Determining the best stem form factor equation for populous deltoides in poplar plantations of Alborz Research Station, Karaj

Populous deltoides has been proven to exceed other poplar clones in terms of growth and wood production per unit area. Thus, it is generally considered as one of the most crucial species for pulp and paper-oriented wood plantations in Iran. Here, a number of 40 trees was selected for developing true form factor (TFF) of P. deltoides. Prior to felling, the height and diameter of trees were measured. Following the felling, a set of variables including the length of tree (cm-accurate), the diameter in the 1/2 of total tree height (i.e. stump height + the length of felled tree), the diameter in 0.1, 0.3, 0.5, 0.7 and 0.9 of tree height and the top diameter of each 2 meter-high log (up to 5 cm stem diameter) were measured. Then, the Artificial, Hohenadl and Natural form factors were calculated, which were then compared with the TFF. The two-way ANOVA-based comparison of means amongst the form factors in different diameter classes revealed significant differences amongst the form factors of 15 and 25 cm with other diameter classes. All form factors showed insignificant differences except for the Artificial form factor which revealed to be significantly different than the TFF. Furthermore, the real tree volume across the study site can be derived by the calculated TFF value of 0.5028. For similar sites, this study concludes the alternative form factors (Hohenadl or Natural) to be able to be used for calculating standing volume being comparable to the real volume of P. deltiodes

Effect of posphate solubilizing bacteria inoculation on Maple (Acer velutinum) seedlings

Soil microorganisms are important components of forest ecosystems. The term plant growth promoting rhizobacteria (PGPR) is used to describe non-symbiotic soil bacteria, which have potential to colonize plant root and stimulate growth. The aim of study was assessment the effects of Acer velutinum seeds inoculation with PSBs. Five isolated bacterial strains (including Pasturella, Acintobacillus, Pseudomonas, Alcaligense and Enerobacter) were cultured separately in liquid Seperb medium at 25 ºC. Bacterial cells were isolated by centrifuge and resuspended in phosphate buffer saline (pH= 7.2) to a density of 3×108  cfu per ml. Seeds of Acer velutinum were sowed in plastic pots and inoculated with bacterial suspension. Control seeds received sterile phosphate buffer saline. After seven months, seedlings were harvested. Shoot height, root length and their dry matter, available phosphorous in soil and seedlings were determined by standard methods. Results indicated the positive effect of PSBs on seedling emergence of Acer velutinum. Inoculated seedlings had more developed root system than those of controls. In conclusion, results indicated the stimulatory effect of PSBs on seedling emergence and their growth. According to results, it seemed inoculation of a mixed inoculums will be more effective in stimulating of growth.  Acer velutinum, PSBs, inoculation, seedling

Evaluation of half-sib progenies and their parents of Populus euphratica based on their morphologic and micro-morphologic traits

Populus euphratica Oliv. is one of the important poplar species which regenerate mainly through asexual reproduction, for which there is not enough genetic variation within its plant populations. This work investigated several morphological and micro-morphological traits on four half-sib progenies of each eleven parental clones of the species which was grown in a collection at Alborz Research Station, located at Karaj, Iran, as new produced genotypes. Therefore, 44 new clones of progenies of 11 parental clones were studied, based on a nested statistical model for the traits. Results indicated a vast variation between the studied parents and their progenies that may be used to produce new commercial varieties of the species. Average performance of the studied progenies increased on the traits such as leaf length and width, of which leaf area would be increased; resultantly this would improve plant photosynthesis. The higher performances of the progenies for the traits imply a suitable potential for selecting the genotypes with higher performance within the new produced progenies. Petiole length and leaf width showed a significant positive correlation to stomata length as well as significant negative correlation to number of stomata. Regarding the role of stomata on plant photosynthesis, the correlation values may be used for indirect selection of suitable genotypes of the species