M. Azimi, S. Massiha, M. Moghaddam, M. Valizadeh,
Volume 3, Issue 4 (1-2000)
Abstract
In order to study the genetic variation among local varieties of onion in Iran, an experiment was conducted in the Research Center, Faculty of Agriculture, Tabriz University. Sixteen populations were evaluated for agronomic characteristics and also total seed proteins via SDS-PAGE. Cluster analysis and principal component analysis were used to group the onion populations under study.
Analysis of variance showed significant differences among varieties for leaf color, leaf length, texture tightness, onion yield per plant, and number of edible layers. No significant differences were observed for the number of twin onions, bulb diameter, and onion dry weight. Hamadan (98-148), Arak (98-95, 98-96, 98-97, 98-103), and Zanjan (98-223) populations acquired the highest onion yield per plant. The significant differences between populations for the majority of characteristics proved the existence of genetic variation in the Iranian onion germplasm. The results from cluster analysis for agronomic characteristics were the same as those from the cluster analysis for the onion yield per plant. The 16 populations were divided into 4 groups. Cluster analysis for the electrophoresis banding pattern resulted in two groups, which was not similar to the dendrogram of agronomic traits. Using principal component analysis, the first principal components determined 97.57% of the total variation. Onion yield per plant was the most important trait in the first principal component and onion dry weight was the second trait in the rank.
S. A. Maybodi, A. R. Amini Hajiabadi, J. Khajeddin,
Volume 6, Issue 2 (7-2002)
Abstract
A number of halophytic species as Salicornia europea, Halocnemum strobilaceum, Aeluropus lagopoides, and Aeluropus littoralis were found to occupy a significant portion of the total vegetation of the surrounding area at the Zayande-Roud inlet to Gavkhoony wetland. However, their ecological demands and bioenvironmental factors by which vegetation community composition has been affected is not undestood. A compehensive knowledge of the establishment is essential for future improvements in using the above species on salanized regions. In this paper, using the ordination method. The establishment pattern of these four species in a range of varied habitats is evaluated based on the recongition of the relative significance of habitat soil chemical properties and vegetion crown cover to the establishment of the four species. For this purpose, 48 plants meansurements were taken along a transect, having more species variation in term of vegetation cover percentage. Furthermore, 48 soil samples were taken from the plot along the same transect in a one-year period in 1999. The soil samples were analysed for PH, EC, available Na, K, Ca and Mg as well as clay, and silt contents. The ground and field vegetation data were analysed using the Principlas Components Analysis (PCA), and Canonical Correspondence Analysis (CCA) to produce summary vectors (PCA axes) of both the soil chemistry and habitat vegetation structure datasets. The summary of ordination method quantified the degree to which soil variables and species cover were related to variability in ground vegetation composition. variation in community composition (type and percentage) was significantly related to gradient of the aforementioned soil factors. Generally, the vegatation community composition in this experiment could be considered as a key component to expand the growth and development patterns of these species to similar salinised regions.
R. Honarnejad, M. Shoai-Deylami,
Volume 8, Issue 2 (7-2004)
Abstract
The results of diallel analysis of 7 parents and 21 F2 progenies of Burley tobacco cultivars, which were transplanted in 2002 as RCBD with 3 replications in the Tobacco Research Center, Rasht, Iran, showed significant genetic differences among genotypes and high GCA and SCA for most of the traits. Therefore the role of additive and non-additive (dominant) effects of genes on the formation of the corresponding characteristics was important. The graphical analysis of progenies of diallel crosses showed partial dominant effect for nicotine percentage in leaves. The distribution of parents around regression line showed most dominant genes in cultivars B.CDL 28, B.Banket, and B.21 while cultivars B.14 and B.TN 86 hade most recessive genes for this characteristic. Also the low and high percentages of nicotine were controlled by dominant and recessive genes, respectively. Estimated simple (phenotypic) relationships between characteristics showed significant correlation between dry leaf yield of tobacco cultivars and its components such as leaf area index (LAI) (r = 0.482**), time to flowering (r = 0.440*), appearance of leaves (r = 0.648**) and percent age of dry matter of leaves. The path coefficient analysis showed very high direct influence of dry matter percent age of leaves, appearance of leaves, and LAI in dry leaf yield. These characteristics would be a favorite selection index for increasing tobacco yield, since characteristics such as leaves per plant, plant height and time to flowering have no significant direct influence on dry leaf yield of tobacco cultivars. These yield components explain 82% of variance of tobacco yield.
Results of factor analysis, using principal Component Analysis (PCA) with Varimax rotation showed that characteristics such as leaves per plant, LAI, and plant height with high positive and significant factor loading as a morphological factor explain 44% of data variance. The second factor including such traits as time to flowering, appearance, and percent of dry matter of leaves with high positive and significant factor loading, form a physiological factor. These two factors together explains 65% of variance of dry leaf yield of tobacco cultivars.
