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Phthorimaea operculella is a significant insect pest of cultivated potatoes in tropical and subtropical regions such as Iran. Since the potato is one of the most valuable sources of human food, non-chemical control of potato pests is essential. Application of medicinal plant extracts is a low-risk alternative method to synthetic chemical insecticides. Hence, the present study was conducted to investigate a potential strategy to improve the insecticidal activity of plant extracts for efficient management of P. operculella. The insecticidal efficacy of pure methanolic extract (PME) and Fe3O4@methanolic extract (FME) of Cuminum cyminum were evaluated against the potato tuber moth under laboratory conditions. The morphological characteristics of Fe3O4@Cumin were investigated by scanning electron microscope. Magnetic properties of the samples were determined using a vibration sample magnetometer. XRD was used to prove the crystalline structure of Fe3O4@Cumin. SEM, FTIR, XRD, and VSM analyses confirmed that the methanolic extract was loaded on Fe3O4. The toxicity of PME and Fe3O4@Cumin were evaluated on one-day-old eggs and penetration the first instar larvae of P. operculella into potato tubers and leaves. The LC50 values of Cumin extract and Fe3O4@ Cumin were 961.07 and 601.48 and 496.84 and 268.82 ppm for penetrating neonate larvae to tubers and leaves, and 874.90 and 595.16 ppm for eggs, respectively. Bioassays revealed that Fe3O4@Cumin was more toxic than non-formulated Cumin methanolic extract against eggs and neonate larvae of P. operculella. The formulated methanolic extract was significantly more repellent against the pest. Our results suggested that the prepared nanocomposite could be used as a new effective tool for P. operculella management strategies to protect potatoes.

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Abstract

Foundation species and invasive species strongly influence community diversity and structure, but typically in different ways. However, when widespread invasive species provide novel habitat within a community, their net effect may depend on both the environment and community composition. Fouling communities in northern and southern California harbors were surveyed to determine whether there was variation between two locations in the percent cover of an invasive bryozoan, Watersipora subtorquata (d'Orbigny, 1852), and its relationship to community diversity and composition in these two environments. Diversity significantly differed between locations and had a location-dependent association with W. subtorquata abundance. Communities were significantly dissimilar between locations, and W. subtorquata abundance had the highest percent contribution to community dissimilarity when compared to other species in the community. These results suggest that invasive species may have both facilitative and inhibitive relationships with species in a community, but that the net balance of these interactions depends on both the environmental and community context.

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The economic threshold level of Meloidogyne incognita, Alternaria dauci and Rhizoctonia solani were determined on carrot (Daucus carota L.) under greenhouse conditions. The results revealed that plant length, plant fresh weight, shoot and root dry weight, chlorophyll and carotenoid decreased progressively with the corresponding increase in the inoculum levels of each pathogen. The significant reduction in plant growth parameters, chlorophyll and carotenoid occurred when 2000 or more second stage juveniles (J2s) of M. incognita, 1.0 g or more inoculum of A. dauci or R. solani per kg soil were inoculated. Maximum reduction in plant growth attributes, chlorophyll and carotenoid occurred at the highest inoculum level of the test pathogens. Increase in the inoculum level of M. incognita caused an increase in the number of root galls, while the multiplication of nematode was found inversely related to the inoculum density. The increase in the inoculum levels of A. dauci and R. solani resulted in a progressive increase in leaf blight and crown rot indices and caused a higher reduction in plant growth parameters. The damaging threshold level of M. incognita was 2000 J2 per kg soil while 1.0 g per kg soil of A. dauci or R. solani was threshold level on carrot. The assessment of infestation levels of test pathogens will enable growers to cost-effectively select and implement the management tactics.

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Introduction

Effect of water stress on the physiology and biochemistry of two different Coleus species, Coleus forskholii and Coleus amboinicus, was studied.

Materials and methods

Drought stress was imposed by withholding the water supply until leaf water potentials reached −0.4, −0.8, and −1.2 MPa. Physiological parameters such as relative water content and water uptake capacity were studied along with lipid peroxidation, superoxide, H2O2, and OH accumulation-, 1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging assays. Antioxidant defense system in Coleus under drought stress was studied by quantifying the Trolox equivalent antioxidant capacity, ascorbic acid, reduced glutathione-, and α-tocopherol content as well as activities of superoxide dismutase, catalase, ascorbate peroxidase, peroxidase, and glutathione reductase. Accumulation of osmolytes proline, glycine betaine, and phytohormone abscisic acid was also used as key parameters for assessing their performance.

Results

There was a marked variation in the antioxidative defense system and osmolyte accumulation in these two species under drought stress. Relative water content was reduced and water uptake capacity was increased.

Discussion

A comparative study in the perspectives of osmolyte accumulation, antioxidant, and physiological responses inferred C. amboinicus as a drought stress-tolerant species when compared to C. forskholii.

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Authors: S. Leon-Cisneros, A. Quirola-Garcés, J. Alvarez-Santana, N. Barriga-Medina, D. Ramirez-Villacís, M. Caviedes, L. Ramirez-Cárdenas and A. Leon-Reyes

Anthocyanins are plants metabolites that are recognized by its red/purple coloration produced in flowers, seeds and leaves. These molecules are potentially important to the industry for its antioxidant capacity, disease prevention and as a natural dye. Currently, the production of anthocyanins is carried out using in vitro culture of Vitis vinifera and its yield is increased by using elicitors or stress factors. Zea mays is relevant due to its high content of cyanidin-3-β-glucoside anthocyanin. In the present study the production of cyanidin-3-β-glucoside was evaluated with different mechanisms of elicitation using in vivo and in vitro culture of purple and white maize varieties. The highest callus induction (85%) for white maize was obtained in MS medium supplemented with 2 mg/L of 2,4-Dichlorophenoxyacetic acid, while for purple maize (93%) was obtained in N6 medium with 2 mg/L of 2,4-Dichlorophenoxyacetic acid, using germinated seed as explant for both varieties. Methyl jasmonate was evaluated as an elicitation tool, however no cyanidin-3-β-glucoside was found to be accumulated or produced in vitro. In contrast, using germinated seeds and radicle tissue, elicitation using phosphorus deficiency treatment produced the highest cyanidin-3-β-glucoside accumulation (0.06 mg g−1) in white maize. No elicitation and further production of anthocyanins was found when purple maize were used using this method. Therefore, in vivo elicitation in white maize is a potential method to produce a stable anthocyanin that could be optimized for future applications.

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Cereal breeding programs are interested in increasing the number of generations per year to reduce the time needed to develop new cultivars. A common method to accomplish this is to extend the photoperiod to speed up plant growth. For oat, this method is problematic because the species responds to changes in light and temperature. Current methods of fast generation cycling in oat require embryo rescue, which is labor intensive and has a low success rate. Recently a method was developed using increased photoperiod and foliar mineral supplement to reduce generation time for wheat and barley. We evaluated this newly published method in oat and found that anthesis occurred 15 ± 3 days faster, however there was a 3-fold reduction in seed count and a 2-fold reduction in inflorescence weight. In addition, we measured endogenous ascorbate to evaluate the physiological status of the plants under fast generation cycling conditions. For oat, fast generation cycling would be effective to more rapidly advance populations using single seed descent, but not as useful when seed yield is important.

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Authors: D. Huang, H. Zhang, M. Tar, Y. Zhang, F. Ni, J. Ren, D. Fu, L. Purnhauser and J. Wu

Stripe or yellow rust (Yr), caused by Puccinia striiformis Westend. (Pst), is one of the most important wheat diseases worldwide. New aggressive Pst races can spread quickly, even between countries and continents. To identify and exploit stripe rust resistance genes, breeders must characterize first the Pst resistance and genotypes of their cultivars. To find new sources of resistances it is important to study how wheat varieties respond to Pst races that predominate in other continents. In this study we evaluated stripe rust resistance in 53 Hungarian winter wheat cultivars in China. Twenty-four cultivars (45.3%) had all stage resistance (ASR) and 1 (1.9%) had adult-plant resistance (APR), based on seedling tests in growth chambers and adult-plant tests in fields. We molecularly genotyped six Yr resistance genes: Yr5, Yr10, Yr15, Yr17, Yr18, and Yr36. Yr18, an APR gene, was present alone in five cultivars, and in ‘GK Kapos’, that also had seedling resistance. The other five Yr genes were absent in all cultivars tested.

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Few researches address the compatibility of organic mulching and entomopathogenic (EPN) and slug-parasitic (SPN) nematodes, although organic mulching may provide favourable conditions for these beneficial organisms. Our aim was to examine the effect of different concentrations (0.1, 0.5, 1 and 5%) of aqueous extracts of green waste compost, the dry leaf litters of the common walnut (Juglans regia) and Norway maple (Acer platanoides) on EPN (Heterorhabditis bacteriophora, Steinernema carpocapsae, Steinernema feltiae, Steinernema kraussei) and SPN (Phasmarhabditis hermaphrodita) species. Experiments were set up in 96-well, flat-bottom microplates. After a 24-hour exposure time, the number of dead animals was counted under a transmission microscope. Green waste compost extracts caused quite low or no mortality in case of all examined species. Mortality caused by the 5% Norway maple leaf litter extract was moderate (34.6%) in the case of S. carpocapsae juveniles, while 100% of juveniles of other species died. The highest (5%) concentration of the common walnut leaf litter extract caused 100% mortality in all species. As a conclusion, green waste compost mulch seems to be more compatible with EPN and SPN species than common walnut or Norway maple leaf litter mulch.

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Authors: Q. Riaz, K. Ács, F. Békés, R.F. Eastwood, A. Farahnaky, M. Majzoobi and C.L. Blanchard

Grain fructans play an important role in the physiology of wheat plants and also impact on the health of consumers of wheat-based products. Given the potential economic importance of fructan levels, if genetic variability could be identified for this trait, it may be a potentially useful breeding target for developing climate-resilient and nutritionally enhanced wheat varieties. The aim of the current study was to screen 78 genetically diverse Australian wheat varieties released between 1860 and 2015 to determine if historic breeding targets have resulted in changes in fructan levels and to identify potential breeding parents for the development of varieties with specific fructan levels. The impact of seasonal conditions on grain fructan levels were also investigated. Analysis of the varieties in this study indicated that historic breeding targets have not impacted on grain fructan levels. Fructan content in flours varied between 1.01 to 2.27%, showing some variation among the varieties. However, a significant variation in fructan levels was observed between different harvest years (mean values for 2015 and 2016 samples were 1.38 and 1.74%, respectively). While large variations in fructan contents of different varieties were not found, there were some varieties with consistently higher or lower fructan contents which could be used to breed varieties with specific fructan levels.

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Maize samples collected in Serbia during a period of seven years were investigated on the presence of fumonisins. Concentration of fumonisins was determined by validated direct competitive Enzyme Linked Immunosorbent Assay method. This method was in accordance with European Union requirements, therefore accredited and performed in the Serbian accredited official laboratory. Summary analysis of all obtained results revealed fumonisins contamination in 82% of the total of 291 maize samples with average contamination being 1.515 mg/kg. An increase in the percentage of contaminated samples (from 51 to 100%), as well as an increase in mean fumonisin concentration in positive samples (from 0.227 to 3.281 mg/kg) and median values in positive samples (from 0.070 to 2.140 mg/kg) was noticed during the observation period. Although in Serbia there is no regular control of fumonisins in corn for animal feeding, long-term results indicate their wide distribution in this grain. Since the data on climate elements show change in temperature and precipitation in relation to multiannual average on the territory of Serbia, further research on the effects of climate change on the development of mold, the appearance of insects and the production of toxins are necessary in order to check the resistance of currently grown hybrids in the territory of Serbia on fungal growth and fumonisins production.

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