Evaluation of chlorophyll fluorescence changes, the amount of biomass of the rootstocks and interspecific hybrids of the genus pistachios (P. vera × P. integerrima) in order to achieve drought tolerant rootstocks

In the present study, chlorophyll fluorescence technique was used as a non-destructive tool to compare the drought tolerance of rootstocks and to estimate the performance of photosystem II. In this regard, this research was conducted as a factorial Completely Randomized Design with four replications in the research greenhouse of Gorgan University of Agricultural Sciences and Natural Resources during 2018-2019. The experimental factors were consisted of ten pistachio rootstocks of Ahmad Aghaei, Akbari, Sorkheh Hosseini, Garmeh, Fandoghi and interspecific hybrids of Ahmad Aghaei × integerrima, Akbari × integerrima, Sorkheh Hosseini × integerrima, Garmeh × integerrima and Fandoghi × integerrima, and three levels of drought stress including control (Field Capacity), mild stress (65% of Field Capacity) and Severe stress (30% of Field Capacity) were applied on 3 months old seedlings for 84 days. The results showed that with increase in drought levels, the maximum fluorescence (Fm), variable fluorescence (Fv), maximum efficiency of photosystem II (F / Fm) and seed biomass were decreased and minimum fluorescence (F0) was increased. The highest amount of these indices except F0 index was observed in the control and there was a significant difference with severe stress. Based on the results, different rootstocks showed different physiological responses in response to the applied stresses. Sorkheh Hosseini × Integrima, Ahmad Aghaei × Integrima and Akbari × Integrima hybrids showed the highest and the Fandoghi rootstock showed the lowest quantum performance (photosystem II) compared to other rootstocks. In terms of fresh and dry weight of stems, roots and leaves, Sorkheh Hosseini × Integrima, Ahmad Aghaei × Integrima and Akbari × Integrima hybrid rootstocks were less affected by drought stress. Based on the results of the present study, it seems that these three rootstocks can be used as containing drought tolerant genes for breeding cultivars with high yield potential in arid regions.