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Phytotoxic effect of essential oil from hyssop (Hyssopus officinalis L.) against spring wheat and white mustard
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Published: 01 May 2021 by MDPI in The 1st International Electronic Conference on Agronomy session Posters

There has been a growing interest in essential oils (EO) as natural botanical herbicides. However, the EOs also display phytotoxic effects against crops. Hence, the study aimed to assess the phytotoxic potential of the essential oil obtained from the hyssop's herb (Oleum hyssopi officinalis) concerning the germination and initial growth of seedlings of two crops: spring wheat (Triticum aestivum L.) and white mustard (Sinapis alba L.). The EO was obtained by steam distillation and subjected to component analysis using the GC/MS method. Two series of laboratory experiments were performed. Oil in water (o/w) solutions of EO with an admission of ethyl alcohol (2.0% v/v) were used in five doses: 0.004; 0.007; 0.01; 0.02, 0.03 g. liter-1 (w/w). Twenty seeds of the tested crops were placed on the Petri dishes lined with a sterile filter paper, previously soaked with the o/w solution. The dishes were left in the dark at room temperature for seven days. The seedlings were then counted, and the length of their roots and stems (in mm) was measured. Statistical analysis was performed based on the one-way analysis of variance; the ED50 dose was calculated using the R program's drc package (version 3.5.3).

In the hyssop herb's EO, 37 chemical compounds (93.4% in total) were identified, among which terpenes (camphor and β-pinene) dominated. Higher doses of the EO completely inhibited the germination of wheat and white mustard. The ED50 was 0.027 g liter-1 for mustard and 0.016 g liter-1 for wheat, respectively. Similarly, the growth of wheat seedlings was inhibited to a greater extent than that of mustard seeds. Simultaneously, the level of tissue damage in both species was independent of the EO dose. In conclusion, wheat is more sensitive than mustard to the effects of hyssop EO. The physiological basis of the reaction of seedlings of both species to hyssop OE will be further investigated.

  • Open access
  • 99 Reads
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The microclonal propagation of potatoes is one of the most effective methods of biotechnology in breeding, since through callus genesis it provides ample opportunities for using various selective factors to induce somaclonal variability. The goal of our research is the problem of the influence of the composition of nutrient media, in particular sugar, on the engraftment of planting material in the in vitro potato culture in the soil.

Six potato varieties were used as the object of the research: Riviera (Netherlands), Kiranda (China), Plushka (Ukraine), Studentska (Ukraine), Hrenada (Ukraine), Kniazhna (Ukraine), and fragments of the apical meristem of potato plants were selected for in vitro introduction into the culture. Murashige and Skoog media (1962) with sucrose content modifications of 30 and 60% were used to induce callus genesis, while the control variant of the medium was 10% sucrose. The results of the research revealed a positive but uneven effect on the nature of rooting of in vitro culture plants of the varieties involved in the study. The promising options of potato varieties of different ripeness groups for further reproduction and use in the breeding process, which were grown on a medium with 10%, 30% and 60% sucrose content, were identified.

  • Open access
  • 51 Reads
Phytotoxic effect of caraway essential oil and its main compounds against germination of spring wheat and two weed species

Increased interest in using biological methods of crop protection has led to research on the various plant's allelopathic potential. Essential oils show phytotoxic properties that can be used to produce alleloherbicides (botanical herbicides), i.e., natural substances to control weeds. The most frequently analyzed effect of essential oils is their influence on the seed germination process and seedlings' development and growth. This study aimed to investigate the phytotoxic potential of oil in water (o/w) solutions of caraway oil and its main components: carvone and limonene, on germination of spring wheat (Triticum aestivum, cv. Tybald), wild oats (Avena fatua), and chamomile (Matricaria chamomilla).

Caraway oil was rectified under reduced pressure to separate the essential oil into fractions containing carvone and limonene. GC-FID-MS analyzes of volatile compounds were performed on a Trace GC Ultra gas chromatograph connected to a DSQ II mass spectrometer (Thermo Electron). Simultaneous GC-FID and MS analysis were carried out using the MS-FID (SGE Analytical Science) splitter.

The Petri dish experiment was performed in the laboratory, in four series and three repetitions. Five doses of caraway oil: 0.6; 1.0; 1.4; 2.8; 4.3 mg cm-3, carvone: 0.2; 0.6; 1.2; 1.7; 2.9 mg cm-3 and limonene: 0.1; 0.3; 0.7; 1.0; 1.4 mg cm-3 were used. Twenty seeds of the tested species were placed on two layers of filter paper in each dish. The filter paper was previously soaked with 7 g of an appropriate o/w solution. The seeds were allowed to germinate for seven days in the dark at room temperature (± 25 ° C). After this time, seedlings were counted, and the length of their roots and stems were measured.

It was found that caraway oil and its fractions containing the dominant ingredients: carvone or limonene, inhibit the germination of spring wheat and both weeds. The most sensitive to caraway oil was chamomile. In turn, spring wheat was the least sensitive to caraway oil. Limonene displayed the smallest effect on the germination of the tested plant species.

  • Open access
  • 39 Reads
Xanthine oxidoreductase (XOR) of pea (Pisum sativum L.) plants is differently regulated, at the protein and gene level, under environmental stress conditions
Published: 01 May 2021 by MDPI in The 1st International Electronic Conference on Agronomy session Posters

Plants are exposed to continuous environmental challenges and depending on the intensity and time of exposition to a specific environmental condition, plants either overcome the adverse situation or undergo a different level of injuries such as nitro-oxidative damages of biomolecules [1,2]. Xanthine oxidoreductase (XOR) is a FAD-, molybdenum-, iron- and sulfur-containing hydroxylase enzyme involved in the purine catabolism pathway that catalyzes the conversion of hypoxanthine/xanthine to uric acid with the concomitant formation of either NADH or superoxide radical (O2•−) which is then dismutated into H2O2. In fact, under environmental stress conditions, XOR is considered to participate in the generation of reactive oxygen species (ROS) [3,4]. Using pea (Pisum sativum L.) plants exposed to six different environmental conditions including high light intensity, low and high temperature, continuous light, continuous dark and mechanical wounding, XOD was analyzed at protein and gene expression levels. The obtained data indicate that XOD is modulated differentially under the assayed stress conditions being the low temperature the situation with causes the highest differences of XOD at gene and protein expression.

[1] Corpas et al., 2008. Plant Cell Physiol. 49, 1711-1722.
[2] Corpas et al. 2009, J Plant Physiol. 165, 1319-1330.
[3] Zarepour et al. (2010) Plant Mol. Biol. 72: 301-310.
[4] Ma et al. (2016) Plant Cell. 28, 1108-1126.

[Supported by grants PID2019-103924GB-I00 and P18-FR-1359 from MICINN and PAIDI-Junta de Andalucía, Spain]

  • Open access
  • 59 Reads
Meeting Agricultural Sustainability through Plant Growth Promoting Bacteria: An Examination of the Mechanisms for Improved Host Uptake of Zinc Nutrient in Maize using Functional Mutants of Azospirillum brasilense

Zinc (Zn) is an essential micronutrient for plant growth and development. Plants can be lacking in Zn since as a trace element it is subject to widespread soil deficiencies. These deficiencies can arise through a lack of diverse agricultural practices, as well as climatic extremes causing excessive soil weathering. It has been estimated that 30% of global arable lands are deficient in Zn resulting in substantial reduction in yield. In recent agricultural practices, plant growth promoting bacteria (PGPB) are finding increased use for reducing crop losses due to conditions of the soil. Among the PGPB, the genus Azospirillum—with an emphasis on A. brasilense—is probably the most studied microorganism for the mitigation of plant stress. Here we report the investigation of functional mutants HM053, ipdC and FP10 of A. brasilense to understand how the biological functions of these microorganisms can affect host Zn uptake. HM053 is a Nif + constitutively expressed strain that hyper-fixes N2 and produces high levels of the plant relevant hormone auxin. FP10 is a Nif- strain that is deficient in N2-fixation and produces auxin. ipdC is a strain that is deficient in auxin production but fixes N2. Zinc uptake was measured in laboratory-based studies of 3-week-old plants using radioactive Zn-65 (t½ =244 days). Uptake kinetics of the tracer were measured using dedicated radiation detectors. Afterwards, tissues were harvested and counted for levels of Zn-65 radioactivity that had accumulated within the roots and shoots of the plant. Principal Component Analysis using XLSTAT software provided comparisons between microbial biological functions and host Zn-65 accumulation. Results showed that low microbial auxin producing capacity resulted in the greatest accumulation of Zn-65 by the host. This research was supported by Agriculture and Food Research Initiative Award No. 2017-67013-26216 from the USDA National Institute of Food and Agriculture and through a startup award from the University of Missouri administered through University of Missouri Research Reactor Center.

  • Open access
  • 74 Reads
Bio-remediation agro-based industry's wastewater and mass production of Spirulina (Spirulina platensis (Gomont) Geitler 1925)

The Spirulina Spirulina platensis (Gomont) Geitler 1925, is a cyanobacteria and used as ecologically sound nutrient-rich dietary supplement. These microalgae have the capability to produce the least-cost protein per unit area than livestock, therefore, being investigated to address malnutrition and food security. Apart from the variety of components like animal feed, fertilizer, and cosmetics produced from Spirulina, phytoremediation of wastewater using Spirulina is an economically viable and environmentally sound tactic. A study carried out with the objectives of quick removal of waste from selected wastewater from agro-based industries, and identify the suitable organic wastes as the costless media for growing S. platensis for its powder production. Wastewater from the fish pond, poultry unit, grain soaked water, and parboiled rice liquid waste was selected as treatments and inoculated with the stock culture of S. platensis. Treatments were replicated three times along with the Zarrouk’s medium as standard control and arranged in a randomized complete block design. The chemical parameters of wastes such as OD value, pH and EC(mS/cm), and the data on the growth of Spirulina using UH5300- Spectrophotometer with a wavelength of 560nm, were measured in 2 days’ interval. The derived data were analyzed using SAS 9.4, and significance among treatments was determined according to the Duncan multiple range test at P <0.05. The results show that the poultry wastewater was identified as a suitable medium for S. platensis growth with the harvestable density of 0.8 at a very low concentration (25 %) in 7 days compare to the standard Zarrouk’s medium. The Maximum and significant OD value of 1.313 was observed on the 15th day in poultry wastewater, and non-significant among other treatments at P <0.05. In fish pond wastewater the maximum OD value of 0.567 was obtained on the 15th day. pH value of poultry wastewater declined from 9.28 to 7.5 after 15 days. The EC values among the treatment were not significant. Among the selected liquid medium poultry wastewater promotes better growth of S. platensis than other locally available wastewater tested. This experiment concludes that agro-based industry's wastewater can be bio-remediated by growing Spirulina, and nutrient-enriched wastewater can be used for mass culturing of Spirulina without nutrient supplements.

  • Open access
  • 48 Reads
Effect of herbicide mixtures on Heracleum sosnowskyi control

Sosnowsky’s hogweed (Heracleum sosnowskyi) is a dangerous perennial invasive alien plant spreading across Lithuania as well as in other European nations. The control of this plant is complicated due to well-developed biological characteristics that impact chemical management and reproductive potential. In order to achieve effective control of this species, it is critical to select effective herbicides or their mixtures. Field experiments, designed to compare the efficacy of different herbicide mixtures used to control Heracleum sosnowskyi, were conducted in 2017–2018 in Lithuania, Marijampolė district, Varnupiai (coordinates 54° 29’ 19.54” north latitude, 23° 30’ 45.9” east longitude). The most rapid control was provided by an herbicide mixture of fluroxypyr 360 g ha-1 + metsulfuron-methyl 4.0 g ha-1 + tribenuron-methyl 7.5 g ha-1. Two weeks after spraying, the amount of Sosnowsky’s hogweed decreased by 2.1 fold.

Significant control (reduction of hogweed stands by 1.3 and 1.5 fold) was also identified with mixtures of fluroxypyr 360 g ha-1 + metsulfuron-methyl 4.0 g ha-1 and fluroxypyr 360 g ha-1 + tribenuron-methyl 7,5 g ha-1. A mixture of metsulfuron-methyl + tribenuron-methyl at both lower and higher rates substantially reduced the amount of Sosnowsky’s hogweed plants at four weeks after spraying. Six weeks later, the efficacy of herbicide mixtures ranged from 44 percent with fluroxypyr 360 g ha-1 + metsulfuron-methyl 4.0 g ha-1 to 59.3 percent with fluroxypyr 360 g ha-1 + metsulfuron-methyl 4.0 g ha-1 + tribenuron-methyl 7.5 g ha-1. In the spring of 2018, control was evaluated and the plant stand in infested fields sprayed with herbicide mixtures fluctuated from 1.0 to 3.6 plants/m2 and was significant lower (by 6.4 to 23.0 fold) in contrast to control fields that were not treated. Herbicide efficacy observed was as high as 86.2–96.2 %. Most efficacious herbicide mixtures included fluroxypyr 360 g ha-1 + metsulfuron-methyl 4.0 g ha-1 + tribenuron-methyl 7.5 g ha-1 and metsulfuron-methyl 6.0 g ha-1 + tribenuron-methyl 11.3 g ha-1.

  • Open access
  • 56 Reads
Comparison of proximal remote sensing devices of vegetable crops to determine the role of grafting in plant resistance to Meloidogyne incognita

Proximal remote sensing devices are novel tools that enable the study of plants health status through specific characteristics, including the color or the spectrum of light reflected or transmitted by the leaves or the canopy. Among these, RGB images can provide detailed information about crop status including estimates of biomass, chlorophyll (and chlorosis) and fractional vegetation cover. The aim of this study is to compare the RGB data collected during five years (2016-2020) of four fruiting vegetables (melon, tomato, eggplant and peppers), non-grafted and grafted onto resistant rootstocks cultivated in Meloidogyne incognita infested soil in a greenhouse. The proximal remote sensing plant health status data collected were divided into three levels. Firstly, leaf pigments were measured using two different handheld sensors (SPAD and Dualex). Secondly, canopy vigor and biomass were assessed using vegetation indices derived from RGB images and the Normalized Difference Vegetation Index (NDVI) measured with a portable spectroradiometer (Greenseeker). Third, we assessed the level water stress experienced by the plant, as a consequence of the root-knot nematodes, using stomatal conductance measured with a porometer (Decagon Leaf Porometer SC-1), plant temperature with an infrared thermometer and the stable carbon and nitrogen isotope composition of leaf dry matter. Among the measured parameters, percentage carbon and percentage nitrogen exhibited the highest positive correlation (r=0.9), whereas flavonoids and NBI (Nitrogen Balance Index) showed the highest inverse correlation (r=-0.87). It was found that the interaction between treatments and crops (ANOVA) was statistically different only 4 of 17 parameters (flavonoid (p=0.002), NBI (p=0.044), NDVI (p=0.004) and CSI (Crop Senescence Index) (p=0.002). Concerning the effect of treatments across all crops, differences existed only in two parameters, which were flavonoid (p=0.003) and CSI (p=0.001). Grafted plants contained less flavonoids (x̄=1.37) and showed lower CSI (x̄=11.65) than non-grafted plants (x̄=1.98 and x̄=17.28, respectively, p=0.020 and p=0.029) when combining all five years and four crops. We conclude that the grafted plants were less stressed and more protected against nematode attack. Leaf flavonoids and the RGB index (CSI) as indicator of crop senescence were good indicators of root-knot nematode impact across multiple crops.

  • Open access
  • 138 Reads
Dairy cattle under grazing systems: An estimate of the carbon footprint in the northern Andes of Ecuador

Border production systems are a threat to biodiversity hotspots. This is due to the dilemma of conservation or economic maximization, while the amount of carbon footprint (CF) generated by the management of border grazing and livestock is an uncertainty. The objectives of this study were to determine the socio-demographic characteristics of households, to describe animal and pasture management on farms and to estimate the CF generated by dairy cattle. The study was performed between two protected areas, being the El Ángel and La Bonita reserves, which are located in the Eastern Andean Cordillera. While the sampling was carried out by conglomerate, the corresponding survey was conducted on the head of the households concerned. A total of 333 farmers from 86 rural households were surveyed. We identified an average of seven individuals per household with no education, while the average pasture area was about 45.3 ha. There was no association of forage species and the modernization of animal management is precarious. In the CF, the Cool Farm Tool programme was used. The CF generated indicated that 79% is enteric fermentation of cattle, followed by management of pasture residues. The results of this study encourage measures focusing on diet management, spread of livestock manure and reuse of grass as compost to reduce the CF of livestock systems.

  • Open access
  • 127 Reads
SiO2 applications as an alternative to insect control in greenhouses

Silicon dioxide (SiO2) has been extensively studied as an alternative method to pest management chemical applications in agriculture. The present work aimed to evaluate the insecticidal efficacy of different SiO2 dust formulations and their effectiveness when integrated into the textiles of an insect-proof net. For this reason, Sitophilus oryzae and Tribolium confusum were exposed to three inert dust formulations, namely Sylobloc® S200, S200-OH, and S200MEC to investigate their effect on the mortality of the aforementioned stored-product insects. The results of this series of bioassays showed that Sylobloc® S200 was the most effective dust among all the formulations tested. Thus, five samples of the same 50 mesh size insect-proof net were coated with the S200 dust followed either by different coating repetitions or by the addition of paraffin. T. confusum was indicated as the most tolerant species, as the recorded mortality rate was significantly low when exposed to all samples tested. However, the mortality rate of S. oryzae was strongly related to the coating repetition as well as the exposure intervals. The highest mortality (70%) was detected after 7 days of exposure to the net and it consisted of three coating repetitions while no paraffin was added to its surface. The results of the present study underline the insecticidal efficacy of SiO2 treated nets against storage insects and their subsequent application in greenhouses for the control of more susceptible insects. This research has been co-financed by the European Union and Greek national funds through the National Action “Bilateral and Multilateral E&T Cooperation Greece-Germany”(project code: T2DGΕ-0120).