مجله گل و گیاهان زینتی
سال یکم شماره 2 (پاییز و زمستان 1395)

Breeding and production of new varieties of ornamental plants as well as their propagation and development is an expanding industry. The application of ornamental plants in landscape and increasing the demand for new varieties has led the breeders to plan for production of new varieties with attractive colors, excessive perfumes, more durability and resistance to biotic and abiotic stresses. Generally, diversity is a basic principle in any breeding program and plant breeding relies on variety, selection, evaluation and production of new genotypes. One way to increase diversity is mutation induction at in vitro conditions. Application of this method can help to increase diversity and enhance the efficiency of breeding programs and improve or achieve useful traits which have been lost in the plants evolution process. This article reviews the new research outcomes for increasing the diversity via induced mutation of ornamental plants combined with modern methods such as plant tissue culture and molecular markers. According to this study, the application of mutagens at in vitro conditions, using the molecular markers for selection of mutant plants in the early stages and increasing the rate of their propagation for enhancing the efficiency of breeding of ornamental plants is suggested.

Indigenous genetic resources of every country are the result of millions of years of evolution and adaptation to special climatic conditions. These resources are valuable and necessary to breed and use beneficial genes in current and future research plans. There are many wild flowers and ornamental plants available in Iran’s vast region such as Tulips, Fritillaria, Rose, Poppy, Narcissus, Lily, Iris, Carnation, Gladiolus, Primula and Cyclamens which most of them also have medicinal properties. Extreme climatic changes caused by excessive modern human interference, the development of modern cultivars with a limited genetic base and the development of gene transfer techniques are important factors causing a sharp decline in biodiversity in the past few years. Preservation and reproduction of the available variation in Iran’s flowers and ornamental plants are the initial and necessary steps for the development and implementation of the next major steps in ornamental plants industry.

Mexican marigold (Tagetes erecta L.) is an annual flower that is sensitive to cold. Seasonal flowers due to their numerous varieties of colors are very important in the landscape design. In order to mass propagate this species, the techniques of plant tissue culture was applied. In this study, four experiments including seed germination at different concentrations of MS medium in the dark and light conditions, callus induction of hypocotyl, regeneration from callus and root formation in different concentrations of plant growth regulators were carried out in a complete randomized design with 3 replications (10 samples). The results showed that the highest percent of seed germination occurred in full strength of MS medium in the light condition (90.00%). The seed germination was significantly higher in the light compared to the dark condition. Hypocotyl explant in MS medium in combination with 1.0 mg.L-1 NAA + 0.1 mg.L-1 BAP produced the highest bulk of callus (1.86 g). The highest regeneration frequency (93.33 %), themaximum number of multiple shoots (6.33) and the maximum shoot length (1.90 cm) was obtained on MS medium supplemented with 3.0 mg.L-1 BAP in combination with 0.3 mg.L-1 IBA. 933.3% of the micro-shoots were rooted on MS medium supplemented with 1.5 mg.L-1 NAA. In conclusion, the hypocotyl explant could be used to achieve an optimal micropropagation protocol for Tagetes erecta.

Production of haploid plants in ornamentals is one of the breeding methods which have been restricted to only a few species. In order to optimize haploid culture in Rosa, the effects of two stress elements (Colchicine and 2,4-D) on microspore viability of R. hybrida cv. Apollo were studied. Two isolation techniques (pestle and magnet bar), three isolation media (NLN, AB, B), five induction media (NLN, A2, AT3 with 90 g.L-1maltose, AT3 with 180 g.L-1 maltose, AT3 with 90 g.L-1 glucose) were also compared. The results showed that, the best isolation technique, isolation medium and induction medium were to use magnet-bar, B medium (medium without any nutrients) and AT3 medium containing 90 g.L-1 maltose respectively. These results provided useful information on microspore isolation and survival for further studies in haploid induction in Rosa.

Bodhi tree (Ficus religiosa) is a long-lived valuable multi-purposed forest tree. The tree is exploited due to its ornamental and medicinal value and is used in religious ceremonies. The propagation rate in natural habitat is low. The current study was conducted to investigate the effects of ascorbic acid, phloroglucinol and activated charcoal in controlling callus browning and shoot multiplication in in vitro culture of Ficus religiosa plantlets using callus from leaf segments. The treatments included various concentrations of ascorbic acid (500 and 1000 mg/l), phloroglucinol (100 and 200 mg/l) and activated charcoal (2 and 4 g/l) added to the basal MS medium supplemented with 1.0 mg/l BAP along with 0.1 mg/l IBA. The culture medium containing 1000 mg/l of ascorbic acid controlled callus browning effectively. In this medium the least number of sub-cultures (2-3) were carried out. The highest regeneration frequency (100%), the maximum number of multiple shoots (5.56) and the highest number of subcultures (11.33) were obtained on basal medium supplemented with 200 mg/l phloroglucinol. Finaly, the results of the current study revealed that production of phenolic compounds of explants was significantly controlled by incorporating higher levels of ascorbic acid and activated charcoal into the culture medium.

Ornamental value, medicinal and economic importance of damask rose has made its mass propagation of great value. The present study was conducted to evaluate and compare vegetative propagation and rooting of two genotypes’ soft wood cuttings at Tarbiat Modarres University. The effect of genotypes (genotypes Camus and yellow white Qalhar) and hormone IBA (various concentrations at 0, 1000, 2000 mg /L-1) on rooting was evaluated. The results showed that there were distinct differences between different genotypes. Genotype significantly affected the rooting percent, number of roots per cutting and length and diameter of roots. Camus genotype showed the highest rate of rooting and other measured characteristics compared to yellow white Qalhar genotype. IBA increased the percent of rooting, root number, length and diameter in both genotypes. Depending on the genotype, IBA stimulated rooting effectively; the highest percent of rooting in the genotype Camus was observed at the concentration of 2000 mg/L-1 and in the genotype yellow white Qalhar at the concentration of 1000 mg/L-1.

Drought is the most important abiotic factor that limits at least 25% of production of world fields. The quantity and quality of plant growth depend on cell division, enlargement and differentiation and all of these factors may be affected by water stress. Also, different plant compounds are strongly influenced by different environmental conditions. The present study was carried out in Eram Botanical Garden Research Center to investigate the degree of drought tolerance in succulents (Crassula portulacaria, Echeveria elegans, Kalanchoe laxiflora, Echeveria affinis) by measuring morphological and physiological characters (amount of chlorophyll, proline, electrical conductivity, wet weight of shoot and root, dry weight of shoot and root) under water deficit conditions. Uniform plants were planted (in 20 cm pots) and kept at open area where they would be finally planted in landscape. Six irrigation intervals (5, 10, 15, 20, 25 and 30 days) were applied until the plant soils reached to field capacity for about 2 critical warmest months of June and July in the area. The experiment was conducted as a complete randomized block design with four replications for each treatment. Results showed that water deficit stress decreased shoot and root fresh and dry weights. Proline content, electrical conductivity and total chlorophyll content was significantly increased in all the succulents under the condition of this experiment. In conclusion, a 5 –day irrigation interval resulted in the highest growth and all of the plants in this study were recommended as drought tolerant plants for landscape design.

Turf grasses have high water requirements during germination and growth and they must be irrigated constantly. If the condition of germination and growth improves, water could be saved. Tall festuca is one of the most important cool-season grasses in arid areas. Using magnet, carrier waves, static electricity, sound waves, etc. could influence some plants growth in specific conditions. In order to study the influence of flux density and different duration of magnetic field seeds of Festuca arandinacea were exposed to 0.5 mT and 5 mT magnetic fields and 50 mT static field for 5, 50 and minutes, respectively. The influence of magnetic field and electromagnetic on the percent of seed germination, germination rate and mean germination time were investigated. The results showed that no significant difference was observed between different treatments for seed germination percentage and mean germination time. Further research with optimized treatments is required to use this technology to improve festuca germination.

Hyperhydricity is the development of an undesirable physiological and morphological change in plant tissue. In vitrified plants, the number of vascular bundles, stomata and cuticle cells are reduced and mesophyll cells contain massive vacuole. Several factors influence this phenomenon and the most important of these factors include: type of the plant growth regulator, type and concentration of cytokinin, ratio of ammonium to nitrate in the culture medium, type and concentration of agar, ventilation and number of subculturing. Increasing agar concentrations leads to decreasing this phenomenon due to reducing the moisture of culture medium. Increasing concentration of cytokinins and decreasing the ratio of nitrate to ammonium in the medium cause the occurrence of hyperhydricity. Presence of BA in compare to other types of cytokinins and also phytagel in compare to other type of gelling agent enhance the rate of hyperhydricity. Use of Parafilm cap decreases the amount of this phenomenon due to increasing gas exchange and decreasing accumulation of ethylene. The application of bottom cooling systems can reduce the activity of antioxidant enzymes and therefore cause reduction in the amount of hyperhydricity. By considering the reported results, to reduce the amount of hyperhydricity in vitro, using cytokinins with lower concentration, replacing BA with other commonly used cytokinins and if possible use lower concentrations of BA (0.5 mg/l), using Parafilm as vessel closure cap, increasing the concentration of agar to an acceptable level (10 g/l), using bottom cooling, reducing the frequency of sub-culturing as much as possible and acclimating tissue culture plantlets as soon as possible, is recommended.