Journal of Plant Ecophysiology
Volume:2 Issue: 3, 2010

In order to study genetic diversity in alfalfa ecotypes collection, 140 ecotypes collected from various regions of Iran and the world were investigated during 2006-2007. Mean of the studied traits calculated for both growing seasons was used for analysis. Simple correlation coefficients between traits, multiple regression, stepwise regression and principal component analysis (PCA) were carried out. Dendrogram of alfalfa ecotypes was created based on Euclidean distances. Traits correlation analysis revealed that weight of herb, number of stem in the herb and plant height had significant positive correlations with green matter yield. The stepwise regression analysis showed that only weight of herb among the other independent variables had a significant positive effect on green matter yield. Alfalfa ecotypes were grouped into 8 clusters. The PCA analysis showed that the first three principal components explained 78.2% of the total variability among the alfalfa ecotypes. Cluster analysis in this study did not separate Iranian ecotypes from foreign ecotypes. It is probably related to traits which did not show high variability in the studied ecotypes. Almost Iranian and French ecotypes were placed in one cluster. Alfalfa is believed to belong to Caucasus region: northeastern Turkey, Turkmenistan and north western Iran; thus, it can be supposed that the French ecotypes have been introduced from Iran and adapted to the climate conditions of France.

As a plant from the family of Brassicaceae, turnip is of interest worldwide because of its food and medicinal properties. However, no study has been carried out for identifying and evaluating its genotypes in Iran yet. The current study was conducted for the evaluation of genetic diversity of 18 Iranian indigenous turnip accessions as well as one British cultivar, Top Millan, by 27 morphological traits under field conditions in Yazd Agriculture and Natural Resources Research Centre, Yazd, Iran in 2010. According to the analysis of variance, there were significant differences in most vegetative traits of the accessions. The results showed that the accession Chenaran had the highest storage root weight, big diameter and small diameter (186.6 g, 52.57 mm and 70.35 mm, respectively). The accession Esfahan had the highest leaf number (16 leaves) and the accession Tabas had the highest flower number (1672 flowers). The results of correlation analysis showed positive significant correlation between some important traits such as leaf size and storage root size and weight. In factor analysis, nine independent major factors explained 87.35% of total variance and cluster analysis grouped the accessions in seven groups. The genetic diversity of samples did not conform to their geographical distribution. In total, the results indicated that the studied genotypes had high diversity and are appropriate genetic resources for breeding programs.

'Khassib' cucumber was grafted onto five Cucurbita rootstocks including three interspecific hybrids and two native cultivars to examine scion-rootstock compatibility and to correlate plant performance under greenhouse conditions. Commercial cultivars, 'Azman', 'Ferro' and 'RS841' and 'C. maxima' and 'C. moschata' were used as rootstock and non-grafted plants used as control. Plant length (at 30 day after planting, DAP and end of experiment), leaf number (30 DAP), hypocotyl diameter for rootstock and scion and internodes length (30 DAP); fruit yield (at early, middle and final harvesting periods), ratio of length to diameter, dry matter and ratio of marketable to unmarketable fruits were recorded. Various rootstocks were significantly different in survival rate with 'C. maxima' having a higher rate. Vegetative growth of the grafted cucumber varied markedly, indicating differences in compatibility between the scion and rootstocks. Significant differences in fruit yield were found in cucumbers grafted onto various rootstocks and 'RS841' had higher fruit yield at early and final harvests. At middle and final harvesting periods, the plants grafted onto 'C. moschata' and 'Ferro' had higher yields, respectively. Significant differences were found among different rootstocks for fruit characteristics except fruit length to diameter ratio. According to the results, among the tested rootstocks, 'RS841' is the best one for cucumber cv. 'Khassib' duce to its high survival rate and high fruit yield.

Hoary alyssum (Berteroa incana L.) is a rangeland weed of British Colombia, Canada and a prolific seed producer. Knowledge of spatial and temporal dynamics of seed banks and factors affecting them is essential to understand the persistence strategy of this weed. Little information on distribution of B. incana seeds dormancy and modification of germination behavior by climatic factors is available. The hoary alyssum seed dormancy and temperature influence on seed germination were investigated. Effects of temperature on seed germination and dry heat on seed viability were studied in Petri dish assays. B. incana seeds showed that 25-30°C were the optimal temperatures for germination; germination did not occur at 40°C and above, exposure to dry heat (80 or 90°C) for 8 hr significantly reduced seed germination at 25°C. While 1 to 3 d of anaerobiosis delayed seed germination (by ~1 d) upon their subsequent incubation in Petri dishes at 25°C, it did not induce dormancy. A 5-d anaerobiosis reduced seed germination by 24-47 %.

To evaluate the effect of sulfuric acid (75%) on breaking the dormancy of the seeds of goosefoot (Chenopodium album L.) and red-root amaranth (Amaranthus retroflexus L.) as potato weeds, an experiment was conducted in Seed Technology Laboratory, Department of Agronomy, University of Mohaghegh-e-Ardabili, Ardabil, Iran in 2010 based on a Randomized Complete Design with three replications. The treatments included pretreatment of the seeds of both species with sulfuric acid (75%) for 0, 7, 14, 25 and 45 minutes. The results showed that with the increase in the duration of treatment with sulfuric acid (75%), the germination percentage of amaranth seeds increased from 2% to 78.5% and its germination rate increased from 0.8 to 4.4 but radicle length and weight decreased from 32 to 7.4 cm and from 0.00054g to 0.00001 g, respectively. There was no significant difference among the treatments of pretreatment with sulfuric acid for 7, 14 and 25 minutes. The highest and lowest germination rates were observed in 45-minute pretreatment with sulfuric acid and control, respectively. With respect to goosefoot seeds, no germination and seedling growth was observed after treated with sulfuric acid (75%).

Genetic diversity is the basis of plant breeding and selection depends upon the existence of an appropriate diversity for the trait being selected for. Given that the yield of crops is a function of genotype, environment and their interactions and that to realize a high yield, the selection is more efficient when conducted for the yield components rather than yield itself, the study of the relationship between yield and its components is crucially important in breeding programs. In the current study, 30 durum wheat genotypes originated from Iran and the Republic of Azerbaijan were planted on the basis of a Randomized Complete Block Design with two replications under rain-fed and irrigated conditions in Ardabil, Iran. The results of the analysis of variance of the evaluated traits showed that the effects of genotype and the interaction between genotype and environment were significant. Since the interaction between genotype and environment was significant, genetic correlation rather than phenotypic correlation was used for studying the relations among the traits. The results of genetic correlation analysis between yield and the traits remained in ridge regression model showed that 1000-grain weight had the highest direct effect on yield, but the highest indirect effect of this trait was applied through plant total weight, although 1000-grain weight showed the highest direct effect in phenotypic correlation analysis, too. Moreover, fertile tiller number had the strongest negative direct effect on yield.

An experiment was conducted in experimental field of Department of Agriculture, Islamic Azad University, Takestan branch, Iran in 2009 to study the effect of irrigation stop at different growth stages on some agronomical traits of sunflower under three plant densities. It was a split plot experiment based on a Randomized Complete Block Design with three replications. The treatments of irrigation stop included irrigation stop at 6-8-leaf stage, at budding stage and at flowering stage as well as control (normal irrigation). The irrigation treatments were regarded as the main plot, and plant density with three levels of 66000, 83000 and 110000 plants/ha as the sub-plot. The studied traits included head diameter, unfilled grain percentage, biological yield, grain number/head, 1000-grain weight, oil content and grain and oil yield. The results showed that different irrigation levels had significant effect on plant height, head diameter, grain number/head, 1000-grain weight and oil content. The lowest amount of all traits was obtained at the treatment of irrigation stop at 6-8-leaf stage. In addition, different plant densities had significant effect on plant height, stem diameter, head diameter, 1000-grain weight and oil content. The interaction between irrigation stop and plant density significantly affected such traits as unfilled grain percentage, biological yield and grain and oil yield. The treatment of normal irrigation at the density of 110000 plants/ha produced the highest grain yield (5033.7 kg/ha) and the treatment of irrigation stop at 6-8-leaf stage at the density of 66000 plants/ha produced the lowest one (528.2 kg/ha). Considering the dependence of oil yield to grain yield, the same treatments produced the highest and lowest oil yield, respectively, too.

Eglantine rose (Rosa foetida) is an important wild, yellow rose species from Rosaceae family with tiny flowers. It is propagated by such methods as cutting and transplanting. Besides being time-consuming, these methods have usually some problems. Therefore, in the current study the effect of different hormonal concentrations and culture medium on micropropagation of this species was studied in tissue culture medium using axillary shoot explants. The experiment was carried out as a factorial based on a randomized complete with three replications. The results of analysis of variance showed that the number and height of shoots had no significant difference in each explant in two culture media of MS and MS 1.2. However, different concentrations of BA and IBA had significant effect on the number and height of shoots. Means comparison showed that the BA concentration of 4 mg/l with a mean shoot number of 3.75 and IBA concentration of 0.1 mg/l with mean shoot number of 3.166 had the highest effect on shoot number. The BA concentrations of 4, 2 and 6 mg/l with shoot heights of 2.866, 2.833 and 2.375 cm, respectively and IBA concentrations of 0.1, 0.2 and 0 mg/l with shoot heights of 3.06, 2.953 and 2.845 cm, respectively ranked in group A and had the highest shoot height. The BA concentration of 4 mg/l and IBA concentration of 0.1 mg/l had the highest effect on both shoot number and height. The effect of environment on rooting percentage and root number was highly significant. Also, the effect of IAA and IBA hormone on root number was significant. The best culture medium for increasing root number and percentage was found to be MS 1.2 with an IAA concentration of 1.5 mg/l and IBA concentration of 1 mg/l.