جستجوی مقالات مرتبط با کلیدواژه « stomatal conductance » در نشریات گروه « جنگلداری »

The slow growth of hazelnut seedlings, particularly during the initial years of afforestation, hampers the rehabilitation and development programs of hazelnut forests. In this context, biological fertilizers, especially plant growth-promoting bacteria, can be an effective strategy to enhance the growth and physiological traits of hazelnut seedlings. In May 2017, new hazelnut potted seedlings from two seed sources - Fandoglou (Ardabil Fandoglou forest) and Makesh (Aghvalar Guilan forest) - were propagated in an Ardabil hazelnut nursery. These seedlings were inoculated separately and in combination with Pseudomonas putida DSM291, Bacillus subtilis FzB24, and Enterobacter cloacae E1. In November 2017, the one-year-old hazelnut seedlings were transferred to agricultural lands bordering the Fandoglou forest. The seedlings were planted in rain-fed conditions following a randomized complete block design with three replications of 12 based on two factors: fertilization and seed origin. After four years, it was observed that inoculated seedlings from both origins outperformed non-inoculated ones in all investigated traits. The largest parameters of the studied variables were attributed to the Fandoglou-origin seedlings inoculated with a combination of three bacteria. These seedlings showed a survival rate of 49.7%, collar diameter growth of 51.1%, height growth of 60.4%, and dry mass increases in roots (85.6%), stems (75.1%), and leaves (68.2%). Additionally, photosynthesis increased by 49.9%, stomatal conductance by 58.04%, water consumption efficiency by 121.7%, and chlorophyll content by 46% compared to non-fertilized Fandoglou-origin seedlings. In conclusion, considering the role of the studied growth-promoting bacteria (especially the combined treatment) in enhancing the growth characteristics and physiology of hazelnut provenances, inoculating hazelnut seedlings with bacteria in nurseries can be a beneficial strategy for successful field transplantation.

The aim of this study was to evaluate the impacts of dust on the morpho-physiologial traits of Fraxinus rotundifolia Mill. seedling, a useful species in urban green space. In a greenhouse, a dust stress was applied using dust simulator with concentrations of 0, 750 and 1500 μg m-3. Experiment was conducted by a completely randomized design with 5 replicates (9 seedlings in each replicate) within 45 days with one-week interval.) . Dust deposition with 1500 µg m-3 concentration caused the appearance of symptoms of chlorosis and necrosis on leaves. This concentration decreased the amount of survival (29%), increment diameter (38%) and height (33%), average leaf area (19%), photosynthesis rate (45%), transpiration (60%), stomatal conductance (46%), mesophyll conductance (55%), spad index (23%), Fm (22%), Fv/Fm (22%), T1/2 (14%)increased intercellular CO2 concentration (22%), water use efficiency (40%), leaf temperature (2.34 oC) and Fo (30%).  For afforestation and tree planting initiatives in dust-polluted areas of urban and suburban regions of Iran,  F. rotundifolia seedling can be usefully used in areas where dust concentration is less than 750 μg m-3.

Wild plant germplasm possesses useful adaptive strategies. Wild plant species, for example, are resistant to biotic and abiotic stress and can be used for reforestation, agriculture, and horticulture. We surveyed the potential of wild pear to resist flooding. We looked at survival, growth, biomass, and several physiological variables. The rootstocks of wild pear are candidates for planting in orchards that experience periodic flooding. For this purpose, we conducted a completely randomized design with two flooding treatments: 1. 15 days flooding plus 15 days recovery and 2. control, for a 30 day experimental period. The results showed no discernible effects of flooding on survival, height, and diameter. Nevertheless, seven days of flooding had negative and extensive effects on photosynthesis, transpiration, and stomatal conductance. This trend continued until the fifteenth day. Photosynthesis, however, recovered 15 days after the flooding. In addition, plant biomass was negatively affected by flooding. Cessation of photosynthesis after 15 days of flooding proves that the wild pear can be used as rootstock in areas prone to flooding for up to 15 days. If the flooding continues, however, the plant will eventually die.

In order to examine the growth, morphological and physiological changes of one-year old potted seedlings of Quercus castaneifolia, a research was performed based on completely randomized design with 3 treatments and 4 replicates (with 48 seedlings) in regimes of permanent flooding and periodic flooding (two weeks in between until 120 days) and in the Natural Resources of Tarbiat Modares University of Noor on 120 days. Analysis of LSD’s test showed that the permanent flooding decreased 19% in survival as compared with control seedlings. This is while, that all seedlings in periodic flooding were survived with respect to controls. This reason may be contributed to producing of adventitious and soil drainage that caused increasing gas exchange of rhizosphere. Also flooding decreased growth characteristics, biomass accumulation, and physiological activity such as photosynthetic, stomatal conductance, transpiration and leaf water potential. Of course, except root length and the root/shoot ratio, other parameters in permanent flooding were smaller than those of in periodic flooding. In contrast, diameter growth response in periodic flooding was higher than that in permanent flooding and it was a little greater than that in control. The reason of this phenomenon may be attributed to the development of woody xylem cells. Generally, on the base of findings in this research, it can be stated that Q. castaneifolia seedling is relatively tolerant to flooding (particularly to periodic flooding). It is suggested that for restoration of degraded forests exposed on flooding stresses and or where the natural regeneration of this species is being restricted by flooding, such a research with further seedlings, in different growth phases and during longer periods can be used with this species and also other species with similar ecological nature.