Effects of endophytic fungi colonization on the growth and physiological responses of Satureja khuzestanica

Plant endophytes deployment at the field level affects the productivity of agricultural products. Savory Satureja khuzestanica Jamzad is a valuable medicinal plant native to Iran. In this study, in order to improve the quantitative and qualitative yield of the plant, the development of a suitable method for inoculation of native fungal endophytes to S. khuzestanica is surveyed. Three fungal endophytes (P.I.S.7, D.2.F.1 and D.1.S.1), isolated from savory plants, were inoculated on S. khuzestanica using four different methods (stem injection, foliar spray, soil drench and adding fungi to the soil in granular form) and their impact on plant's growth and its physiological response was analyzed. All inoculation methods, except adding granular form of fungi to the soil, resulted in endophytic colonization of the savory tissues. However, P.I.S.7 isolate was not established in these plants using any inoculated methods. Extent of fungal colonization showed a significant difference with the inoculation method, such that foliar spray had the highest colonization level, followed by stem injection and root drench. The highest rate of fungal colonization belonged to D.1.S.1. isolate. Spraying leaves and stem injection with endophytic fungi, especially in the case of D.1.S.1, significantly enhanced the morphological and physiological characteristics of host plants and the percentage of essential oil yields in these plants. All in all, using the D.1.S.1 isolate and foliar spray method led to savory plants' improved quantitative and qualitative product.