Journal of Plant Research
Year:2013 | Volume:26 | Issue:3|Papers Count:13

Among polyploids, triploids produce seedless fruits. Triploids are produced through combining diploid and tetraploid plants. Reduction of seeds in citrus fruits will increase the customer’s tendency. Tetraploids are the important prerequisite to create seedless triploid citrus fruits. In this research, colchicine was used to generate tetraploid lemon which is necessary for triploid production. The effect of colchicine at 0.2, 0.6, 1 and 1.4 percent were examined at apical meristem of lemon seedlings. To determine the ploidy level of the plants, two methods are used including flow cytometriy, and analysis of size and density of stomata. In addition, some characteristics such as plant height, secretory sacs size and density, leaf area and thickness, spongy parenchyma thickness, as well as the level of total phenol and flavonoid among tetraploid and diploid seedling of Citrus aurantifolia have been compared. The highest ploidy level in C. aurantifolia was 48.6 percent. Ploidy induction led to decrease the height of C. aurantifolia. Comparison of secretory sac and stomata of treated plants showed that the density of secretory sac and stomata decreased in tetraploid plants compared with diploid ones. However, in tetraploid plants the size of secretory sacs and stomata were significantly larger than diploid ones. Doubling of chromosom increased the thickness of leaves, spongy and palisade parenchyma. Increasing ploidy level had no significant effect on total phenol and flavonid content of tetraploid C. aurantifolia.

Protection and reproduction of plants is one of the main objectives in botanical gardens, so masting mechanism of different species has special importance. Unfortunately, there is no information about acorn production of tree species in Hyrcanian collection of National Botanical Garden of Iran. This research was carried out in this collection to estimate acorn production of adult trees of Quercus castaneifolia, as one of the main tree species, during 2009-2011. Thirty sample trees were selected using stratified random sampling method in 2009. For each tree, acorn density (acorns number/m2 crown area) was estimated using ground counting. In this method, 4 circular plots with an area of 0.5 m2 were placed under each sample tree (totally 2 m2 per tree) and acorns were counted every two weeks from early September until all acorns had fallen (typically early December). All of measurements were repeated during next years. The result showed that the mean of acorn density were 80, 23 and 68 in 2009, 2010 and 2011, respectively. Furthermore, the mean of acorns number per tree were 4807, 1377 and 4144 during studied years, respectively. Totally, acorn production results showed weak acorn production in 2010. Year-to-year variation and variation among individuals were observed in sample trees, too.

Estimation of acorn crops has special importance due to the role of acorns in oak forest silviculture and wildlife management. There are no adequate researches about acorn production of Iranian oaks because direct measurements of acorn production are difficult. Regarding to vast distribution area of oaks in forests of Iran especially in Zagros Forests, this research was carried out in Halou village of Baneh, Kurdistan Province, in 2010. We tried to calculate the best regression model for estimating acorn crop of Quercus brantii by the aid of morphological quantitative characters of tree. At first, 100 sample trees were selected using stratified random sampling. Diameter at breast height, collar diameter, total height, crown length and small and big diameter of crown were measured on sample trees, then their acorn crops was measured by crown counting method. Four simple regression models were used to determine the relationships between acorn crops and quantitative characters including Linear, Quadratic, Power and Exponential. The highest significant correlation was found between average diameter of crown and acorn crop (P<0.001; R2=0.6). The results of this research confirmed the effective application of some quantitative characters for predicting acorn production in Q. brantii.

Future of natural forests depends on stand regeneration. In this research impact of standing dead trees (snags) on the species diversity and density of established regeneration was studied in district No. 2 Forest of Nav-Asalem, Guilan. In this regard, 32 snags with D.B.H. above 50Cm were taken as the centers of sampling plots. Canopy gap areas caused by snags and their decay degree were measured and determined. Also in a 50m distance from snags with same canopy, one safe tree with same D.B.H. and species were selected as the sampling plots. At each of these plots variables of number, species and growing stage (seedling, small sapling and sapling) of regeneration were counted in a 1000 m2 circular sample area. For each sample plot frequency and species diversity calculated from Shannon Winner diversity index, Pielous evenness index and Minhinich richness index. Mean of frequency and species diversity indices in each statistical population were compared from ANOVA and t-test. Results showed that frequency and species diversity of established regeneration in the snag plots were more than safe tree plots and this different was significant at a=0.01 statistical level. Reason of different diversity amount was more amount of richness in snag plots. More of frequency and species diversity in snag plots was occurred due the established and growth of more number and species from seed trees. Snags with medium canopy gap areas (50-113 m2) had more influence on frequency and species diversity of regeneration. Also, snags with degree 3 of decay had more frequency and snags with degree 2 of decay had more regeneration species diversity. Snags with create of gaps in forest canopy and increasing sun light to forest floor, moreover, have positive influence with preparing suitable condition and resources to establishment and growth of different tree seeds. Saving snags in forest stands in different sizes and species can be useful to regeneration and sustainability in these ecosystems.

Rosa hybrida is a perennial plant that after cut off head of the stem, lateral buds become free from apical dominance and begin to growth. In each new period of growth, new and young leaves can be formed. The four leaf samples were numbered from apex to base, showing young to mature leaf stages and some biochemical pigment markers changes were studied. The results suggest that during maturation, in addition to morphological differences, some physiological and biochemical markers are change. Data showed age dependent increase in the amount of pigments such as chlorophylls and carotenoids to reach the stage of leaf maturity to improve the leaf photosynthetic system efficiency. Gradually reducing in content of phenolic compounds, anthocyanins and flavonoids suggest reduction on oxidative damage.

The effect of mild salinity (25 mM NaCl) on growth and photosynthesis of sugar beet (Beta vulgaris L) plants in hydroponic medium was studied. Polyamines (PAs) including putrescine (Put) and spermidine (Spd) were applied at 0.5 mM to the rooting medium. Salinity caused a significant improvement of shoot and root weight up to 37% and 58% respectively. Application of Put did not influence plants growth significantly. However, exogenous Spd decreased growth of control plants and diminished positive effect of mild salinity. Mild salinity increased chlorophyll a and chlorophyll a/b ratio. Application of Put increased these parameters in control plants, while Spd did not affect them either in control or treated ones. Low salinity caused stimulation of net CO2 assimilation rate following increased stomatal conductance. Exogenous Put led to reduction of CO2 fixation, while Spd increased gas exchange parameters in control plants but decreased it in salinized ones. Total leaf phenolics did not influence by salinity, but increased after application of PAs. Activity of leaf phenylalanine ammonia lyase (PAL) was not affected by salinity and exogenous PAs caused a significant rise of its activity in control plants. Similar with PAL, polyphenol oxidase (PPO) activity of leaves was not influenced by salinity and increased after application of Spd. Total soluble proteins reduced under saline conditions in both leaves and roots and exogenous PAs further reduced it. Results suggested that, growth improvement due to low salinity is the result of stimulation of net CO2 uptake following lowered stomatal resistance. Moreover, increased PPO activity of leaves that would lead to production of oxidized phenolics and free radicals is likely one of mechanisms for growth reduction by Spd. Results suggested that, in contrast to salt sensitive species, exogenous PAs not only did not affect positively growth of salinized halophyte species, but also diminished stimulating effect of mild salinity.

Selkeh or Sofiandeh lagoon as wildlife refuge is located in north of Iran, it covers an area about 366 hectares. This area is between the 37o 23’-37o 24’ north latitude and 49o 27’-49o 30’ east longitude. In Selkeh lagoon 102 species recognized, which belong to 46 families and 84 genera. Among these families represented in the area 5 species belong to pteridophyta, 64 species to dicotyledons and 33 species to monocotyledons. The following families have the highest number of species: Poaceae (13 species), Asteraceae (9 species), Brassicaceae (7 species) and Cyperaceae (6 species). Cryptophytes and therophytes with 41.2 % and 40.2 % were respectively the most frequent life forms of the lagoon. 53 % of species are cosmopolitan and 17.6 % have Euro-Siberian - Irano-Turanian - Mediterranean chorotype. Hygrophytes and Helophytes - Hygrophytes with 57 % and 21.6 %, respectively have the highest frequency in the Selkeh lagoon.

Purple coneflower is a herbaceous and perennial flowering plant and described as a traditional valuable species. It has several active compounds including phenolic acids and alkamides. In order to survey of micropropagation condition of this plant, an experiment was conducted as a factorial arrangment in completely randomized design with three replications. The factors were including explant type (hypocotyl and cotyledon), BAP hormone (0, 0.2, 0.4, 1.2 and 2.4 mg l-1) and NAA hormone (0, 0.05, 0.1, 0.3 and 0.6 mg l-1). Analysis of variance revealed significant differences among some studied treatments for callus induction and regeneration in explants. Results of means comparison for triple interaction among factors indicated that the highest percentage of callus induction occurred on a MS medium containing 0.2 mg l-1 BAP and 0 mg l-1 NAA (97%) in cotyledon and 0.2 mg l-1 BAP and 0.6 mg l-1 NAA (91%) in hypocotyl explant. Moreover, no significant differences observed between two explants. Combination of 0.4 mg l-1 BAP and 0 mg l-1 NAA) has the most effective, providing the highest frequency of shoot regeneration (31.5%) and (32.5%) in cotyledon and hypocotyl explants respectively.

This study was performed in order to investigation of nutrient of twig grey mangrove (Avicennia marina) at Govater Bay mangrove’s forests that consist in end of east south of Iran. For this order four transects was randomly chased and sampling of twig with three repeats was done at first (fringing the sea), transition (between sea and land) and end (fringing the land) each of transects. Some parameter such as N, P, K and Organic Matter of stem and leaf were measured and were statistically analyzed. The result shown significant differences (p<0.1) in totally of studied parameter between leaf and stem and concentration of these in leaf were higher than stem, except Organic Matter that was higher in stem. There was significant difference (p<0.1) in N value between transition and fringing the land at leaf samples along transects. There were significant differences (p<0.5) in some of measured parameters in leaf and stem at two creek. Food chain in these ecosystems started with mangrove leaves, so it's necessary to know amount of these elements to mention their important role in food chain and habitat fertility.

Walnut is one of the most important trees that are cultivated in the large area in Iran. Various microorganisms comprising useful and harmful agents are associated with walnut root and rhizosphere. Almost all of the studies carried out for identification of microorganisms related to walnut until now, have been achieved on plant pathogen agents. Therefore in this research isolation and identification of Trichoderma spp. associated to walnut root and rhizosphere was studied. Sampling has performed of 68 places from Hamedan province and 235 isolates of Trichoderma were obtained. Macroscopic and microscopic features such as shape and size of conidium, conidiophore, phialide, chlamydospore, presence of aerial and submerged mycelia on culture media and growth rate as well as temperature examination data were used for identification of Trichoderma species. Consequently six species comprising T. atroviride, T. brevicompactum, T. citrinoviride, T. harzianum, T. ghanense and T. longibrachiatum were identified. Regarding to positive role of Trichoderma related to root and rhizosphere that cause increasing health and improving growth of plants, this study recommend a kind of horticultural management that could be able to protect and support these fungi in walnut root and rhizosphere.

Arbuscular mycorrhiza fungi have beneficial symbiosis with plants and help them to absorb nutrient and water, especially in regions with these limitations. For studying the effects of environmental factors on mycorrhizal fungi associated with Pistacia atlantica and P. khinjuk in Ilam, soil and physiographic factors was sampled in their habitats and N, P, K, Ca, Mg, Na, pH, Ec, apparent specific weight of soil, Clay, Silt and Sand were analyzed. Moreover fungi were identified and frequency of spore determined. Result showed that Glomus genus and G. fasiculatum had the most number of spores in this region. Mishkhas, Eyvan and Nakhchir habitat in north had the most and Tangevar and Badre in south had the least spore abundance. Result also showed that number of spores have positive correlation with elevation, tree cover, tree diameter, litter and organic matter and negative with P, Mg and apparent specific weight of soil. Moreover result showed that spores were abundance in spring.

In order to study the effects of different chitosan concentrations (0, 0.05, 0.1, 0.2, 0.4, 0.5, 1, 2, 3%,) along with a additional treatment of distilled water on seed germination of safflower (Carthamus tinctorius L.) seedling, under water stress conditions(0, -4, -8 and -12 bar) an experiment was conducted in a controlled-environment condition. Results showed that germination percentage, germination index, shoot and root height, shoot and root dry weight and protein content decreased with increasing water stress. Proline and malondialdehyde (MDA) content, Catalase (CAT) and peroxidase (POX) activities increased by increasing osmotic potential to -8 bar. The greatest shoot height and dry weight (19.3 and 36% more than distilled water treatment, respectively) were observed at 0.4% chitosan concentration. At low concentrations of chitosan (0.05 - 0.4%) protein and proline contents and CAT activity increased and MDA content decreased. In osmotic potential -8 bar, the highest germination percentage, shoot and root height obtained by 0.4% chitosan concentration. Also at this osmotic potential a decline in and MDA proline contents, CAT and POX activity and an increase in the concentrations of protein (in comparison with distilled water treatment) were detected in low concentrations of chitosan. In the highest level of osmotic potential (-12 bar), germination percentage, shoot and root height increased by low concentrations of chitosan in comparison with distilled water treatment. Also at this osmotic potential the least rate of former parameters obtained by 1-3% chitosan. Thus, it suggests that chitosan concentration at 0.4% or lower levels may improve germination percentage of safflower seeds and benefit for seedlings growth under water deficit stress.

Considering studies that done most species of hawthorn have problem in seed germination. Species that examined in this study is C.assadii that is native plant of Iran. Percentage of the number of embryos was determined that 35% of fruits in this species have active embryos. 9 treatments with 3 replications were applied as follows:- insert seeds under water flow (with and without scarification), put in 18oC for 3 months and then cold for 4.5 months in pot.- Insert seeds in GA3 with concentrations 150 and 300 ppm in darkness for 24 hours and then 1 month cold. – Using potassium nitrate with 0.25%, 0.5% and 1% concentrations.- Over wintering in farm soil (with and without scarification) till spring of the second year. All cold treatments were applied in 4oC. Pots after treatment in lab. Were transfer to incubators. Treatment scarification and warmth 18oC followed by cold stratification with 62% has the highest germination percentage that indicating this treatment is successful treatment among the treatments in this study.