جستجوی مقالات مرتبط با کلیدواژه « سفیدک پودری » در نشریات گروه « زراعت »

Field monitoring is the basis of many information, actions and researches in agriculture. As long as there is no real information and data from fields and orchards, many of the initial steps in research and implementation will be incomplete and inconclusive. Today, continuous monitoring, as the foundation of sustainable production of healthy food, is on the agenda of international organizations and institutions, and global threats are being monitored through remote sensing systems and ground monitoring in high-risk areas. Of the three main components of monitoring (i.e. environment, plant and damaging factors), climate and host plant variables can be monitored using remote sensing systems, but accurate and reliable monitoring of variables related to damaging factors (especially pests, diseases and weeds), even in developed countries, is done based on field monitoring (or in some cases a combination of both methods). The purpose of this research was to present a real picture of the state of wheat fields in Golestan province in terms of plant protection characteristics.

To determine the status of infection of wheat fields in Golestan province with important diseases, a team consisting of plant protection experts of the province was formed and wheat fields in 14 counties of the province were surveyed in the crop year 2017-2018. At each survey, a monitoring form was completed containing field information, crop specifications, and the amount of pests and disease of the field. After the finalization of the data obtained from monitoring and the elimination of their problems, the statistical and geostatistical analyses of the data were done and the geographic information system (GIS)-based maps were prepared.

After five months of project implementation, 238 wheat monitoring forms were received by the center. The total area of monitored wheat fields was 773 (with an average of 4.3) hectares and 31015 kg of seeds (with an average of 190.3 kg per hectare) were planted in these fields. Of the 18 cultivars of wheat planted, 20% of the fields were allocated to Marwarid and Ehsan varieties. In terms of planting date, eight two-week groups were defined, where 39% of fields were planted in the first half of December. Eight types of autumn crops and 8 types of spring crops were grown in rotation with wheat in the fields, and wheat (77%) and fallow (39%) were ranked first. The average final severity of powdery mildew, Septoria leaf blotch and tan spot was 5.3, 3.5 and 15%, respectively. The average percentage of occurrence and severity of Fusarium head blight was 1.1 and 1.2 out of 3, respectively, and the average severity of stripe rust disease was 0.6 out of 2. The percentage of field infection with powdery mildew, Septoria leaf blotch, tan spot and stripe rust was 60, 38, 77 and 50, respectively.

The highest disease intensity for three diseases of powdery mildew, Septoria leaf blotch and tan spot was recorded in Ramian and Turkmen counties, and the highest intensity of stripe rust was observed in Kordkuy county. The maps drawn in this research were different from the maps drawn before by the researchers of the Agricultural Research Center and plant conservation experts for Golestan province, and the changes made after six years were evident in the case of some diseases. The findings of this research showed that disease monitoring should be done as a continuous program to determine the gradual changes in the distribution of diseases and high-risk areas in the the studied region, and the effect of climate change and other factors on these maps can be tracked and analyzed.

Wheat powdery mildew caused by the biotrophic fungus Blumeria graminis f. sp. tritici, is a serious threat to wheat production in many regions of the world. This disease can reduce the yield up to 45% and reduce the quality of the grains by affecting the flour protein. Due to the adoption of high-yield crop systems that require high use of nitrogen fertilizers and high irrigation, as well as due to climate changes towards milder winters and increased rainfall in wheat production areas, the importance of powdery mildew disease is also increasing. One of the most useful strategies to control powdery mildew disease is to identify the sources of resistance among germplasm, which is also known as the most economical method among farmers. This research was conducted to identify resistant genetic samples to powdery mildew in the bread wheat collection of the National Plant Gene Bank of Iran.

The plant materials of this research were 173 accessions of bread wheat from the collection of the National Plant Gene Bank of Iran received from different countries, which were investigated to identify the sources of resistance to powdery mildew under natural incidence conditions at the research stations of Gorgan and Sari as the disease hotspots during three crop years (2018-2021). A two-digit scoring system was used to evaluate the response of the genotypes to the disease, in which the first digit is measured based on the infection development in plant height and the second is measured based on the disease severity in terms of the infection percentage on flag leaf surface. Then, by combining these two criteria, disease development and disease severity, the infection coefficient was calculated and used for the statistical analysis. K-means cluster analysis was used to group the germplasm and determination function analysis based on principal components was used to confirm the cluster analysis results. The relationship between the reaction of accessions in different years and locations was also investigated using multidimensional scaling analysis, and then the stability of the studied accessions over the experimental years and locations was investigated using the Wricke’s equivalence stability criterion based on the infection coefficient.

The results of this experiment showed that the average coefficient of infection during the studied three crop years varied from 0.05 to 0.29 percentage in Sari station and from 0.25 to 0.29 percentage in Gorgan station. The studied genetic materials were separated into five groups using K-means cluster analysis, and the fourth group consisting of 68 accessions was identified as the most resistant group. Based on the results of this experiment, the accessions KC 5292 (Turkey) and KC 5824 (Austria) were identified as the resistant genotype, and the accessions KC 5389, KC 5579 and KC 5476 (Iran), KC 5772, KC 5773 and KC 5384 (Afghanistan), KC 5133 and KC 5147 (Portugal), KC 5715 (Japan) and KC 5801 (unknown origin) as the resistant to semi-resistant genotype, and had the most stable response to the disease in various environments.

The results of the current research showed that there is a suitable genetic capacity to identify sources of powdery mildew resistance in wheat genetic stocks. The superior and resistant genetic materials identified in this research can be used to improve resistance to powdery mildew in wheat in the future breeding programs.

Powdery mildew (Blumeria graminis f. Sp. Hordei) is one of the most destructive foliar diseases in barley that cause yield reduction worldwide. DNA molecular markers can be used to study the genetic diversity and better understanding of genetic predisposition to disease resistance to powdery mildew in barley at early growth stage. Selection of resistance and tolerance need to identify molecular markers associated with disease. In present study, genetic and phenotypic variations and also molecular markers linked to tolerance to powdery mildew in 34 of cultivated and wild barley genotypes were investigated. Using 16 ISSR ma rkers in total amplified 125 alleles that 124 (99.27%) of that were identified as polymorphic alleles. Number of amplified alleles ranged from 5 to 10 with an average 7.93 was different for each primer. Polymorphic Information Content (PIC) were varied from 0.17 (15) to 0.44 (LBMB-B) and also Molecular Index (MI) varied from 0.84 (primer No. 809) to 3.85 (UBC836). Resistance and susceptible genotypes show the highest genetic distance, however, resistance and tolerant genotypes show the lowest genetic distance. Multiple regression analysis (stepwise) between trait resistances amplified 125 alleles identified six fragments 1000 bp (primer No. 826), 700 bp (LBMB), 1500 bp (ISSR10), 300 bp (primer No. 826), 1000 bp (UBC840) and 1000 bp (primer No. 12), respectively. Results indicated that ISSR markers are suitable for screening of barley germplasm tolerant to powdery mildew disease.

A total of 1198 Iranian accessions of Bread Wheat Collection of National Plant Gene Bank of Iran were evaluated and screened for resistance to powdery mildew disease. The genetic materials were evaluated separately in three different sets, each comprising about 400 accessions, in three disease hot spots of Sari, Moghan and Gorgan under natural infection of the disease. The resistant accessions were purified leading to 168 lines which were then evaluated again in three hot spots for resistance under the field condition. Different number of resistant genotypes were determined in each location, however, two genotypes B1G11 (From Khorasan) and B2G6 (From Ilam) were resistant in all three location. The pathogen isolates were collected from different regions and purified by single clones and were inoculated on the differential cultivars. Three pathotypes were determined, all had virulence factors for Pm3b, Pm4a, Pm5, Pm6 and Pm7. The pathotypes lacked virulence factor for Pm2, Pm4b and Pm17. The resistance of 165 genotypes was also evaluated with these three pathotypes at seedling stage in greenhouse. Eighty-nine genotypes were resistant to three pathotypes. Forty-two genotypes had different reaction patterns compared to differential varieties suggesting different resistance gene(s) other than those in differential varieties. The results of this research indicated the potential of Iranian bread wheat germplasm as a source for determination of resistant genotypes to powdery mildew disease.

The present experiment was carried out to identify the effect of organic fungicides bicarbonate potassium (Kaliban® SP 85%) and Mildew Cure® 83% in controlling of cucurbit powdery mildew. The results revealed that Kaliban 0.50.7 and 1% decreased disease by the 34.8, 57.2 and 59.6% respectively in field and 55.4, 59.5 and 64% in glasshouse, but no competitiveness ability was observed when compared to reference (Karathane® WP 18.25%) at 25%. Integrated application of Kaliban with Kresoxim Methyl (Stroby® WG 50%) and Tetraconazole (Domark® EC 10%) in spraying programs at glasshouse conditions revealed that two times spraying of Kaliban in incorporation with Domark and Stroby as third and fourth or second and fourth sprayings, decreased disease by the rate 87.86 and 86.43% respectively compared to control. Also 3 times spraying by Kaliban after Stroby or Domark, decreased disease 75.71 and 74.29% respectively, compared to control. Mildew cure 0.75,1 and 1.5% as an organic fungicide, decreased disease 49.3, 69.2 and 74.3% in field and 69.12, 78.57 and 81.8% in glasshouse compared to control respectively. Based on the results application of Mildew Cure 1% is the best economic choice for the powdery mildew management.

Sugar Beet cultivation is of great importance in Isfahan province. Powdery mildew is a major limiting factor to sugar beet. To evaluate powdery mildew status in sugar beet fields, samples were collected from main sugar beet growing areas including, Isfahan, Semirom, Farydan and Komsheche during 2009-10. In order to determine the disease severity, in each region, samples were taken at six growth stages from 10 fields. Disease severity was measured based on 0 -100 scale. Results showed significant difference among fields in each location in relation to disease severity. The highest rate of disease was found in Isfahan and Semirom with 50.30 and 46.31%, respectively, whereas in Komsheche and Freydan it was 18.94 and 14.44%, respectively. In all studied regions, the disease progress began from first week of August and reached to its maximum level in the first week of September up to first week of October in Isfahan. In Fraydan, Semirom, and Komsheche, the maximum level was recorded in September, early September, and last week of September, respectively. The disease severity continued up to last week of October in almost all regions. The sexual stage was observed as black points (cleistothecium) at the last stages of the growth. Miscroscopic studies confirmed the production of ascospores in the region.

Current study was designed to fine map the Ol-qtl1 area by evaluation of F2, BC2 and BC2S1 progenies, obtained by hybridizing the susceptible L. esculentum cv Money Maker with the resistant L. parviflorum G1.1601, for segregation of resistance to Oidium lycopersici. Two flanking markers, ct21 and ct184 were used to screen recombinant plants. To monitor the targeted area effectively, 24 out of 54 new designed primers have been identified as SCAR and CAPS markers. The results confirmed the presence of resistant controlling area flanked by ct21 and ct184. Resistant homozygote individuals were resistant, with average 0.5 disease index (DI) value, heterozygote plants had intermediate responses and susceptible homozygote individuals showed susceptible performance. Results of recombinant screening showed that the targeted area is located in the upstream of tg25. Based on the results of this research, targeted area was narrowed down to a region of approximately 15 cM. Newly developed SCAR and CAPS markers can be used in marker assisted selection based breeding programs.

Development of Blumeria graminis f.sp. tritici (Bgt) on leaf surface of six advanced wheat lines and some resistance components were studied using a pathotype of Bgt having numerous virulence factors. Wheat lines were two resistant, M-81-13 and N-78-8, two moderately resistant, C-80-4 and N-80-6 and two susceptible, N-79-7 and N-80-19. Seeds of lines were sown in greenhouse and seedlings were inoculated with conidia. Plants were incubated and maintained in constant conditions (95-100% R.H. and 12 /12 hour light / dark period at 18-20ºC) in the greenhouse. Latent period and colony size were measured regularly after inoculation, and different developmental stages of the fungus were studied under light microscope, The results showed that percentages of conidia germination, primary and secondary germ-tube, conidiophore and conidia formation, colony size and fungal development were lower in resistant line than those in moderately resistant and susceptible lines. Slow development of the pathogen on resistant lines due to these mechanisms of resistance, caused longer latent period in those lines.

Resistance of 60 advanced lines of wheat to three pathotypes of powdery mildew fungus collected from Gorgan, Moghan and Varamin was evaluated in greenhouse conditions. Infected samples of wheat were collected from different provinces in 2005 and transferred to the greenhouse. After purification and multiplication of spores on susceptible cultivar Bolani, pathotypes of the pathogen were determined by inoculating pure spores of each isolate separately on the first leaves of 17 near isogenic lines(differentials) in the greenhouse. Pure spores of each pathotype were then inoculated separately on the first leaves of advanced lines. Infection types were assessed based on 0 to 9 scale, 12 and 16 days after inoculation. All lines were susceptible at seedling stage. In field experiment, in Gorgan Agricultural Research Station, line N-83-13 was highly resistant,33 lines were resistant and the remainings were moderately susceptible. Susceptible reactions of those lines at seedling stage and resistance reactions at adult plant stage indicated that they may carry adult plant resistance.

Identification of grapevine cultivars resistant to the powdery mildew disease has a main role in integrated management of the disease. In this study, the response of 45 native grapevine cultivars to powdery mildew, caused by Uncinula necator, was evaluated during 2003-2004, in West Azarbaijan proviance. After artificially inoculation of leaves of grapevine cultivars with conidia of the pathogen, abd completely development of the disease, severity index of disease was assessed on leaves and clusters of each cultivar. Results indicated that almost all of the cultivars were susceptible or highly susceptible to the disease. Among 45 cultivars, based on severity index of leaf, three cultivars Gharashani, Gharashirah and Aghshani, and based on severity index of cluster, cultivars Gharashani, Aghshani and Gharashirah were recognized as resistant cultivars. A negative significant correlation was found between the severity index of the infected clusters and fruits color in various cultivars. There was also a strong positive correlation between leaf and cluster infection and epicuticular wax of fruit. The chemical removal of fruit epicuticular wax, decresed resistance of grapevine cluster.

Wheat powdery mildew is an important disease of wheat especially in humid areas. The disease which is caused by Blumeria graminis f.sp. tritici , has recently become serious in different provinces of Iran.The present study was carried out to investigate virulence factors and pathotypes of the pathogen in different provinces of Iran. Infected samples of wheat were collected from different provinces in 2005 and transferred to the greenhouse at Seed and Plant Improvement Institute in Karaj. After purification and multiplication of spores on susceptible cultivar Bolani, 18 isolates were evaluated for their virulence genes. Pure spores of each isolate was inoculated separately on the first leaves of 17 near isogenic lines (differentials) in the greenhouse. Infection types were assessed based on 0 to 9 scale, 12 and 16 days after inoculation. From the total of 18 isolates of Blumeria graminis f.sp. tritici , 14 pathotypes were identified. This indicated the high genetic variability in the population of the pathogen and presence of different pathotypes. Pathotypes No. 6 and 12 from Varamin with 87.8 % pathogenicity , were the most virulent pathotypes. Only one of the pathotypes were isolated from more than one region. High frequencies of virulence for genes Pm3b , Pm5 and Pm3d were found. Frequencies of virulence for Pm1,2,9 and Pm 2,4b,8 were low. Comparing the results of virulence surveys in different provinces during 2000 to 2006 showed an increase in frequencies of virulence for some resistance genes while virulence for some of genes had been decreased. It shows frequently variable pathotypes in every region.

To study the inheritance of resistance to powdery mildew in barley, four winter and facultative barley cultivars (Hebe, Afzal, Legia and Igri) along with six F1s, derived from monolateral diallel crossing, with Karaj isolate of the pathogen were examined in a complete randomized block design with three replications. The components of resistance including latent period and infection type were scored. Variance analysis revealed significant differences among genotypes for these two components. Among the parents, Igri possessed the greatest general combining ability for increasing the resistance. Among the hybrids, Afzal*Hebe and Afzal*Igri hybrids respectively possessed the most specific combining ability for increasing the resistance. The findings of the study showed that the frequency of dominant resistance genes was greater than non-dominant genes. General and specific inheritability were 98.3 percent and 36.5 percent respectively. The low figure for specific inheritability indicated that the type of selection would not be effective in decreasing the latent period and infection type characteristics. The extent of dominance for the two features of latent period and infection type were greater than 1, which confirms that genetic dominance and super-dominance were effective in controlling these two features.

Forty four dryland barley advanced lines were tested at adult plant and seedling stages to determine their responses to barley powdery mildew in two locations, Karaj and Gorgan, in a RCDB design with three replications for two years 2001-2003. Field responses of the lines were assessed by Saari and Prescott method. For greenhouse experiment, isolates of barley powdery mildew collected from Karaj and Gorgan were transferred to the greenhouse. After multiplication of each isolate, the lines were inoculated with them separately. Seedling infection types were recorded based on Mains, and Dietz. The results showed that at adult plant stage in Gorgan, four lines were resistant and in Karaj, six lines were immune and four lines were resistant. The most susceptible line was T-2 (2R)//Lignee131/Arabi Abiad. Lines ICB-111028, ICB-111838, Obruk-86, Wieselburger/Ahor, Alpha//Sul/Nacta/3/80-5001 ICB, ICB1, ICB-100974/Acton and 4679/105//Yea132TH/3/Tipper showed resistance response in both locations. At seedling stage in the greenhouse, with Karaj isolate, only two lines were resistant and the remainings were susceptible. With Gorgan isolate, 15 lines were resistant, and 29 lines were susceptible. At seedling stage, only line Wieselburger/Ahor was resistant to isolates of both locations.

Several samples of wheat leaves infected with powdery mildew were collected from Mazandarn, Golestan and Fars provinces in 2003 and 2004. After purification, 23 isolates of the pathogen were selected for pathotype determination. Seeds of 17 near-isogenic lines carrying the known Pm genes, were grown in pots in a greenhouse with 18-22 C, 95-100 RH and 12 hours light and darkness period. Each set of the isogenic lines were inoculated separately with pure condia of each isolate. Infection types of each line were recorded 12 and 16 days after inoculation. Twenty one different pathotypes were identified, having different virulence formula. Based on the results, 95% of the isolates were virulent on Pm3c and Pm5. Virulence for lines carrying Pm4b, Pm2,6, Pm1,2,9 and Pm2,4b,8 genes was rare among the isolates. This is the first report on the presence of virulence for Pm1,2,9 gene combination in Iran. Frequency of virulence for genes Pm4a, Pm8, Pm2,6, Pm1,2,9, Pm7 and Pm2,4b,8 was higher in 2004 than in 2003, but frequency of virulence for genes Pm1, Pm2, Pm3b, Pm3a, Pm6, Pm5, Pm3d and Pm9 was higher in 2003. No change in frequency of virulence for Pm3c was detected during two years. Pathotypes of Gharakhil in Mazandaran province, contained the highest number of virulence factors among the isolates.

Pathogenicity of 4 isolates of Erysiphe betae from 4 different geographical zones of Iran on 5 genotypes of beet, with different levels of resistance to powdery mildew, was investigated. Eight-week old plants were inoculated by conidia from 4 isolates separately. Indices for infection were estimation of leaf infection and number of produced conidia on the leaf surface 3 weeks after inoculation. Results indicated that there was no significant difference on the virulence level of 4 isolates but the genotypes showed significant difference in susceptibility to fungal isolates. The genotype 7233 indicated the highest susceptibility and two genotypes 10417 and 14442 showed highly resistance to powdery mildew. The genotype “Leaf Beet” which in the field experiments in Germany had proved resistance to the disease, in our greenhouse studies showed susceptible response. Conclusive results indicated that different isolates of E. betae belonging to different geographical zones were similar in pathogenicity and also greenhouse experiments can be an appropriate manner for screening sugar beet genotypes against E. betae.

In this study, recently produced fungicide Opus was compared with current fungicides Dinocap, Sulfur and Calyxin for controlling powdery mildew disease of sugar beet in completely randomized block field experiments conducted in Kermanshah and West Azarbaijan provinces. Fungicides were applied according to the recommended field dosages. There were five treatments (four fungicides plus a water-spray control) each with four replicates. Disease incidence was evaluated 15 days after the last application based on infection index on sugar beet leaves collected from different treatments. Infection index varied from 1 (no infection) to 6 (81-100% infection). Analysis of the results indicated that in Miandoab experiment for both years there were significant differences among different treatments in disease incidence and the fungicide Opus was the most effective in reducing infection. In the first year of Mahidasht experiment there were no significant differences among different treatments due to very low occurrence of the disease in the field. In contrast, in the second year significant differences were observed in different treatments. Despite higher root yield and sugar content in fungicide treatments, compared to the control, these differences were not significant.

Powdery mildew caused by Blumeria gamines f. sp. tritici (Erysiphe gamines f. sp. trifici) has become one of the most widespread and important diseases of wheat in several provinces of Iran including Mazandaran. The impact of environmental (temperature, relative humidity, rainfall and number of sunny days) on the incidence and severity of the disease and the alternative hosts of the causal agent were studied during 1996-1999 in Mazandaran province. Wheat cultivars Atrak, Milan, Tajan, Falat, Hirmand and Rasoul were grown in six locations in central Mazandaran. Stepwise regression analysis with cultivars as treatments and locations as replications was employed. The results revealed existence of a linear correlation between disease severity and mean air temperature in all cultivars. There was a linear increase in disease severity with rise in temperature until mid-May, when powdery mildew reached its peak in severity. The fungus appeared to oversummer and overwinter as cleistothecium. The cleistothecia were fully matured, with fully developed asci and ascospores in July- August and emptied in late September. Cleistothecia appear to play a role, in addition to conidia and hyphae, in persistence and dispersal of the fungus. Powdery mildew infection of Aegilops triuncialis, Phalaris minor and Lolium temolentum were observed and pathogenicity of B. graminis f. sp. trifici on these weed species was confirmed by artificial inoculation. This is the first report on infection of Aegilops triuncialis and Lolium temolentum by the wheat powdery mildew in Mazandaran.

In order to evaluate heritability and gene action for resistance to barley powdery mildew, two resistant cultivars were crossed with a susceptible one. P1, P2, F1, F2 and F3 generations were planted in a Randomized Complete Block Design. At seedling and booting stages, susceptible cultivar was inoculated with a isolate of the pathogen. Infection type and disease severity were recorded and generation mean analysis was performed. The results showed that additive, dominance and epistasis effects were important for the two examined traits. Analysis of generation indicated that dominant variance was more important than additive variance in both traits. The approximate number of genes were estimated to be between one and two.