Evaluation of phosphorus use efficiency and drought and salinity stress resistance index in pistachio rootstocks coexisted with mycorrhiza arbuscular

Environmental stresses are serious threats for agricultural production. Abiotic stress is a serious threat to agricultural products. Pistachio is one of the most important agricultural products in Iran and United States and its developing in other countries. Pistachio has good yields in rain fed condition and increases the flush and quality of yield by irrigation. Arbuscular mycorrhizal fungi (AMF) are one of the most useful microorganisms in the soil, and most plants can be symbiosis with mycorrhiza, that help to improve nutritional conditions and other functions such as photosynthesis and osmotic regulation under stress conditions.

AMF, (Funneliformis mosseae) were propagated using corn (Zea mays). Four pistachio rootstocks in symbiosis with mycorrhiza were subjected to drought and salinity stress in two separate experiments. Plants were divided randomly into three treatments (three replications and 6 plants per treatment), Treatments included drought, salinity, mycorrhiza and rootstock (In Shahrekord university, 2017-18, and 32 °21 N 50° 49 E ). At the end of the experiment, the plants were harvested. Then all parts of the plant, including roots, shoots and leaves, were separated and weighted. The amount of phosphorus was measured using a spectrophotometer (UV-Vis Spectrometer) at a wavelength of 470 nm (Olsen et al., 1954). Data were evaluated by Three-way analysis of variance (ANOVA) with SPSS 25.0.0.

The rootstock biomass in this experiment influenced by different treatments (mycorrhiza, rootstock type and stress). P content of both leaves and root tissues of pistachio rootstocks was affected by both drought and salinity stress (data not showed). Mycorrhiza increased root, stem and leaf fresh weight under drought and salinity stress and leaf area ratio and specific leaf area under salinity stress. Mycorrhiza-inoculated plants had lower phosphorus use efficiency and more tolerance to drought and salinity stresses. Growth indices and phosphorus use efficiency of root, leaf and total, decreased under both drought and salinity stresses. The Sarakhs rootstock was more salinity-sensitive than other rootstocks.

In this research, pistachio rootstocks showed differences in biomass and biomass was diminished under salinity and drought stress. Biomass reductions under abiotic stress (drought and salinity stress) conditions in previous studies on almond, peaches, olives, apple and pistachio fruit trees has been reported. Biomass was higher in +M rootstocks, which could be owing to effects of mycorrhizal symbiosis on P absorption. The difference between rootstocks is related to rootstock absorption capacity that it is related to root condition. Therefore, rootstocks that have better roots growth and can obtain root survive under stress conditions, they can be better in mineral uptake and more tolerant to stress statue, because the ability of plants to withstand stresses depends to a large extent on roots.