نشریه نهال و بذر
سال بیست و هفتم شماره 2 (تابستان 1390)

To evaluate some agronomic and physiological characteristics under drought stress, determining the best quantitative indices for drought resistance, and identifying drought resistant sunflower genotypes, a field experiment with 36 sunflower genotypes was carried out in 2008-2009 at the research farm of Dryland Agricultural Research Institute (Sararood), Kermanshah, Iran. Thirty six genotypes of sunflower were evaluated in a 6 ´ 6 lattice design with two replications under normal and drought stress at flowering and seed development stages. Some agronomic and physiological characteristics under drought stress and seed yield under both conditions were measured during the growing season. The results of analysis of variance showed that differences among the genotypes for plant height, relative ionic leakage and cell membrane stability traits were significant at the 1% and for seed yield at the 5% probability levels. Drought tolerance indices MP, GMP, HarM and STI exhibited a high correlation with seed yield in both stress and non-stress conditions and were recognized as the best indices for selecting genotypes with high yield potential and resistant to drought stress. Using biplot method, SIL-237, SIL-218, SIL-210, SIL-206, SIL-240, SIL-140, SIL-42, SIL-96, SIL-238 and SIL-227were recognized as resistant genotypes. Genotypes that produced higher seed yield and were drought resistant can be used to develop resistant hybrids.

Thirty quantitative and qualitative characters related to the vegetative and reproductive growth were recorded on 257 plum seedlings in Karaj during 2006 to 2009. Results showed high variability in studied characters among seedlings. Height of seedlings were 60-231, 100-317 and 430-125 cm in the second, third and fourth years of growth respectively. Increase in height was 4-197 cm between the second and third, and 9-141 cm between the third and fourth years of growth. Simple correlation coefficients were significant among some important characters such as height and trunk diameter, growth habit, vigor and yield. In cluster analysis seedlings were divided into five groups, including very strong, strong, intermediate, weak and extremely weak groups. Based on the results, slow-growth seedlings, suitable for rootstock, were S11-23, S11-25, S11-26 and S7-37 and high-growth genotypes were S1-1, S1-20, S1-22, S3-1, S9-3 and S4-30.

In the present study microspore embryogenesis and regeneration were investigated in canola (Brassica nupus L.) to develop doubled haploid plants. Canola cultivars Hyola 420, Hyola 401 and F1 hybrid RGS003 ´ ARC5 were used as plant materials. Microspores at late unicellular- early bicellular developmental stages were isolated from flower buds with an approximate length of 2.5-3.5 mm and cultured in NLN medium containing 13% sucrose. Isolated microspores were stressed with heat shock in different durations and temperatures including 37°C for 8 hours, 35 °C for 18 hours, 32°C for 72 hours and 30 °C for 10 and 14 days. Microspore-derived embryos were induced only when heat shock treatment of 30oC for 10-14 days was applied, although 30oC for 14 days showed better embryogenesis and regeneration. For blocking the secondary embryogenesis, embryos in cotyledonery stage were transferred to B5 medium supplemented by GA3 (0.01 mgl-1) in dark condition for 10 day at 4 oC and then transferred to the light condition at 25 oC to B5 medium without GA3. For doubling the ploidy level of haploids and production of doubled haploids, plantlets were treated with colchicine (0.34%) for 1.5 hours. Doubled haploid seeds were collected from all three genotypes tested.

The effects of genotype by environment interactions on the grain yield of twelve promising durum lines along with a durum (Zardak) and a bread (Sardari) wheat as checks were investigated at three locations, representative for multi-location durum yield trials, in Iran under rain-fed and supplementary irrigation conditions for three cropping seasons. Main effects due to E, G and GE interaction as well as four interaction principal component axes (IPCA 1-4) were found to be significant (P <0.01). AMMI biplot was able to distinguish genotypes, with wide and specific adaptation, and environments, with high and low genotype discrimination ability. Genotypic responses were similar in Kermanshah and Ilam in two (2005-06 and 2008-09) out of three years. In Shirvan genotypic responses generally were similar. Based on AMMI analysis, the check cultivars were more adapted to rainfed conditions while the promising genotypes G8, G2, G7, G4 and G6 were adapted to supplementary irrigation conditions. According to AMMI and some stability parameters, the genotypes G3, G10 and G5 were more stable and were more adapted to the whole target regions.

In order to map QTLs of yield and its components in oilseed rape under normal and drought stress conditions, 135 doubled haploid lines derived from the cross between a Korean spring line "Yudal" and a French winter line "Darmor" were evaluated. Genetic map of 19 linkage groups of oilseed rape using doubled haploid population was constructed by 459 molecular markers including isozyme, RFLP, RAPD, SSR and SNP. Using the composite interval mapping method, a total of of 38QTLs detected for measured traits under normal and drought stress conditions. Most QTLs were located on DY13 and DY6. It’s thought that these two linkage groups have a basic function in the genetic control of some agronomic traits. One of the important QTLs was detected on chromosome DY6 linked to the dwarf gene Bzh. This QTL had pleiotropic effects on most traits. As this QTL had a major effect, it could be used in marker assisted selection. The major QTLs for yield and its components were the same under both normal and stress conditions.

In the present study virulence factors of 30 wheat leaf rust isolates were determined in the cereal rusts greenhouses in Seed and Plant Improvement Institute, Karaj, Iran. Rust samples were collected from 13 parts of Iran during 2007. After purification and multiplication of urediniospores, all isolates were separately inoculated on 40 leaf rust near-isogenic lines and maintained in a greenhouse at 22-24˚C. Avirulence/virulence formula was determined for each isolate. The results showed that near-isogenic lines carrying genes Lr3, Lr3bg, Lr14b, Lr20, Lr22a, Lr22b, Lrb, Lr35 and Lr37 were susceptible to all isolates indicating the presence of virulence factors for them in all parts of the country. Virulence factor was not existed for genes Lr9, Lr19, Lr10+, Lr25 and Lr28 in any of the isolates. Genes Lr23+ and Lr2a with 16.6% and 20%, had also the lower.

To identify high yielding drought tolerant genotypes with yield stability and good bread making quality, an experiment was conducted using 22 bread wheat genotypes (20 promising lines and 2 checks, Sardari and Azar-2) during two cropping seasons (2007-2009) in Sararood (Kernamshah) and Karaj (moderate cold areas). The genotypes were evaluated in a RCBD with three replications under two separate experiments, full irrigation and rainfed conditions. Based on the results, some genotypes performed higher drought stress tolerance among them genotypes no. 11 (KATILA-13), 19 (CRR/ATTILA),1 (ORF1.158/FDL//BLO/3/SHI4144/CROW/4/C), 14 (KAUZs'/MACHETE) and 7 (Jcan/Emu"s"//Dov"s"/3/Alvand/4/MV17/AHila) had higher grain yield, yield stability and good baking quality compared to the other genotypes. Genotypes no. 10 (HAMAM-4) and 12 (KATILA-1) had also most of the grain quality characteristics. Based on the results of different characteristics, the genotypes no. 1, 11, and 19 were selected for drought tolerance, yield and yield stability and genotypes no. 10 and 12 for drought tolerance and quality characteristics.

To determine yield stability in bread wheat lines and cultivars for dry and warm areas of Iran, 18 elite lines together with Chamran cultivar as check were studied in a randomized complete block design with three replications at six warm and dry stations (Ahvaz,, Dezful, Darab, Zabol, Iranshahr and Khorramabad) during 2005- 2007 cropping seasons. The results revealed that the interactions of location × year and location × year × genotype were significant. Stability analysis for grain yield of genotypes based on Eberhart and Russell linear regression coefficient, Wrick’s ecovalence, Shukla’s stability variance, simultaneous selection index, non-parametric statistic method (mean rank of yield, standard deviation of rank of yield, and yield index ratio), AMMI and SHMM models, the genotype no. 11 (Weebill 1) was determined as the most stable genotype. AMMI and SHMM models were also suggested as efficient methods for determining of stable genotypes in breeding programs based on the results of these experiments.

To produce embryogenic callus and somatic embryos, tendril explants were collected and cultured in MS medium supplemented with various concentrations of hormones. After one month most of explants produced callus. The highest percent of embryogenic callus obtained in MS medium supplemented with 4.5 µM BAP and 1µM 2,4-D. Production of somatic embryos was depended on genotype and medium. Yaghouti cultivar in MS medium without hormone, Bidaneh Sefid in MS medium supplemented with 10.4µM NAA and 0.4µM BAP and Shahroudi cultivar in MS medium supplemented with 4.5µM BAP and 1µM 2,4-D produced the highest percent of somatic embryos. For germination, embryos were transferred in to MS medium supplemented with 1µM BAP at the torpedo stage. At this medium most of embryos germinated and produced plantlet.

Line S-80-18 (Deberia) a spring bread wheat line with pedigree of HD160/5/Tob/Cno/23854/3/Nai60//Tit/Son64/4/LR/Son64 was selected from the High Temperature Wheat Yield Trial, received from CIMMYT and evaluated at Zabol research station in 1994-95 cropping season. As a superior line, it was advanced to the Preliminary Yield Trial at Zabol station in 1995-96 cropping season. Due to high grain yield and desirable agronomic characteristics, it was further evaluated in a replicated yield trial at Zabol during 1998-99 cropping season and later in the Preliminary Regional Wheat Yield Trial of the southern warm and dry agro-climatic zone of Iran in five research stations of Ahvaz, Darab, Zabol, Iranshahr and Dezful in 1999-2000, where this line out-yielded Chamran (improved check) by more than 7%. The new line was advanced to the Advanced Regional Wheat Yield Trial for further evaluation in Ahvaz, Darab, Zabol and Dezful in 2001-01, and again yielded 5.2% more than Chamran. The adaptability and grain yield stability of this line was evaluated for two years in Elite Regional Wheat Yield Trial in six stations of Ahvaz, Darab, Zabol, Iranshahr, Dezful and Khorramabad during 2001-2003 cropping seasons. The results confirmed the wide adaptability and grain yield stability of the new line, therefore, it was finally evaluated in on-farm trials in different locations across the southern dry and warm areas of Iran in 2003-04 cropping season. Considering high grain yield, high resistance to stripe and leaf rust, exhibited in different hot spots locations, good grain quality (protein contents of 11-13.2%) as well as good agronomic performance including earliness, resistance to terminal heat stress and shattering, this line was officially introduced in Iran with the name of Aflak in 2010.