Iranian Journal of Rangelands and Forests Plant Breeding and Genetic Research
Year:2002 | Volume:- | Issue:7|Papers Count:12

In order to examine and evaluate the variation and process of deterioration of accessions of Bromus tomentellus seeds, which have been collected in natural resources genebank, research programs were carried out using 22 accessions. All of the accessions were examined in a complete randomized design with three replications under two different conditions, germinator and glasshouse. The recorded traits of the Germinator test included, germination percentage (G.P.), speed of germination and vigor. The recorded traits of the test in glasshouse, included G.P., speed of germination, plant height, number of tillers and root length in 40 days after planting.Significant differences were found between accessions for all of the studied traits. Variation between accessions was significant in one or both of the environments.The results of correlation coefficient study showed that, 1000 seed weight could affect G.P. and preliminary growth of plants in the both environments. Speed of germination, could be very good indicator of seed vigor. This result was confirmed by regression model. Negative correlation was found between reduction of G.P., speed of germination and seed vigor in germinator condition and G.P., speed of germination and plant height in glasshouse condition. Therefore, seed deterioration not only reduces G.P. but also decreases the speed of germination and seed vigor. In all of the Bromus tomentellus accessions, because stored samples of each year were different from other years, therefore reduction of G.P., was highly affected by origin of the accessions. It was not possible to differentiate between the effect of maintaining condition and origin of the seeds. It was suggested that, for better genebank management, accessions, have to be considered as regeneration unites of collected seeds.

In order to evaluate induced genetic variation of Populus euphratica Oliv. through cell culture, cytological and isozyme electrophrosis analysis were carried out. To induce genetic variation, immature influences of female tree containing microspore mother cells were isolated and cultured. Significant different was observed between growth regulator hormone treatments for callus induction at 0.01 level. MS medium supplemented with 2 mg/l 2, 4-D and 0.1 mg/l kinetin produced higher callus from immature influences and showed significant differences with the other hormonal treatments at 0.01 level. The calli were subculture for8 month in MS medium to increase variation among regenerated plantlets. Higher plant regeneration (75.5 %) was observed in solidified MS medium containing 3 mg/l BA and 0.5mg/l NAA. High degree of morphological behavior (leaves and stems) was observed among regenerated plants. Cytological analysis on root tip of regenerated plantlets showed the presence of haploid, diploid, aneuploid and polyploid plantlets.

Variation in breeding systems of different plant species has been observed. Cross and self-pollination and apomixis are the main methods of seed production in plant species. In present research work, it has been tried to find out breeding systems of five grass species, namely Agropyron elongatum, A. pectinoforme, Festuca ovina, Secale montanum and Bromus percicus. Assays of flower organs in these species have shown that, situations for cleistogamy are suitable. Thus for determination of either cross-pollination or self-pollination, isolation in species were used. S. montanum, and B. persicus, in isolation and non-isolation, expressed the same seed production. So, they could be classified as cross pollinators, since they produced seed in isolated conditions. A. elongatum had shown to be self-pollinator with some percent of cross-pollinations.Pollen morphology testing is another method for determination of pollination systems, which was used in this research, but because of Lack of access to suitable microscope, electron microscope, there were no acceptable differences between pollens of the plant species.

Vitrification (Hyperhydricity) is a problem which often occurs in in vitro culture of woody plants. Vitrified shoots are abnormally glassy, thick and translucent. The so-called vitreous plants appear turgid, watery at the surface, less green and easily breakable. During the study tissue culture of Eucalyptus spp., vitrified leaves and tissue were mostly observed in E. camadulensis and E. viminalis. Type and concentration of gelling agents, vessel types and also antivitrification agents to overcome such physiological disorder were examined for both species. The percentage of water content of tissue with Phytogel was significantly more (88.22%) than tissue with agar (81.29). Moreover, shoots of E. camadulensis grown on medium with 7.0 gr-1 Bacto-agar exhibited low levels of vitrification. The ant vitrifying agent EM2 statistically decreased vitrified shoots with higher concentration of agar in E. camaldulensis. Results also showed that there was no significant difference between effects of the two agar concentrations in E. viminalis, but the antivitrifying agent EM2 at 5.0 gr-1 significantly reduced vitrification in comparison with control. Despite the lower growth and proliferation of the micropropagated shoots on the medium supplemented with EM2, the shoots produced with high quality and most of them were free of any symptoms of vitrification.

This research was carried out to study the relationship between different populations of several medic species based on morphological characters and to determine the best character for detection of genetic variation between the species and populations, in order to prepare basic information required for breeding projects as well as primary assessment of the medic populations. In this study eleven populations of annual medic belonging to seven species from Gene Bank of Natural Resources of Research Institute of Forests and Rangelands were prepared. Nine characteristics were recorded from five single plants in every experimental plots. Averages of these data were used in this paper. Then correlation analysis was performed between all combinations of the characters, using principal components analysis. The role of each character was determined in the available variation of the data. Several principal components were produced to identify the nature of the variations as well as ploting the first two components to visualize the relationship between the populations. Cluster analysis was also used for grouping and clustering the populations for the same purposes.

Seed collected from twenty three single trees from different parts of the country were used in this study. After seed storage protein extraction, SDS-PAGE method of electrophoresis was used to investigate existing genetic variation between the mentioned genotypes, in protein's macromolecule level. Performing electrophoresis, fixing and staining the electrophoresis gel and protein bands, presence and absence of the particular bands along the gel was studied. Although, significant differences were not observed between the genotypes of each species based on the protein bands to be used for genotype classification within the species, but significant differences were observed between the two species, Haloxylon persicum, H. aphyllum.

In order to mass usability of appropriate culture vessel for the use in the plant cell and tissue culture laboratories and with modification of outgoings, the glass vessels which are used in food industries in the commercial name of "Perarin" were investigated. These vessels had all of the required specifications for the culture, including limpidity and autoclavability but the mere difference with standard vessels was the type of lid. Therefore, to make comparison between existing lids (Aluminium lids) with standard polypropylene lids (Sigma Co.) and their effects on growth of the model plants, the experiments were undertaken on potato plants on the hormone free MS medium with two factors of type of lid and different light density with five replications. Results indicated relative superiority of vented lids and lying cultures with metallic lids, by the positive effects of increasing ventilation and vertical penetration of light. With the view of aerial growth to root ratio, there was no significant difference between the two types of lids which indicate possibility of using the metallic lids. The comparison of different light density showed that it is essential to supply sufficient light density (up to 60 mmol m-2s-1) for appropriate plantlets growth.

The objective of this research experiment is determination and evaluation of percentage of germination, total speed of germination and vigor index of seeds of 9 medicinal plant species. According to the International Seed Test Association (ISTA), different tests including standard germination test with normal condition and standard germination test with prechilling condition were used for determination of percent and total speed of germination of the species. The vigor indices were calculated by following equation: percentage of germination x mean of total length of root and shoot. The results were a function of the results of percent of germination and total speed of germination.