جستجوی مقالات مرتبط با کلیدواژه "seedling height" در نشریات گروه "جنگلداری"

Drought stress is the most important factor in the growth of plants in arid and semi-arid regions and plays an important role in the establishment of plants in these ecosystems. Russian olive seedlings were planted in environmental plan in the form of Complete Randomized Block Design (RCBD) with four replications and treat mental plan in the form of factorial with 2 factors in the greenhouse. The test factors were Arbuscular mycorrhizal inoculum (Rhizophagus irregularis, Funneliformis mosseae and control without inoculation) and four drought stress intensity (25, 50, 75 and 100% of field capacity (FC)). Seedlings growth rate include height, collar diameter, number of leaves, number of branches, weight of aerial and underground organs was calculated by comparison of the growth rate at the beginning and end of the experimental period. With increasing drought stress intensity, vegetative traits such as height, collar diameter, number of branches and leaves, root dry weight and shoot dry weight of Russian olive seedlings were decreased significantly. With increasing drought stress to 50% of FC, the main root length of seedlings showed an increasing trend, indicating an increase in root length under dehydration. The highest and lowest dry weights of seedlings shoot were observed in treatments of F. mosseae and control, 36 g and 18 g, respectively. Fungal species of F. mosseae in all morphological traits except root dry weight provided more favorable conditions for the seedlings, as well as the F. mosseae, showed more abundance and better coexistence with Russian olive seedlings.

In a study of growth and morphological differences among Populus caspica Bornm., trees within Hyrcanian biogeographical region, 15 stands were selected from which one-year cuttings were cut from three plus-trees in each stand. The cuttings were planted in March 2017 at Chamestan Research Station, and the rooted cuttings were cut from the collar base after one year. Cuttings were separated from the one-year sprouts in the next winter and planted based on Randomized Complete Block Design with three replications. We sampled five leaves of each stand-tree seedling on late June and 17 leaf morphological and growth traits as well as collar diameter and height of the rooted cuttings. Data were analysed by hierarchical cluster analysis, two-way ANOVA and Duncan comparison of means test. Four groups were separated according to cluster analysis, among which rooted cuttings from Golestan province showed the highest morphological diversity. The maximum and minimum collar diameters and height growth were observed in seedlings originated from Rostam-Abad (Guilan province) and Golestan National Park (Golestan province) respectively, yet they were similar in some of their morphological traits like their minimum leaf width at 10% of the total length, maximum leaf width, lobe depth and number of veins, which id presumably due to the location of their mother stands at the border of Hyrcanian and Irano-Turanian regions. Thus, they can be considered as morphological traits of P. caspica in the ecotone regions. However, the two regions had a high value for conservation, especially in Rostam-Abad due to high growth rate as well as prominent morphological differences in comparison with the other genotypes. Therefore, they are suggested for being integrated in tree improvement programs in the future.

Purple (Cercis siliquastrum L.) is one of the most important species in landscaping and afforestation. Due to both ecological and economical values, knowledge on the water needs and resistance of purple to different levels of drought stress is essential. Therefore, an experiment in a completely randomized design with four levels of drought stress including field capacity 100% (control), 75% (mild stress), 50% (medium stress) and 25% (severe stress) was performed in greenhouse conditions to study the effect of drought stress on morpho-physiological and biochemical traits of purple seedlings. Results showed that severe drought stress decreased seedling height, leaf area, relative leaf water content (63.3, 77.7 and 62.6%, respectively) and increased electrolyte leakage and malondialdehyde concentration (63.6 and 334.5%, respectively) compared with plants in the control treatment. Drought stress level of 25% of field capacity increased root length by 42.1%. In addition, activity of catalase, peroxidase and ascorbate peroxidase enzymes (862, 553.9 and 349.6%, respectively) increased with increasing drought. The results also showed that only the level of drought stress of 25% of field capacity reduced the survival of seedlings by 55%. Therefore, this species was concluded to be able to withstand water stress up to 75% of field capacity without causing damage, while its growth and yield will be severely affected if the amount of water is reduced to the threshold of 25% of field capacity.

Pilu (Salvadora oleoides Decne.) is a shrub or a small tree indigenous to southeast of Iran and is known as a multipurpose species for forage production, soil protection and medicinal value, which altogether reveal its importance in forestry and reforestation projects in warm and arid areas. The purpose of this study was to investigate the effects of runoff and moisture storage methods in the soil (Bankette arches, pan (control), plastic sheets, straw in the bottom of the pit, superabsorbent polymers and canopy) on the establishment, survival and growth of the pilu species in Southeast of Jazmurian in Sistan and Baluchestan province. The factors studied in this experiment included seedlings survival, seedling height, seedling crowns, seedling collar diameter and seedling vigor, which were measured in the middle of March, 2017. The results showed that the development of plastic layer improved the survival rate and seedlings cover. Creating a shadow increases the height growth and slenderness coefficient of seedlings and decreases the diameter growth of seedlings. In general, it can be concluded that planting plastic surfaces on the surface of the pit and planting canopies on seedlings are the most suitable treatments with respect to the percentage of seedling's survival and seedling growth characteristics. It seems that combination of these two treatments could help to improve seedling establishment across similar areas.

Northern Zagros Forests has remarkable diversity of oaks (Quercus sp.) as one of the most important tree species in Iran. Based on the modern taxonomy of this genus، five species of Q. libani، Q. carduchorum، Q. ophiosquamata، Q. magnosquamata and Q. apiculata were recognized form Q. libani complex. In order to complete the previous studies، here we evaluated the vegetative characteristics of acorns for those five species. Acorns of studied species were gathered from native forest stands of Baneh Forests in Kurdistan province. The acorns were then planted in a fully-identical condition in greenhouse. A completely randomized statistical design with three replications and 50 acorns per replication was used for statistical analysis. The results showed that the acorn length، acorn width and germination rate were significantly different (p < 0. 01) amongst the five species. Furthermore، seedling height، wet and dry mass of stem، dry mass of root and total biomass of seedlings showed significant differences (p < 0. 05) amongst the five species. Based on cluster analysis، Q. carduchorum was separated from other species and categorized in different category.