جستجوی مقالات مرتبط با کلیدواژه "resistance components" در نشریات گروه "زراعت"

Fusarium head blight disease caused by Fusarium graminearum is one of the most important and destructive diseases of wheat in warm and humid zone. The importance of this disease is to reduce the yield and accumulation of mycotoxin in the harvested grains from infected heads, which are dangerous to humans and animals. Production of resistant varieties with using genetic resistance sources is the most effective method of sustainable control of this disease. To study the inheritance of resistance-controlling genes in cv. Morvarid, the resistant cv. Morvarid, was done cross with susceptible cv. Falat, and generations of F1, F2, BC1 and BC2 were produced. Resistance components include the area under the disease progress curve (AUDPC), the relative area under the disease progress curve (rAUDPC) and the final severity infection (FSI), was recorded. Parents and generations were planted in a randomized complete block design with three replications. Parents and generations were inoculated at the adult plant stage by a mixture of Fusarium head blight isolats at the Gorgan Research Station. Analysis of variance showed significant differences among generations for measured traits. The average degree of dominance was approximately equal to unit (one) for all traits, indicating dominance genetic control. Epistasis interaction effects of additive × dominance, dominance × dominance were significant for the all traits. Broad-sense (0.45- 0.56) and narrow-sense (0.37-0.48) heritability was estimated as moderate, indicating the important role of additive effects and dominance in genetic control of these traits. The number of segregating genes for measured traits 1 to 7 genes was estimated. Since Morvarid Cv. is currently the most commercially resistant cultivar to Fusarium head blight, due to the additive effects of resistance genes in controlling these traits, selection can be applied to improve these traits in the early generations of this cultivar.

A total of 17 wheat landraces were evaluated for resistance to powdery mildew in filed and greenhouse environments. The field experiment was performed at three disease hotspots in Sari, Gorgan and Moghan under natural disease incidence and the reaction of the genotypes was evaluated at adult plant stage. In order to evaluate the resistance of the genotypes at seedling stage, the isolates of the disease were collected from different regions and the pathotypes were identified by inoculation on the differential varieties. The results of field evaluation indicated that average reaction level of genotypes to the disease in Sari and Gorgan was similar and both lower than that of Moghan. A total of ten pathotypes were distinguished, all of which had virulence factors for Pm3a, Pm3c, Pm3g, Pm4a, Pm5, Pm6, Pm8 and Pm2. The varieties Shamrock (with unknown R gene), Normandie (Pm1+ Pm2+ Pm9), Axona (Pm2+Pm3d+Mld), Maris Dove (Mld+Pm2) and Wembley (Pm12) were resistant to all the pathotypes. The presence of Pm7 was postulated in genotype 7 as the resistance spectrum of this genotype was similar to that of Transfed. Genotypes 4 and 11 appeared resistant and moderately resistant at adult plant stage while they were susceptible to all pathotypes at seedling stage and therefore they were identified as genotypes with adult plant resistance. The total results of this research led to identification of seedling and adult plant resistance sources with different resistance gene combinations which could be exploited in breeding programs.

Leaf Rust or rust fungus Pucciniatriticinacauses leaf, Is one of the most destructive fungal disease of wheat worldwide. In this study, in order to resistance evaluate to brown rust on 41cultivars of wheat was in field and greenhouse situation and based on randomized complete block design with three replication. Traits including infection type, disease severity, Area under Disease Progress Curve and latent period were recorded. Analysis of variance showed significant differences between genotypes for all traits. Correlation analysis showed a high and positive correlation between the traits in the field and showed high and negative correlation between the traits in greenhouse situation. Cluster analysis based on Euclidean distance and complete linkage algorithm was used to clustering of genotypes. In the cluster analysis cultivars were divided in to 2 groups in field and 3 groups in greenhouse.

Wheat yellow rust caused Puccinia striiformis Westend f. sp. tritici is one of the most economically important diseases of wheat in Iran and wordwide. In order to determine the heritability، gene action and estimate of genetics parameters for yellow rust resistance components، six bread wheat cultivars and advance lines including Pishtaz، MV17، Moghan 3، SERI/KAUZ، KAUZ//KAUZ/PVZ as well as a susceptible cv. Bolani were crossed using half diallel 7  7 design. Evaluation of F1s and parents were carried out using a randomized complete blocks design with three replications. Plants were inoculated with 134E134A+ race using talk powder. Four resistance components latent period، infection type، pustule density and size were measured. Analysis of variance for combining ability using Griffing method showed that general combining ability (GCA) and specific combining ability (SCA) for four were significant which implies the additive and non-additive effects in genetic control of these components. Among parents cv. MV17 with high GCA for all four traits was identified as suitable parent to be used in breeding programs for enhancement of resistance to yellow rust. Bolani had the highest GCA next to MV17 but for susceptibility. Crosses of MV17 with Bolani، Pishtaz، Kauz//Kauz/PVZ had higher SCA (-) for infection type، number of pustules and pustule size، and the highest SCA (+) for latent period in enhancement of resistance which implies non-additive (dominance and epitasis) gene effects in these crosses. Graphic analysis of Vr and Wr indicated that latent period، infection type، pustule size، and number of pustules were recessive in some genotypes but dominant in some others. Broad and narrow sense heritabilities for all four traits were relatively high، therefore، selection based on these traits for enhancement of resistance to this race is useful.

To study genetic architecture of resistance of rice to blast disease، five diverse rice cultivars viz. Neda، Dasht، Domsiah، SHZ-2 and Ahlami tarom were selected and all cross combinations were made among them (a half-diallel). All genotypes including ten F1 together with their five parents، were evaluated in RCBD with three replications for components of resistance to blast in Rice Research Institute of Iran in Rasht and Amol during 2005-2007. Analysis of variance showed that there were significant differences among all rice cultivars and their cross combinations for all traits. Combining ability analysis based on Method II and Model Mixed B (Griffing) revealed that mean of squares for GCA and SCA were significantly different، hence both additive and non-additive components of genetic variance were important in controlling of traits. For most of traits additive components were predominant. Cultivars Neda، Dasht and SHZ-2 were good combiner for increasing resistance to blast disease. Most of combinations showed high significant SCA for components of resistance. Genetic analysis through Hayman`s method also proved the results obtained via Griffing’s method.