Seed and Plant
Year:2006 | Volume:21 | Issue:4|Papers Count:13

Leaf (brown) rust, caused in wheat by the fungus Puccinia triticina is an important disease in north, west and south of Iran. Leaf rust is an endemic disease in Iran, which appears in many parts of the country annually. Use of resistant cultivar is the best way to control this disease. To find resistant sources to the pathogen and use in the breeding program, it is necessary to determine virulence factors of the pathogen. In the present study, 12 locations were allocated in different parts of Iran to study virulence factors of the pathogen in trap nurseries with 37 leaf rust near isogeneic lines and a susceptible cultivar Bolani. Each line was sown in two rows of 1 meter length. The nurseries were maintained under natural infection of the pathogen. Reaction of each line was recorded at the time when infection on the susceptible control was at the maximum level, and presence of virulence for different resistance genes was determined. Results indicated presence of virulence for genes Lr1, Lr2b, Lr2c, Lr3, Lr3ka, Lr3bg, Lr10, Lr11, Lr12, Lr13, Lr14a, Lr14b, Lr15, Lr16, Lr17, Lr20, Lr21, Lr22a, Lr22b, Lr23, Lr24, Lr26, Lr30, Lr32, Lr33 and Lrb. No virulence was detected for Lr9, Lr18, Lr19, Lr25, Lr28, Lr29, Lr34, Lr35, Lr36 and Lr37 genes. Use of these genes with combination of adult plant resistance genes is expected to be a useful method to control of leaf rust disease. 

Fire blight is the most important disease of pome fruits in Iran, as well as in more than 40 other countries. Using the resistant cultivars is the most effective and economic method to decrease damages of the disease. To find resistant cultivars for subsequent use at the breeding programs, correlation between fire blight resistance and different vegetative and reproductive traits were evaluated in the local, foreign and spur type apple cultivars. Evaluation of resistance was carried out by natural infection through using the severity (IS), percentage of infected shoots (IINF) and USDA (IUSDA) indices during two epidemic years (1998-1999). The highest frequency of resistant cultivars was observed in spur type (66.7%), local (59.5%) and foreign (43.6%) cultivars, respectively. In addition, the frequency of resistance, in the local cultivars originated from North East region of Iran was approximately twice of those originated from North West regions. The results did not show any correlation between time of vegetative bud burst and resistance to the disease, but more susceptible cultivars intended to flower earlier than the resistant ones. In the local apple cultivars, percentage of shoot lignification had a high correlation with fire blight resistance, while in the foreign and spur type cultivars, the internode length and tree vigor, respectively had the highest correlation with the fire blight resistance.

Oilseed rape (Brassica napus L.) is one of the world’s main sources of vegetable oil. The quality of the oil derived from oilseed rape is determined by its fatty acid composition. Breeding oilseed rape for enhanced oleic acid is one of the most important breeding programs that increases oil shelf life. In order to identify molecular markers associated with high oleic acid, a doubled haploid population derived from a cross between the lines T099-5318-20 and DH12075, RAPD and ISSR markers and bulked segregant analysis method were used. Six markers were found to be associated with oleic acid. The markers UBC 2830 and UBC 5381650 accounted 43% and 34% of genetic variation for oleic acid, respectively. In order to make SCAR marker, UBC 2830 was cloned and sequenced. From sequenced information, specific primers were designed. SCAR marker produced a 399 bp fragment linked to oleic acid. The markers identified in this study and the SCAR marker should be useful tools for the selection of high oleic acid genotypes in oilseed rape breeding programs.

In order to determine the reaction of some selected maize lines and cultivars to southern corn leaf blight (SCLB), 17 lines and cultivars were evaluated in RCBD with 2 and 4  replications in 1999 and 2000, respectively at Gharakhil Research Station. In this study, each plant was inoculated at 3-4 leaf stage with a suspension of spore (C= 3 x 104  spore/ml) by syringe and once again at 6-8 leaf stage with infected sorghum seeds (10-15  kernel/whorl) by Bazooka. The percentage of infected area on the leaves of different cultivars were scored two times by 0-5 and 0-100 scales, as disease severity index, at an thesis and two weeks after on. Results showed a significant difference among lines and cultivars to SCLB. Hybrids showed to be more resistant than lines. Meanwhile, line K3547/212 was highly resistant and K3653/111 highly susceptible. Among cultivars, K3547/212 MO17 and K SC 604 were highly resistant.  Commercial lines, MO 17, K18 and K19 were moderately resistant and B73 susceptible.

Ten diallel combinations of five maize tester lines were evaluated for grain yield and some related traits using randomized complete block design with two replications in Karaj and Gorgan during year 2004. Combined analysis of variance over two locations revealed significant differences among crosses for all the traits. Diallel analysis indicated presence of additive and non-additive gene action for grain yield, plant height, ear row number, kernel width and number of kernels per ear, as well as, additive effects for tassel length and tassel main axis length above the branches, ear length, kernel number per ear row and kernel thickness. MO17 and B73 were identified as efficient testers in screening maize germplasm, and K1264/1 and KL17/2-5 as non-efficient ones.

In order to study the adaptability and yield stability of rainfed durum wheat promising lines, an experiment was conducted with 20 genotypes in RCBD during three cropping seasons (1998-2001) in four warm and semi-warm stations in Iran. Simple ANOVA and combined analysis of variance for three years in each location and combined analysis of variance for three years and four locations were implemented. Lin and Binns parameter, coefficient of variation of grain yield and rank method were used for determination of stable lines. Results of combined ANOVA (three years  four locations) showed that interaction effect of year location genotype was significant. The highest grain yield was belonged to line no. 6 (Mrb11//Sinpe/Magh/…) with 2.33 tha-1 and line no. 5 (Mrb11//Sinpe/Magh/…) with 2.26 tha-1. Results of stability analysis with Lin and Binns method showed that lines no. 16, 18 and 15 had the lowest inside location variance for grain yield and the lowest grain yield coefficient of variation was belonged to lines no. 18, 16 ,15 and 6, respectively. The results of rank method showed that lines no. 6 and 5 had the lowest and lines no. 17 and 7 had the lowest SDR among the experimental lines. Based on the results, lines no. 6 and 5 had the highest grain yield and yield stability, therefore can be recommended for warm and semi-warm dry land regions.

The local grape cultivars of Kurdistan province were studied From 1993 to 1995 and 1997 to 2001. In different stages of plant growth such as bud break, fruit maturity, fruit harvesting and rest of grapevines, about 100 characters on different parts of plant were recorded using IBPGR (International Board for Plant Genetic Resources) descriptor. As a result, 59 cultivars were identified, 17 cvs. were grown in non-irrigated condition. All non-irrigated grapes grown in Kurdistsn were seeded grape, color of berries were black blue (7 cvs.), red (6 cvs.) and white (4 cvs.). Sex of flower in all cultivars was hermaphrodite except in Dovreevy cv. that flower was female with descending stamens. Minimum leaf area (57cm2) and maximum leaf area (147cm2) were belong to Khoshnav and Jabbali cultivars, respectively.Total soluable solide (TSS) was variable, from 16/5% in Sharbager cv. to 23.0% in Sahani cv. According to cluster analysis, similarity level of Khoshnave and Siavah cultivars was 80%. This results support  a theory that Khoshnav and Siavah cultivars are one cultivar. Finally, with regard to desired characteristics, some cultivars such as Sahani and Sarghoolah, due to large berries with attractive color, and Khoshnav and Siavah due to high yielding, large clusters and adaptation to water stress condition, are introduced as superior cvs. for using in grape breeding programs and development of non-irrigated vineyards.

Annual species of Medicago are important pasture legumes in western parts of Iran. Due to limited karyotypic reports on annual Medicago species, the present study was conducted on accessions available in gene bank of Iran. Total length of chromosomes, size of long and short arms and their ratio were the basis for karyological measurement. Karyotypic studies showed that M. radiata 29, M. radiata 588, M. minima 316, M. polymorpha 1123, M. orbicularis 449, M. litiralis 1038, M. trancatulla 1146 and M. polymorpha 612, carried 2n=2x=16 chromosomes and Medicago rigidula 2n=2x=14 chromosomes. Among species with 2n=2x=14, M. rigidula 1126 had the highest total chromosomal length and  M. rigidula 454 the least total length. Species M. littoralis 1038 and M. minima 316 both with 2n=2x=16, had the highest and the lowest total chromosomal length, respectively. Total chromosome length and mean of chromosome length in most of exotic species were more than those of landraces. Species and varieties with larger karyotype had larger seed size. B chromosome found only in the M. littoralis and M. polymorpha species. Satellite chromosome observed in varieties 606, 1126 and 1199 of M. rigidula, 1123 and 612 of M. polymorpha and M. radiata 588. Resultes of cluster analysis revealed that varieties and species with similar karyotypice size and mean chromosomal length, did not show any significant differences, hence they were located in one group. Factor analysis revealed that chromosomes number 5, 6, 7 (2x=14) and 7, 5, 2 (2x=16) showed maximum structural change among accessions. Karyotype symmetry were determined by using coefficient of variation (CV) and total form percentage (%TF). Resultes of CV showed that the most of variation between chromosomes belongs to M. polymorpha 612 and the least of variation between chromosomes belongs to M. rigidula 1128. According to TF, M. minima 316 had the most karyotype symmetry and M. rigidula 1126 showed the least karyotype symmetry.

Reactions of fifty commercial wheat cultivars were evaluated against common bunt in Karaj during 2000-2004 (ten cultivars in 2000 and 2001, twenty cultivars in 2002 and 2003, and twenty other cultivars in 2003 and 2004 together with a susceptible check). All three experiments were carried out in randomized complete block design with three replications. Race L-10 of Tilletia leaves was used for artificially inoculation of seed before planting. Combined analysis of variance on mean percentage of infected heads showed significant differences between years and cultivars in all experiments. In 2000 and 2001 cultivar Hyrmand with 0.08% and Bolani with 59.8% infected heads showed high levels of resistance and susceptibility, respectively. In 2002 and 2003, cultivars Zarrin with 0%, Alvand with 0.3%, Pishtaz with 1. 3%, Azadi with 1.5% and Soisson with 1.8% infected heads were assessed as resistant cultivars. In 2003 and 2004, cultivars Karaj 3, Bayat, and Aria with 0.3%, 0.3% and 1.5% infected heads were resistant. As sources of resistance to common bunt in irrigated wheat cultivars are rare in the world, resistant cultivars found in the present study are very suitable for cultivation in infected areas or to be used as sources of resistance in breeding programs.           

An experiment was conducted in the experimental field of Seed and Plant Improvement Institute in Karaj for three consecutive cropping seasons, 2001-2003, to study the effects of eight different fertilizer treatments including some microelements on grain yield and protein content of a bread wheat cultivar Pishtaz. The experiment was in a RCBD with three replications. Eight fertilizer treatments were: NPK (control), NPK-An, NPK-Fe, NPK-Mn, NPK-Zn, NPK-Fe-Mn, NPK-Mn-Fe, NPK-Mn-Zn and NPK-Fe-Mn-Zn. To provide the experimental treatments, 10 kgh-a Secostrin 138, 40 kgha-1 Sulphate of Zinc, and 30 kgha-1 Sulphate of magnesium were added to NPK. Based on the results, the highest grain yield was obtained from the NPK-Fe-Mn-Zn treatment with a yield increase of 900 kgha-1 comparing with the check treatment (NPK). Other treatments with different microelements also caused increase in yield. Protein contents of grains obtained from the treatments containing Zn + Mn, Zn and Mn increased by 5.2, 4 and 3.2 percent, respectively.