Iranian Journal of Horticultural Science and Technology
Year:2005 | Volume:6 | Issue:2|Papers Count:6

Experiments were conducted to micropropagate the garden thyme (Thymus vulgaris L.) using stem single-node explants. Ten mm long stem explants were disinfested by 10% liquid bleach for 10 min and then rinsed three times with sterilized distilled water. Fun and half-strength Murashige and Skoog (MS) media were compared. Both media were supplemented with benzyladenine (BA) and α-naphthaleneacetic acid (NAA) at different concentrations. The best proliferation rate was obtained using medium containing 1 mg 1-1 BA and 0.2 mg 1-1 NAA. In a separate experiment, the explants were four times sub cultured on a medium containing best growth regulator concentrations of establishment stage with a 4-week interval. No significant differences were found between subcultures. For rooting, shoots were placed on MS medium supplemented with different concentrations of growth regulators, 25 g 1-1 sucrose and 8 g 1-1 agar. After 8 wk the best rooting treatment was application of 1.25 mg 1-1 NAA without BA. Rooted plantlets were transferred to pasteurized media consisting a mixture of 1/6 peat, 1/6 sand, 1/6 loam soil and 3/6 perlite. Plantlets were gradually acclimatized to natural conditions after 2 weeks.

Dezful region has a suitable climate for grapefruit production. Exporting this product to neighbor countries has been increased in recent years. In order to select the best rootstocks for commercial cultivars, an experiment was conducted from 1997 to 2001 at Safiabad Agricultural Research Center. Two cultivars of grapefruit, 'Ruby Red' and 'Marsh Seedless', were bud grafted on eight rootstocks namely: Cleopatra mandarin, Citrus amblycarpa, Kin mandarin, Citrus volkameriana, Swingle Citromelo, Carizo Citrange, Citrus aurantium and Troyer citrange. The experiment was arranged in a split plot (with cultivars in the main plots and rootstocks in subplots) layout with complete randomized block design. The results were evaluated from fifth year when trees commercially productive. The results revealed that there was a significant yield differences between rootstocks at 1% level of probability. Citrus volkameriana and Carizo citrange showed better performance than other 6 cultivars. 'Roby Red' on these two rootstocks produced 18211 and 16459 kg ha-1. yield and compared to Citrus aurantium there was an increase of 111.81 and 91.44 percent, respectively. 'Marsh seedless' on volkameriana rootstocks produced 15006 kg ha-1, and on Carizo citrange produced 11793 kg ha-1 yield compared to sour orange rootstocks showed an increase of 43.83 and 13.04 percent.

In spite of being the main commercial substrate in the world, peat moss is not so economic for grower to use because of its high cost. The purpose of this study was to investigate the substitution of peat moss with some organic wastes as growing media. The study was conducted on pathos in college of Agriculture, Tehran University. A factorial experiment was arranged using a completely randomized design with 6 replications. During this experiment the effects of 4 organic media including: peat moss, coca peat, palm peat and baggasse with two level of perlite (0 and 50%) on pothos growth were investigated. The highest values of leaf area, leaf number, offset number, shoot and root fresh and dry weights and shoot length were observed in coca peat and the lowest values of measured growth indices were obtained in baggasse. Peat moss and palm peat showed similar effects on most growing indices. Coco peat and palm peat were similar in some of their characteristics such as CEC, pH, bulk density and total porosity but different in water holding capacity which was higher in coco peat than the other. If this characteristic of palm peat be improved, it would be a good substitute for peat moss in future. The results showed that baggasse was not a proper organic media. Coco peat despite of having best result on plant growth rate is not recommended because it is an imported media and is not so economic. The results of adding perlite to media were different according to the type of media.

To investigate the interaction of scarification, stratification and gibberellic acid (GA3) treatments on the seeds of golden rain tree, the following treatments were used: concentrated sulfuric acid for 0, 30, 45 and 60 min, stratification at 3-5°C for 0, 15, 30 and 60 d and GA3 with the concentrations of 0, 100, 200 and 300 mg rl. Results indicated that the highest germination percentage (67%) was obtained from 60 min acid scarification with 60 d stratification. The interaction between seed coat removal and stratifying for 0, 5, 10, 15, 20, 25 and 30 d was also studied. Results indicated that the highest germination percentage (96.3%) was obtained from seed coat removal and keeping the seeds for 30 d at stratification temperature. Among all treatments, the highest germination rate (2.4) was obtained from seed coat removal and 25 d stratification. Similarly, the highest germination value was also obtained from the same treatment. Finally, it was concluded that golden rain tree seeds had a double dormancy of both seed coat and embryo dormancies. Results of using treatments on Chinese rain tree seeds indicated that scarification and stratification could only enhance gennination rate, and since just scarification improved seed germination, it was concluded that the seeds of Chinese rain tree had only seed coat dormancy.

Genomic DNA extraction with a high quantity and quality is one of the most important primary needs in genomics laboratories. Extraction of DNA from woody plants, such as fruit trees, besides the presence of polysaccharides, is faced with the problem of phenolic compounds, which negatively affects the DNA quality. Therefore, use of methods for DNA extraction to be able to reduce these compounds to the lowest level is highly preferred. In order to select the best genomic DNA extraction method from pomegranate plant tissues, which is distinct in phenolic compounds, six DNA extraction methods were compared. The methods were: 1- Vroh Bi et al. (1996), 2- Dellaporta et al. (1983). 3- Ziegenhagen et al. (1993). 4- Doyle and Doyle (1990), 5- Lodhi et al. (1994), 6- Murry and Thompson (1980). Young, mature and old leaves and also peel and aril of fruits were used as plant materials for DNA extraction. Quantity and quality of extracted genomic DNAs were compared using the spectrophotometric, agarose gel electrophoresis, digestion by restriction enzymes and polymerase chain reaction (PCR) methods. Ultimately, considering the quantity and quality of DNA, the method of Vroh Bi et al. for young, mature and old leaves and also fruit parts and the method of Murry and Thompson for young leaves were chosen. Highest amount of DNA (64.7 µ.g) from 1 g young leaf tissues with good quality was obtained using Vroh Bi et al. method, which was not significantly different from the amount of extracted DNA (62.4 p.g) from 1 g mature leaves. According to the results, the method of Vroh Bi et al. is recommended for DNA extraction from different tissues of plants having high level of polysaccharides and phenolic compounds.