The almond is one of the most important nut crops in many countries, including Iran. On the other hand, due to the difficult rooting in conventional propagation methods such as cuttings, its propagation has faced challenges. Therefore, this study was aimed at optimizing in vitro culture conditions for the promising 2-22 genotype as a high-yield and late-blooming cultivar. To this end, after collecting apical and lateral buds of 2-22 genotype, surface sterilization and establishment treatments were applied to explants. The second-order equation is selected for the central compound design (CCD) with two variables (HgCl2 and NaClO) to obtain a good fit in the sterilization treatment. The results showed that 1.8 % NaClO for 12 min + 0.1 % HgCl2 for 3 min and 1.5 % NaClO for 8 min with 81.25%, and 100% of healthy seedlings were the best treatment in contamination control and explant Viability, respectively. The experimental establishment was conducted as a factorial experiment using a completely randomized design (CRD) with four replications. The establishment treatments indicated that the WPM medium was more effective than the MS medium and Knop medium. The hormonal composition of 1 mgL-1 BA + 0.05 mgL-1 IBA had the best results in the percentage of the establishment (72.25%), number of foliage (7.24), and shoot length (13.77 mm). تفاصيل المقالة

Drought is one of the main important adverse environmental events, certainly has an impact on plant growth and development. Pistachio is cultivated in areas where soil water deficits and salinity conditions are higher than normal. In most orchards, deficit irrigation is a common practice. There is only limited understanding of the physiological mechanisms pistachio uses to survive in drought. Many adaptive strategies have been developed in plants for dealing with water stress. The objective of the present study was to evaluate the effect of drought stress on the photosynthetic, physiological and biochemical parameters in one-year-old seedlings of 12 pistachio hybrids. Therefore, a greenhouse experiment was carried out to assess the effects of two drought stress treatments (drought stress and full-irrigation) for 40 days with a subsequent two weeks’ recovery period and several parameters (pigments (total chlorophyll, anthocyanins and carotenoids), internal CO2 concentration (Ci), chloride (Cl-) ions and fluorescence parameter) were evaluated at four different times (beginning, middle and end of stress and then recovery). After the end of the stress period, the seedlings were irrigated for two weeks. Results revealed that the drought stress treatments led to a change in the studied parameters and the mechanism of drought tolerance was variable at different times. Pistacia atlantica hybrid, P. vera “Sarakhs” and P. vera “Shasti” hybrid rootstocks had the highest water use efficiency; P. vera “Sarakhs” hybrid, P. vera “Khanjari” hybrid and P. vera “Badami” hybrid had the highest Cl- and mesophyll efficiency. P. atlantica and P. vera “Khanjari” had the highest anthocyanins and carotenoids. P. vera “Shasti”, P. vera “badami”, P. mutica and P. mutica hybrid rootstocks have been able to withstand drought stress by increasing the amount of K+ ion and maintaining gas exchanges. The results also showed that the response of the rootstocks to rehydration was different. Seedlings that recovered well after rehydration had a higher tolerance threshold. The “Khanjari” cultivar was recovered better than the others. تفاصيل المقالة