Iranian Journal of Rangelands and Forests Plant Breeding and Genetic Research
Year:2004 | Volume:12 | Issue:2|Papers Count:9

Drought stress in plants in arid and semi arid zones is a normal phenomenon. Inviter selection using tissue culture can help to determine and evaluate the tolerant genotypes. It could be used as a complementary of a classical breeding method for producing, maintaining and applying of germplasm. In this experiment, a Yazdi seed which was selected previously using in vivo selection for drought tolerance, was used. Assessment and selection of calli in a completely randomized design (CRD) with control and different concentration of polyethylene glycol (PEG) 30, 60, 90, 120 and 150 gr/lit, (10 replication in each treatment) was carried out. In the next step, the rate of regeneration and invitro selection is evaluated for drought tolerance with 40 replication in each treatment. In hydroponic experiment, plant selection for drought tolerance was done in - 12bar potential. The results of invitro selection showed that low concentration of PEG, has not significant effect on callus production. There was no significant difference on seed germination and plantlets growth, in population derived from different seeds under PEG stress.

This study was conducted to investigate the responses of blond psyllium (plantago ovata Forsk.) to drought stress during the heterotrophlic seedling growth. The experiment was designed to verify the effects of six osmotic potential and two seed populations in a factorial arrangement using CRD with three replications. The drought stress levels and control included 0, -3, - 6, -9, -12 and -15 bar at PEG 6000. The seed populations were collected from Golestan and Isfahan provinces. Morphological characteristics, including shoot and root length and shoot/root ratio were analyzed. The shoot length between two seed populations was significantly different (p<0.01), but the root length did not show any significant difference. The SIR ratio between two seed populations was also significantly different (p< 0.05).

In order to study genetic variation on forage and seed yields and their components among 12 varieties of white clover (Trifolium repens L.), a randomized complete blocks design with three replications was conducted  over two consecutive years in Karaj, Iran. The data were collected for leaflet size, internodes length, petiole length, canopy height, stolon density, internode thickness, persistency, head density, head per stolon, floret per head, seeds per floret, 1000 seed weight, seed yield and dry matter yield. Results showed significant differences between the genotypes for all of the traits except for head density and thousand seed weight. The varieties of Alice, Huia, Chiftan and Aran with average values of 14.2, 12.8, 12.2 and 11.8 tha-1 produced higher forage dry matter yield. For seed yield Alice and Mikanova with average values of 148.7 and 122.4 kg h-1 had the highest seed production per year, respectively. The results of correlation analysis showed positive and significant relationships between forage yield and canopy height, leaflet size, stolon density, petiole length and persistency. Seed yield had positive relationships with both 1000 seed weight and floret per head. Using principal components analysis, the first three independent components accounted for 80% of the total variation. The first principal component indicated that forage dry matter yield, canopy height, head per stolon, petiole length and persistency were the important characters for classification with 52% of the total variation. Seed yield, floret per head and thousand grain weights were the enetial characters in the second component. Based on the results, it was suggested that components 1 and 2 could be known as forage yield and seed yield. Based on Ward Cluster Analysis, entries were divided into 3 groups. Accessions in cluster 1 (Huia, Chiftan and Aran) and cluster 2 (Alice, Mikanova and Avoca) averaged well above the overall mean for forage dry matter and seed yield, respectively.

To evaluate the germination and dormancy breaking of seeds in Natural Resources Gene Bank, regard to ecological condition of their habitat, many specific treatments were used. The treatments included prechilling (30, 45 and 60 days) on two beds (sand and filter paper), chemical scarification with sulfuric acid (10-60 min) and hot water (70-80°C). In addition, the effects of container material, seed coats and seed origin on viability of Medicago Sativa maintained in uncontrolled storage was investigated. The results showed that the optimum condition similar to habitat condition must be provided, in order to overcome seed dormancy. In most species with intermediate origin, the prechilling was the effective factor for breaking seed dormancy. The sand bed was more suitable for germination of large seeds. To conquer conquer in tropical seed and seed of legume family, the hot water and sulfuric acid were better treatments respectively. In Medicago sativa, the type of container material (hemp and nylon) affected seed viability, so that after 9 years, the seed lot in hemp container had a higher viability than which contained by nylon. The results showed that decreasing viability in the un-coated seed of M truncatulla was greater than the coated seed. Therefore, the rate of deterioration of the coated seed and the uncoated seed were 1.49% and 3.57%, respectively.

Mountain Rye (Secal montanum) is one of the important perennial forage grasses that grows in Iranian pasture and rangelands. In order to evaluate relationships between seed yield, forage dry matter yield and their components, 10 domestic ecotypes of this species were planted in Agriculture Research Station, Brojerd, Iran. These ecotypes were evaluated under optimum irrigation and dryland farming system using 2 separate complete blocks design with three replications in 2002. The data were collected and analyzed for flag leaf length, plant height, spike length, spike number per area, peduncle length, seed number per spike, thousand grain weight, seed yield, dry matter yield and harvest index in 2003. The results showed significant relationships between seed yield and spike length (r=0.78) and seed yield with thousand grain weight (r=0.79). Forage yield had a positive and significant relationship with plant height, peduncle length, seed number per spike and thousand grain weight. Two separate stepwise regression analysis were used for seed yield and forage yield (as dependant variables). The results showed a significant effects of spike length, spike number and seed number per spike on seed yield production (R2=0.92). For forage dry matter yield, the following traits; plant height, seed number per spike, flag leaf length, harvest index and spike length, were included in regression equation model. The results derived from path analysis indicated that, spike length and spike number per area had significant effects on seed yield. For dry matter yield, plant height had the most direct and indirect effects through increasing spike length and harvest index on forage production.

Genetic variation is the base of plant breeding so that plant selection with desirable characters be possible. One of the methods for determination of genetic variation among the plant species is the use of electrophoresis method. In this research for evaluation of genetic variation between perennial Trigonella, seed samples of six accessions from Natural Resources Gene Bank, Research Institute of Forests and Rangeland and two accessions from Fars province were under investigation.Electrophoresis of seed storage proteins was carried out by SDS-PAGE method. In this experiment, 16 different bands were observed and according to the results, banding patterns in some multitude were similar and others were completely different. Most bands belonged to genotypes 770 and 7271 and the lowest bands belonged to genotypes 120 and 460. The accessions with the same banding patterns, located in a same group in cluster analysis. The similarity between accessions was 29.29 percent.

Genetic diversity in eight genotypes of Rosa damascena Mill. from west parts of Iran, was analyzed in a randomized complete blocks design with three replication, at the experimental field at Research Institute of Forests and Rangelands in 2003 and 2004. Principal components analysis (PCA) and cluster analysis were applied, in order to analyze flower yield and its components including flower number, single flower weight and dry matter percentage of flower and also morphological characteristics, such as plant height, canopy, branch angel, leaf number, leaflet size, spine density and spine length. The results showed significant differences among genotypes for-all of the traits. The first four components determined 87.88% (34.86%, 22.41%, 16.95% and 13.66%, respectively) of the total variation. The highest special values for flower yield belonged to the fourth component, based on which genotype of Azar-W Province could be selected for this trait. Cluster analysis classified the genotypes in 3 groups, based on the traits under study. It could then concluded from the results that a considerable genetic variation in Rosa damascena germplasm originated from west parts of the country. Also the highest heterosis could be achieved, through combining genotypes in the first and third groups.