Iranian Journal of Rangelands and Forests Plant Breeding and Genetic Research
Year:2004 | Volume:12 | Issue:1 |Papers Count:9

Genetic potential and variation of 30 Haloxylon genotypes from four arid zone of Iran have been evaluated in 1998-2003. Experiment was done in Hossein-Abad station in Qom area. Considering Randomized CompleteBlock Design with three replication. Measured traits of each genotype in five years were as following: plant height, stem diameter, diameter of longer and smaller canopy cover. Variance analysis and compound analysis were done. Correlation coefficient of plant height in 5 year with plant height and diameter of stem in the years ago was positive and significant (p≥0.05). Factor component analysis determined. Twenty–one factors that first five of them were eginvalue more than one so entering in factor analysis. Factors: diameter of canopy cover” and “pest damages” recognized by factor analysis. Cluster analysis divided genotypes to five groups: first group was almost from Yazd and second group was one genotype from Yazd and two genotype of Sistan. In this group, the trials plant height, stem diameter and canopy diameter were higher of other groups. 3th and 4th group include several genotypes from different zones. 5th group almost from Semnan.

In order to determine relationships between 21 species of Astragalus studies were based on 11 karyotypic characters with multivariate statistical methods.Pierson´s correlation coefficient between traits was r>0.9. Different chromosomic dimensions showed that A. aharicus with A. angustiflorus and A. apricus and so also A. angustiflorus with A. apricus have a high correlation. Diploid species of Astragalus were similar in short Arm length. Principal component analysis based on all haracters revealed that the first 2 principal components could describe over 80% variability between the species. It was understood to classify the species, characters of short arm length, total form percent, arm ratio, centromic index and chromosome length are important. Cluster analysis based on Ward´s method of 11 characters divided the species into 4 groups.

Symbiotic relationship has been found between endophytic fungi and most cool-season grasses including 80 genera and 100 species of subfamily Pooideae. In this relation, endophytic fungi gain their food and energy from host plants and instead improve host characteristics such as yield and render plants resistant to dense grazing and biotic and abiotic stresses. This effects induced from endophytic fungi can increase net production and stability in ecosystem. Results of studies conducted in past years by authors in tall fescue showed that endophytic fungi improve phenotypic characteristics of plants under stress and non-stress environments. That includes increase of root biomass, tiller number, crown depth and forage yield. Conferred traits are generally through production of some bioactive compounds that can affect ecosystem maintenance. Other studies showed that occurrence of stress environment may cause more superiority of endophyte - infected plants than endophyte-free versions and extensive prevalence of plants containing endophyte may be predictable in the future. Research strategies at present and in future, are better conception of host- endophyte genetic interactions and transfer of this symbiosis to other forage plants.

To investigate cytogenetics of Aloe litoralis and Aloe vera, samples were taken during flowering stage from several local populations of the species in the southern parts of IRAN, such as Bushehr and Hormozgan provinces. The samples were fixed at the sites and studied at the Forests and Rangelands Research Institute. Chromosome behaviors in miosis cell division were studied in the populations and a number of parameters such as number and type of formed chiasmas were recorded. One hundred cells per population were studied for the purposes. Despite the big size of the chromosomes of the species, the most portion of the observed chiasmas were one chiasma per pairs of homologes. Two chiasmas per homologes were in the next level. Four chiasma were hardly observed, but a population of A.litoralis showed a high level of the phenomenon, so that on the whole, the population presented the higher number of chiasma. Since chiasma formation and miotic behaviors is believed to be genetically controled, these can be due to genomic diffrentiation between the populations in the locations. One or two lag chromosomes were observed in several populations. Late separation of the chromosomes at anaphase II was also observed for all of the populations. Presence of these phenomena at different stages of the mitotic cell division may imply an active trend of evolution in the studied populations.

The main purpose of this experiment was, evaluation of the characteristics of the seed samples for four alfalfa population in reaction with two fungi species of (Fusarium solani, F. oxysporum). The seeds samples of four alfalfa population with source of Iranian and foreign countries were used for this experiment. The seed samples of alfalfa were exposed with two level spores of Fusarium solani, F. oxysporum, the inoculated seed samples of each population were considered as treatment, also the non-inoculated of the seed samples of each population were considered as control. The main characteristics of the inoculated seed samples including (percent and speed of germination, length of root and shoot, fresh weight and dry weight, vigour index) were compared with non-inoculated seed samples for each population. The result showed that there was significant difference between the agents of infection and alfalfa for the characteristics of seed samples comparing with control.

Continuous grain cropping in many areas of the world has reduced soil nitrogen levels to a degree such that agricultural production is now largely dependent upon nitrogen fertilizer. Identification of highly effective legume and Rhizobium strain combinations, increased production of protein rich livestock forage and also improved the soil structure. Four species of annual medics (Medicago truncatula, M. littoralis, M. polymorpha, M. rigidula) were grown in all combinations with four various strains of Rhizobium meliloti (Locally, Hoomand, R95 and S13). There was also uninoculated check for each species. Control treatment (uninoculated) included mineral nitrogen (2.5 mM nitrate). All combinations of medics and rhizobium were grown without nitrate. Control treatment watered with nutrient solution contained 2.5 mM nitrate. Growth chamber experiment was conducted for 90 days to evaluate shoot dry matter and total shoot N. Medic lines varied in their ability to form an effective symbiosis with the rhizobia. M. truncatula has highest symbiotic with the strains Locally, Hoomand and R95. M. littoralis also in four inoculated treatment has %N near to control treatment. M. rigidula had highest symbiosis with R95 and then S13. M. polymorpha had low symbiosis with all strains. M. truncatula had highest shoot dry matter (SDM) among five inoculated and uninoculated treatments (250 mg/plant). M. truncatula and M. littoralis exhibited similar response to all strains. M. rigidula required specific strains of Rhizobium meliloti in order to fix more nitrogen. M. plymorpha hasn’t effective symbiosis with any of the strains that can result this plant required specific strain.

In order to study the genetic variation for forage and seed yields and their components among 9 genotypes of red clover (Trifolium pratnse L.), a complete randomised block design with three replications was conducted under spaced plant condition over two consecutive years in Karaj, Iran. Data were collected for leaf lamina area, internodes length, petiole length, canopy height, persistency, number of inflorescences per stem, number of inflorescences per plant, number of stems per plant, number of floret per head, number of seeds per head, thousand seed weight, growth habit, seed yield and dry matter yield. The data were subjected to analysis of variance for each year and combined over the two years. The data were also analyzed using principal components and cluster analysis. The results showed significant differences between genotypes for all the traits except internodes length and Inflorence number per plant at 0.01 and 0.05 level. Genotypes No. 324 with average values of 10 ton h-1 and 432 Kg h-1 produced higher forage dry matter and seed yield respectively, than other genotypes. Using principal components analysis, the most important variables for dry matter yield and seed yield were identified. First three independent components accounted for 81% of total variation. The first principal component indicated that forage dry matter yield, internodes length, canopy height, inflorence per plant and persistency were important characters for classification with 55% of total variation. Seed yield, inflorence per stem, seed per inflorence and thousand grain weight were important characters in the second component. In the third component, inflorescence per stem, floret per head and growth habit were determined. Based on the results, it was suggested that components 1,2 and 3 could be known as forage yield, seed yield, and growth habit components, respectively. Based on Ward cluster analysis, entries were divided into 3 groups. Genotypes in cluster number 1 (1753, 4 and 618) averaged well above the overall mean for seed yield and seed components.  enotypes in cluster number 2 (324 and 1568) that were exotic germplasm, had higher values for dry matter yield and its components. Genotypes in cluster 3 were poor for both seed and forage production.