe how much Cr metal was attached to the nanoparticles, potentially for future use. The analysis found that Ag-NPs captured 18% of Cr, while Cu-NPs captured 12% from the aqueous solution. More precise experimental conditions are needed for higher Cr removal from wastewater and determination of the best conditions for industrial-level Cr reuse. Although nanomaterial exhibit high efficiency and selectivity for Cr removal and recovery from wastewater, more research is necessary to optimize their synthesis and performance for industrial-scale applications and develop efficient methods for Cr removal and recovery.

Synergistic effect of ß-sitosterol and biochar application for improving plant growth of Thymus vulgaris under heat stress.

Climate change has become the global concern due to its drastic effects on the environment. Agriculture sector is the backbone of food security which remains at the disposal of climate change. Heat stress is the is the most concerning effect of climate change which negatively affect the plant growth and potential yields. The present experiment was conducted to assess the effects of exogenously applied ß-sitosterol (Bs at 100 mg/L) and eucalyptus biochar (Eb at 5%) on the antioxidants and nutritional status in Thymus vulgaris under heat stressed conditions. The pot experiment was conducted in completely randomize design in which thymus plants were exposed to heat stress (33 °C) and as a result, plants showed a substantial decline in morpho-physiological and biochemical parameters e.g., a reduction of 59.46, 75.51, 100.00, 34.61, 22.65, and 38.65% was found in plant height, shoot fresh weight, root fresh weight, dry shoot weight, dry root weight and leaf area while in Bs + Eb + heat stress showed 21.16, 56.81, 67.63, 23.09, 12.84, and 35.89% respectively as compared to control. In the same way photosynthetic pigments, transpiration rate, plant nutritional values and water potential increased in plants when treated with Bs and Eb in synergy. Application of Bs and Eb significantly decreased the electrolytic leakage of cells in heat stressed thymus plants. The production of reactive oxygen species was significantly decreased while the synthesis of antioxidants increased with the application of Bs and Eb. Moreover, the application Bs and Eb increased the concentration of minerals nutrients in the plant body under heat stress. Our results suggested that application of Bs along with Eb decreased the effect of heat stress by maintaining nutrient supply and enhanced tolerance by increasing the production of photosynthetic pigments and antioxidant activity.