فصلنامه علوم زراعی ایران
سال سیزدهم شماره 4 (پیاپی 52، زمستان 1390)

Primary Tritipyrum is a new synthetic allohexaploid amphiploid cereal which has been developed by crossing the durum wheat (Triticum durum, AABB, 2n=4x=28) and wild brackish grass (Thinopyrum bessarabicum, EbEb, 2n=2x=14). Although primary Tritipyrum lines are tolerant to salt stress but have few undesirable agronomic traits such as brittle rachis and late maturity. To overcome these problems, the new potential secondary introgressed Tritipyrum genotypes were developed from crossing the primary Tritipyrum (St/b) or combined primary Tritipyrum (Ka/b)(Cr/b) lines [AABBEbEb, 2n=6x=42] and bread wheat (Triticum aestivum:AABBDD, 2n=6x=42) cv. Omid and cv. Navid in which the various D chromosomes of bread wheat will probably be substituted with different Eb chromosomes of Tritipyrums. Identification of Eb chromosomes in chromosomal mitotic preparations of new potential secondary Tritipyrum genotypes including F3 progenies of (Omid × St/b) and [Navid × (Ka/b)(Cr/b)] by genomic DNA in situ hybridization (GISH) technique, using indirect labeling for genomic St DNA with Biotin-11-dutp as probe, was carried out. Results showed that using St genomic DNA instead of genomic DNA of Eb genome as probe made less St cross hybridization with A, B, D chromosomes and high differentiation between Eb chromosomes with A, B and D genomes chromosomes. This indicated that in spite of high genetic similarity between Eb and St (Pseudoroegneria stipifolia, StSt, 2n=2x=14) genomes, the St genomic probe is recomended for identification of Eb chromosome, because genetic similarity of St genome with A, B and D genomes is less than Eb genome with these three genomes of bread wheat. A range of 1-6 Eb chromosomes in mitotic chromosomal spreads of [Omid × St/b] and [Navid × (Ka/b)(Cr/b)] F3 progenies were detectable which indicated that producing new potential secondary Tritipyrum introgressed genotypes (NPSTIGs) with specific substituted Eb chromosomes with D chromosome was feasible. Therefore, GISH can be used as a powerful selection tool in chromosome engineering of intergeneric hybridization progenies of primary Tritipyrum lines and bread wheat cultivars combinations for selecting the favourable 42 chromosomal constitution genotypes of Eb, A, B and D as a new substituted or recombinant chromosome(s) lines.

An investigation was carried out in order to study the genetic variation of barley genotypes in terms of winter survival, LT50 and leaf soluble carbohydrates under field and greenhouse conditions using 40 barley genotypes in the research station and greenhouse of Faculty of Agriculture, University of Tabriz, Iran. The field evaluation was performed in the form of randomized complete block design in two years and percentage of winter survival was estimated. Multivariate analysis of variance indicated significant differences among genotypes for the traits measured in greenhouse and laboratory. Combined analysis of variance showed significant differences among genotypes for percentage of winter survival, but the effects of year and genotype × year interaction were significant for this character. The greenhouse experiment for percentage of plant survival was carried out in the form of split plot design on the basis of randomized complete blocks with two replications. Barley genotypes were assigned in subplots and five freezing temperatures (-8, -11, -13, -15 and -17°C) were assigned in main plots. Other traits measured in the greenhouse, such as LT50, percentage of seedling dry weight, soluble carbohydrates content before and after hardening and leaf length and width were analyzes based on randomized complete block design. Significant differences were observed among barley genotypes in terms of survival percentage at temperatures -8, -11, -13, -15 and -17°C, LT50, percentage of seedlings dry weight, leaf width and the soluble carbohydrates content after hardening. The heritability of field survival percentage, LT50 and leaf width were high. The heritability of soluble carbohydrates content after hardening and the percentage of seedling dry weight were moderate. The highest and lowest heritability were observed at temperatures -8°C and -17°C, respectively. Percentage of survival at temperature -15°C had the largest squared genetic coefficient of variation and other traits had low squared genetic coefficient of variation. It can be concluded that genotype #38 (Athenise) was susceptible to cold stress and considerable number of genotypes had desirable characteristics for cold tolerance from which genotypes #36 (Schulyer) and #15 (EC83-12) can be recognized as more cold tolerant genotypes with regard to percentage of winter survival and LT50.