نشریه نهال و بذر
سال سی و یکم شماره 4 (زمستان 1394)

The present study was carried out to evaluate phonological and pomological characteristics of five pistachio cultivars (Ouhadi, Badani, Momtaz, Ahmmad Aghaie and Kallehghoochi) in a randomized complete block design with five replications at research station of Mahneshan during 2012-2013. The results showed that the overlapping period of polinizer cultivar with Ouhadi, Badami, Momtaz, Ahmad Aghaie and Kallehghoochi cultivars was 7, 8, 7, 3 and 9 days, respectively. There were significant differences among the cultivars for fruit set, Kallehghoochi cultivar had the highest and Momtaz cultivar had the lowest percentage of fruit set. Cultivars also differed for nut characteristics such as fresh and dry weight of nut, and nut length and width. Kallehghoochi had the highest and Ouhadi and Momtaz cultivars had the lowest values of these characteristics. Momtaz cultivar had the highest and Ahmad Aghaie cultivar had the lowest percentage of blankness of nut. Kallehghoochi cultivar had the highest and Ahmad Aghaie had the lowest percentage of non- split nut. The highes ounce weight of nut was recorded for Badami, Momtaz and Ouhadi cultivars, while Kallehghoochi cultivar had the lowest ounce.

Main losses of bacterial blight caused by Xanthomonas arboricola pv. juglandis on walnuts is throught unripe fruit fall and mature fruit effects. In this research, the relative susceptibility of 72 walnut cultivars and local genotypes to bacterial blight was studied in laboratory condition in years 2012 and 2013. Additionally, the efficacy of the evaluation method and correlation of resistance with unripe fruit size and total phenol concentration were investigated. Based on combined analysis of data, 10.7% of germplasm was susceptible, 32.1% moderately susceptible and 57.1% moderately resistant. Analysis of two years data means indicated that the evaluation method was repeatable. The highest phenol concentration was detected in the Pedro resistant cultivar and the lowest in the susceptible genotype 2-1, but the relation between resistance and phenl level was not significant. No correlation was found between fruit size and resistance. Based on the results, a great variation was detected in resistance of unripr fruits of different genotypes and this variation can be evaluated by inoculation in laboratory condition, but phenolic levels is not reliable in assessing blight resistance.

To assess the genetic control of morphological traits related to grain yield in rice, six cultivars, Hassani, Shahpasand, Kadous, Vandana, Hashemi and IR36, together with F2 generations derived from complete diallel crosses, were evaluated in a randomized complete block design with three replications in research field of College of Agricultural Siences, the University of Guilan, during 2012, and morphological traits related to yield and yield components were measured. Analysis of variance of the data showed that there were significant differences among genotypes at 1% probability level for all measured traits. The genetic analysis by Hayman method showed that except panicle number per plant, flag leaf length and 1000 grain weight, other traits were influenced by partial dominance effects and relatively high narrow-sense heritability indicating that the proportion of addative gene effects were more than non-additive effects. In contrast, panicle number per plant, flag leaf length and 1000 grain weight were controlled by over-dominance gene effects and their low narrow-sense heritability indicated the role of non-addative gene effects. Results of current research showed that there is considerable variation transferable from parents to offspring for most traits related to grain yield in the studied population, so selecting superior genotypes can be improved grain yield and it’s related traits in this population.

Fireblight disease caused by Erwinia amylovora is a serious disease of apples worldwide. In this research, resistance of 30 apple superior local genotypes and introduced cultivars was evaluated to fire blight using shoot-tip-inoculation method in glasshouse condition. Repeatability of the inocultion method was also investigated by repeating the experiments for two years (2012 and 2013). The inoculum comprised of four E. amylovora strains including EO1, E4, En and Ek originated from Kordestan, Alborz, Khorasan Razavi and West Azarbijan provinces. Based on the results, different cultivars and genotypes exhibited different resistance level to fire blight disease. In both years, Boshghabi was the most susceptible and Ferdovs and Delicious Mari the most resistant genotypes. Analysis of mean fire blight severity revealed that the first-year data was directly correlated with the second-year (R = 0.54), indicating relative accurence of shoot-tip-inoculation method for fire blight resistance assessment. Collectively, 6.7% of Iranian genotypes were rated as highly susceptible, 46.7% susceptible, 26.7% moderately susceptible, 13% moderately resistant and 6.7% resistant, indicating hight fireblight susceptibility in Iranian apple germplasm.

To determine the genetic diversity and relationships between morphological traits, 350 samples of Chitti bean from collection of Khomein Bean Research Station were evaluated in an augment design with twelve blocks in 2011. Nineteen different traits were evaluated. The results showed that seed yield, number of seeds per plant, number of nodes on the main stem, number of pods per plant and plant height had the highest diversity. Days to flowering, leaf length, plant type, number of pods per plant, number of seeds per plant and seeds per pod had the highest correlation coefficient with seed yield. Results of principle component analysis revealed that four main components namely ideotype characteristics, yield components, phenological period and yield, explained 75.02% of the total variations. According to Ward's method of cluster analysis, genotypes were placed in six groups. Based on biplot of the second and fourth components, 64 samples were selected to be used in further breeding programs.

Septoria tritici blotch (STB) caused by Mycosphaerella graminicola is one the most important diseases of wheat worldwide. Chamran is a widely cultivated STB-resistant wheat cultivar in Iran but its genetics of resistance to the disease is unknown. To investigate the genetics of resistance of Chamran to STB, the susceptible genotype Darab-2 was crossed with Chamran and F1, F2, F3 and BC1F2 families were prepared. The reaction of progenies derived from direct and reciprocal crosses to an avirulent isolate of the pathogen indicated that the resistance was delivered through nuclear inheritance rather than cytoplasmic inheritance. The heterozygous F1 population displayed a semi-resistant phenotype that was an intermediate between the phenotypes of both homozygous parents. The phenotypic evaluation of F2, F3 and BC1F2 populations indicated that a single incompletely dominant gene in Chamran controls resistance to the studied isolate. The previous results of virulence assays along with molecular experiments performed in this study showed that this resistance gene is an unknown gene.

To estimate the narrow-sense heritability and combining ability of seed yield and yield components, half diallel crosses of eight oil seed rape lines L41, Zafar, L56, L31, L22, LF2, L420 and L401 along with their parents were evaluated based on randomized complete block design with three replications. The results of diallel analysis revealed significant mean squares for general and specific combining abilities (GCA and SCA) in all traits except 1000-seed weight, indicating the importance of additive and non additive genetic effects for these traits. Estimation of high narrow-sense heritability for pods length (0.50), 1000-seed weight (0.69), seed yield (0.63) and harvest index (0.53) indicated the prime importance of additive genetic effects for these traits. Parents L41, Zafar and L22 with significant positive GCA effects for seed yield were determined as superior parents. The crosses with significant positive SCA effects for seed yield had at least one parent with significant positive GCA effects for this trait. The crosses L41× L22, L41×LF2, Zafar×L22 and Zafar×L420 with seed yield of 3421.7, 3400, 3348.1 and 3311.3 kgha-1, respectively were superior combinations.

In the present study, virulence factors of two isolates of stripe rust, collected from Karaj and Kermanshah, Iran were determined on differential lines, and for genes Yr2, 2+, 6, 6+, 7, 7+, 8, 9, 17, 18, 25, 26, 27, 32, A, DN virulence was observed in both isolates. Reaction of 150 doubled haploid lines together with parents and check cultivars to stripe rust (Puccinia striiformis f.sp. tritici) was evaluated at seedling and adult plant stages by assessment of coefficient of infection and infection type in an agmented design. The results of analysis of variance showed significant differences among check cultivars for infection type and coefficient of infection of two races of Karaj (7E158A+, Yr27) and Kermanshah (110E158A+, Yr27). Using Ward’s method of cluster analysis based on infection type and coefficient of infection of both races, doubled haploid lines and 7E158A+,Yr27 were classified in two groups of susceptible and resistant. Overall, 28 doubled haploid lines at both stages of seedling and adult plant showed resistance reaction to race of Karaj which indicates the probability of carrying one or more minor genes of adult plant resistance in addition to seedling major genes.