Suppression of essential oil biosynthesis in sweet basil cotyledons under hypergravity conditions.

The mechanism through which gravity influences the biosynthesis of essential oils in herbs is an important issue for plant and space biology. Sweet basil (Ocimum basilicum L.) seedlings were cultivated under centrifugal hypergravity conditions at 100 g in the light, and the growth of cotyledons, development of glandular hairs, and biosynthesis of essential oils were analyzed. The area and fresh weight of the cotyledons increased by similar amounts irrespective of the gravitational conditions. On the abaxial surface of the cotyledons, glandular hairs, where essential oils are synthesized and stored, developed from those with single-cell heads to those with four-cell heads; however, hypergravity did not affect this development. The main components, methyl eugenol and 1,8-cineole, in the essential oils of cotyledons were lower in cotyledons grown under hypergravity conditions. The gene expression of enzymes in the phenylpropanoid pathway involved in the synthesis of methyl eugenol, such as phenylalanine ammonia lyase (PAL) and eugenol O-methyltransferase (EOMT), was downregulated by hypergravity. Hypergravity also decreased the gene expression of enzymes in the 2C-methyl-d-erythritol 4-phosphate (MEP) pathway involved in the synthesis of 1,8-cineole, such as 1-deoxy-d-xylulose-5-phosphate synthase (DXS) and 1,8-cineole synthase (CINS). These results indicate that hypergravity without affecting the development of glandular hairs, decreases the expression of genes related to the biosynthesis of methyl eugenol and 1,8-cineole, which may cause a decrease in the amounts of both essential oils in sweet basil cotyledons.

Aquaponic growth of basil (Ocimum basilicum) with African catfish (Clarias gariepinus) in standard substrate combined with a Humicacid Fiber-Substrate (HFS).

A major challenge in agriculture, horticulture and aquaponics practices is the reduction of mineral fertilisers and peat to reduce CO2 emissions and increase sustainability. This study used a three-phase-natural fertiliser, the Humicacid Fiber-Substrate (HFS), made from natural regenerative organic and mineral-fractions (Humus-Mineral-Complex), to reduce the peat content in plant pots for aquaponics farming. Basil (Ocimum basilicum) growth was compared with i) 100% standard media substrate ("Einheitserde", white peat 80%, clay 20%), and ii) 85% "Einheitserde" and 15% of HFS under irrigation with aquaculture process waters from an extensive and intensive production of African catfish (Clarias gariepinus) under coupled aquaponic conditions. The substitution with 15% HFS and use of intensive fish water resulted in comparable plant growth to a fertiliser solution as control, and in higher leaf width and leaf green weight and lower root dry weight compared with the standard media substrate "Einheitserde". Basil leaf chlorophyll content from the aquaponics was higher compared with local market plants. This suggests the possible substitution of the peat substrate "Einheitserde" with at least 15% HFS to reduce the natural peat fraction. Further studies on crop-specific substrates are needed to reduce peat in aquaponics farming plant cultivation.

Variations in photoperiods and their impact on yield, photosynthesis and secondary metabolite production in basil microgreens.

BACKGROUND: The effects of different photoperiods on plant phytochemical synthesis can be improved by adjusting the daily light integral. Photoperiod is one of the most important environmental factors that control growth, plant's internal rhythm and the synthesis of secondary metabolites. Information about the appropriate standard in terms of photoperiod for growing basil microgreens as one of the most important medicinal plants is limited. In this study, the effects of five different photoperiods, 6 (6 h × 3 cycles), 8 (8 h × 2 cycles), 16, 18, and 24 h day- 1 on the yield, photosynthesis and synthesis of secondary metabolites of three cultivars and one genotype of basil microgreens in floating system were evaluated. The purpose of this research was to determine the feasibility of using permanent light in growing basil microgreens and to create the best balance between beneficial secondary metabolites and performance. RESULTS: The results showed that the effects of photoperiod and cultivar on all investigated traits and their interaction on photosynthetic pigments, antioxidant capacity, total phenolic compounds, proline content and net photosynthesis rate were significantly different at the 1% level. The highest levels of vitamin C, flavonoids, anthocyanins, yield and antioxidant potential composite index (APCI) were obtained under the 24-h photoperiod. The highest antioxidant capacity was obtained for the Kapoor cultivar, and the highest total phenolic compound and proline contents were measured for the Ablagh genotype under a 24-h photoperiod. The highest yield (4.36 kg m- 2) and APCI (70.44) were obtained for the Ablagh genotype. The highest nitrate content was obtained with a photoperiod of 18 h for the Kapoor cultivar. The highest net photosynthesis rate was related to the Violeto cultivar under a 24-hour photoperiod (7.89 µmol CO2 m- 2 s- 1). Antioxidant capacity and flavonoids had a positive correlation with phenolic compounds and vitamin C. Yield had a positive correlation with antioxidant capacity, flavonoids, vitamin C, APCI, and proline. CONCLUSIONS: Under continuous light conditions, basil microgreens resistance to light stress by increasing the synthesis of secondary metabolites and the increase of these biochemical compounds made basil microgreens increase their performance along with the increase of these health-promoting compounds. The best balance between antioxidant compounds and performance was achieved in continuous red + blue light. Based on these results, the use of continuous artificial LED lighting, due to the increase in plant biochemical with antioxidant properties and yield, can be a suitable strategy for growing basil microgreens in floating systems.

Enhancing french basil growth through synergistic Foliar treatment with copper nanoparticles and Spirulina sp.

BACKGROUND: This study investigates a novel idea about the foliar application of nanoparticles as nanofertilizer combined with a natural stimulant, blue-green algae Spirulina platensis L. extract, as a bio-fertilizer to achieve safety from using nanoparticles for enhancement of the growth and production of the plant. Thus, this experiment aimed to chemically synthesize copper nanoparticles via copper sulfate in addition to evaluate the impact of CuNPs at 500, 1000, and 1500 mg/L and the combination of CuNPs with or without microalgae extract at 0.5, 1, and 1.5 g/L on the morphological parameters, photosynthetic pigments accumulation, essential oil production, and antioxidant activity of French basil. RESULTS: The results revealed that foliar application of CuNPs and its interaction with spirulina extract significantly increased growth and yield compared with control, the treatments of 1000 and 1500 mg/L had less impact than 500 mg/L CuNPs. Plants treated with 500 mg/L CuNPs and 1.5 g/L spirulina extract showed the best growth and oil production, as well as the highest accumulation of chlorophylls and carotenoids. The application of CuNPs nanofertilizer caused a significant increase in the antioxidant activity of the French basil plant, but the combination of CuNPs with spirulina extract caused a decrease in antioxidant activity. CONCULOSION: Therefore, foliar application of natural bio-fertilizer with CuNPsis necessary for obtaining the best growth and highest oil production from the French basil plant with the least damage to the plant and the environment.

PFOA accumulation in the leaves of basil (Ocimum basilicum L.) and its effects on plant growth, oxidative status, and photosynthetic performance.

BACKGROUND: Perfluoroalkyl substances (PFASs) are emerging contaminants of increasing concern due to their presence in the environment, with potential impacts on ecosystems and human health. These substances are considered "forever chemicals" due to their recalcitrance to degradation, and their accumulation in living organisms can lead to varying levels of toxicity based on the compound and species analysed. Furthermore, concerns have been raised about the possible transfer of PFASs to humans through the consumption of edible parts of food plants. In this regard, to evaluate the potential toxic effects and the accumulation of perfluorooctanoic acid (PFOA) in edible plants, a pot experiment in greenhouse using three-week-old basil (Ocimum basilicum L.) plants was performed adding PFOA to growth substrate to reach 0.1, 1, and 10 mg Kg- 1 dw. RESULTS: After three weeks of cultivation, plants grown in PFOA-added substrate accumulated PFOA at different levels, but did not display significant differences from the control group in terms of biomass production, lipid peroxidation levels (TBARS), content of α-tocopherol and activity of ascorbate peroxidase (APX), catalase (CAT) and guaiacol peroxidase (POX) in the leaves. A reduction of total phenolic content (TPC) was instead observed in relation to the increase of PFOA content in the substrate. Furthermore, chlorophyll content and photochemical reflectance index (PRI) did not change in plants exposed to PFAS in comparison to control ones. Chlorophyll fluorescence analysis revealed an initial, rapid photoprotective mechanism triggered by PFOA exposure, with no impact on other parameters (Fv/Fm, ΦPSII and qP). Higher activity of glutathione S-transferase (GST) in plants treated with 1 and 10 mg Kg- 1 PFOA dw (30 and 50% to control, respectively) paralleled the accumulation of PFOA in the leaves of plants exposed to different PFOA concentration in the substrate (51.8 and 413.9 ng g- 1 dw, respectively). CONCLUSION: Despite of the absorption and accumulation of discrete amount of PFOA in the basil plants, the analysed parameters at biometric, physiological and biochemical level in the leaves did not reveal any damage effect, possibly due to the activation of a detoxification pathway likely involving GST.

Effect of common horsetail extract on growth characteristics, essential oil yield and chemical compositions of basil (Ocimum basilicum L.).

To investigate the effect of horsetail extract containing high silicon on morphological traits, growth, content, and compositions of essential oil of sweet basil (Ocimum basilicum L.) an experiment turned into carried out in the shape of a randomized complete block design with three replications. Foliar treatment of horsetail extract with zero, 0.5, 1, and 2% concentrations was applied on 6-8 leaf plants. The assessed traits include plant height, number of leaves per plant, number of sub-branches, leaf area index, plant fresh weight, plant dry weight, total anthocyanin, the content of total phenol and total flavonoid, antioxidant activity, essential oil content, and compounds were measured. The findings demonstrated that the increase of silicon-containing horsetail extract enhanced the improved increase in growth and phytochemical trait values. The use of horsetail extract in the 2% treatment increased plant height, the number of leaves per plant, the number of sub-branches, leaf area index, fresh weight, and dry weight of the plant by 49.79, 45.61, 91.09, 99.78, 52.78 and 109.25%, respectively, compared to the control. The highest content of total phenol (2.12 mg GAE/g DW), total flavonoid (1.73 mg RE/g DW), total anthocyanin (0.83 mg C3G/g DW), and antioxidant activity (184.3 µg/ml) was observed in the 2% extract treatment. The content of essential oil increased with increasing the concentration of horsetail extract, so the highest amount of essential oil was obtained at the concentration of 2%, which increased by 134.78% compared to the control. By using GC-MS, the essential oil was analyzed. The main components of the essential oil include methyl eugenol (12.93-25.93%), eugenol (17.63-27.51%), 1,8-cineole (15.63-20.84%), linalool (8.31-19.63%) and (Z)-caryophyllene (6.02-14.93%). Increasing the concentration of horsetail extract increased the compounds of eugenol, 1,8-cineole, and linalool in essential oil compared to the control, but decreased the compounds of methyl eugenol and (Z)-caryophyllene. Foliar spraying of horsetail extract, which contains high amounts of silicon, as a stimulant and biological fertilizer, can be a beneficial ingredient in increasing the yield and production of medicinal plants, especially in organic essential oil production.

Characterization of Basil Volatile Fraction and Study of Its Agronomic Variation by ASCA.

Basil is a plant known worldwide for its culinary and health attributes. It counts more than a hundred and fifty species and many more chemo-types due to its easy cross-breeds. Each species and each chemo-type have a typical aroma pattern and selecting the proper one is crucial for the food industry. Twelve basil varieties have been studied over three years (2018-2020), as have four different cuts. To characterize the aroma profile, nine typical basil flavour molecules have been selected using a gas chromatography-mass spectrometry coupled with an olfactometer (GC-MS/O). The concentrations of the nine selected molecules were measured by an ultra-fast CG e-nose and Principal Component Analysis (PCA) was applied to detect possible differences among the samples. The PCA results highlighted differences between harvesting years, mainly for 2018, whereas no observable clusters were found concerning varieties and cuts, probably due to the combined effects of the investigated factors. For this reason, the ANOVA Simultaneous Component Analysis (ASCA) methodology was applied on a balanced a posteriori designed dataset. All the considered factors and interactions were statistically significant (p < 0.05) in explaining differences between the basil aroma profiles, with more relevant effects of variety and year.

Production of basil (Ocimum basilicum L.) under different soilless cultures.

The main aim of this paper was to investigate the possibility of growing basil under three soilless systems (aeroponic, hydroponic and peatmoss slab systems). A model was developed to predict the nutrients consumption by basil plants. Shoot and root height, fresh and dry mass of whole plant, nutrients uptake, and oil content were studied during the growth period (after 4 and 7 weeks from transplanting). The results indicated that the shoot lengths of basil plants were 71.67 ± 2.89, 65.67 ± 1.15 and 62.33 ± 2.31 cm at the end of growth period for aeroponic, hydroponic and peatmoss slabs, respectively. The highest value of root height of basil plants was 37.67 ± 6.66 cm for aeroponic system. The dry mass of shoot of basil plants ranged from 28.48 ± 0.91 to 44.77 ± 0.97 and 72.98 ± 0.83 to 117.93 ± 1.40 g plant-1 after 4 and 7 weeks from transplanting, respectively. The highest values of the N, P, K, Ca and Mg uptakes were 753.99 ± 5.65, 224.88 ± 3.05, 449.75 ± 4.59, 529.12 ± 6.63 and 112.44 ± 1.67 mg plant-1 at the end of experimental period, respectively. The basil oil content ranged from 1.129 (1.11%) to 2.520 (1.80%) and 2.664 (1.42%) to 6.318 (1.44%) g plant-1 after 4 and 7 weeks from transplanting, respectively at the same pervious order. The production costs of basil plant were 2.93, 5.27 and 6.24 EGP kg-1 of plant. The model results were in a reasonable agreement with the experimental ones.

Effects of indoor, greenhouse, and field cultivation on bioactive compounds from parsley and basil.

BACKGROUND: Aromatic herbs are an important source of bioactive compounds. Different cultivation systems should give each plant a specific amount of those compounds, which should be of a particular quality. In this study, the effects of three cultivation systems (indoor, greenhouse, and organic field) on the composition of bioactive compounds in parsley (Petroselinum crispum cv. 'Flat Leaf'), green basil (Ocimum basilicum var. minimum cv. 'Greek'), and purple basil (Ocimum basilicum cv. 'Red Rubin') were evaluated. RESULTS: ß-Carotene and lutein were the carotenoids with the highest concentration in the three plants in all the cultivation systems. Overall, parsley proved to be a source of flavonoids. The major phenolic compound found in basil plants was rosmarinic acid, whereas most anthocyanins were derived from cyanidin aglycone. Among the three plants studied, the highest vitamin C content was found in parsley from the field. This was 2.6 and 5.4 times higher than the indoor and greenhouse cultivation, respectively. CONCLUSION: The results suggest that different cultivation systems influence and modulate the concentration of bioactive compounds in plants differently, varying according to their class, and that, above all, an indoor system is an effective cultivation system for the production of bioactive compounds. © 2021 Society of Chemical Industry.

The impact of different Zinc (Zn) levels on growth and nutrient uptake of Basil (Ocimum basilicum L.) grown under salinity stress.

Salinity is among the most important abiotic stresses, which negatively affect growth, nutrient uptake and yield of crop plants. Application of different micronutrients, particularly zinc (Zn) have the potential to ameliorate the negative impacts of salinity stress. However, the role of Zn in improving salinity tolerance of basil (Ocimum basilicum L.) is poorly understood. This study evaluated the impact of different Zn levels (0, 5 and 10 mg kg-1) on growth and nutrient acquisition traits of basil under different salinity levels (0, 0.5, 1.0 and 1.5% NaCl). Data relating to biomass production, chlorophyll index, sodium (Na), potassium (K) uptake, K/Na ratio, Zn, copper (Cu), manganese (Mn) and iron (Fe) uptake were recorded. Increasing salinity level reduced biomass production, chlorophyll index and nutrient uptake traits (except for Na and Fe accumulation) of basil. Zinc application (10 mg kg-1) improved biomass production, chlorophyll index and nutrient acquisition traits under normal as well as saline conditions. The reduction in chlorophyll index and biomass production was higher under 0 and 5 mg kg-1 than 10 mg kg-1 Zn application. The K concentration decreased under increasing salinity; however, Zn application improved K uptake under normal as well as saline conditions. Different growth and nutrient acquisition traits had negative correlations with Na accumulation; however, no positive correlation was recorded among growth and nutrient uptake traits. The results revealed that Zn application could improve the salinity tolerance of basil. However, actual biochemical and genetic mechanisms involved in Zn-induced salinity tolerance warrant further investigation.

Investigation of Different Selenium Sources and Supplying Methods for Selenium Enrichment of Basil Vegetable (A Case Study under Calcareous and Non-calcareous Soil Systems).

BACKGROUND: Selenium (Se) is a crucial component of selenoaminoacids and selenoproteins. Therefore, Se-enriched agricultural products can reduce health complications induced by Se deficiency. OBJECTIVE: This research was carried out to investigate the effects of Se bio-enrichment on Basil grown in calcareous and non-calcareous soil systems and also to evaluate the changes in Se concentration in the soil after harvesting. METHODS: The experiment executed in two calcareous and one non-calcareous soil systems, and different Se application methods (control, soil application, seed inoculation, foliar application, and soil + foliar application) were administered. Selenobacteria, a plant growth-promoting rhizobacteria (PGPR), derived from the soil was used as a biofertilizer, compared to the other Se sources. RESULTS: The results showed that both soil types and the methods of Se application had significant effects (P ˂ 0.01) on root and shoot dry weights and concentrations of P, K, Zn, Fe, and Se in both of the root and shoot. Shoot dry weight of plants treated with foliar Se was maximum in the calcareous soil. Compared to the control treatment, foliar application of Se increased shoot Se content in both calcareous and non-calcareous soils by 242% and 204%, respectively. Furthermore, the increase in shoot Se concentration in calcareous soil induced by Se application increased the concentration of other nutrients in the shoot and root. Plant growth parameters and concentrations of nutrients were significantly increased by using selenobacter inoculum. CONCLUSION: The application of Se-containing compounds can improve vegetable quality. Considering the daily requirement of the human body for minerals and nutrients, enriching basil with Se can play an important role in community health. Moreover, some patents have reported the effectiveness of endophyte bacteria.

Metabolic Insights into the Anion-Anion Antagonism in Sweet Basil: Effects of Different Nitrate/Chloride Ratios in the Nutrient Solution.

Sweet basil (Ocimum basilicum L.) is a highly versatile and globally popular culinary herb, and a rich source of aromatic and bioactive compounds. Particularly for leafy vegetables, nutrient management allows a more efficient and sustainable improvement of crop yield and quality. In this work, we investigated the effects of balanced modulation of the concentration of two antagonist anions (nitrate and chlorine) in basil. Specifically, we evaluated the changes in yield and leaf metabolic profiles in response to four different NO3-:Cl- ratios in two consecutive harvests, using a full factorial design. Our work indicated that the variation of the nitrate-chloride ratio exerts a large effect on both metabolomic profile and yield in basil, which cannot be fully explained only by an anion-anion antagonist outcome. The metabolomic reprogramming involved different biochemical classes of compounds, with distinctive traits as a function of the different nutrient ratios. Such changes involved not only a response to nutrients availability, but also to redox imbalance and oxidative stress. A network of signaling compounds, including NO and phytohormones, underlined the modeling of metabolomic signatures. Our work highlighted the potential and the magnitude of the effect of nutrient solution management in basil and provided an advancement towards understanding the metabolic response to anion antagonism in plants.

Cold stress changes antioxidant defense system, phenylpropanoid contents and expression of genes involved in their biosynthesis in Ocimum basilicum L.

Environmental stresses might alter the activity of antioxidant defense system and both quantity and quality of the essential oil constituents in aromatic plants. In the current study, a greenhouse experiment was designed to assess the influence of cold stress on total phenolic (TPC) and flavonoid contents (TFC), DPPH radical scavenging, antioxidant and phenylalanine ammonia-lyase (PAL) enzymes activity and content of phenylpropanoid compounds in Ocimum basilicum L. The genes expression levels of chavicol O-methyl transferase (CVOMT), cinnamate 4-hydroxylase (C4H), eugenol synthase 1 (EGS1) and eugenol O-methyl transferase (EOMT) were also investigated. Results revealed the highest TPC, TFC and DPPH at 4 °C for 12 h. Positive significant correlation was observed between TFC and DPPH, as well as TPC and PAL enzyme activity. The highest activity of superoxide dismutase and guaiacol peroxidase was recorded in 4 °C for 48 h, while this treatment caused the highest reduction in the activities of ascorbate peroxidase and catalase. In plants exposed to 10 °C for 48 h, the contents of methyleugenol and methylchavicol was positively associated with the expression levels of EGS1 and EOMT. A positive correlation was also found between C4H expression and eugenol, methyleugenol and methylchavicol contents under 4 °C for 12 h.

Plant architecture and phytochemical composition of basil (Ocimum basilicum L.) under the influence of light from microwave plasma and high-pressure sodium lamps.

Potted herbs such as basil are in high year-round demand in Central Europe. To ensure good quality in winter, artificial light is required. Many horticulturists, who want to replace their high-pressure­sodium (HPS) lamps with light-emitting diodes (LEDs) to save electricity energy, struggle with high investment costs. In addition, switching to LEDs can overwhelm many smaller horticultural enterprises since there is a requirement of adjusting individual light recipes and furthermore cultivation problems can occur due to the lack of infrared radiation. In this study, the influence of light from microwave plasma lamps (MPL), acting as alternative light sources, on secondary metabolites and morphology of basil plants (Ocimum basilicum L.) was tested. Basil plants were grown in a climate chamber with MPL with two different light bulbs emitting either artificial sunlight (AS) or broad white light with increased blue and green light content (sulfur plasma light; SPL). The effect of these new lamp types was compared to standard commercial HPS lamps. In addition to morphological parameters such as height, internode length and fresh weight, plant secondary metabolites were examined. Essential oils and monoterpenes were quantified by GC-MS analysis, whereby phenolic compounds were analyzed calorimetrically. Elongation growth and biomass production was increased under the AS spectrum in comparison to HPS-grown plants. Increased stem elongation was attributed to a higher content of far-red light in the AS spectrum. Furthermore, basil plants grown under the AS spectrum contained the highest total phenolic and total flavonoid content compared to plants grown under the SPL and HPS lamps, probably due to the higher content of UV-A radiation. The lowest content of phenolic compounds was observed when HPS light was used, which was assumed to be caused by a low blue light content in the emission spectrum. An impact of the different light spectra on essential oil composition was determined. A significantly increased content of linalool was found in basil leaves developed under both tested MPL spectra compared to HPS-grown plants. The total yield of the four major essential oils was lowest under HPS treatment.

Parasitoids diversity in organic Sweet Pepper (Capsicum annuum) associated with Basil (Ocimum basilicum) and Marigold (Tagetes erecta ) / Diversidade de parasitoides em Pimentão Orgânico (Capsicum annuum) associado com Manjericão (Ocimum basilicum ) e Cravo Amarelo (Tagetes erecta)

Abstract The sweet pepper (Capsicum annuum L.) is one of the most important crops in Brazilian farming. Many insect are related to this crop, compromising the quantity and quality of the fruit, representing a production problem. Vegetable diversification is one of the main elements that can be managed for suppressing undesirable insect populations in organic production, once that supports the presence of natural enemies. The basil Ocimum basilicum L. and the marigold Tagetes erecta L. are attractive and nutritious plants for parasitoids, being important candidates for diversified crops. This study evaluated the parasitoids attracted by the association of basil and marigold to organic sweet pepper crop. The experiment comprised three treatments: a) sweet pepper monoculture; b) sweet pepper and basil intercropping; c) sweet pepper and marigold intercropping. Hymenopteran parasitoids were collected over 14 weeks. 268 individuals from 12 families and 41 taxa were collected. Sweet pepper monoculture, sweet pepper-basil intercropping, and sweet pepper-marigold intercropping hosted 40, 98, and 130 individuals and richness of 24, 24, and 23, respectively. Furthermore, the insects of greater abundance in the basil and marigold were different to those collected in the monoculture. The number of parasitoids increased in the associations of sweet pepper with basil and marigold, providing advantages in the use of vegetable diversification for the organic pepper crops management.

Resumo O pimentão (Capsicum annuum L.) é um dos vegetais mais importantes dentre os cultivados no Brasil. Muitos insetos pragas estão relacionados a esta cultura, comprometendo a quantidade e a qualidade do pimentão, tornando-se um grande problema para a produção. A diversificação vegetal é um dos principais componentes a serem manejados para suprimir as populações de pragas na produção orgânica, devido ao apoio a inimigos naturais das pragas. O manjericão ( Ocimum basilicum L.) e cravo amarelo (Tagetes erecta L.) são plantas atrativas e nutritivas para parasitoides, importantes candidatas em cultivos diversificados. Este trabalho avaliou os parasitoides atraídos pela associação de manjericão e cravo amarelo em cultivo de pimentão orgânico. O experimento foi composto por três tratamentos: a) monocultura de pimentão; B) pimentão consorciado com manjericão; C) pimentão consorciado com cravo amarelo. Foram coletadas amostras de parasitoides himenópteros durante 14 semanas. Os espécimes foram identificados até o menor nível de taxonomia possível. Foram coletados 268 indivíduos ao longo de 12 famílias e 41 táxons. Os tratamentos de monocultura, pimentão consorciado com manjericão e pimentão consorciado com cravo amarelo resultaram em 40, 98 e 130 indivíduos e riqueza de espécies de 24, 24 e 23, respectivamente. Além disso, os insetos de maior abundância coletados no manjericão e cravo amarelo, foram diferentes daqueles coletados na monocultura. Houve um aumento na abundância de parasitoides nas associações de pimentão com manjericão e cravo amarelo, proporcionando vantagens no uso da diversificação vegetal, podendo ser usada no manejo do pimentão orgânico.

Plantibacter flavus, Curtobacterium herbarum, Paenibacillus taichungensis, and Rhizobium selenitireducens Endophytes Provide Host-Specific Growth Promotion of Arabidopsis thaliana, Basil, Lettuce, and Bok Choy Plants.

A collection of bacterial endophytes isolated from stem tissues of plants growing in soils highly contaminated with petroleum hydrocarbons were screened for plant growth-promoting capabilities. Twenty-seven endophytic isolates significantly improved the growth of Arabidopsis thaliana plants in comparison to that of uninoculated control plants. The five most beneficial isolates, one strain each of Curtobacterium herbarum, Paenibacillus taichungensis, and Rhizobium selenitireducens and two strains of Plantibacter flavus were further examined for growth promotion in Arabidopsis, lettuce, basil, and bok choy plants. Host-specific plant growth promotion was observed when plants were inoculated with the five bacterial strains. P. flavus strain M251 increased the total biomass and total root length of Arabidopsis plants by 4.7 and 5.8 times, respectively, over that of control plants and improved lettuce and basil root growth, while P. flavus strain M259 promoted Arabidopsis shoot and root growth, lettuce and basil root growth, and bok choy shoot growth. A genome comparison between P. flavus strains M251 and M259 showed that both genomes contain up to 70 actinobacterial putative plant-associated genes and genes involved in known plant-beneficial pathways, such as those for auxin and cytokinin biosynthesis and 1-aminocyclopropane-1-carboxylate deaminase production. This study provides evidence of direct plant growth promotion by Plantibacter flavusIMPORTANCE The discovery of new plant growth-promoting bacteria is necessary for the continued development of biofertilizers, which are environmentally friendly and cost-efficient alternatives to conventional chemical fertilizers. Biofertilizer effects on plant growth can be inconsistent due to the complexity of plant-microbe interactions, as the same bacteria can be beneficial to the growth of some plant species and neutral or detrimental to others. We examined a set of bacterial endophytes isolated from plants growing in a unique petroleum-contaminated environment to discover plant growth-promoting bacteria. We show that strains of Plantibacter flavus exhibit strain-specific plant growth-promoting effects on four different plant species.

Production of selenium-biofortified microgreens from selenium-enriched seeds of basil.

BACKGROUND: Microgreens (i.e. tender immature greens) are a popular alternative to sprouts (i.e. germinating seeds) because of their higher content of vitamins, carotenoids and phenols, as well as their lower content of nitrates. Their nutritional value can be improved by biofortification, which increases micronutrient levels during plant growth. Because selenium (Se) plays a significant role in antioxidant defense, biofortification with Se is a good way of improving the nutritional quality of sprouts and microgreens. The present study investigated the production of Se-fortified microgreens from Se-enriched seeds of sweet basil (Ocimum basilicum L.). These microgreens could be used as new beneficial dietary supplements. RESULTS: Basil plants were grown in a nutrient solution, containing 0 (control), 4 or 8 mg Se L-1 as sodium selenate, to full maturity. Seeds accumulated a high amount of Se and were then used to produce microgreens. The germination index was higher in the seeds from Se-treated plants and the microgreens were enriched in Se. The antioxidant capacity of Se-fortified microgreens was higher compared to the control. CONCLUSION: The production of microgreens from Se-enriched seeds could comprise a good system for obtaining microgreens with a high nutritional value. Basil plants treated with Se could be used to produce both Se-fortified leaves and microgreens. © 2019 Society of Chemical Industry.

Invisible signals from the underground: A practical method to investigate the effect of microbial volatile organic compounds emitted by rhizobacteria on plant growth.

Rhizobacteria that colonize plant roots and promote plant growth are referred to as plant growth-promoting rhizobacteria, and this can stimulate plant growth either indirectly or directly. Volatile organic compounds (VOCs) emitted by rhizobacteria have the capacity to promote plant growth as well as perform biocontrol of fungal pathogens. The microbial volatile organic compounds (mVOCs) are characterized by a low molecular weight and a high vapor pressure, which facilitate evaporation and diffusion at normal temperatures and at above-ground and below-ground pressures. mVOCs can travel far from the point of production through the atmosphere, porous soils and liquids, thereby making them ideal infochemicals for mediating interspecific interactions. However, knowledge about the biological and ecological roles of microbial VOCs is still limited compared with that of plant VOCs. Here, we describe a simple and inexpensive laboratory class aimed at biotechnology or soil microbiology students, which uses techniques to increase their understanding of the mechanisms of plant growth promoting rhizobacteria and also illustrate the effects of mVOCs emitted by rhizobacteria on plant growth promotion, as well as evaluating their potential as a biocontrol. The laboratory class is divided into two sessions: an initial 3-hour experimental session and a second 2-hour analytical one. The experimental session involves two separate experiments: one of which is dedicated to illustrating the effect of mVOCs on plant growth parameters, while the second explores the capacity of VOCs as a biocontrol. Also, the class provides students with an opportunity to perform useful assays, draw conclusions from their results, and discuss possible extensions of the study. © 2019 International Union of Biochemistry and Molecular Biology, 47(4):388-393, 2019.

Parasitoids diversity in organic Sweet Pepper (Capsicum annuum) associated with Basil (Ocimum basilicum) and Marigold (Tagetes erecta ).

The sweet pepper (Capsicum annuum L.) is one of the most important crops in Brazilian farming. Many insect are related to this crop, compromising the quantity and quality of the fruit, representing a production problem. Vegetable diversification is one of the main elements that can be managed for suppressing undesirable insect populations in organic production, once that supports the presence of natural enemies. The basil Ocimum basilicum L. and the marigold Tagetes erecta L. are attractive and nutritious plants for parasitoids, being important candidates for diversified crops. This study evaluated the parasitoids attracted by the association of basil and marigold to organic sweet pepper crop. The experiment comprised three treatments: a) sweet pepper monoculture; b) sweet pepper and basil intercropping; c) sweet pepper and marigold intercropping. Hymenopteran parasitoids were collected over 14 weeks. 268 individuals from 12 families and 41 taxa were collected. Sweet pepper monoculture, sweet pepper-basil intercropping, and sweet pepper-marigold intercropping hosted 40, 98, and 130 individuals and richness of 24, 24, and 23, respectively. Furthermore, the insects of greater abundance in the basil and marigold were different to those collected in the monoculture. The number of parasitoids increased in the associations of sweet pepper with basil and marigold, providing advantages in the use of vegetable diversification for the organic pepper crops management.

Biological value and chemical components of essential oils of sweet basil (Ocimum basilicum L.) grown with organic fertilization sources.

BACKGROUND: Environmental safety of the agricultural utilization of livestock and poultry manures from intensive farming is attracting great attention and is effective as a good source of nitrogen for sustainable crop production. The present study aimed to determine the effects of organic poultry manure applications on the biological value and essential oil content of sweet basil (Ocimum basilicum L.). In this context, different doses of chicken, kibele (fermented chicken manure) and turkey manure (750, 1000, 1250 and 1500 kg da-1 ) with a control (no manure) were applied by sowing. RESULTS: The essential oils consisted of p-Allyl-anisole as the most abundant component (5.65-17.90%), followed by nerol (6.69-16.11%), linalool (5.10-10.81%) and z-citral (5.23-10.73%). The contents of most of the chemical constituents varied significantly (P < 0.05) with organic poultry manure applications. The highest concentration for essential oils components was found in the chicken manure application. Both the antioxidant activity and total phenolic amounts of the basil extracts varied significantly as the organic poultry manure applications changed. The highest antioxidant activity and total phenolic amounts were obtained in the treatments with chicken manure doses of 1000 and 1250 kg da-1 , which were significantly different compared to the other treatments and the control treatment. Evaluation of antimicrobial activity of the essential oils against bacterial strains: Escherichia coli ATCC 35218, Staphylococcus aureus ATCC 43300 and Candida albicans ATCC 10231 was assessed by the disc diffusion method and determination of the minimum inhibitory concentration. The results of antimicrobial assays indicated that all of the tested microorganisms were affected. The highest antibacterial activity against all tested microbial species was observed with 1250 kg da-1 chicken manure applications. CONCLUSION: Among the organic poultry fertilizations, chicken fertilization was of particular interest. Especially, chicken manure doses of 1000-1250 kg da-1 had the highest antibacterial and antioxidant activity, as well as total phenolics, flavonoids and essential oil components. © 2018 Society of Chemical Industry.