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Utilizing biostimulants like protein hydrolysates is one of the most creative and promising approaches to improving nutritional efficiency, abiotic stress tolerance, or crop quality traits. In the present study, whey protein was hydrolysed with trypsin for 4 h at an enzyme/substrate ratio (1/300, w/w). The obtained whey protein hydrolysates (WPH) were chemically characterized, and their antioxidant activity was estimated. WPH, which was produced using trypsin for 4 hours and presented the highest antioxidant activity. Therefore, it was selected as a bio stimulant with potassium fertilization for enhancing the productivity and tuber quality of sweet potatoes. A field experiment was carried out during the two successive summer seasons, at a private vegetable farm in Faques City, Sharkia Governorate, Egypt, to study the effect of different potassium rates (50, 75, and 100 kg K2O/fad) and WPH at 0.10 and 0.20% as a foliar application compared to unsprayed plants (control). The interaction between K2O at 100 kg /fad and spraying with WPH at 0.15% increased shoot dry weight/ plant, N, P, and K uptake by shoots, yield/plant, marketable yield, and total yield/fad, as well as average tuber root weight. It was concluded that the most efficient bio-stimulating foliar spray treatment for increasing sweet potato productivity was WPH (0.20%).

While the individual influences of melatonin (MT) and polyamines (PAs) have been widely studied under various abiotic stresses, little is known about their interaction under salinity stress. In the present study, salt stress applied by 50 mM of sodium chloride (NaCl) on snap bean seedlings has been supplemented with 20 μM of MT and/or 100 μM of putrescine (Put) (individually and in combination). The results indicated that under salinity stress, the combination of MT + Put achieved the highest significant increase in shoot fresh and dry weight, chlorophyll (Chl a), Chl a + b, carotenoids, total soluble sugars, proline, K, Ca, and cell membrane stability index (CMSI), as well as catalase (CAT) and peroxidase (POX) activities. This improvement was associated with an obvious decrease in Na, Na/K ratio, and oxidative damage as indicated by reducing leaf contents of methylglyoxal (MG), hydrogen peroxide (H2O2), and the rate of lipid peroxidation (malondialdehyde; MDA). Moreover, the combination of MT + Put demonstrated a significant decrease in the activities of diamine oxidase (DAO) and polyamine oxidase (PAO) leading to the reduction of the rate of polyamine oxidation. Meanwhile, MT applied individually gave the highest significant increase in leaf relative water content (RWC), Chl b, superoxide dismutase (SOD), and ascorbate peroxidase (APX). Conclusively, the combination treatment of MT + Put could decrease the degradation of polyamines and enhance tolerance to salinity stress in snap bean seedlings.

Selenium (Se) plays several significant roles in regulating growth, development and plant responses to various abiotic stresses. However, its influence on sulfate transporters (SULTRS) and achieving the harmony with other salt-tolerance features is still limited in the previous literatures. This study elucidated the effect of Se supplementation (5, 10 and 20 µM) on salt-stressed (50 mM NaCl) snap bean seedlings. Generally, the results indicated that Se had dual effects on the salt stressed seedlings according to its concentration. At a low level (5 µM), plants demonstrated a significant improvement in shoot (13.8%) and root (22.8%) fresh weight, chlorophyll a (7.4%), chlorophyll b (14.7%), carotenoids (23.2%), leaf relative water content (RWC; 8.5%), proline (17.2%), total soluble sugars (34.3%), free amino acids (FAA; 18.4%), K (36.7%), Ca (33.4%), K/Na ratio (77.9%), superoxide dismutase (SOD; 18%), ascorbate peroxidase (APX;12.8%) and guaiacol peroxidase (G-POX; 27.1%) compared to the untreated plants. Meanwhile, most of these responses as well as sulfur (S), Se and catalase (CAT) were obviously decreased in parallel with increasing the applied Se up to 20 µM. The molecular study revealed that three membrane sulfate transporters (SULTR1, SULTR2 and SULTR 3) in the root and leaves and salinity responsive genes (SOS1, NHX1 and Osmotin) in leaves displayed different expression patterns under various Se treatments. Conclusively, Se at low doses can be beneficial in mitigating salinity-mediated damage and achieving the functioning homeostasis to tolerance features.

Despite the role of γ-aminobutyric acid (GABA) in plant tolerance to chilling stress having been widely discussed in the seedling stage, very little information is clear regarding its implication in chilling tolerance during the reproductive stage of the plant. Here, we investigated the influence of GABA (1 and 2mM) as a foliar application on tomato plants (Solanum lycopersicum L. cv. Super Marmande) subjected to chilling stress (5°C for 6h/day) for 5 successive days during the flowering stage. The results indicated that applied GABA differentially influenced leaf pigment composition by decreasing the chlorophyll a/b ratio and increasing the anthocyanin relative to total chlorophyll. However, carotenoids were not affected in both GABA-treated and non-treated stressed plants. Root tissues significantly exhibited an increase in thermo-tolerance in GABA-treated plants. Furthermore, applied GABA substantially alleviated the chilling-induced oxidative damage by protecting cell membrane integrity and reducing malondialdehyde (MDA) and H2O2. This positive effect of GABA was associated with enhancing the activity of phenylalanine ammonia-lyase (PAL), catalase (CAT), superoxide dismutase (SOD), and ascorbate peroxidase (APX). Conversely, a downregulation of peroxidase (POX) and polyphenol oxidase (PPO) was observed under chilling stress which indicates its relevance in phenol metabolism. Interesting correlations were obtained between GABA-induced upregulation of sugar metabolism coinciding with altering secondary metabolism, activities of antioxidant enzymes, and maintaining the integrity of plastids’ ultrastructure Eventually, applied GABA especially at 2mM improved the fruit yield and could be recommended to mitigate the damage of chilling stress in tomato plants.

Table grape berries are classified as a perishable crop that deteriorates quickly after harvest. The application of melatonin after harvest was found to be effective for retarding senescence and slowing ripening. In the current study, we tested the influence of two melatonin concentrations (50 and 100 µmol) as a postharvest application on quality, bioactive compounds, and enzyme activities of grape berries cv “Crimson” stored at 0 ± 1 °C and 90% relative humidity (RH) for 35 days. Our results indicated that melatonin application extends the shelf-life of berries by reducing weight loss and maintaining total soluble solids (TSS), titratable acidity (TA), berry adherence strength, and firmness. Melatonin treatment also reduced pectin methyl esterase (PME) and polygalactouranase (PG) enzyme activities compared to the control. Moreover, O2•− and H2O2 rates in berries were reduced by high melatonin concentration. Moreover, peroxidase (POD) and catalase (CAT) enzyme activities were increased by melatonin application. Our findings suggested using melatonin postharvest to increase shelf life and maintain quality attributes during refrigerated storage, which could be advantageous on a large scale.

Biofumigant and crop sequencing are effective and safe control system activators that maintain soil fertility and reduce pest populations. The study goals were to find new pesticide-free therapies for root-knot nematode management on cucumbers to maintain high yields and protect the environment and human health. In 2018 and 2019, the research employed a fully randomized block design under field conditions with five treatments and control: two bio- fumigants, cultivation of cucumber after broccoli plantlets incorporation (BPI) and radish plantlets incorporation (RPI), two crop sequence treatments (cultivation after broccoli (BCS) and radish (RCS), and nematicide treatment). Cucumber cultivation after BPI treatment exhibited the best horticultural traits, which reflected positively on early and total productivity. The increased yield was gained by suppressing all nematode parameters, the number of nematode larvae, galls, and egg masses, as well as egg hatching reduction. The most effective biocides, total phenols, myrosinase activity, total glucosinolates (GSLs), and isothiocyanates (ITCs) in brassica crops were estimated for their pesticide properties. The highest amount was released with BPI treatment, compared to adult plants and radish in its two stages. The bio-managed treatments revealed superior effectiveness compared to nematicide application and control to suppress the nematode population while enhancing cucumber growth and production.

A field trial study was conducted for two consecutive seasons 2020 and 2021 in approximately 8-month-old jojoba plants to evaluate the physiological responses following salt treatment and the role of proline as a foliar application to enhance jojoba tolerance to salinity stress. Jojoba plants were irrigated once a week for four months with diluted seawater in concentrations of 5000, 10,000, and 15,000 ppm and tap water (control). Anti-stress proline was applied four times throughout the experiment, the first at the beginning of the experiment and another three times at 30-day intervals, at concentrations of 0, 300, and 450 ppm. The effect of proline treatments on jojoba plant behavior includes growth vegetative characteristics, namely plant height increase percentage (PHIP), shoot number increase percentage (NSIP), stem diameter increase percentage (SDIP), number of leaves, leaf thickness, leaf area, and fresh and dry weights of leaves, and chemical characteristics, namely chlorophyll a and b, total chlorophyll, carotenoids, leaf mineral contents (N, P, K, Na, and Cl), total phenolic content (TPC), and proline concentration. Moreover, the impacts of proline on hydrogen peroxide (H2O2), superoxide anion (O2•−), malondialdehyde (MDA), and ion leakage (IL) under salinity stress were investigated. Briefly, proline at 450 ppm enhanced all studied growth and physiological characteristics and promoted the antioxidant system of jojoba plants compared with the control and other treatments. The anatomical structure of leaves was also examined, and favorable variations in the anatomical structure were detected in the stressed and proline-treated plants. Exogenous application of proline enhanced most of this anatomical characteristic of jojoba leaf under saline stress. In conclusion, proline as a foliar application at 450 ppm under salinity stress of 10,000 ppm enhances jojoba tolerance to salinity stress by modifying the physicochemical and morphological characteristics of jojoba plants.

Cysteine (Cys) and α-lipoic acid (ALA) are naturally occurring antioxidants (sulfur-containing compounds) that can protect plants against a wide spectrum of environmental stresses. However, up to now, there are no conclusive data on their integrative roles in mitigation of drought stress in wheat plants. Here, we studied the influence of ALA at 0.02 mM (grain dipping pre-cultivation treatment) and Cys (25 and 50 ppm as a foliar application) under well watered and deficit irrigation (100% and 70% of recommended dose). The results showed that deficit irrigation markedly caused obvious cellular oxidative damage as indicated by elevating the malondialdehyde (MDA) and hydrogen peroxide content (H2O2). Moreover, water stressed plants exhibited multiple changes in physiological metabolism, which affected the quantitative and qualitative variables of grain yield. The enzymatic antioxidants, including superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and peroxidase (POX) were improved by Cys application. SOD and APX had the same response when treated with ALA, but CAT and POX did not. Moreover, both studied molecules stimulated chlorophyll (Chl) and osmolytes’ biosynthesis. In contrast, the Chl a/b ratio was decreased, while flavonoids were not affected by either of the examined molecules. Interestingly, all above-mentioned changes were associated with an improvement in the scavenging capacity of reactive oxygen species (ROS), leaf relative water content (RWC), grain number, total grain yield, weight of 1000 kernels, gluten index, falling number, and alveographic parameters (P, W, and P/L values). Furthermore, heatmap plot analysis revealed several significant correlations between different studied parameters, which may explore the importance of applied Cys and ALA as effective compounds in wheat cultivation under water deficit conditions.

γ-aminobutyric acid (GABA) is a non-protein amino acid involved in various physiological processes; it aids in the protection of plants against abiotic stresses, such as drought, heavy metals, and salinity. GABA tends to have a protective effect against drought stress in plants by increasing osmolytes and leaf turgor and reducing oxidative damage via antioxidant regulation. Guard cell GABA production is essential, as it may provide the benefits of reducing stomatal opening and transpiration and controlling the release of tonoplast-localized anion transporter, thus resulting in increased water-use efficiency and drought tolerance. We summarized a number of scientific reports on the role and mechanism of GABA-induced drought tolerance in plants. We also discussed existing insights regarding GABA’s metabolic and signaling functions used to increase plant tolerance to drought stress.

Due to their beneficial, stimulating impact on plant growth, productivity, and alleviating environmental stresses, protein hydrolysates have recently received increasing attention as a possible substitute. This investigation aimed to explore the effects of foliar application of papain-produced whey protein hydrolysates (WPH) on the yield attributes and nitrogen use efficiency (NUE) of soft wheat. Wheat plants were cultivated under a Mediterranean arid environment and received four soil nitrogen (N) fertilization levels with ammonium nitrate (145, 185, 215, and 250 kg N ha−1) and compared to control treatment and urea foliar application. WPH increased grain yield, yield attributes, and N accumulation in wheat plants. Partial productivity factors of applied nitrogen, as NUE indicators under relatively steady-state cropping systems, were also enhanced by WPH compared to control treatment. WPH significantly improved flag leaf area, spike number m−2, and grain yield compared to urea foliar application. Increasing the soil N fertilization level from 145 up to 215 kg N ha−1 was accompanied by significant increases in all yield traits and N accumulation measurements, except for the partial factor productivity of applied N, which decreased. A strong positive association was detected among grain and straw yields, their attributes, and total N uptake. Results highlighted the efficacy of WPH in increasing wheat yield and NUE.

Coatings that reduce the fat content of fried food are an alternate option to reach both health concerns and consumer demand. Mucilage of garden cress (Lepidium sativum) seed extract (MSE) was modified into an edible coating with or without ascorbic acid (AA) to coat fresh-cut potato strips during cold storage (5 °C and 95% RH for 12 days) and subsequent frying. Physical attributes such as color, weight loss, and texture of potato strips coated with MSE solutions with or without AA showed that coatings efficiently delayed browning, reduced weight loss, and maintained the texture during cold storage. Moreover, MSE with AA provided the most favorable results in terms of reduction in oil uptake. In addition, the total microbial count was lower for MSE-coated samples when compared to the control during the cold storage. MSE coating also performed well on sensory attributes, showing no off flavors or color changes. As a result, the edible coating of garden cress mucilage could be a promising application for extending shelf-life and reducing the oil uptake of fresh-cut potato strips.

The present work reveals the beneficial role of sodium nitroprusside (SNP; NO donor concentration: 50 and 100 µM) in mitigation of water stress accompanied by a reduction in viral disease incidence in tomato plants subjected to deficit irrigation. The plants were grown under two irrigation regimes: well-watered (WW; irrigated after the depletion of 55–60% of available soil water) and water deficit (WD; irrigated after the depletion of 85–90% of available soil water) in two seasons of 2018 and 2019. The results indicated that under water stress conditions, plant growth, chlorophyll, relative water content (RWC), and fruit yield were decreased. Conversely, water stress significantly increased the MDA, proline, soluble sugars, and antioxidant enzymes’ activities. Moreover, it was obvious a negligible increase in the fruit content from NO2 and NO3. Water-deficit stress, however, had a positive impact on reducing the percentage of viral disease (TMV and TYLCV) incidence on tomato plants. Similarly, SNP application in the form of foliar spray significantly reduced the disease incidence, the severity, and the relative concentrations of TMV and TYLCV in tomato plants raised under both WW and WD conditions. The treatment of SNP at 100 µM achieved better results and could be recommended to induce tomato plant tolerance to water stress. Thus, the present work highlights the role of NO (SNP) in the alleviation of water stress in tomato plants and subsequent reduction in viral disease incidence during deficit irrigation.

Few reports explain the mechanism of PEG action on stomatal behavior and anatomical structure and analyze the photosynthetic pigments of in vitro date palm plantlets for better tolerance to ex vitro exposure. The main challenge for in vitro micropropagation of date palm techniques remains restricted to high survival rates and vigorous growth after ex vitro transplantation. In vitro hardening is induced by Polyethylene glycol PEG (0.0, 10, 20, 30 g L−1) for 4 weeks. Leaf anatomy, stomatal behavior, water loss %, photosynthetic pigments, and reducing sugars were examined in date palm plantlets (Phoenix dactylifera L.) cv. (Sewi) after 4 weeks from in vitro PEG treatment and after 4 weeks from ex vitro transplanting to the greenhouse. Leaf anatomy and the surface ultrastructure of in vitro untreated leaves showed a thin cuticle layer, wide opened malfunctioning stomata, and abnormal leaf anatomy. Furthermore, addition of PEG resulted in increasing cuticle thickness, epicuticular wax depositions, and plastids density, improving the stomatal ability to close and decreasing the stomatal aperture length while reducing the substomatal chambers and intercellular spaces in the mesophyll. As a result, a significant reduction in water loss % was observed in both in vitro and ex vitro PEG treated leaves as compared to untreated ones, which exhibited rapid wilting when exposed to low humidity for 4 h. PEG application significantly increased Chlorophylls a, b and carotenoids concentrations, especially 10, 20 g L−1 treatments, which were sequentially reflected in increasing the reducing sugar concentration. However, leaves of plantlets treated with PEG at 30 g L−1 became yellow and had necrosis ends with death. In vitro hardening by 20 g L−1 PEG increased the survival rate of plantlets to 90% after ex vitro transfer compared to 63% recorded for the untreated plantlets. Therefore, this application provides normal date palm plantlets developed faster and enhances survival after ex vitro transfer.

Melatonin “N-Acetyl-5-methoxytryptamine” (MT) has recently been considered as a new plant growth regulator with multiple physiological functions. Although many previous studies have confirmed that exogenous applied-MT can alleviate the deleterious effects of drought stress in many plant species, most of these studies were exclusive on seeds, seedlings, and young plants for a short period of their life cycles. Therefore, the knowledge of using MT as a potential promising agricultural foliar application to improve crop productivity and quality is still insufficient under adverse open field conditions. In this study, we investigated the effect of MT as a foliar application at 0, 20, and 40 ppm on tomato plants that were grown in the open field under the long term of optimal and deficit irrigation conditions. The results indicated that exogenous MT significantly enhanced plant growth, chlorophyll and activities of antioxidant enzymes, including ascorbate peroxidase (APX), catalase (CAT), and peroxidase (POX). This improvement was associated with a marked reduction in proline and soluble sugars. In addition, applied-MT worked as a protective agent against oxidative damage by reducing the cellular content of toxic substances such as H2O2 and malondialdehyde (MDA). Similarly, MT-treated plants showed greater total fruit yield with improving its quality attributes like total soluble solids (TSS), ascorbic acid, and lycopene. Generally, the highest significant fruit yield either under well-watered (13.7%) or water deficit (37.4%) conditions was achieved by the treatment of 20 ppm MT. These results indicate that exogenous MT played an essential role in enhancing tomato tolerance to deficit irrigation and could be recommended as a promising agricultural treatment under such conditions.

A number of obstacles, including irrigated wastewater and soil contamination, arise in the growth of aromatic and medicinal plants. This study aimed to reduce the effects of contaminated soil and wastewater irrigation on rosemary ( Rosmarinus officinalis L.) plants by using biosynthesized silver nanoparticles (AgNPs) produced by the ginger ( Zingiber officinale ) plant extract. The AgNPs were characterized using Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR). The experimental design involved three distinct groups of plants: one group was irrigated with regular tap water, another group was rooted in soil contaminated by sewage-wastewater and irrigated with processed wastewater, and the final group consisted of plants grown in wastewater-contaminated soil, irrigated with processed wastewater, and sprayed with 200 mM l ^−1 AgNPs. The study also examined the impact of different treatments on gene expression and secondary metabolite levels in rosemary plants. According to HPLC investigations, nineteen phenol compounds and flavonoids were identified in a methanolic extract of rosemary that was grown in contaminated soil, irrigated with wastewater, and sprayed with AgNPs. Plants treated with wastewater and nanoparticles produced quantities of secondary compounds, including resvertol, vanillic acid, and gallic acid with 1.11, 0.15, and 0.01 mg g ^−1 respectively, which are all regarded as significant antioxidants employed in the pharmaceutical industry. Hexokinase synthase (HK), geranyl diphosphate synthase (GPPS), and linalool synthase (LS) coding genes were found to have highly expressed expressions when plants grown in contaminated soil, wastewater-irrigated plants, and nanoparticle-sprayed plants, respectively, at a 23.2- and 5.54-fold level, where the HK gene was 8.7 times more strongly expressed. Conversely, plants grown in contaminated soil and irrigated with treated wastewater showed downregulation of these genes. Conclusively, using silver nanoparticles significantly reduced the influence of wastewater pollution on secondary metabolites in rosemary plants, which was increased by the gene expression results and was completely consistent with HPLC analysis.