Vermicompost and/or compost and arbuscular mycorrhizal fungi are conducive to improving the growth of pistachio seedlings to drought stress

Abstract

Symbiosis with arbuscular mycorrhizal fungi (AMF) has a remarkable role in alleviating the stress caused by adverse conditions on the growth of host plants. The effectiveness of AMF is usually influenced by environmental variables and soil conditions. In the present study, we aimed to enhance soil conditions by compost and vermicompost, thereby affecting plant response to AMF under drought stress conditions. AMF communities were collected from pistachio (Pistacia vera) orchards in adverse conditions (i.e. dry and saline soils). Composts and vermicomposts were produced by Trichoderma longibrachiatum fungus and Amynthas gracilis worms, respectively. Pistachio seedlings were planted in the soil that was inoculated with native AMF and amended by compost or vermicompost. The experiment was conducted under drought stress or otherwise in well-watered conditions. Based on the results, drought stress decreased plant growth, Zinc (Zn), and phosphorus (P) uptake of pistachio seedlings. Vermicompost and compost had a noticeable effect on plant growth (37 % and 64 %) and nutrient uptake (67 % and 11 % P uptake and 138 % and 105 % Zn uptake) under well-watered. These effects were observed in plant growth (232 % and 29 %) and nutrient uptake (30 % and 52 % P uptake and 35 % and 1 % Zn uptake) under severe drought stress conditions. The highest percentage of root colonization by AMF was observed in plants that grew on soils amended with vermicompost. Zinc (39 %) and phosphorus (100 %) uptake increased by the effect of native AMF, while vermicompost and compost also enhanced nutrient uptake. The results of the present study strongly demonstrated that the use of composted materials improved pistachio seedling's response to native AMF under drought conditions, however, we are still far from understanding which mechanisms of AMF and/or organic fertilizer improved P and Zn uptake and growth of pistachio seedlings.