نشریه نهال و بذر
سال بیست و هفتم شماره 1 (بهار 1390)

To study the resistance of potato cultivars grown in Markazi Province of Iran to Alternairia solani, five isolates of the pathogen were provided from infected fields of the region. Resistance if nine commercial potato cultivars to these isolates was evaluated in four replications in a factorial model with completely randomized design in greenhouse. Potato cultivars exhibited different responses of resistance and susceptibility. Two resistant and susceptible cultivars and two isolates of the pathogen with high and low virulence were selected for studing the total phenol contents in these two cultivars 2, 4, 6 and 8 days after inoculation with two isolates. Significant differences, related to the resistance of the host, in total phenol contents were detected at different days after inoculation. A significant difference was also observed in total phenol contents of a cultivar in response to different isolates, indicating differences in the pathogenicity of isolates.

To evaluate drought tolerance in durum wheat, 49 lines along with one check cultivar Aria, were studied in an RCBD with two replications under drought stressed (rainfed) and non-stressed conditions at the Gonbad Agricultural Research Station, Golestan, Iran. Six drought tolerance indices, i.e. Stress Susceptibility Index (SSI), Tolerance Index (TOL), Mean Productivity (MP), Stress Tolerance Index (STI), Geometric Mean Productivity (GMP) and Harmonic Mean (HM) were calculated based on grain yield under stressed (Ys) and non-stressed (Yp) conditions. The analysis of variance of the data showed significant difference between genotypes. Lines SULA/AAZ-5//CHEN/ALTRA… and LIRO-3/LOTAIL-6 had the highest grain yield under stressed (447 gm-2) and non-stressed (529 gm-2) conditions, respectively. The highest MP, GMP, STI and HM were observed in line SULA/AAZ-5//CHEN/ALTRA…, but lines CNDO/PERIMADUR//HAI-OU17/3/SNITAN and R143/RUFF//STIL/3/YAV79/4/SHAWA/MALD/… had the greatest TOL and SSI, respectively. The correlation coefficients between tolerance indices and mean yield under stressed and non-stressed conditions revealed that the most effective indices for screening under these conditions were MP, STI, GMP and HM.

Relative resistance of 58 local apple genotypes to Erwinia amylovora (Burrill.) Winslow et al., the causal agent of fire blight was studied. Bacterial strains were collected from pome fruit orchards of Orumieh, Karaj, Mashhad, Shahrud, Qazvin and Sanandaj cities and identified using phenotypical and molecular tests. A mixture of seven strains were used as inoculum. Evaluation was performed using shoot tip inoculation method nuder glasshouse condition on one-year old seedlings grafted onto M26 rootstocks and blight severity was scored six weeks after inoculation. Based on the results, 5% of genotypes were rated as resistant, 17% moderately resistant, 18% moderately susceptible, 28% susceptible and 32% highly susceptible. Based on these results, it is concluded that local apple germplasm is relatively susceptible to fire blight.

In this research, characteristics of thirteen native cultivars of National Pear Collection of Iran were evaluated based on Descriptor of Distinctness, Uniformity and Stability (DUS). Among 5, 9 and 13 vegetative traits respectively belong to the tree, one-year-old shoots and leaves, 4, 5 and 9 traits showed variation. Among 11 and 29 reproductive traits belong to the bloom and fruits, 9 and 21 traits, respectively showed medium to high variations. From the common tree traits, tree vigor was the most indicative, and five cultivars were with high, seven cultivars with medium and cultivar Sefasleh with low vigor index. Despite logic relation of one-year-old shoots with other tree traits, they were not distinctive traits due to low diversity. Nine leaf traits also showed significant diversity, but among them length/width ratio, form of basal and apical part, and incision of margins were stable and distinctive traits. In addition, marginal position and size of petals demonstrated high diversity levels, and were appropriate for cultivar distinctness. Fruit traits also showed significant diversity and fruit size, position of maximum diameter, profile of sides, color of pulp, sepal positions and fruit texture characteristics, as well as fruit ripening period were the most distinctive traits. Cluster analysis using all traits together, resulted more efficient categorization of cultivars based on apparent similarity or origin. In this categorization, some Khorasan and Isfahan cultivars were set in separate clusters. Additionally, key traits of descriptor successfully distinguished the native pear cultivars.

Self-incompatibility is one of the main problems in almond production. In this research work, at the first step, some local cultivars as well as some imported ones were evaluated from the point of their male and female organ compatibility. Then, ten selected commercial self-incompatible cultivars(female parents) were crossed with two self-compatible cultivars(male parents) i. e. Tuono and Supernova. To discriminate self-compatible progenies from others, all seedlings were evaluated through bagging method and molecular marker. With using SfF-SfR primers, self-compatible genotypes produced band of 450bp. However, self-incompatible genotypes did not produce any band. According to the results, out of 195 seedlings, 110 were self-compatible and the other 85 were identified as self-incompatible. This ratio was according to the mendelian law and there was no significant difference between the number of cultivars or genotypes in two groups. In another work, S-alleles of some doubtful cultivars and genotypes as well as their situation from the point of Sf were determined by simple and multiplex PCR.

To evaluate some morphological and biochemical traits of pomegranate fruit, eleven commercial cultivars were assessed using 26 quantitative and qualitative traits. Analysis of variance showed that all evaluated traits, except peel and aril percent, were significantly different among cultivars showing variation in each trait. The highest antioxidant capacity was assessed in ‘Malase Shirin’, ‘Yousef Khani’, and ‘Shishekap’ cultivars. Analysis of simple correlation among traits showed positive and negative correlations among some of traits. Total phenol had a positive and significant correlation with antioxidant capacity, but there was no correlation between amount of anthocyanin and antioxidant capacity. Cluster analysis divided all cultivars in to five main groups. The groups were different in aril and fruit weight, TSS and TA traits. Total phenol was also effective in grouping. By factor analysis, effective traits were located in six main groups and accounted for 93.9 % of total variance. Fruit, aril, peel weight and volume of fruit juice in 100 arils were traits that constituted the first factor (PC1) and pH, EC, TA, antioxidant capacity and total phenol the second factor (PC2). Tri-plot analysis showed that ‘Shirine Shahvar’, ‘Naderi’ and ‘Binikaje Sabzevar’ cultivars were important for the first factor and ‘Shishekap’, ‘Malase Yazd’ and ‘Malase Torsh’ cultivars for the second factor. Generally, considering the main effective traits, ‘Malase Esfahan’, ‘Malase Shirin’, ‘Naderi’ and ‘Shirine Shahvar’ were located in one group, ‘Shishekap’, ‘Malase Torsh’, ‘Yosef Khani’, ‘Ashkezar’ and ‘Bini kaj’ in another group and ‘Pust Siahe Saveh’ in a separate group.

Infected barley leaves were collected from different areas of Iran during 2007-2008 and transferred to the greenhouse at Seed and Plant Improvement Institute in Karaj. After purification and multiplication of spores on susceptible barley cultivar Afzal, 13 selected isolates were evaluated for their virulence genes. Pure spores of each isolate was inoculated separately on the first leaves of 20 near isogenic lines (differentials) in the greenhouse. Based on infection types on leaves, virulence or avirulence factors for different resistance genes(Rph) were determined and eleven pathotypes were identified. Isolate Ard-86-1 with 17 virulence factors was the most virulent and isolate Ard-87-3 with 8 virulence factors was the least virulent pathotypes. The genes Rph 15.ad and Rph 7.g were effective against all 13 isolates, whereas for genes Rph 1.a, Rph 2.b, Rph 3.c, Rph4.d, Rph 6.f + Rph 5, Rph 8.h, Rph 9.i, Rph 10.o, Rph 11.p, Rph 12, Rph 9.z +Rph12, Rph 13.x, Rph 14.ad, Rph 2.j, Rph 2.y and Rph 2.t virulence was detected, and gene Rph 5.e had the lowest virulence frequency. Based on these results, resistance genes being effective against all or the majority of isolates, can be used as the sources of resistance to leaf rust in barley breeding programs in Iran.

To study the genetic variation in some durum wheat lines, 102 pure lines from wheat Collection of Cereal Research Department, Seed and Plant Improvement Institute were evaluated using augmented design in six blocks with four durum whear check cultivars (Yavaros, Arya, Dena and Shotordandan) in the experimental field of Faculty of Agriculture, Islamic Azad University, Karaj Branch, during 2008-2009 cropping season. Morphological and phisyological traits were recorded during the growth period. Analysis of variance of the data indicated significant differences among the genotypes for most traits. Correlation between grain yield and biological yield, day to physiological maturity, grain/spike and spike length was positive and significant. Linear regression indicated that biological yield, harvest index and day to heading explained 84% of yield means variance among the lines. Path analysis results showed a direct positive and high effect of biological yield and harvest index on grain yield, but day to heading had an indirect and negative effect on grain yield. The accessions were divided into four groups by cluster analysis based on Ward method, using squared euclidian distance coefficient. Results demonstrated that traits such as day to heading and biological yield could be used as selection indices in breeding programs for grain yield improvement in durum wheat.

To evaluate the genetic diversity in Sardari bread wheat landrace, purification and selection of lines with good agronomic traits, were carried out for ten cropping seasons (1995-2006) in Maragheh and six other dryland Agricultural Research Stations. One hundred and six individual spikes were selected among Sardari landrace in the first phase of study (1995- 2000). Results of morph-physiological characteristics and molecular studies (SSR) confirmed a high diversity within Sardari landrace. In the second phase of study (2003- 2006) adaptability and grain yield stability of selected pure lines were studied in five locations. Based on the results, the pure line Sar-HR 39 exhabited a good performance and yield stability. Similar to check cultivars (normal Sardari and Azar 2), SAR-HR 39 is early maturity, is high 1000 kernel weight, suitable plant height and tolerance to winter cold (winter type). It is also tolerant to drought. The mean protein contents of this line has 10.5% but it is susceptible to yellow rust. The mean grain yield of the new line was 2185 kgha-1, that was higher than those of Azar 2 (2050 kgha-1) and normal Sardari (2070 kgha-1). The new line was officially released in 2010 through the Agricultural Research, Education and Extension Organization (AREEO), under the name of Homa.

To evaluate the genetic diversity in Sardari bread wheat landrace, purification and selection of lines with good agronomic traits, were carried out for ten cropping seasons (1995-2006) in Maragheh and six other dryland Agricultural Research Stations. One hundred and six individual spikes were selected among Sardari landrace in the first phase of study (1995- 2000). Results of morph-physiological characteristics and molecular studies (SSR) confirmed a high diversity within Sardari landrace. In the second phase of study (2003- 2006) adaptability and grain yield stability of selected pure lines were studied in five locations. Based on the results, the pure line Sar-HR 39 exhabited a good performance and yield stability. Similar to check cultivars (normal Sardari and Azar 2), SAR-HR 39 is early maturity, is high 1000 kernel weight, suitable plant height and tolerance to winter cold (winter type). It is also tolerant to drought. The mean protein contents of this line has 10.5% but it is susceptible to yellow rust. The mean grain yield of the new line was 2185 kgha-1, that was higher than those of Azar 2 (2050 kgha-1) and normal Sardari (2070 kgha-1). The new line was officially released in 2010 through the Agricultural Research, Education and Extension Organization (AREEO), under the name of Homa.