Iranian Journal of Rangelands and Forests Plant Breeding and Genetic Research
Year:2002 | Volume:- | Issue:8|Papers Count:10

Application of Lalium germplasm in breeding of available Lalium species requires sufficient information about different aspects, including variIous karyotypic characteristics. For this reason, nine populations of Lalium multiflarum and L. rigidum species, randomly taken from Natural Resources Gene Bank, were investigated for karyotypic characteristics. Five metaphase cells were studied from each population for several karyotypic characteristics, including long and short arm length, by which total length of the chromosomes, long arm to short arm and short arm to long arm ratios were calculated. The number and locations of the possible satellites were also identified. Using several available estimation formula, karyotypic asymmetry of the populations were also investigated. Using Levan ratios, karyotypic formula of the populations and species were also determined. Amongst the studied populations, two populations were tetraploid, five populations were diploid and two populations were a mixture of tetraploid and diploid genotypes. Several populations had one to two satellites on their chromosomes. Most of the observed chromosomes of the populations were metacentric, in which the centromers were located in median region. Based on one of the karyotypic asymmetry measurment parameters, DRL, within the tetraploid populations, two populations of L. multiflorum showed the most symmetric and asymmetric karyotypes. Within the diploid populations, a population of L. rigidum species showed the most symmetric and a population of the L. multiflorum species showed the most asymmetric karyotype.

Artificial hybrids were produced using embryo rescue technique. For evidence of heterosis among these interspecific hybrids, stem cutting of parents (Populus euphratica OLIV. and Populus alba L.) and three years old field grown hybrid trees (Populus euphratica OLIV.X P. alba L. hybrid and Populus alba L. X P. euphratica OLIV.) were rooted in a green-house and transplanted to a nursery plot. There were significant differences between parents and progenies based on height and basal diameter for both kinds of hybrids. High-parent heterosis effects were observed for hybrids in diameter and height characters. In spite of significant increase of diameters for both hybrids, the higher amount of hetrosis was detected for height (96.42% for Populus euphratica OLIV.X P. alba L. and 92.85% for Populus alba L. X P.euphratica OLIV.).

In pistachio, the majority of fruits does not reach maturity and drop up to 8 weeks after pollination. The fruits that reach maturity, a proportion are abnormal, seedless (blank) or their shell is not split. In this study, pollination and fruit development were investigated in relation to abscission and abnormalities.A medium containing 1% agar and 10% sucrose was used to assess the pollen quality. Fresh and 24 hours dried pollen showed high germination in vitro as did pollen stored at freezer (-15°C) up to usage time. The stigma surface of Pistcia vera turned to pale red with some secretion on top and among papillas at anthesis. Female Pistacia vera trees were hand pollinated with pollen from male of P. atlantica and P. vera at 0, 1, 2, 3, and 4 days after anthesis. Results were measured by mature fruit set and by fluoresence microscopy of pollen germination and tube growth in the pistil. Maximum pollen tube growth and fruit set of split nuts were achieved following pollination within two days of anthesis. Three days old pistils supported pollen tube growth, but fruit set was low. Four days old pistils supported little pollen tube growth and fruit set. Significant differences were also apparent between pollen parent, with low pollen tube growth and fruit set following inter-specific pollination with P. atlantica pollen. All pollen tubes were observed to penetrate chalazogamously, and parthenocarpic production of blank fruits occurred in both unpollinated and pollinated treatments. The results indicated that for optimum fruit production of pistachio, pollen transfer must be achieved within two days of anthesis and inter-specific pollinator genotypes should be abandoned.

This research was carried out on seed storage proteins of several medic species (annual Medicago species) using an electrophoresis method, in order to investigate their genetic relationship. For this purpose, seeds of twelve populations of eight medic species were prepared from Alborz Research Complex.SDS-PAGE method of electrophoresis was carried out in five replications on the seed storage proteins. First, to optimize the method of electrophoresis on medic seed storage proteins, two protein concentrations and two gel concentrations were examined. The 'best result was obtained when a low concentration of the protein and a high concentration of the seperator gel were combined. Using the best prepared gel, the distances of each band was measured from the loading well. Presence or absence of the common bands was also specified by 1 or 0 respectively. Using cluster analysis, the populations were classified and their genetic relationship was discussed.

Regarding the importance of different Mentha species from different point of views, such as food industry, medicinal and health subjects and also regarding the necessity of achieving efficient tools in distinguishing different species, seven species and varieties were studied in this research for anatomic aspects. For these reasons, sections were prepared from stems and leaves of the species and various characteristics were studied by photomycroscope.General pattern of the stem sections were almost similar between the species. However, there were some differences between them for density of collanchim tissue, type and density of trichomes. Type and density of upper and lower epiderm trichomes of leaves followed the stems trichome patterns. There were also some differences between the species based on the type of the leaf parenchyma tissues of the species. The dominant stomata type in the species was diacytic, but anisocytic type of the stomata was also observed in one of the species. The species were significantly different in density and length of the stomata.

In order to study the effect of sulfuric acid concentration on dormancy breaking of silk tree (Albizia julibrissin L.) and Carob tree (Ceratonia siliqua 1.), two separate experiments were conducted under laboratory conditions. Each of experiments had 5 treatments of sulfuric acid concentrations (0, 6.25, 12.5, 25 and 50 percent). The experiments were completely randomized design with 3 replications. In the first experiment (Silk tree), the result showed that as the rate of sulfuric acid increased, the germination percent and germination speed were increased. The highest and lowest values were obtained in 50% and 0% sulfuric acid treatment respectively. But, there were no significant differences between 6.25, 12.5 and 25 percent of sulfuric acid. In the second experiment (Carob tree) contrast result were obtained. Increasing of acid concentration were led to a decrease in germination percent and speed of germination, however there were no significant differences between the treatments.

Water deficit is the most predominant environmental stress, limiting plant growth and productivity. However, there are considerable differences in sensitivity to adverse conditions, between or within species. Therefore, improvement of drought tolerance is suggested as one of the most desirable breeding objectives. This study was conducted to assess differences in stress responses, in order to screen drought tolerant genotypes of Rosa damascena.Plant survival, vigor and growth components in different genotypes of Rosa damascena were analyzed. There was a considerable variation for water deficit responses. All of the characteristics including plant vigor, survival, leaflet number, leaf area, branch number, and the longest branch were found to be significantly different in the drought stressed genotypes, in recovery environment. Also, plant survival correlated positively with plant vigor, leaflet number, leaf area, branch number, and the longest branch. Positive correlation was also revealed between plant vigor and leaf area, leaflet number, branch number and the longest branch. The variation in growth components detected between the genotypes, and the correlation between different traits, could support a suggestion for improvement of Rosa damascena, towards a capability of growth in semi-arid and arid conditions.

Effects of five NaCl dosage treatments, 0, 50, 100,150, and 200 mM were carried out on germination of two rangeland species including Melilotus officinalis and M.alba. Germinatin percentage, radicle and plumule length were recorded and the data were analyzed by one-way ANOVA. The salinity showed a significant effect on germination percentage and radicle length but not on plumule length. Also, polynomial analysis of results showed a significant effect with a linear trend. In Malba salinity effects on all traits were statistically significant. Polynomial analysis on germination had a linear trend, whereas, radicle and plumule length had squared trend. Bivariate correlations coefficient in M. officinalis, between radicle and plumule length and between radical and germination percentage were statistically significant. In M.alba, correlation coefficient between radicle length and germination percentage was significant.