Non-treated Plants Research Articles

English

Fungal pathogens have been investigated previously for biological control of goosegrass (Eleusine indica), but there is little research on the compatibility of herbicides with fungal pathogen Bipolaris bicolor for control of glyphosate-resistant E. indica. The aims of this study were to 1) examine the in vitro compatibility of Bipolaris bicolor and three herbicides (ametryn, flumiozaxin and sodium chlorate) and 2) determine the efficacy of a combination of B. bicolor and ametryn for inhibiting glyphosate-resistant E. indica biotypes in the greenhouse. Mycelial growth inhibition area was measured after B. bicolor spores were treated with ametryn, flumiozaxin, or sodium chlorate at one-fifth of their recommended rates. The findings showed that ametryn had the lowest inhibitory effect (10%), while flumioxazin and sodium chlorate had 80 and 30% inhibition, respectively, indicating that ametryn is the most compatible herbicide with B. bicolor. E. indica seedlings were then subjected to four treatments, including non-treated plants, at the 3 to 4-leaf stage where T1: negative control plant, T2: one-fifteenth of the recommended dose of ametryn, T3: B. bicolor spore suspension and T4: ametryn plus B. bicolor spore suspension. B. bicolor in combination with ametryn was the most effective treatment for E. indica inhibition one week after treatment. The treatment reduced seedling height, leaf greenness and shoot dry weight by 50 to 94% and caused plant death seven days after treatment. These findings suggest that B. bicolor in combination with ametryn is a viable integrated strategy to control the glyphosate-resistant E. indica biotype. © 2022 Friends Science Publishers

Effects of a Powder Formulation of Streptomyces cameroonensis on Growth and Resistance of Two Cocoa Hybrids from Cameroon against Phytophthora megakarya (Causal Agent of Black Pod Disease).

In the present study we evaluated the efficacy of a bioformulation of Streptomyces cameroonensis for control of black pod disease in cocoa and enhancement of seedling growth. The formulation developed using talc powder and cassava starch as carriers showed high shelf-life of 1.07 × 106 CFU/g after six months storage at 4°C. The formulation was tested for inhibition of spore germination in Phytophthora megakarya and showed 100% inhibition at 10% (w/v) of formulation. To determine the efficacy of the formulation, we performed an in planta assay in the greenhouse on two hybrids of cocoa seedlings, the tolerant SNK413 × (♂) T79/467 and the susceptible UPA 134× (♂) SCA 12. Detached leaf assay showed a significant reduction in the disease severity index of about 67% for the tolerant hybrid and 55% for the susceptible hybrid compared to non-treated plants. A significant enhancement in stem length, leaf surface area and root weight was observed. Analysis of biochemical markers of defense showed a significant increase in total polyphenol, flavonoid, and total protein contents. There was also significant upregulation of PR-proteins such as chitinases, peroxidases and β-1, 3-glucanases following treatment of both tolerant and susceptible hybrids, though with a higher level of synthesis in the tolerant hybrids. A significant increase was also observed in polyphenol oxidase activities in plants treated with the formulation. This work demonstrated the stability and effectiveness of the S. cameroonensis powder formulation in suppressing black pod disease in cocoa and subsequently enhancing the growth of seedlings.

Trichoderma hamatum Strain Th23 Promotes Tomato Growth and Induces Systemic Resistance against Tobacco Mosaic Virus.

Trichoderma hamatum strain Th23, isolated from tomato roots, was molecularly identified using phylogenetic analysis based on ITS, tef1, and rpb2 gene sequences and evaluated for its efficiency in suppressing tobacco mosaic virus (TMV) infection for the first time. Under greenhouse conditions, the application of Th23 promoted tomato growth with significant increases in shoot and root parameters as well as improved total chlorophyll content. Compared to the nontreated tomato plants, the soil pretreatment of tomato plants 48 h before TMV inoculation produced a significant reduction in the TMV accumulation level by 84.69% and enhanced different growth parameters. In contrast, TMV had a deleterious impact on fresh and dry matter accumulation and inhibited photosynthetic capacity. Furthermore, the protective activity of Th23 was associated with a significant increase in reactive oxygen species scavenging enzymes (PPO, CAT, and SOD) as well as decreased nonenzymatic oxidative stress markers (H2O2 and MDA) compared to the TMV treatment at 15 days post-viral inoculation (dpi). In addition, considerable increases in the transcriptional levels of polyphenolic genes (HQT and CHS) and pathogenesis-related proteins (PR-1 and PR-7) were shown to induce systemic resistance against TMV. Consequently, the ability of T. hamatum strain Th23 to promote plant growth, induce systemic resistance, and boost innate immunity against TMV infestation supported the incorporation of Th23 as a potential biocontrol agent for managing plant viral infections. To the best of our knowledge, this is the first report of the antiviral activity of T. hamatum against plant viral infection.

Primary metabolism in an Amaranthus palmeri population with multiple resistance to glyphosate and pyrithiobac herbicides

The objective of this work was to characterize the resistance mechanisms and the primary metabolism of a multiple resistant (MR) population of Amaranthus palmeri to glyphosate and to the acetolactate synthase (ALS) inhibitor pyrithiobac. All MR plants analysed were glyphosate-resistant due to 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene amplification. Resistance to pyrithiobac was more variable among individuals and was related to point mutations at five positions in the ALS gene sequence: A122, A205, W574, S653 and G654. All MR plants were heterozygous for W574, the most abundant mutation. In nontreated plants, the presence of mutations did not affect ALS functionality, and plants with the W574L mutation showed the highest ALS resistance level to pyrithiobac. The accumulation of the transcripts corresponding to several genes of the aromatic amino acid (AAA) and branched-chain amino acid (BCAA) pathways detected in nontreated MR plants indicated additional effects of EPSPS gene amplification and ALS mutations. The physiological performance of the MR population after treatment with glyphosate and/or pyrithiobac was compared with that of a sensitive (S) population. The increase induced in total soluble sugars, AAA or BCAA content by both herbicides was higher in the S population than in the MR population. Physiological effects were not exacerbated after the mixture of both herbicides in S or in MR populations. This study provides new insights into the physiology of a multiple resistant A. palmeri, which could be very useful for achieving effective management of this weed.

Dose–response screening of industrial hemp to herbicides commonly used in corn and soybean

AbstractRecent legalization of industrial hemp in the United States has led to increased interest among stakeholders to produce hemp for grain and fiber. However, owing to the lack of herbicides registered for use in hemp, producers are left with limited weed management strategies. Moreover, much of the agricultural land that could be used to cultivate industrial hemp may be prone to carryover of previously applied residual herbicides or physical drift from herbicides sprayed nearby. Industrial hemp sensitivity to herbicides is not well documented. Dose–response studies were conducted under controlled conditions in Madison, WI, screening two industrial hemp grain cultivars for tolerance to 44 preemergence and postemergence herbicides commonly used in corn and soybean. Treatments consisted of herbicides applied at 0×, 0.125×, 0.25×, 0.50×, 0.75×, 1×, 2×, and 4× the recommended maximum labeled rates based on soil type. Preemergence applications were delivered immediately after planting, whereas postemergence applications took place when hemp plants reached 5 to 10 cm in height. Nontreated plants served as the control and were used to estimate percent biomass reduction; dose–response curves were generated. Biomass reduction was >50% for rates under the suggested label rate for 23 preemergence and 21 postemergence herbicides tested. All herbicides tested resulted in >25% biomass reduction at the 0.125× rate, except for clopyralid applied preemergence and postemergence and saflufenacil applied preemergence. This is concerning, as the label rates are determined for effective weed control and the mitigation of herbicide resistance. Overall, these results indicate that industrial hemp is very sensitive to most herbicides tested. Growers should consider herbicide use history and surrounding crops when determining industrial hemp field selection to prevent significant plant injury due to herbicide carryover and drift. Further research into alternative methods of weed control will be vital to establishing hemp as a dominant crop once again.

Miscanthus×giganteusgrowth and control in simulated upland and wetland habitats

AbstractGlobally, giant miscanthus (Miscanthus × giganteusJ.M. Greef & Deuter ex Hodkinson & Renvoize [sacchariflorus × sinensis]) is used as a biofuel crop due to its ability to persist in a wide range of climates. However, little work has assessed this plant’s ability to invade and persist in wetland habitats. In outdoor mesocosms, we examinedM.×giganteus’s ability to grow in simulated wetland versus upland habitats and examined chemical control strategies for both habitats using aquatic-labeled herbicides.Miscanthus×giganteusgrowth was consistently greater in simulated wetland habitats, with wetland plants 2.4 to 3 times taller than upland plants at 6 wk after treatment (WAT) and 2.8 to 3.3 times taller than upland plants at 12 WAT.Miscanthus×giganteusaboveground biomass was 12.7 to 17.7 times greater in wetland- versus upland-grown plants at 6 WAT and 9.6 to 12.5 times greater at 12 WAT. Belowground biomass was 4.5 to 10.7 times greater in wetland versus upland grown plants at 6 WAT and 4.0 to 6.1 times greater at 12 WAT.Miscanthus×giganteusbelowground biomass was always greater than aboveground in both habitats at 6 (6.0 times greater in wetlands and 2.9 times greater in uplands) and 12 WAT (3.8 times greater in wetlands and 1.3 times greater in uplands). Generally, all herbicide treatments reducedM.×giganteusheight (66% to 100% reduction) and biomass (84% to 100%) compared with nontreated plants at 12 WAT; however, glyphosate (5,716.3 g ai ha−1) and imazapyr (1,120.8 g ai ha−1) performed better than imazamox (560.4 g ai ha−1) and penoxsulam (98.6 g ai ha−1). This is the first work to provide evidence thatM.×giganteuscan be chemically controlled in wetland habitats. Furthermore, this is the first work to show that penoxsulam (an acetolactate synthase–inhibiting herbicide) can reduceM.×giganteusgrowth in upland or wetland habitats.

Timing and Rate of Foliar Potassium Application to Improve Yield, Fruit Size and Quality Attributes of Pomegranate: Based on Data Generated in Field Experiments Conducted in Iran and Egypt

ABSTRACT It is proven that potassium (K) plays a key regulatory role in many physiological processes of plant growth and that K fertilization can improve the yield and quality attributes in fruit crops. This study was carried out to evaluate the effect of timing and various concentrations of foliar sprays of potassium sulfate, during fruit growth and maturation, on yield and quality of pomegranate fruit in Iran and Egypt, which have different pomegranate production systems. In Iran one, two or three sprays of 1% or 2% K-Leaf® (a high grade foliar potash booster) was used, and in Egypt a single spray of either 10 or 20 kg/ha, and two sprays of 10 and 20 kg/ha K-Leaf® were applied. Results showed that in both experiments in Iran and Egypt, foliar K treatments increased total and marketable yield of pomegranates, as well as fruit weight and size, flavor index (the ratio of total soluble solids/total acid). The treatments also improved the fruit’s peel and aril color compared to the non-treated control plants. Results also demonstrated that multiple potassium sprays (two or three applications) were more effective than applying higher concentrations; as in many cases, there were no significant differences between 1 and 2% concentrations of K fertilizer in treatments with same number of applications (one, two or three sprays). Although three sprays of 2% K-Leaf® were the most effective treatments, it can be concluded that three sprays of 1% K-Leaf®) is probably more economically sound for use in pomegranate orchards.

Foliar application of sodium silicate mitigates drought stressed leaf structure in corn (Zea mays L.)

A hydroponic study of maize cv. SC 705 was performed to determine the effectiveness of 1.0 mM sodium silicate to alleviate drought stress. Measurements were taken between 5 and 100 mm above the base of the third leaf. Stress negatively affected all growth parameters. As a general trend, a 1.0 mM Na2SiO3 foliar application increased growth parameters for stressed, but not un-stressed plants, compared to the control. Leaf cross sectional area increased 35%, and midrib area decreased 25% less than in untreated stressed plants, compared to the control. Protoxylem area in treated, drought-stressed plants increased by 40%, and Si application increased xylem in non-stressed plants compared to the control. In drought stressed seedlings the stomatal area increased 24% when Si treated compared to the control. In drought stressed plants, electrolytic leakage decreased from 0.64 to 0.52% when Si treated. Membrane stability increased 12% in drought stressed plants when Si treated. When drought stressed plants were Si treated, chlorophyll a increased by 35%, chlorophyll b increased by 31%, and carotenoids increased by 51% compared to the control. Drought stressed plants had a relative water content 15% higher than non-treated plants, and leaf elongation rate increased 33%, compared to the control. Compared to the control, drought stressed plants had a 20% higher K+ and 38% higher Ca2+ level when treated with Si. These data strongly support the hypothesis that foliar Si application could mitigate the effects of drought stress. Growth improvements could be correlated with increased K+ and Ca2+ accumulation, which may play an important role in increased midrib cross-sectional area, RWC, and third-leaf elongation under drought stress. Foliar application of Si could be a low cost, easy, and effective way to improve seedling establishment in corn affected by drought early in the season.

Regulation of nutrient accumulation by γ-aminobutyric acid associated with GABA priming-enhanced heat tolerance in creeping bentgrass

<italic>γ</italic>-Aminobutyric acid (GABA) is known for its positive effects on improving plant stress tolerance, while the association of its role in regulating nutritional availability and GABA priming-enhanced heat tolerance is not well documented. The objective of this study was to determine whether GABA priming may improve heat tolerance in cool-season grass species involving regulation of plant nutrition for macronutrients and micronutrient elements. Plants of creeping bentgrass (<italic>Agrostis stolonifera</italic>) (cv. 'Penncross') in each pot were treated with 10 mL of water (control) or 0.5 mM GABA (GABA priming) by foliar spray and then subjected to heat stress (35/30 °C, day/night) or optimal growth temperature (control) (21/19 °C, day/night) (non-stress control) for 30 d in growth chambers. GABA-primed plants had significantly higher endogenous GABA content associated with improved heat tolerance compared to non-treated plants, as reflected by higher leaf cell membrane stability, relative water content, osmotic adjustment, chlorophyll content, photochemical efficiency, and net photosynthetic rate. Plants pretreated with GABA exhibited significantly higher content of nitrogen (N), phosphorus (P), calcium (Ca), sodium (Na), and copper (Cu) but lower content of boron (B) and manganese (Mn) in leaves than non-treated plants under heat stress. The enhanced accumulation of N, P, Ca, Na, and Cu and restricted B and Mn accumulation by GABA priming indicate that GABA could modulate mineral nutrient availability in plants, contributing to improved heat tolerance for creeping bentgrass.

결구상추 육묘방법에 따른 생육 및 저장방법에 의한 선도 비교

The research was aimed to improve pre-harvest methods to maintain marketability in postharvest coniferous lettuce. Non-woven pots or plug plates were used to generate seedlings. No difference was found in growth characteristics of lettuce grown in non-woven pots vs plug plates. Since, seedling method with non-woven pots was convenient, lettuce harvested from non-woven pots used for water dipping treatment. The quality parameters, such as fresh weight loss, SPAD value, and appearance of lettuce were investigated after harvest. The lettuce with dipping treatment inside the plastic box container showed lower weight loss, higher SPAD value and better appearance compared to those exposed to the control (non-packaging) during the storage at 2oC. The treated plant showed higher SPAD and hue angle values 21.9 and 113.8o, respectively, compared to that of 18.8 and 108.3o, in non-treated plants. Therefore, it seems that the water dipping treatment is effective for storage method to maintain freshness of the lettuce. We showed the non-woven pot growing as a convenient seedling method for packaging treatment. Further studies will be continued to improve freshness postharvest of other horticultural crops.

Comparative analysis of iron oxide nanoparticles synthesized from ginger (Zingiber officinale) and cumin seeds (Cuminum cyminum) to induce resistance in wheat against drought stress

In the present study, iron oxide nanoparticles (Fe3O2-NPs) synthesized from ginger (Zingiber officinale) and cumin seeds (Cuminum Cyminum L.) extracts were investigated to reveal their potential to enhance the growth and drought resistance of wheat plants under drought stress. In an In Vitro experiment, four different concentrations for Fe3O2-NPs (0.3 mM, 0.6 mM, 0.9 mM, and 1.2 mM) of ginger and cumin seeds were tested. Among all the concentrations tested, ginger Fe3O2-NPs (0.6 mM) and cumin seeds Fe3O2-NPs (1.2 mM) were more effective to enhance wheat germination, biomass, and survival percentage under drought stress and irrigated conditions than the non-treated control plant. In a pot experiment, wheat plants under induced water stress showed marked up-regulation in the biochemical resistance mechanisms when treated with ginger Fe3O2-NPs (0.6 mM) and cumin seeds Fe3O2-NPs (1.2 mM) than the non-treated control. Cumin seeds Fe3O2-NPs (1.2 mM) were more effective than ginger Fe3O2-NPs (0.6 mM) in ameliorating adverse effects of drought stress in wheat. Results demonstrated that cumin seeds Fe3O2-NPs (1.2 mM) exhibited a higher increase in chlorophyll a, b and carotenoids (72%, 265% and 96% respectively), proline (127%), superoxide dismutase (115%), peroxidase (43.8%), ascorbate peroxidase (44.6%). This also showed higher reduction in lipid peroxidation, electrolyte leakage and increased soluble sugars and total Fe content in the roots and shoots than non-treated plants under drought. Hence, nano-priming can be considered an effective strategy for sustainable food production in marginal soils.

Pre-Harvest Application of Salicylic Acid, Abscisic Acid, and Methyl Jasmonate Conserve Bioactive Compounds of Strawberry Fruits during Refrigerated Storage

The short shelf-life and loss of bioactive compounds of strawberry fruit are the most important problems during strawberry refrigerated storage. This study was carried out to evaluate the effect of the pre-harvest foliar application of salicylic acid (SA) (2 and 4 mM), abscisic acid (ABA) (0.25 and 0.50 mM), and methyl jasmonate (MeJA) (0.25 and 0.50 mM) three times, 10 d apart, at fruit development and ripening stages on storage ability and bioactive compounds of strawberry fruit (cv. Festival) stored at 4 °C for 12 d. Our results showed that fruit obtained from both concentrations of ABA and 0.25 mM MeJA was firmer and had higher total soluble solids (TSS) than fruit from non-treated plants. However, all previous applications had no significant effect on weight loss, pH, or color. Applications of 4 mM SA and 0.25 mM MeJA conserved fruit from ascorbic acid (AsA) loss compared to control at the end of the storage period. In addition, all pre-harvest applications remained higher in total phenolic compounds (TPC) and anthocyanin contents compared to controls at the last storage period. Hence, the pre-harvest application of SA, ABA, and MeJA could be used to conserve TPC and anthocyanin as well as the quality of strawberry fruits during refrigerated storage.

Direct Foliar Application of dsRNA Derived From the Full-Length Gene of NSs of Groundnut Bud Necrosis Virus Limits Virus Accumulation and Symptom Expression.

Groundnut bud necrosis virus (GBNV) is the most significant member of the genus Orthotospovirus occurring in the Indian subcontinent. There is hardly any effective measure to prevent GBNV in crop plants. In order to develop GBNV infection prevention procedure, we examined the effect of the direct foliar application of double-stranded RNA (dsRNA) derived from the full-length NSs gene (1,320 nucleotides) of GBNV. The bacterially expressed dsRNA to the non-structural (dsNSs) gene of GBNV was purified and delivered to plants as an aqueous suspension containing 0.01% Celite for evaluating its efficacy in preventing GBNV infection in systemic host, Nicotiana benthamiana as well as in local lesion and systemic host, cowpea cv. Pusa Komal (Vigna unguiculata). The dsNSs application and challenge-inoculation were conducted in three different combinations, where plants were challenge-inoculated with GBNV a day after, immediately, and a day before the application of dsNSs. N. benthamiana plants, which were not treated with dsRNA showed severe systemic wilting and death by 9–16 days post-inoculation (dpi). The non-treated cowpea plants exhibited many chlorotic and necrotic lesions on the cotyledonary leaves followed by systemic necrosis and death of the plants by 14–16 dpi. The dsNSs treated plants in all the combinations showed significant reduction of disease severity index in both N. benthamiana and cowpea. The treatment combination where the GBNV inoculation was conducted immediately after the dsNSs treatment was found to be the most effective treatment in preventing symptom expression. The viral RNA analysis by real time PCR also showed 20 and 12.5 fold reduction of GBNV in cowpea and N. benthamiana, respectively. Our results suggest that the foliar application of dsRNA derived from the full-length NSs gene of GBNV through Celite is successful in delivering long dsRNA leading to effective prevention of GBNV infection.

Seaweed Extract Improves Lagenaria siceraria Young Shoot Production, Mineral Profile and Functional Quality

Vegetable landraces represent the main source of biodiversity in Sicily. Lagenaria siceraria is appreciated by Southern Mediterranean consumers for its immature fruits and young shoots. Plant-based biostimulants supply, such as seaweed extract (SwE), is a contemporary and green agricultural practice applied to ameliorate the yield and quality of vegetables. However, there are no studies concerning the effects of SwE on L. siceraria. The current study evaluated the effects of SwE foliar application (0 or 3 mL L−1) on five L. siceraria landraces (G1, G2, G3, G4 and G5) grown in greenhouses. Growth traits, first female flower emission, fruit yield, young shoot yield, fruit firmness, young shoot nitrogen use efficiency (NUEys) and specific young shoot quality parameters, such as soluble solids content (SSC), mineral profile, ascorbic acid, and polyphenols, were appraised. Plant height and number of leaves at 10, 20 and 30 days after transplant (DAT) were significantly higher in plants treated with SwE as compared with untreated plants. Treating plants with SwE increased marketable fruit yield, fruit mean mass, young shoot yield and number of young shoots by 14.4%, 15.0%, 22.2%, 32.4%, and 32.0%, respectively as compared with untreated plants. Relevant increments were also recorded for NUEys, P, K, Ca, Mg, ascorbic acid and polyphenols concentration. SwE application did not significantly affect total yield and SSC. Furthermore, SwE treated plants produced a lower number of marketable fruits than non-treated plants. The present study showed that SwE at 3 mL L−1 can fruitfully enhance crop performance, young shoot yield and quality of L. siceraria.

Wood production and nutritional and antioxidant status of field-grown Eucalyptus under a differential supply of lime and copper plus zinc

The Eucalyptus grandis L. plantations for industrial purposes (e.g., wood charcoal and pulp) are largely adopted worldwide, mainly in acidic and poorly fertile soils. The application of lime to soil is recommended for eucalyptus plantation, but lime reduces the availability of metallic micronutrients to plants. Therefore, the aim of this study was to investigate the performance of field-grown Eucalyptus grandis in Ferralsol amended with lime at different rates (0.0 and 1.6 and 3.7 Mg ha-1) and Cu plus Zn [0.0 and 0.0 kg ha-1 (-CuZn) and 0.5 and 1.5 kg ha-1 (+CuZn)]. The soil chemical attributes, shoot biomass, and nutrient accumulation were evaluated, while nutrient use efficiency, chlorophyll (Chl) and flavonoid (Flav) contents, and enzymatic antioxidant performance [superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), ascorbate peroxidase (APX), guaiacol peroxidase (GPOX), and glutathione peroxidase (GPX)] were assayed to assess the nutritional status of the plants. Despite the lime application rate increasing Ca and Mg soil availabilities, effective cation exchange capacity (eCEC), base saturation (BS), and pH values, the available Cu, Fe, and Zn concentrations decreased at 6 and 30 months after planting. Conversely, Mn soil availability increased with lime application rates. Liming augmented Cu-, Fe-, Mn-, and Zn-use efficiency, while +CuZn supply increased enzymatic antioxidant performance in 30-month-old plant. Overall, the combined application of lime and +CuZn enhanced shoot biomass relative to that of non-treated plants. However, there was no observed difference in shoot biomass in 30-month-old limed and non-limed eucalyptus trees that were supplied with +CuZn. This result can be partially explained by the improvement in soil chemical attributes, such as soil pH, eCEC, and BS. In conclusion, the use of integrative approaches and temporal evaluations provided new insights into wood yield, biochemical traits, antioxidant metabolism, and the nutritional status of field-grown eucalyptus under lime and +CuZn application rates.

First Report of Protective Activity of Paronychia argentea Extract against Tobacco Mosaic Virus Infection

The widespread use of chemical control agents and pesticides for plant-pathogen control has caused many human health and environmental issues. Plant extracts and biocontrol agents have robust antimicrobial activity against different plant pathogens. However, their antiviral activities are still being investigated. In the present study, the methanol extract of Paronychia argentea was characterized and evaluated for its protective activity against the tobacco mosaic virus (TMV) infection in tomato plants under greenhouse conditions at 21 days post-inoculation. The results showed that the foliar application of P. argentea extract (10 µg/mL) enhanced tomato plant growth, resulting in significant increases in shoot and root parameters and total chlorophyll contents. Moreover, a significant reduction in TMV accumulation level in P. argentea-treated plants of 77.88% compared to non-treated plants was reported. Furthermore, induction of systemic resistance with significant elevation in production of antioxidant enzymes (PPO, CAT, and SOD) and transcriptional levels of the pathogenesis-related proteins (PR-1 and PR-7) and polyphenolic genes (CHS and HQT) were also observed. Out of 16 detected compounds, HPLC analysis revealed that the most abundant polyphenolic compounds found in P. argentea extract were gallic acid (5.36 µg/mL), kaempferol (7.39 µg/mL), quercetin (7.44 µg/mL), ellagic acid (7.89 µg/mL), myricetin (8.36 µg/mL), and ferulic acid (8.69 µg/mL). The findings suggest that the use of P. argentea extract as an effective and safe source for the production of bioactive compounds may offer a solution for a promising approach for the management of plant viral infections. To the best of our knowledge, this is the first report of the protective activity of P. argentea extract against plant viral diseases.

Effect of Exogenous Selenium Intake on Yield and Quality of Tomatoes Grown Under Salt Stress

The aim of the work undertaken is to study the impact of the exogenous supply of a biostimulant, which is selenium (sodium selenate Na2SO4), on tomatoes fruits quality under salt stress conditions. To this end, an experimental trial has been conducted on a seasonal tomato crop. Within the agricultural domain of the Regional Centre for Agricultural Research (CRRA), Sidi Bouzid, Tunisia (9°430 E, 35° 010 N; altitude 354 m above sea level). The variety used is Firenze. The latter is irrigated with saline water with two different concentrations of NaCl (3 and 6 g/l of NaCl). For each type of salinity, three levels of treatment with the biostimulant were used which correspond to the control plants (without foliar spraying) and to the two doses of application of sodium selenate C1 and C2 which are respectively in the order of 0.5 mM and 1 mM Na2SeO4. The results show that salt stress has a depressive effect on the morphometric and physicochemical characteristics of fruits such as weight, size, color, Brix degree, and lycopene content. However, the application of selenium further improved these parameters. This improvement was more significant in plants that were grown at moderate salinity (3g/l) and were also sprayed with a high dose of selenium (1mM Na2SeO4). For example, yield and fruit weight increased by 228.45 percent and 73.07 percent, respectively, when compared to non-treated plants. Also, fruit width and length increased by 42.31% and 35.57%. In addition, for the physiocochemical parameters the Brix degree and the lycopene content increased respectively by 18.45% and 237.38%.

Regulatory role of folic acid in biomass production and physiological activities of Coriandrum sativum L. under irrigation regimes

Water deficiency represents the major cause that affects agricultural output globally. A water-saving strategy was introduced by using water deficit conditions and growth regulators. Foliar application of folic acid (FA) has been found suitable not only for drought stress alleviation in Coriandrum. sativum but also beneficial for improvement in growth and yield under water deficit circumstances. The current study examined the potential roles of FA under drought to improve C. sativum growth. The C. sativum variety was subjected to three levels of irrigation regimes (IR100, IR75, and IR50) with or without the foliar application of FA concentrations. The results showed that the application of 50 mM FA was very effective in improving the plant height, number of secondary branches, number of umbels, and leaf area index in comparison to FA water deficit treated plants alone under IR75 and IR50. Similarly, physiological and gaseous exchange parameters also upgraded that improved the economic yield (81 and 163%), fresh biomass (28 and 131%), dry biomass (63 and 66%), and harvest index (10 and 58%) of C. sativum plants under irrigation regimes IR75 and IR50 compared to their non-treated FA plants. All the observed growth parameters showed a positive correlation with each other vs. LAI except a weight of 1,000. Overall, this study indicated that foliar-applied 50 mM FA may be used as an alternate strategy to improve C. sativum performance in biomass production and can play a key part in solving difficulties caused by drought stress on plant development.

Protective Effect of γ-Aminobutyric Acid Against Chilling Stress During Reproductive Stage in Tomato Plants Through Modulation of Sugar Metabolism, Chloroplast Integrity, and Antioxidative Defense Systems.

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.

Influence of Zinc Oxide Nanoparticles to Regulate the Antioxidants Enzymes, Some Osmolytes and Agronomic Attributes in Coriandrum sativum L. Grown under Water Stress

Climatic variations adversely affect the limited water resources of earth which leads to water stress and influences agricultural production worldwide. Therefore, a novel approach has been introduced to improve the tolerance against water stress in herbaceous nature medicinal plants such as Coriandrum sativum by the usage of nanotechnology (foliar applied nanoparticles of ZnOx) coupled with the application of water deficit irrigation. This is an alternative water saving strategy that proved to be efficient to mitigate the Coriandrum sativum tolerance against water stress regimes for sustainable yield production through the activation of antioxidant system. Thus, the phenomena of green synthesis have been deployed for the formation of Zinc oxide nanoparticles (ZnOx NPs) from the leaf extract of Camellia sinensis L. and zinc acetate dihydrate was used as precursor. Different techniques have been used for the thorough study and confirmation of ZnOx NPs such as UV-vis spectroscopy (UV-vis) X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Elemental dispersive spectroscopy (EDS). The prepared ZnOx NPs exhibit hexagonal wurtzite crystal nature has an average size of 37 nm with high purity. These ZnOx NPs have been further studied for their role in amelioration of water stress tolerance in Coriandrum sativum in a pot experiment. Two levels of water stress regimes were employed, IR75 (moderate) and IR50 (Intense) to evaluate the behavior of plant compared to full irrigation (FI). Results showed that under water stress regimes, the 100 ppm of prepared NPs stimulate the antioxidant system by increasing the activity of catalases (CAT), super oxidases (SOD) and ascorbate peroxidase (APX) enzymes and found the maximum at IR50, while the concentration of malondialdehyde (MDA) decreased due to increase in activity of antioxidative enzymes. Furthermore, chlorophyll content and amount of proline also enhanced by the foliar application of prepared ZnOx NPs under moderate water stress (IR75). The results suggested that all the investigated agronomic attributes significantly increased, including plant biomass and economic yield (EY), compared to non-treated ZnOx NPs plants, except for the number of primary branches and LAI. Further, the 100 ppm of prepared ZnOx NPs have great potential to improve water stress tolerance in Coriandrum sativum by improving the antioxidant enzymes activity that enhance agronomic attributes for high crop productivity that require further research at transcriptomic and genomic level.