Infestation Of Wheat Research Articles

The Effect of Crop Production Systems and Cultivars on Spring Wheat (Triticum aestivum L.) Yield in a Long-Term Experiment

The aim of this study was to determine the impact of different crop production systems (organic, integrated, and conventional) on the yields of several spring wheat (Triticum aestivum L.) cultivars. A field experiment was carried out at the Agricultural Experimental Station of the Institute of Soil Science and Plant Cultivation in Osiny (Poland) in three consecutive growing seasons (2014, 2015, and 2016). Two factors were included in the experiment: the crop production system (organic, integrated, and conventional) and spring wheat cultivars (Kandela, Izera, Ostka Smolicka, and Waluta). The crop production system significantly differentiated the yield, health, and weed infestation of the spring wheat. Wheat yield in the conventional system (6.12 t·ha−1) was higher than in the organic system (3.68 t·ha−1) by 67%, whereas, in the integrated system (7.61 t·ha−1), it was greater than in the organic system by 109%. The lower yields in the organic system were mainly due to fewer ears per m2 and a smaller 1000-grain weight. In the organic system, we also observed a higher infestation of wheat by foliar fungal pathogens and weeds compared with the conventional and integrated systems. The spring wheat cultivars differed in yield structure and resistance to infestation by fungal pathogens. The Waluta and Izera cultivars performed well in all systems but yielded the best in the integrated and conventional ones. The Kandela cultivar was the most suitable for the organic system, as it achieved the highest yield (4.16 t·ha−1). This was mainly due to its ability to form a compact canopy with relatively high ear density, a large 1000-grain weight, and the highest resistance to fungal pathogens. The results for cultivars’ performance in the organic system may be useful for farmers in decreasing yield gaps in relation to integrated and conventional systems.

The selected agrotechnical factors affecting the occurrence of black grass Alopecurus myosuroides in winter wheat crops in north-western Poland

Alopecurus myosuroides of the family Poaceae is a highly competitive species for winter cereal crops, particularly for barley and wheat, less frequently for root vegetables or rapeseed. This study aimed to determine the predominant factor or group of factors affecting the cover of A. myosuroides in winter wheat field depending on the tillage systems, time, and amounts of herbicides used. The following variables differentiating the quantitative contribution of A. myosuroides in the analyzed fields were assumed: plough or no-plough tillage, date of biocidal application, and the total amount of herbicides (active substances) used. When spring-only herbicide was applied, the lowest A. myosuroides cover, not exceeding 25%, was observed in the margins of winter wheat fields. The coverage of A. myosuroides, reaching 25–100% of the winter wheat area, regardless of the tillage system, was found when the herbicides from the group of sulfonylurea derivatives (acetolactate synthase ALS inhibitors) were frequently used. Winter wheat infestation with A. myosuroides was significantly lower when ploughing was applied. The highest cover of A. myosuroides, reaching 50–100% of the area, was observed only in the central part of the analyzed winter wheat fields, following the application of herbicides in autumn and spring or in autumn only.

Effect of Acarus siro L. infestation on germination of wheat and barley seeds under laboratory conditions ​

A laboratory study was conducted to assess the effect of mite infestation with the grain on the germination of wheat (IPA-99 variety) and barley (Al-Khair variety) seeds. The mite was diagnosed in stored and infested wheat and barley seeds as grain mite (cheese mite) Acarus siro L. The results showed that infestation of wheat and barley seeds with A. siro had a significant impact on their germination percentage, whether the seeds were unwashed or washed. The percentage of infestation and germination in wheat seed samples reached 20, 40, 60, 80, and 100 reached 45.00%, 80.00%, 91.67%, 93.75%, and 96.00% with a germination rate of 55.00%, 20.00%, 8.33%, 6.25%, and 4.00% for unwashed seeds, respectively. For washed seeds, the infestation rate was 40.00%, 62.50%, 80.00%, 85.00%, and 90.00% with a germination rate of 60.00%, 37.50%, 20.00%, 15.00%, and 10.00%, respectively. Whereas, for barley seeds, the percentage of infestation and germination in the samples 20, 40, 60, 80, and 100 reached 35.00%, 72.50%, 83.33%, 88.75%, and 94.00% with a germination rate of 65.00%, 27.50%, 16.67%, 11.25%, and 6.00% for unwashed seeds, respectively. For washed seeds, the infestation rate was 25.00%, 57.50%, 70.00%, 81.25%, and 90.00% with a germination rate of 75.00%, 42.50%, 30.00%, 18.75%, and 10.00%, respectively. The results also showed that infestation of wheat and barley seeds had a greater impact on reducing their germination percentage in unwashed samples compared to washed samples, with significant differences. Unwashed wheat seed samples achieved the highest infestation rate and the lowest germination rate at 81.28% and 18.72%, respectively. Unwashed barley seed samples achieved the highest infestation rate and the lowest germination rate at 74.72% and 25.28%, respectively. It is also noted that the highest infestation rate and the lowest germination rate for wheat and barley seeds were observed in the 100 samples, while the lowest infestation rate and the highest germination rate were found in the 20 samples for both unwashed and washed seeds, respectively. The results indicated that wheat was more preferred by the mite than barley in both unwashed and washed seed samples.

Mycotoxin Level in Winter Wheat Grain as Impacted by Nitrogen and Manganese Fertilisation

A field experiment with winter wheat (Triticum aestivum L.) cultivation was conducted at the Research and Education Centre in Tomaszkowo, Poland (53°72′ N; 20°42′ E) in the years 2013–2016. Fertilisation with nitrogen at 150 and 200 kg ha−1 and foliar application of manganese at 0.5 and 1.5 kg ha−1 were the research factors. Wheat infestation by Fusarium spp. was determined by the habitat conditions during crop growth. Neither nitrogen nor manganese fertilisation affected the presence of Fusarium spp. symptoms on wheat ears, but the infestation intensity decreased with increasing nitrogen and manganese content in the grain. Only the level of deoxynivalenol (DON) was correlated with Fusarium spp. infestation. Increasing the nitrogen fertilisation rate from 150 kg ha−1 to 200 kg ha−1 resulted in higher grain contamination with toxins. Supplementation of nitrogen fertilisation with manganese reduced the number of mycotoxins in wheat grain. The grain yield was mainly affected by the varied weather conditions during the wheat-growing periods. Neither nitrogen nor manganese fertilisation differentiated the wheat grain yield. The objective of this study was to examine the impact of the weather conditions and nitrogen and manganese fertilisation on the grain yield, occurrence of Fusarium head blight and mycotoxin level in winter wheat grain.

Unleashing the power of diatomaceous earths for sustainable management of Tribolium castaneum infestation in wheat

The utilization of diatomaceous earths (DEs) has been considered as a potential alternative to traditional insecticides for controlling grain storage insect pests. In this study, 19 different commercial DEs obtained from various regions of the world were evaluated for their effectiveness to manage Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), in vitro. Two different series of bioassays were carried out, with the first screening all 19 DEs and the second evaluating the eight most effective ones at different doses and exposure intervals for mortality assessment and progeny production. Four enhanced DEs, namely InertPMS, DEA, DiaHerb, and DEBBM were highly effective compared to other DEs tested. InertPMS exhibited complete adult mortality at 50 mg/kg, followed by DEA at 75 mg/kg, DiaHerb at 100 mg/kg, and DEBBM at 125 mg/kg, while GrainGuard exhibited 94.52 % at 125 mg/kg, 14 days post-exposure. Protect-It, SilicoSec, and DiaFil 610 were less effective at 400 mg/kg, causing 87.3 %, 84.4 %, and 79.2 % mortality after 14 days, respectively. The offspring was suppressed in wheat treated with InertPMS at 75 mg/kg, while DEA, DiaHerb, and DEBBM revealed no progeny emergence at 125 mg/kg. GrainGuard, Protect-It, SilicoSec, and DiaFil 610 were not successful at progeny suspension after 62 days. These findings suggest that the use of specific DEs at low doses could be a viable option to mitigate the use of conventional insecticides and diminish the residues of insecticides on stored grains, making them the most feasible components for integrated pest management (IPM) in stored grain systems.

Inorganic Fungicides (Phosphites) Instead of Organic Fungicides in Winter Wheat—Consequences for Nitrogen Fertilizer Productivity

Substitution of organic with inorganic fungicides (phosphites, Phi) does not change the efficiency of fertilizer nitrogen (Nf) in winter wheat. This hypothesis was tested in the 2016/2017 and 2017/2018 growing seasons. A two-factorial experiment with three phosphite variants (Cu–Phi, Mg–Phi, and Cu/Mg) and six plant protection methods (fungicides + Phi ⟶ reduced fungicide frequency + phosphite ⟶ phosphite). Grain yield decreased with increasing frequency of phosphites instead of fungicides. The decrease in yields was 3.6 t ha−1 in the favorable 2016/2017 and 1.1 t ha−1 in the dry 2017/2018. The primary reason for yield decrease in a given growing season was increased wheat infestation by pathogens. The direct cause was disturbances in the nitrogen status of wheat after flowering on treatments with a predominance of phosphites. The thousand grain weight (TGW) responded negatively to reduced fungicide application frequency. The critical stage in the assessment of pathogen pressure on wheat was the medium milk phase (BBCH 75). At this stage, indices of SPAD and leaf greenness together with indices of wheat infestation with pathogens allowed for a reliable prediction of both TGW and grain yield. It can be concluded that phosphites do not substitute organic fungicides in limiting pathogen pressure in winter wheat. Moreover, increased pressure of pathogens significantly reduces Nf productivity.

Antagonistic Strain Bacillus halotolerans Jk-25 Mediates the Biocontrol of Wheat Common Root Rot Caused by Bipolaris sorokiniana

Common root rot caused by Bipolaris sorokiniana infestation in wheat is one of the main reasons for yield reduction in wheat crops worldwide. The bacterium strain JK-25 used in the current investigation was isolated from wheat rhizosphere soil and was later identified as Bacillus halotolerans based on its morphological, physiological, biochemical, and molecular properties. The strain showed significant antagonism to B. sorokiniana, Fusarium oxysporum, Fusarium graminearum, and Rhizoctonia zeae. Inhibition of B. sorokiniana mycelial dry weight and spore germination rate by JK-25 fermentation supernatant reached 60% and 88%, respectively. The crude extract of JK-25 was found, by Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), to contain the surfactin that exerted an inhibitory effect on B. sorokiniana. The disruption of mycelial cell membranes was observed under laser scanning confocal microscope (LSCM) after treatment of B. sorokiniana mycelium with the crude extract. The antioxidant enzyme activity of B. sorokiniana was significantly reduced and the oxidation product malondialdehyde (MDA) content increased after treatment with the crude extract. The incidence of root rot was significantly reduced in pot experiments with the addition of JK-25 culture fermentation supernatant, which had a significant biological control effect of 72.06%. Its ability to produce siderophores may help to promote wheat growth and the production of proteases and pectinases may also be part of the strain's role in suppressing pathogens. These results demonstrate the excellent antagonistic effect of JK-25 against B. sorokiniana and suggest that this strain has great potential as a resource for biological control of wheat root rot strains.

Volatile Metabolite Profiling of Wheat Kernels Contaminated by Fusarium graminearum.

Traditional methods used to detect fungi or mycotoxins are time-consuming and prevent real-time monitoring. In this study, solid-phase microextraction combined with full two-dimensional gas chromatography time-of-flight mass spectrometry was utilized to detect volatile organic compounds (VOCs) produced by fungi during grain infestation predictive F. graminearum PH-1 infestation in wheat. The results show that the VOCs emitted by F. graminearum can distinguish strains at different growth stages. The growth matrices (potato dextrose agar medium and wheat kernels) play a large role in VOC production. The infection of wheat sample F. graminearum showed that a specific relationship between VOCs and the composition of fungal flora, for example, 5-pentyl-cyclohexa-1,3-diene, 3-hexanone, and 1,3-octadiene, was positively correlated with the infection rate of PH-1. In the correlation study of fungal mycotoxins and VOCs, zearalenone produced by F. graminearum was predicted based on the VOCs released. Further analysis determined the correlation of three VOCs, 6-butyl-1,4-cycloheptadiene, hexahydro-3-methylenebenzofuran-2(3H)-one, and (E,E)-3,5-octadien-2-one, with zearalenone production, confirming the ability of VOCs as characteristic markers of mycotoxins.

Comparative transcriptome analysis of wheat in response to corn leaf aphid, Rhopalosiphum maidis F. infestation.

Aphids are one of the most important insect pests of wheat crop in all wheat growing regions of the world. Amongst various aphid species, the corn leaf aphid (Rhopalosiphum maidis F.) is considered one of the most destructive insect pests of wheat in the North Western Plains region of India. Transcriptome profiling of highly susceptible wheat Triticum durum genotype, A-9-30-1 and tolerant wheat Triticum aestivum genotype, HD2967 was performed to investigate aphid-host interactions. The results obtained from differential gene expression analysis of R. maidis on the highly susceptible genotype, A-9-30-1 plants, when compared with the tolerant genotype, HD2967, showed that 212 genes were significantly upregulated and 1009 genes were significantly downregulated. Our findings demonstrated that the genes associated with defense were significantly higher in response to R. maidis on HD2967 as compared to A-9-30-1. Additionally, various genes with physiological attributes were expressed during aphid attack. Based on gene ontology classification, three classifications, such as, cellular components (CC), molecular function (MF), and biological processes (BP) of sequences were identified. KEGG enrichment analysis revealed that twenty-five pathway genes were differentially expressed during the infestation of wheat with R. maidis. Notable changes were observed in A-9-30-1 and HD2967 transcriptomic profiling after infestation. The results obtained in the present study will help to elucidate the mechanism governing host-pest interaction and may lead to the development of new methods for increasing the resistance level of wheat against R. maidis, including over-expression of defense-related genes.

Podobieństwo glebowego banku nasion i aktualnego zachwaszczenia łanu pszenicy ozimej w różnych systemach produkcji rolnej

The aim of the research was a comparison of soil seed bank, formed by the influence of different crop production systems (organic, integrated, conventional and monoculture of winter wheat) with weed infestation in the winter wheat. The study was conducted at the Experimental Station of the Institute of Soil Science and Plant Cultivation – State Research Institute in Osiny (Lublin province), where these crop production systems, characterised by different crop rotations and agricultural practices, have been compared since 1994. The assessment included the analysis of weed species composition and the number of weeds in winter wheat cultivated in different crop production systems as well as the weed seed stock in the 0–20 cm soil layer under winter wheat. The soil seed bank and winter wheat infestation was analysed using ecological indices: Shannon's diversity index (H') and Simpson's dominance index (SI). 
 The number of weed seed species in the soil was higher than the number of weed species in a winter wheat canopy in all compared systems. The difference between the number of species in a canopy and in the soil was the smallest in the organic system. The monoculture of winter wheat was characterised by the lowest diversity of weed flora and soil seed bank. Shannon and Simpson indices showed the bigger similarity between soil seed bank and weed infestation in the organic system and the lowest in conventional one and monoculture. Small differences of species number in weed seed stock in the compared systems and the narrow ranges of Shannon and Simpson indices suggest smaller dynamics of change of soil seed bank than weed flora.

Effects of soil fluoride pollution on wheat growth and biomass production, leaf injury index, powdery mildew infestation and trace metal uptake

Fluoride (F) is an emerging pollutant that originates from multiple sources and adversely affects plant growth and nutrient bioavailability in soil. This greenhouse study investigated the effects of soil F (0, 10, 20, 50, 100, 200 mg kg−1) on morpho-physiological growth characteristics of wheat, soil F contents, and bioavailability and uptake of F, phosphorus (P), sulphur (S), potassium (K), calcium (Ca), magnesium (Mg), aluminium (Al), iron (Fe), manganese (Mn), silicon (Si) and zinc (Zn) by wheat. Higher F significantly reduced plant height and number of leaves particularly at early growth stages and increased visible leaf injury index. Powdery mildew infestation coincided with leafy injury and was higher in elevated soil F treatments. Fluoride treatments (>50 mg kg−1) significantly increased water (H2O)- and calcium chloride (CaCl2)-extractable F contents in soil. Water-extractable soil F contents from soil in all concentration were higher than CaCl2-extractable F. This increased F bioavailability resulted in significantly higher F uptake and accumulation in live leaves, dead leaves and grains of wheat which followed order: live leaves > dead leaves > grains. Leaf injury index and number of dead leaves correlated significantly positively with soil H2O- and CaCl2-extractable F contents. Patterns of nutrient (P, K, S) and trace metals (Al, Ca, Mg, Fe, Mn, Si, Zn) varied significantly with F concentrations and between live and dead leaves, and grains except for Zn. Dead leaves generally had higher nutrients and trace metals than live leaves and grains. Fluoride contents in live leaves, dead leaves and grains showed positive correlations with nutrient elements but negative with trace metals. Number of dead leaves correlated negatively with Al, Ca, Fe, Mg, S and Si but positively with P and Zn contents in dead leaves whereas leaf injury index showed positive correlation with Fe, K, P, Si, Zn, S but negative with Al, Ca and Mg contents. These observations provided evidence of higher F uptake and associated impairment in nutrient and trace metal accumulation which caused leaf injury accompanied by powdery mildew infestation in wheat. However, further research in the region is required to confirm the relationship between F pollution, leaf injury and trace metal accumulation in crops under field conditions.

Effect of Seed Treatment with Insecticides on Germination, Grain Yield and Infestation of Termite (Odentotermis obesus Rambur) on Wheat under Rainfed Condition

Field experiment on the seed treatment for the management of termite infestation in wheat were conducted at Crop Research Farm of C.S. Azad University of Agriculture & Technology, Kanpur during Rabi 2016-17 and 2017-18 under rainfed condition. Eight treatments including untreated check were tested on wheat cultivar Maghar (K 8027). Seven insecticidal treatmens viz; thiamethoxam 25 WG @ 3.2 g, acephate 50% + imidachloprid 1.8 % @ 4.0 g , fipronil 5 SC @ 10 ml, imidacloprid 600 FS (48%) @ 4.0 ml, clothianidin 50 WDG @ 1.5 g, fipronil 40% + imidacloprid 40 WG @ 3.0 g and chlorntranil pride @ 3.0 ml were applied at the rate of one kg of seed before sowing. Non significant differences in germinatbility of wheat were observed between all the treatments. The order of effectiveness of insecticides on termite damage was , fipronil 40% + imidacloprid 40 WG > fipronil 5 SC>imidacloprid 600 FS (48%)> clothianidin 50 WDG> thiamethoxam 25 WG> in both the year chlorntranil pride s. Significant highest seed yield being 21.0 q/ha was recorded in seed treated with fipronil 40% + imidacloprid 40 WG which was at par with fipronil 5 SC (20.92 q/ha) and imidacloprid 600 FS (48%) (20.50 q/ha) in the year 2016-17. In the year 2017-18 fipronil 40%+imidacloprid 40 WG gave maximum yield of 20.46 q/ha followed by fipronil 5 SC (20.38 q/ha) and imidacloprid 600 FS (19.17 q/ha).

The effect of combinations of cyproconazole and fludioxonil on infestation of wheat and barley grains

The most popular and affordable means to protect plants from fungal diseases are fungicides. Development of new products is aimed at preparation of the composition of several substances to achieve the effect of mutual enhancement of action. We used the grains of wheat (Triticum sp. variety Julius) and barley (Hordeum sativum variety Gloria), they were significantly infected with phytopathogenic fungi, which allows us to get reliable data on the effectiveness of active substances of fungicides. All wheat grains treated with fungicides were infected less than the control ones. Analysis of the effect of individual fungicides demonstrated that the fungi were more sensitive to fludioxonil, especially at doses of CF 0: 2 (56.7% of infected grains) and CF 0:4 (36.7% of infected grains) 5.0 and 10.0 g/t. After the treatment of cyproconazole, the smallest number of infected grains was obtained when grains were treated at a dose 5.0 g/t (80.0 % of infected grains). The fungistatic effect of cyproconazole (C) and fludioxonil (F) was greatest when ratios of C : F were 2.5:10; 5:10; 10:2.5; 10:5; 10:10 g/t.

X-RAY MICROANALYSIS IN PHYTOPATHOLOGY

X-ray microanalysis methods have significantly expanded the functionality of electron microscopy. X-ray microanalysis is widely applied in activities, which deal with plant physiology. The paper explores the functioning of the stomach apparatus of fodder beans (Vícia fába). The regulation of the stomatal function depends on the potassium concentration in the closing cells. The authors investigated the infestation of wheat leaves with mildew (Erysiphe graminis) (Triticum astivum) and obtained the data that reveal the changes in the elemental composition of tissues in the affected area. This has contributed to find out the role of various elements during the infectious process in case of wheat plants with powdery dew contamination. The paper summarizes the materials on the application of X-ray microanalysis in phytopathology. It stipulates the participation of calcium in the formation of the mechanism of nematode capture in different age colonies of predatory fungi Arthrobotrys oligospores Fres was revealed. The data on tissue barrier in wheat roots, where the transport of both sodium and chlorine salting elements and potassium and calcium macro elements is controlled, are obtained. The authors show that transporting of these elements is regulated by active mechanisms in the endoderm cells. The article demonstrates the results of X-ray microanalysis aimed at determining the content of elements of magnesium, phosphorus, sulfur, potassium and calcium in soybean leaves affected by various diseases. The authors observed the changes in potassium, calcium, magnesium and phosphorus concentration in leaves with bacterial burn, ascochytosis and alternative. They argue the participation of elements in formation of plant resistance to disease and the role of these elements in the physiology of the infectious process.

Efficiency of application of fungicides for spring wheat protection against root rots

Infestation of grain crops by common root rot in the conditions of Ural Federal District was studied. In previous years, infestation of wheat by Bipolaris sorokiniana pathogens predominated, but in recent years, there has been a gradual shift in the structure of microbiocenosis with the prevalence of Fusarium spp. fungi. With zero and minimum grain crop tillage technologies (no-till, mini-till), chemical disinfection of seeds and fungicidal crop treatment becomes imperative. The efficiency and feasibility of using fungicides was studied on the seeds of spring wheat, cultivar Omskaya 36. Field experiments were conducted in the conditions of Kurgan region on leached chernozem in the period of 2009-2017. Yield losses caused by phytopathogenic fungi were largely determined by the hydrothermal conditions during the growing season. The largest damage to wheat productivity was caused by diseases of this group during dry periods (11% in years with satisfactory growing conditions, 22% in extremely dry years). It was discovered that the approach to protecting seeds from infections should be differentiated. Batches of seeds with high contamination by root rot pathogens are subject to mandatory chemical disinfection. Application of seed disinfectants based on two active agents is effective on wheat seeds infected by root rot pathogens over 15%, with the predominance of fungi genus Fusarium spp. Economic efficiency from the use of single-component seed disinfectants (tebuconazole, triticonazole) was 8-9%. When seeds were treated with seed disinfectants based on two active agents, the yield increased by 1416%. The use of systemic seed disinfectants is not recommended on relatively healthy seed material. It is more appropriate to use biological fungicide based on Bacillus subtilis.

Quality of winter wheat grain depending on the development of pathogenic mycoflora

One of the main conditions for cultivating grain crops is the production of high yields of high quality grain. However, even well-formed healthy-looking seed are not always of good quality.
 Wheat grain infestation with mycoflora occurs at different times, e.g. in the period of vegetation, during harvesting, especially in conditions of high humidity, during threshing, during storage of seeds with high humidity. Mycoflora on the seeds can be saprophytic (penicillas, mucor, alternaria, aspergillas, etc.) and pathogenic (helminthiosporium, fusariosis, septoriosis, etc.).
 The purpose of our research was to study the level of winter wheat infestation with pathogenic microorganisms, to determine their species composition and to investigate whether the level of grain infestation affects protein and gluten content.
 The species composition of the epiphytic mycoflora of winter wheat grain during the harvesting period and its influence on the food quality of grain are studied, measures are taken to limit its harmfulness.

Plant-Mediated Interactions between Two Cereal Aphid Species: Promotion of Aphid Performance and Attraction of More Parasitoids by Infestation of Wheat with Phytotoxic Aphid Schizaphis graminum.

Here, we investigated changes in physiological characteristics in wheat affected by phytotoxic-aphid Schizaphis graminum feeding and nonphytotoxic-aphid Sitobion avenae feeding. We also determined whether shared host-mediated interspecific interactions occur between S. graminum and S. avenae. S. graminum feeding but not S. avenae feeding induced significant chlorophyll loss and hydrogen peroxide accumulation in wheat. Gene-expression analysis and GC/MS metabonomic results indicated that S. graminum infestation induced stronger salicylic acid mediated defense responses than S. avenae did and significantly increased the contents of several amino acids in wheat leaves. Feeding on wheat preinfested with S. graminum significantly increased the reproduction of both aphids and shortened the development time of S. graminum. However, olfactometer bioassays showed that the parasitoid wasp Aphidius gifuensis was more attracted to the odors of S. graminum infested wheat than to those of control and S. avenae infested wheat. This study demonstrates that S. graminum and S. avenae feeding induced different defense responses and changes in plant nutritional quality. Additionally, plant-mediated interactions occurred between these cereal aphids.

Mentha piperita L. Essential Oil and its Constituents as Stored Grain Protectant

Mentha leaf essential oil extracted from dried and powdered menthe leaves was subjected to column chromatography to obtain its fractions. Three compounds namely pulegone, menthol, p-cymene were isolated from polar fraction. Menthol was chemically transformed to menthone using pyridinium chlorochromate. All the compounds were identified by spectroscopic techniques. Mentha leaf essential oil (pure) was tested for its insecticidal activity at five different concentrations in the range 50–500 μg g−1 respectively against F1 generation of red rust flour beetle (Tribolium castaneum Herbst.) adults. Maximum inhibition was observed at 500 μg g−1. The activity was both time and concentration dependent. The fractions of mentha leaf essential oil and the compounds isolated were tested at 250 μg g−1 concentration. Polar fraction was more active as compared to the non-polar fraction. Adults of the beetle were more susceptible to menthone as complete corrected per cent mortality was observed on 22nd d in menthone as compared to 25 d for menthol. The results indicated that mentha leaf essential oil may have potential to control infestation of wheat by T. castaneum.

Biological technologies are the factors of winter wheat productivity improvement

The studies were conducted in 2012–2014 in OOO “Znamenskoe” in the Znamensky district of the Orlov region in order to determine the influence of forecrops on winter wheat productivity. Field trials have shown that the forecrops have a great effect on soil moisture. The use of weedfree fallow and oil radish as green manure crop provides 1.3–3% soil moisture increase in the 0–10 cm layer before winter wheat sowing compared with annual grasses. Sown in bare fallow, winter wheat infestation was on 17.6–18.8% less in the tillering phase compared with the use of oil radish oil as green manure crop and annual grasses for green mass. It was determined that the forecops had an effect on the height of winter wheat plants. In weedfree fallow it was the maximum (122.7–127.1 cm), depending on the fertilizing ratio, which was on 8.0–10.3 cm more than in other variants of the trial. It was established that winter wheat sown in bare fallow exceeded other variants by the number of productive stems, kernels per ear, 1000-kernel weight on 2.1–7.2; 1.7–4.4; 13.9–19.5% respectively. This ensured a higher productivity of winter wheat. It has been identified that the use of oil radish improves the winter wheat quality, namely protein and gluten content, grain unit on 2.0–2.2, 1.4–2.2; 11–12.5 g/l respectively. The norm of mineral fertilizers N98R64K64 in comparison with N66R32K32 in all forecrops provided an increase in protein and gluten content on 0.4–0.7% and 0.7–2.6% respectively. Thus, biological technologies provide productivity improvement of winter wheat.

Influence of Phenological Growth Stages and Meteorological Parameters on Leaf Blight Infestation of Wheat in Gangetic Plains of West Bengal

Influence of Phenological Growth Stages and Meteorological Parameters on Leaf Blight Infestation of Wheat in Gangetic Plains of West Bengal