نشریه نهال و بذر
سال سی و یکم شماره 2 (تابستان 1394)

To evaluate drought tolerance in chitti beans، twenty lines and Sadri cultivar (check) were examined in normal and drought stress conditions using randomized complete block design with three replications. The experiments were carried out at Khomein research station in 2010 and 2011. Seeds of each genotype were planted in three lines 3m long. Irrigation in normal and drought stress conditions was applied based on 50 and 100mm evaporation from class A pan، respectively. Drought stress was applied at V4 growth stage. Different characteristics such as days to flowering، days to maturity، pods/plant، seeds/pod، 100 seed weight and seed yield were recorded during the growth period. The results of analysis of variance for data of both years showed significant differences among genotypes in both normal and drought stress conditions. Drought stress decreased all the characteristics mostly seeds/plant. Evaluation of drought stress tolerance indices showed that the best indices for selection of drought stress tolerant genotypes were MP، GMP and STI. Based on principal component analysis of evaluated indices and biplot of STI and SSI، lines KS21181، KS21247، KS21255 and KS21216 were identified as the most tolerant genotypes to drought stress.

Application of elicitors for inducing plant defense genes is one of the methods used for controlling diseases. This research was carried out for evaluation of effects of the BTH elicitor on the PR2 gene expression and fire blight severity in quince. Two year- old quince plants of Isfahan and Torsh cultivars were treated with BTH at 400 mgl-1 twice at a four day interval. The treated trees were then infected with bacterium suspension and the disease severity was assessed after four weeks. Leaf samples were taken before inoculation and after extraction of RNA and synthesis of cDNA، a part of the PR2 gene was amplified with the degenerate primers and it was sequenced. Alignment of the sequence with other sequences in the data base showed high similarity with glucanases from other plants including apple. Specific primers were designed according to the sequence and expression of the PR2 gene was evaluated by real time PCR. The results showed that expression of the PR2 gene was increased several times after treatment of plants with BTH. Evaluation of the disease severity also showed % 21. 66 and %13. 76 decrease in plants treated with 400 and 300 mgl-1 BTH، respectively. These results show that decreasing the fire blight severity after treatment with the BTH elicitor could be related to induction of genes encoding PR proteins including PR2 and this material can be used in the integrated fire blight disease management program.

The current research was conducted to set a protocol for mass propagation of two semi-dwarfing pear rootstocks Pyrodwarf and OH × F87 in vitro condition. Three subsequent experiments were carried out for evaluation of the effects of growth media، iron source and rooting potential of plant materials. At the first experiment، effects of five growth media including MS، modified MS، DKW، QL and modified QL with different ratios of nitrate to ammonium، calcium and chloride were tested on proliferation and growth of shootlets. The results showed advantages of modified QL and QL، respectively for Pyrodwarf and OH×F87. Compared ratios of critical ions showed susceptibility of pears to high ratios of ammonium/nitrate and presence of chloride in the media، in which negative effects of these ions appeared as reduced proliferation of the rootstocks. Evaluation of iron source، conducted by using Fe-EDTA and Fe-EDDHA chelates and results demonstrated slight reduction of proliferation and higher quality of shootlets on Fe-EDDHA medium. In order to test the rooting potential of pear rootstocks، the micro-cuttings were more suitable exposed to 0 (control)، 0. 5 and 1 mgl-1 IBA in two MS and QL media. Rooting was observed in all micro-cuttings، but MS media enriched by 1 mgl-1 IBA caused higher number of roots per explants and length of rootlets in both rootstocks.

In the present study seedling response of 21 wheat differential cultrivars carrying different Stb resistance genes and four check cultivars to thirteen isolates of M. graminicola، collected from Golestan، Khuzestan and Ilam provinces during 2011، 2012 and 2013، were investigated in greenhouse، using a completely randomized design. Analysis of variance on leaf necrosis area and pynidial coverage percentage showed significant differences at 1% probability level among the isolates and also isolate × cultivar، indicating high variation in pathogenicity of isolates and specific interaction between isolates and cultivars. Cluster analysis of the data showed that Riband (Stb15) and Shafir (Stb6) cultivars were the highly resistant and highly susceptible cultivars to all isolates، respectively. Isolates showed different virulence patterns on differential cultivars. Isolate SPII91005 from Gorgan with 42% necrosis area and 41% pycnidial coverage had the highest and isolate SPII91004 from Sardasht with 19% necrosis and pycnidial coverage had the lowest disease severities. The results of this investigation showed a high variation in pathogenicity of the isolates which can be related to the virulence factors exist in these isolates.

Sunflower hybrids derived from crossing between four restorer lines and eight CMS lines were evaluated to access new sunflower hybrids and evaluate combining ability of the sunflower CMS and restorer lines in 2012. Restorer lines were RN-3، RN-137، R-864 and R-217 and CMS lines were CMS 19، CMS 51، CMS 156/1، CMS 456/2، CMS 522/2، CMS 1052/1، CMS 60/30 and CMS 1221/1. Results showed that hybrids CMS19×R217، CMS1221/1×R137 and CMS19×R137 had the highest seed yield (7008، 5545 and 5526 kgha-1، respectively). Hybrid farrokh (check) with 5412 kgha-1 located in the forth rank. Combining ability variance analysis of line × tester showed that restorers and CMS lines effect، general combining ability، was significant for the most evaluated traits. Restorers R137 and R864 and CMS19 had the highest positive general combining ability for seed yield. Interaction effect between restorers and CMS lines، specific combining ability، was significant for days to flowering، end of flowering، days to physiologic maturity، head diameter، 100 seed weight and seed yield. The highest specific combining ability for seed yield belonged to hybrids CMS19×R217 and CMS 456/2× R217..

Tree decline induced by pathogenic soil fungi is one the most important problems in the orchards of stone fruit trees in Iran. Phytophthora spp. are the most principal fungi that particularly prevent the root and crown growth of stone fruit trees. This study aimed to assess the relative resistance of five new stone fruit trees rootstocks Penta، Cadaman، Tetra، Mr. S2/5 and GF677، to Phytophthora cactorum and P. drechsleri. The experiment was conduced in laboratory by active and dormant cutting shoot method and also the pot soils artificially inoculated with the fungus. The inoculum grown on vermiculite containing cannabis extract was placed next to the crown and root and the necrosis length was measured four months after inoculation. Results showed that trees exhibited different sensitivity to two Phytophthora species. P. drechsleri was less virulent than P. cactorum. The results of the laboratory and glasshouse assessments showed that Cadaman and GF677 rootstocks had the maximum necrosis length، while Penta and Tetra indicated the minimum value. Hence، Penta and Tetra rootstocks seem to have high relative resistance to crown rot.

Cytoplasmic male sterile hybrids are rapidly producing and developing. In order to determine general and specific combining ability and hetrosis of air-cured tobacco lines and cultivars، 20 hybrids and 12 parental genotypes were investigated in a ramdomized complete block design with three replications in Tirtash Research and Education Center in 2011. Variance analysis based on line × tester method showed that there were significant differences among genotypes for number of leaves and sugar percent at 5 % probability level and for leaf length and width، stem diameter، yield and nicotine percent at 1 % probability level. The results of general combining ability of lines and testers showed that combining ability in genotypes B. B 16A، Burley TMV3، BA1 and BCE were positive and significant for yield. Therefore، this genotypes can be use as one of the parents in breeding programs to improve yield. Based on the results of specific combining ability، crosses of BA1 × BNC21-3 and Iraburbon × BC21-103 due to positive and significant specific combining ability and heterosis of yield 18% and 5. 3% and B. B16A × BC21-103 and BCE × BNC21-3 due to positive specific combining ability and heterosis of yield 12. 6% and 5. 3% can be used to for production of CMS hybrid tobacco.

In the persend study، 120 genotypes of rapeseed including ten lines، ten testers and their one hundred progenies were grown in normal sowing dates (first half of October) and late sowing date (first half of November) in two separate alpha-lattice designs with two replications in Karaj in 2010-11. The analysis of variance in each environment and the combined analysis of variance over the environments revealed significant differences among adjusted treatments in terms of yield and related traits in both normal and late sowing conditions. Therefore، there were high genetic diversity among genotypes for all traits. Line×tester analysis indicated a higher proportion of non-additive gene effects for yield and related traits in both conditions. Broad sense heritability was high for all traits under both normal and late sowing conditions (from 63. 14 to 89. 12%) which indicates the importance of genetic variation than environmental variance. However، narrow sense heritability was moderate for number of branches per plant، seed yield، plant height and number of siliques per plant (from 43. 42 to 56. 02 %) and low for number of seeds per silique and 1000-seed weight in both sowing conditions (36. 33 and 24. 61%)، respectively. Therefore، selection for seed yield and its components، especially the number of seeds per silique and 1000-seed weight in early generations would not be very effective. Both additive and non-additive gene action involved in the genetic control of all characters، but the role of non-additive gene action for number of branches per plant and seed yield (only late sowing)، plant height، number of siliques per plant، number of seeds per silique and 1000-seed weight (in each experimental conditions) was more evident. Estimation of combining ability of traits showed that testers T9، T2 and line T1 were the best general combiner for increasing seed yield. Hybrids T7×L1، T8×L5، T3×L8 and T8×L9 under normal sowing date and T3×L1، T9×L2 and T7×L3 under late sowing date conditions were the best specific combiner to increase seed yield. Some of hybrids also had the highest positive and significant heterosis for seed yield.

One of the methods in walnut breeding is identification and selection of the best genotypes in different regions of the country. To achieve promising genotypes in Chahar Mahal va Bakhtiari province، this research carried out in walnut growing areas of the province. Some phenological and pomological traits of 58 selected walnut genotypes were evaluated based on the IPGRI descriptor during three years. Analysis of variance showed significant differences among genotypes for all traits. The highest kernel percentage (62. 88) and the lowest shell weight (4. 27 g) belonged to the genotype 20. The late leafing genotype was genotype 3. The most productive genotypes were genotype 18 and 42 (code number 9). Genotype 21 produced the highest nut weight (17. 28 g) and kernel weight (10. 11 g). Results of correlation analysis showed significant negative and positive correlations between some important traits. Based on cluster analysis، genotypes with desirable traits of kernel and nut were separated from other genotypes. By principal component analysis، effective characteristics were categorized in seven groups that explained 75. 35% of total variance. In diplot analysis، differences among genotypes were evident and supported the results of cluster analysis. Finally، genotypes 3، 5، 15، 18، 20، 21، 22 and 42 were recognized as promising genotypes and recommendable for orchard establishment and for use in breeding programs.

Many characteristics of pear trees such as growth، fruit size and yield، are influenced by the genetic characteristic of the rootstocks. In Iran، mainly European pear seedlings (Pyrus communis L.) are used as the rootstock in the pear orchards. Thus، evaluation of pear seedling rootstocks is an important task. This experiment was conducted in 2009 and 2010 growing seasons in order to explore the genetic diversity of 105 rootstock seedlings originated from two pear seedling populations from Mashhad and Karaj regions. Seedling rootstocks assessment was performed based on differentiation، uniformity and stability tests (DUS) of pear. Results showed significant differences (P≤0. 01) in the height and trunk diameter increase، between Karaj and Mashhad seedling populations. However، significant correlation between the seedlings height and growth vigor (r = 0. 68) and trunk diameter (r = 0. 43) was also observed. Cluster analysis، classified the seedlings into 30 groups، so that، 10 and 12 groups belonged to Mashhad and Karaj populations genotypes، respectively. Two pear seedling populations (Mashhad and Karaj genotypes) were successfully separated by cluster analysis. Based on the sum of the results، high variation for all measured characteristics were observed in two rootstock seedling populations.

Blackleg disease of oilseed rape، caused by Leptosphaeria maculans، is one of the three most important diseases of the plant in Iran. It is also considered as one of the most important diseases of oilseed rape worldwide which causes serious yield losses. During 2010 the oilseed rape fields were surveyed at province Golestan and plant samples demonstrating suspected symptoms of the disease were collected. Isolation، purification and mass-production of the isolates were done at the Plant Pathology Unit of Oilnseeds Crops Research Department in Karaj. The the isolates were studied based on production of pigments in culture medium PDA. Employing representative isolate from Golestan province، 25 lines and cultivars of oilseed rape were tested against the disease. The well developed and expanded leaves of three- month- old plants were inoculated in central area with the pathogen inoculum، and the diameter of induced lessions was measured. Based on the results lines HW101، HW104، and SW104 demonstrated resistance against the disease.