Showing 2 results for Zarafshar
Peyman Ashkavand, Masoud Tabari, Mehrdad Zarafshar,
Volume 1, Issue 1 (9-2014)
Abstract
Undoubtedly, identifying and introducing drought resistant species for reforestation of the Zagros forests should be considered by forest specialists.,the current research identified mechanisms of drought tolerance in Hawthorn (CrataegusaroniaL.) and Mahaleb (Prunusmahaleb L.) seedlings in a greenhouse experiment using a completely randomized design. The experiment contained 3 stress treatments with 5 replications each. The treatments were soil moisture as control (based on field capacity), moderate stress (based on 50% field capacity) and severe stress (water withholding). Our findings showed that relative water content and stem water potential decreased in both species with increasing of drought severity. Although the total chlorophyll content was no affected by drought stress, carotenoid content was declined in response to the stress. Proline and total soluble carbohydrate concentration, as osmotic adjustments, increased in both species. According to electrolyte leakage and malondialdehyde results, we concluded that Hawthorn can tolerate moderate and gradual drought stress by the means of some adaptations but accidental water withholding stress leads to oxidative stress in this species. On the other hand, although moderate and gradual drought stress leads to oxidative stress on the Mahaleb, but accidental water withholding stress did not have the same course of negative effect as it had on Hawthorn.
Fatemeh Aliyari, Mehrdad Zarafshar, Ali Soltani,
Volume 1, Issue 2 (3-2015)
Abstract
Accessing to the data that could increase our knowledge associated with the response of seed to moisture content and temperature, is very important on exact time of planting decisions making. In this study Hydro-thermal-time modeling of Platycladus orientalis germination, one of the most planted trees in Iran forests, by applying 5 levels of water stress (0.-0.5, -1, -1.5, -2 MPa) and temperature treatments (10, 15, 20, 25, 30 ° C) was performed. The results showed that the optimum temperature (To) for germination is 23.12° C and basic temperature (Tb) for germination is 8.18 ° C. Meanwhile amount of the hydrotime constant (θH) for this species is 0.45. The outcomes indicated that the reduction in water potential and temperature germination is linearly reduced. Interaction of temperature and water potential factors affected significantly on time and percent germination value. A Hydro-thermal-time model was introduced for Platycladus orientalis L. in which its constant value was 105.1 MPa°C.d.
