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Silicon (Si) and biochar (Bc) are key signaling conditioners that improve plant metabolic processes and promote drought tolerance. However, the specific role of their integrative application under water restrictions on economical plants is not yet well understood. Two field experiments throughout 2018/2019 and 2019/2020 were conducted to examine the physio-biochemical modifications and yield attributes of borage plants mediated by Bc (9.52 tons ha−1) and/or Si (300 mg L−1) under different irrigation regimes (100, 75, and 50% of crop evapotranspiration). Catalase (CAT) and peroxidase (POD) activity; relative water content, water, and osmotic potential; leaf area per plant and yield attributes; and chlorophyll (Chl) content, Chla/chlorophyllidea (Chlida), and Chlb/Chlidb were considerably reduced within the drought condition. On the other hand, oxidative biomarkers, as well as organic and antioxidant solutes, were increased under drought, associated with membrane dysfunction, superoxide dismutase (SOD) activation, and osmotic adjustment (OA) capacity as well as a hyperaccumulation of porphyrin intermediates. Supplementation of Bc and Si lessens the detrimental impacts of drought on several plant metabolic processes associated with increasing leaf area and yield attributes. Their application under normal or drought conditions significantly elicited the accumulation of organic and antioxidant solutes as well as the activation of antioxidant enzymes, followed by lessening the formation of free radical oxygen and mitigating oxidative injuries. Moreover, their application maintained water status and OA capacity. Si and/or Bc treatment reduced protoporphyrin, magnesium-protoporphyrin, and protochlorophyllide while increasing Chla and Chlb assimilation and boosting the ratio of Chla/Chlida and Chlb/Chlidb, resulting in a rise in leaf area per plant and yield components following these modifications. These findings highlight the significance of Si and/or Bc as (a) stress-signaling molecule(s) in regulating defensive systems in drought-affected borage plants by boosting antioxidant aptitude, regulating water status, and accelerating chlorophyll assimilation, thus leading to increasing leaf area and productivity.

High fertilization rates and pesticides are required for the intensive production of strawberries, which offer several therapeutic health benefits. Recently, chitosan (CHI), and phosphorus fertilizer based on Micro Carbon TechnologyTM (MCT-P) were applied to encourage strawberry sustainable production and enhance phosphorus-use efficiency. Field trials were conducted throughout 2020/2021 and 2021/2022, to evaluate the effectiveness of MCT–P and CHI in improving strawberry cv. Fortuna growth and yield as well as their quality. Foliar spraying of CHI and MCT-P considerably improved strawberry plant growth (i.e., plant height, secondary crown number per plant, leaf number and area per plant, and foliage fresh weight), photosynthetic pigment concentration (chlorophylla, chlorophyllb, and carotenoids), as well as its yield and quality (early fruit yield, total yield, average fruit weight, fruit firmness, fruit dry matter %, soluble solid content, total sugars (%), ascorbic acid, acidity, and anthocyanin). Compared to untreated plants, 1200 mgL−1 MCT-P and 1000 mg/L CHI supplementation was the most effective concentration for improving all studied characteristics. The interaction between CHI and MCT-P had a greater impact on all examined characteristics. It is recommended to spray strawberry cv. Fortuna with 1200 mg/L MCT-P plus 1000 mg/L CHI every two weeks, from 60 days after transplanting until two weeks before the end of harvesting season for the best fruit yield and quality.

In order to alleviate the shortage of irrigation water in dry regions, refining water use efficiency (WUE) is a key issue in sustainable productivity. Furthermore, glycinebetaine (GlyBet) is a vital osmoprotectant produced in crops for improving drought tolerance; however, little is known about its role in improving plant WUE under field conditions in non-accumulating plants such as cucumber. In order to elucidate the effectiveness of GlyBet concentrations (0, 2000, 4000, and 6000 mg/L) in mitigating the deleterious effects of drought (e.g., well-watered (1250 m3/fed), moderate drought (950 m3/fed), and severe drought (650 m3/fed)), field experiments were conducted at Elmia village, Dakahlia, Egypt in the 2020 and 2021 seasons on vegetative growth, some physiological attributes, as well as yield and quality. Drought considerably decreased vegetative growth, yield and its components, leaf relative water content, and photosynthetic pigment concentrations compared with well-watered plants while increasing electrolyte leakage. The most harmful causes were severe drought. However, exogenous spraying with GlyBet substantially boosted the mentioned attributes, but reduced electrolyte leakage within well-watering. Commonly 6000 mg/L contributed to the maximum growth and productivity, preserving cucumber plant water status above other concentrations or untreated plants. Under extreme drought, the application of 6000 mg/L GlyBet had a beneficial effect on moderating the damage of water deficit on cucumber plant growth and productivity. Overall, using GlyBet as a cost-effective and eco-friendly biostimulant six times (10, 20, 30, 40, 50, and 60 days from sowing) has the potential to mitigate drought damage while also increasing yield; however, more research is needed to determine the optimal rate and timing of application.

Salinity is the principal natural obstacles for sustainable agriculture, adversely impacting 30% of the world’s irrigated land, resulting in food insecurity, particularly in arid and semi-arid areas. Zinc has several functions in plants; nevertheless, the promising roles of nano-zinc oxide particle in plants under salinity stress are not clear. The current study aims to investigate the roles of zinc (water, 75 mg L−1 zinc sulfate (Zn), and 10 mg L−1 zinc oxide nanoparticle (ZNP)) on the mitigation of NaCl stress (6000 mg L−1) on morpho-physiological attributes and yield of canola plants. Salinity exhibited a substantial reduction in canola plant growth, enhanced photosynthetic pigment degradation, and decreased nutrient concentrations. A decrease in the overall yield and a decrease in various individual components were considerably stimulated by zinc application under non-salinized and salinized conditions. Salinity caused a visible increase in membrane permeability (MP%), malondialdehyde (MDA), and hydrogen peroxide (H2O2) concentrations. Interestingly, zinc application significantly decreased MP%, MDA, and H2O2 concentrations by the upregulation of antioxidant enzymes (superoxide dismutase, catalase, peroxidase) and levels of non-enzymatic antioxidants (ascorbic, carotenoids, and total soluble phenolic compounds). Furthermore, zinc application also enhanced osmoregulation by increasing proline and total soluble carbohydrates accumulation, as well as increased nitrogen, potassium, and phosphorus in the plant tissues in correlation with a decline in sodium and chloride contents. Zinc’s, especially ZNP, role in the mitigation the negative effects of salinity on canola growth and yield may be connected with the upregulating oxidative defense system and osmolyte synthesis as well as ionic regulation.

Cocoa is an economical cash crop that is formerly planted worldwide. Cuttings are a method of vegetative propagation suitable for maintaining desirable characteristics in cocoa trees. A greenhouse experiment was performed to evaluate the optimal concentrations of Pectimorf® (0, 10, 50, and 100 mg L-1) for rooting ability and seedling establishment as well as some physiological trials of 4 months EETP-800 national cocoa cuttings grown under two different substrates (S1: 80% soil + 20% sand and S2: 70% soil + 20% sand + 10% rice husk). The data showed that in most cases there are no significant differences in vegetative growth and root characteristics as well as gas exchange parameters between the two substrates. On the other hand, the application of Pectimorf® concentration enhanced all tested traits compared to untreated plants. The most effective in this regard was 100 mg L-1, that giving the highest value of all trials. As for the interaction effect, the result also shows that the application of Pectimorf® concentration in special at 100 mg L-1 among two substrates had an additive effect on plant growth, gas exchange, and survival percentage compared to non-treated cuttings. The application of 100 mg L-1 Pectimorf® with S2 substrate produced stronger seedlings with a higher survival percentage. This protocol can be used commercially for cocoa propagation commercially.

Iron (Fe) deficiency exists as a widespread nutritional disorder in alkaline and calcareous soils; therefore, Fe-enriching strategies may be used to overcome this issue. Field experiments were conducted with a randomized complete design with three replicates for evaluating the effectiveness of iron oxide nanoparticles (Fe-NPs) against traditional Fe compounds (sulfate or chelate), which have various shortcomings on Rose-scented geranium (RSG) herb in terms of plant growth, phytopharmaceuticales, essential oil (EO), and its constituents. Supplementation of Fe-sources considerably improved RSG plant growth and EO yield in the 1st and 2nd cut throughout the two seasons over non-treated control plants. A total of 11 compounds of RSG-EO were identified; the main constituents were citronellol, geraniol, and eugenol. The results indicate that EO composition was significantly affected by Fe-sources. Amendments of Fe-sources considerably augmented photosynthetic pigments, total carbohydrates, nitrogen, phosphorous, potassium, iron, manganese, zinc, phenols, flavonoids, and anthocyanin. Commonly, Fe-NPs with humic acid (Fe-NPs-HA) supplementation was superior to that of traditional sources. The highest values were recorded with spraying Fe-NPs-HA at 10 mg L−1 followed by 5 mg L−1, meanwhile, the lowest values were recorded in untreated control plants. Current findings support the effectiveness of nanoparticle treatment over Fe-sources for improving growth and yield while also being environmentally preferred in alkaline soil. These modifications possibly will be applicable to EO quality and its utilization in definite food and in medical applications.

Sodium nitroprusside (SNP) has a decisive function for mitigating water deficit; nevertheless, the specific roles of SNP on chlorophyll biosynthesis, water relation, and osmotic adjustment in marjoram (Origanum marjorana L., Lamiaceae) have not well been established. To assess the function of SNP in alleviating water stress (50% of field capacity), potted marjoram herbs were subjected to watering regimes (well-watered or water-deficit) with or without SNP concentrations (0, 30, 60 μM). Drought caused a significant reduction in water potential (Ψw), osmotic potential (Ψs), turgor potential (Ψp), relative water content (RWC), photosynthetic pigment, chlorophyllide (chlide)a, chlideb, chlorophyll (chl)a/chlidea, chlb/chlideb, and ions, however increased pheophytina (pheoa), protoporphyrin (Proto), Mg-protoporphyrin (Mg-proto), and protochlorophyllide (pchlide). Conversely, osmotic adjustment (OA) was improved, associated with the hyper-accumulation of osmotic adjustment solutes (OAS) leading to an increase in water saturation deficit (WSD), which induced a decrease in dry matter accumulation and shoot fresh weight. Application of SNP decreased Ψw, Ψs, and Ψp and WSD while maintained higher RWC, comparing the plants devoid of SNP supplementation. Supplementary SNP additionally motivated the energetic buildup of various OAO in drought-affected plants that improved OA aptitude, improved water retention capacity, and increased plant growth. Additionally, SNP application increased chlorophyll, carotenoid, pheoa, chlidea, chlideb, chla/chlidea, chlb/chlideb, and decreased Proto, Mg-proto, pchlide, and ions. The findings of the present study clarified that the SNP application improved drought tolerance of marjoram plants, through maintaining ion homeostasis, enhanced OA capacity, increased OAO accumulation, and stabilized chlorophyll biosynthesis.

Salinity is a key worldwide ecological restriction to sustainable crop production and food security. Various methods were used for inducing salinity tolerance including biotechnological approaches or application of stress tolerance-inducing substances. Silicon supplementation has a decisive role in alleviating of salinity injury, however, the definite mechanisms behind stay scantily understood, and must be examined. The imperative roles of sodium metasilicate (Si, 100 ppm) application methods (foliar spraying at 100 mg/l; soil additive at 100 mg/kg soil; foliar spraying at 100 mg/l plus soil additive at 100 mg/kg soil), in improving growth and essential oil yield, maintaining water status, activating antioxidant system, and keeping ion homeostasis of salt affected-sweet basil (6000 mg NaCl/kg soil) were studied. Salinity induced a notable increase in oxidative biomarkers, coupled with higher osmolyte concentration and osmotic potential (OP) values, as well as increased superoxide dismutase and peroxidase activities. Alternatively, sweet basil growth, essential oil yield, and catalase activity were reduced under salinity. Furthermore, salinity aggravated ion imbalance, decreased photosynthetic pigment and disrupted the plants' water status. Silicon application drastically increased osmolyte accumulation associated with sustained water status, increased OP, and improved osmotic adjustment (OA) capacity. Additionally, Si application enhanced antioxidant aptitude associated with decreased oxidative biomarkers and improved growth, photosynthetic pigment, and essential oil yield. Greater outcomes were achieved with the foliar spraying method, compared with other application methods. Salinity stress evoked modification in protein assimilation capacity and possibly will withdraw protein biosynthesis and reduce total protein band number; however, Si application may adjust the expression of salinity inducible proteins. Foliar spraying of Si with or without soil additive accelerates the expression of peroxidase isozyme over salinized or control plants. Collectively, Si foliar spraying alleviated salinity-related injuries on sweet basil by maintaining water status, increasing osmolyte assimilation, improving OA, enhancing redox homeostasis, and antioxidant capacity.

Arsenic (As) recognized as a group I human carcinogen additionally poses a threat to plants which limit growth, metabolic activity, and productivity. Melatonin (MEL) is a naturally occurring compound in plants that have been recognized to mediate numerous morphological, physiological and molecular processes. Conversely, the role of MEL in inducing As-tolerance remains inexpressible and the plausible mechanisms in inducing As tolerance have remained largely unknown. The present investigation was designed to understand the protective role of MEL concentrations in rosemary herbs cultivated under As contamination. Arsenic evoked a deleterious decline on herb productivity, photosynthetic pigment, ion concentration, water status, ascorbic acid, essential oil (EO) yield and induced malformation of the chloroplast. Alternatively, increased organic osmolytes, oxidative impairment criteria, additionally antioxidant enzymes, phenol, flavonoid, anthocyanin, and EO%. Exogenous application of MEL with or without As, considerably increased growth, photosynthetic pigment, ion concentration, organic osmolytes as well as EO yield regarding polluted or non-polluted treatment respectively. Moreover, MEL treatment stabilized the cell membrane integrity, suppressed oxidative impairment criteria, and enhanced antioxidant capacity, additionally upregulation antioxidant enzymes. Plant treated with As showed a significant increase in As contamination and a bioconcentration factor in both root and shoot system. MEL supplementation under normal or As concentration, reduced As accumulation and bioconcentration factors, in either shoot or root systems. Additionally As decrease transfer factor, however, supplementation of MEL further decreased it. Application of 50 μM MEL might help the herbs to withstand As stress by strengthening their antioxidant machinery and osmoregulation capacity.

Seed priming is currently a wide used commercial process that accelerates the germination rate and improves seedling uniformity in several crops. A laboratory study was conducted to evaluate the effect of grain priming treatments on barley grain germination and seedling growth under drought stress imposed by PEG-6000. The experiment was performed employing a factorial completely randomized block design with four levels of drought stress (0,10,20 and 30% PEG6000) and 14 priming treatments (dry, hydropriming, 5, 10, 15% PEG-6000; 500, 1000, 1500 mg/l KNO3; 25, 50, 75 mg/l thiamin; 50, 100, 150 mg/l sodium metasilicate) with five replications for each treatment. Germination percentage, germination index, energy of germination, mean germination time, seedling vigor, seedling length, 10 seedling fresh and dry weights were measured below the experimental conditions. Variance analysis results (ANOVA) showed extremely significant (p