پژوهشنامه اصلاح گیاهان زراعی
پیاپی 2 (تابستان 1388)

In order to investigate the effects of water deficit stress on grain yield and sometraits three sunflower cultivars, have been used based on randomized complete blockdesign using a split plot experiment at Agricultural Research Station of Azad Universityof Tabriz in 2007. Five levels of water deficit (50, 100, 150, 200 and 250 mmevaporation from evaporation pan, class A) were assigned as main-plot and three leveleof cultivars (Armavirsky, Allstar and Euroflour) were used as sub-plot in present work.Results indicated that grain yield were reduced to 4865 to 2122, kg.ha-1 when plots were irrigated after 50 to 250 mm evaporation from the pan class A. Among cultivars studied 'Armavirsky' produced higher yield than 'Allstar' but it did not show significant difference from 'Euroflour'. Increasing water deficit stress decreased seed yield, oil yield, oilpercentage, 100 grain weight, achene hull weight, kernel weight and increased numberof unfilled seed.

To study yield, yield component and some morphological traits in cotton, six parentswith 15 hybrids (totally 21 genotypes) were evaluated using a randomized completeblock design with three replications at a salty farm Bandar Torkaman area in 2005. Ninetraits were measured including the percentage of germination, plant height, number ofmonopodial branches, length of monopodial branches, number of sympodial branches,length of sympodial branches, boll number, boll weight and yield. Analysis of varianceand mean comparison show highly significant differences among the genotypes for thetraits, such as plant height, length of monopodial branches, boll number, boll weight andyield. Also results showed that a positive and significant simple correlation betweenyield and germination, plant height, number and length of sympodial branches and bollnumber but non significant for number and length of monopodial branches and bollweight.

In order to study effect of drought stress on morphologic traits, yield and yieldcomponents of 28 new hybrids of corn to heat and drought stress in addition 6commercial hybrid (as control), an experiment was carried out on based of completerandomized block design with three replication under normal irrigation and droughtstress in Khorasan Razavi Agricultural Research and Natural Resources InstituteMashhad, Iran on 2010. Results of analysis of variance showed that in both conditionthere are significant different between all hybrids for all traits. Results of hybrid meanscomparison with Duncan’s multiple range test showed that in normal irrigation conditionS.C500 hybrid and in stress condition N.11 hybrid was better than others in yield trait(13.79 and 5.69 respectively). Genetic correlation between traits under stress conditionshowed that number of kernel in row was the highest correlation with yield and innormal irrigation ear diameter was higher than other traits correlated. The results showedthat under no stress conditions, hybrids with the mean number of ear per plants that have more thick ear, heavier and more kernel per row and the same time have a lowerpercentage of wood, will be higher in total yield. Generally, according to results of pathanalysis, review and compare traits affecting grain yield in two environments can beconcluded that plant traits in maize, kernel weight per ear, ear weight and percentage ofkernel, deficit quickly affected and determining the limitations of plant production.Breeding for these traits can be obstacles on the path taken from the performance and the ultimate goal of increasing performance in low-Irrigation conditions.

In three-line system, cytoplasmic male sterile (CMS) lines often were contaminatedwith cognate iso-nuclear maintainer lines during seeds multiplication processes.Therefore fingerprinting of breeding lines and identification of line-specific markers areprerequisite in genetic purity test. Six CMS lines including Neda-A, Nemat-A, Dasht-A,Amol 3-A, Champa-A, IR58025A and their iso-nuclear maintainers were used in thisstudy. Twenty-five random amplified polymorphic DNA (RAPD) primers used forscreening CMS lines and maintainer lines. The result indicated that the iso-gene lineshad similar band patterns in most marker loci due to similar genetic background thatpresent between CMS lines and co-maintainer lines. However two specific bands, 950bp and 850 bp were produced by OPH20 and OPH01 primers that could uniquelyrecognize the CMS lines from their cognate maintainer lines, respectively. The geneticnature of OPH20-950 band was determinated by isolation of fragment from gel, clone toEscherichia coli bacteria via T/A cloning system, and was sequenced. A BLAST searchof OPH20-950 sequence with GenBank indicated 95% homology to a ricemitochondrial DNA. These line-specific fragments could be used as a specific feature(scare marker) for characterization and genetic purity test of WA CMS lines.

In order to determine the best index for evaluating maize genotypes, 28 maize hybrids were evaluated in two planting dates, 6 July to coincide heat stress with pollination time and 27 July as normal planting to avoid high temperature during pollination and grain filling period, using a randomized complete block design with three replications, in Shushtar city, in 2008. Results showed that in stepwise regression analysis for heat stress condition,grain dry matter weight and grain depth traits were entered in model but, for normal condition, nothing trait werenot entered in model. Factor analysis, for heat stress and normal conditions indentified three and five independent factors which explained 73.59 and 75.78 percent of all variations, respectively. In heat stress condition, first factor, named yield and yield components and in normal condition named ear morphology, explaining 43.78 and 18.96 percent of total variations, respectively. Second factor for heat stress and third factor for normal condition named grain characteristic, which explained 15.67 and 17.58 percent of total variations, respectively. Third factor in heat stress named ear morphology. Second factor, yield components, fourth factor grain width and grain dry matter weight and fifth factor grain yield named in normal condition.Based on the results, grain dry matter weight and grain depth under heat stress revealed as suitable traits which can discriminate maize genotypes.

Fenugreek (Trigonella foenum-graecum) is an annual herbaceous plant belongs toPapilionaceae family and is important as a pharmaceutical, agronomic and pasturalplant. In order to study the effect of trifluralin on ploidy induction and cytogeneticcharacteristics of cells in the root meristem of fenugreek some seeds of this species wereplanted in the incubator and after germination root tips were used for karyotypic studies.For treating the seeds trifluralin liquid 48% were applied at 7.5, 15 and 22.5 μMconcentrations for 12 and 24 h. The Video Analysis System was used for karyotypeanalysis. The basic chromosome number was X=8. The results showed thatconcentration of trifluralin, treatment duration and interaction between them on theploidy induction were statistically significant. The maximum ploidy induction washappened by immersion seedlings in 22.5 μM trifluralin at 24 h. The result of analysisof variance based on completely randomized design (CRD) showed a significantdifference among the karyotypes for all chromosomal traits (P<%1). Trifluralin affectedseverity on the length of chromosomes and karyotypic formula so that the longestchromosomes belonged to the karyotype control sample and the shortest chromosomeswere observed after treating with trifluralin. After applying treatment was reduced thepercentage of submetacentric chromosomes and were added to the percentage ofmetacentric chromosomes.

In order to evaluate the interaction of rice genotypes to salinity stress, responses of16 rice genotypes were assessed to 4 salinity levels (0, 4, 8, 12, dS/m) through a splitplot experiment seedling stage in hydroponic culture. In this experiment characters suchas plant height, leaf area, root length stem length, dry weight of root and stem, dryweight of leaf and total biomass were measured. All the characters in reaction to salinityshowed significant. And correlation coefficient of seedling stage had all the characterspositive and significant differences. At seedling stage, total biomass proved to be thetrait of choice for assessing the tolerance among cultivars as well as treatments. Totalbiomass of the PSBRC88 variety was decreased about 42% compared to control.Whereas this decrease for Shafagh was 26%. Also Nemat A/19R had the most decreasecompared to control (81%). The decrease of stem dry weight of PSBRC88 variety at 12dS/m salt level was less than other varieties with comparison to control (about 23%).The most decrease in stem dry weight of was for IR60819R/IR58025A by 86% relativeto control. The decrease of leaf area in Gerdeh variety was less than other varieties withcomparison to control (about 61%).