عنوان مقاله [English]
Pistachio (Pistacia vera L.) is one of the most important agricultural products and export items in Iran, which alone accounts for about one third of non-oil revenues in the agricultural sector. Although pistachio is known as a plant adapted to environmental stresses, drought and salinity are the most important factors in reducing production and one of the main problems to achieve the real potential of this crop in Iran. The subject of the present project was to evaluate the drought tolerance of two new genotypes "Jookar1" and "Jookar2" as compared to two common native rootstocks "Badami Zarand" and "Qazvini", which have tolerance to drought stress. In this regard, genotypes Jookar1 and Jookar2 along with Badami Zarand and Qazvini were conducted in a factorial completely randomized design (CRD) with five replications and five observations in each replication in two consecutive years (2018 and 2019). Evaluation of drought tolerance of rootstocks was done at three levels of normal (5-day irrigation cycle), mild stress (10-day irrigation cycle) and severe stress (15-day irrigation cycle) using by morpho-physiological traits related to water stress. The results of irrigation treatments in the first and second year of the experiment showed that there were significant differences between different levels of drought in all morpho-physiological traits with the exception of stem water percentage and the number of main root branches. Analysis of traits related to vegetative growth and physiological traits related to plant water status showed that Jookar2 in mild stress and Badami Zarand and Jookar1 in optimal and severe stress were selected as superior rootstocks. Although Jookar2 showed significant sensitivity to drought in the early stages of growth in the first year of the experiment and both vegetative growth and leaf area decreased significantly, this sensitivity decreased in the second year of the experiment. Evaluation of morphological characteristics of roots, crown and stem also confirmed the superiority of Jookar2 in mild drought stress condition. However, no significant differences were observed between the four rootstocks under normal and severe stress conditions. The clustering of the rootstocks based on all the evaluated traits showed that in all three irrigation conditions, Badami Zarand and Jookar1 were located in the same subgroup, which indicated the close genetic proximity of these two rootstocks. Evaluation of three indices of uniformity, stability and viability in greenhouse and orchard conditions screened Badami Zarand, Jookar1 and Qazvini as suitable rootstocks. There was no damaged seedling in the orchard condition. The findings showed that Jookar1 can be identified as a tolerant rootstock compared to Badami Zarand and Qazvini which are considered as the best rootstocks in Iran and drought tolerance of them has been confirmed in several researches. Jookar1 showed acceptable drought tolerance and higher vegetative growth. Jookar2 was also significantly superior to the other rootstocks in the mild drought stress, but its uniformity and viability were lower than the other rootstocks after germination. In this study, Badami Zarand and Jookar1 were selected as the best rootstocks that had desirable vegetative growth, drought tolerance, uniformity, stability and viability.