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Showing 3 results for Zolfaghari

Maryam Sisakht Nejad , Roghayeh Zolfaghari ,
Volume 1, Issue 2 (3-2015)

Drought is the major environmental stresses that it can have a negative impact on plant growth. The study of gas exchange under drought stress can help to identify factors affecting stress resistant. Due to this fact that Zagros forests has Mediterranean and dry climate, with the aim of this study was to assess the impact of drought on leaf gas exchange in two oak species (Quercus brantii and Quercus libani). Water stress consisted of four levels of water stress (100%, 70%, 50% and 30% FC) in the greenhouse situations. Those seedlings were intended for water stress weren’t irrigated to reach to the desired field capacity (70%, 50% and 30% of field capacity), but control seedlings were irrigated every day in order to soil water content at field capacity shall be kept 100%. Results showed that water stress treatment has a significant reduction of stomatal conductance, photosynthesis, conduct mesophilic, carbon dioxide emission, and transpiration. Also Quercus libani showed higher level of photosynthesis, water use efficiency and transpiration than Quercus branti. Overall, results in both species, showed stomatal and non-stomatal limitation would cause of photosynthesis reduction. Also, due to higher water efficiency and lower gas parameter variations, Quercus libani would gain better mechanism of waster stress and Quercus brantii would gain the use drought avoidance mechanism.
Sabrieh Moradi , Roghayeh Zolfaghari ,
Volume 2, Issue 2 (3-2016)

Morphological characteristics of individuals are due to hereditary and environmental factors. Regarding to the importance of leaf morphology in systematics investigations and bearing up the effects of environmental variations, especially altitudinal variations on these traits, the differentiation feasibility of brant oak in a restricted altitudinal gradient is investigated. A total number of 400 leaves from 40 individual ramets in Armarde, in an altitudinal ranges from 1580 to 1844 meters above sea level were sampled and 29 quantitative and qualitative traits were measured. The results revealed that the number of teeth and the shape of leaf at lower altitudes are lesser than higher altitudes. Also, leaf base angle has a negative and significant correlation with the altitude. In two altitudinal classes, the shape of leaf tip and the angle of midrib and vein, showed the lowest plasticity and coefficient of variation with respect to environmental conditions. Ramets were classified in three different classes based on cluster analysis and the separator traits were the maximum leaf width, leaf area and sinusoidal angle. Considering the fact that the separator traits would not showed any significant association with altitude,  it seems that some variations might be likely due to physiological response of leaves to environmental variations. However, itchr('39')s more likely that the occurrence of inter and intra specific hybridization between brant´s oak species would culminated in separation of the individuals.

Somayeh Homayounfar , Roghaiyeh Zolfaghari , Payam Fayyaz ,
Volume 3, Issue 2 (3-2017)

Background and objectives: Plant species with wide geographic ranges, exhibit high tolerance to cold stress. Trees in temperate regions must cope with freezing temperatures, especially in late autumn and winter. One of the mechanisms to tolerate cold stress is through decreasing photoperiod and temperature during acclimation. In addition, provenance of a species could be one of the main factors contributing to cold resistance. Therefore, in the present study, the effect of cold stress on physiological responses of Pistacia atlantica seedlings from three provenances was investigated in southern Zagros to select the most cold-resistant provenance.
Material and methods: Seeds of three provenances, namely Margon, Noor Abad and Yasuj, from southern Zagros, were collected and planted in pots. After germination of seeds, induction of acclimation was carried out at two stages for four weeks. This was accomplished through the simulation of temperature and photoperiod of Yasuj region from September to November. Following that, the indexes of photosystem efficiency and chlorophyll content were measured. After each acclimation stage, leaves and stems of seedlings were exposed to three levels of temperature, +4°C (control), -20°C for one hour, and -20 for two hours. Then, relative water content (RWC) and electrolyte leakage (EL) of stems and leaves were measured. This study was conducted as a factorial with three factors of provenance (three levels), cold treatments (three levels) and acclimation (two levels), adopting a completely random design.
Results: The results showed that EL increased with decreases in temperature and this increase was the highest in the case of the Noor Abad provenance. In addition, the stem RWC of Yasuj and Margoon provenances decreased in the second cold acclimation stage. Chlorophyll content, photosystem efficiency and electron transport rate were lower in Noor Abad provenance, compared with other two provenances. Moreover, except the electron transport rate, all fluorescence parameters significantly decreased during the cold acclimation.
Conclusion: The results showed that measuring EL and fluorescence parameters could be a useful indicator for identifying cold-tolerant provenances. The seedlings of Noor Abad provenance exhibited the least and Margoon provenance showed the highest resistance to cold stress. This could be due to high altitude and cold climate of Margoon provenance.

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