Effects in Mentha piperita growth parameters cultivated under drought stress and inoculated with PGPR.

CHIAPPERO, J., CAPPELLARI, L., GIORDANO, W., BANCHIO, E.

Congreso; XIII Congreso Argentino de Microbiología General (SAMIGE); 2018

Mentha piperita L. is a popular, commonly-used flavoring agent worldwide. Fresh or dried leaves of Mentha species are used primarily as condiments. Essential oils of these plants are used as food and beverage flavorings, as fragrances, and as fungicides or insecticides in a variety of pharmaceutical and industrial products. Drought is undoubtedly one of the most important stresses having huge impact on growth and productivity of the crops. One alternative for growing plants under dry conditions is the use of plant growth promoting rhizobacteria (PGPR). PGPR can be found in the rhizosphere in association with plant root systems, and can either directly or indirectly facilitate plant growth. Many PGPR have been shown to alleviate drought stress effects in plants by the reduction of ethylene production, increase phytohormone concentration, give protection against reactive oxygen species (ROS), generate compatibles solutes, phosphate solubilization, exopolysaccharide production and phytopathogen control. To evaluate PGPR effects: M. piperita young shoots from Traslasierra Valley (Córdoba province, Argentina) were transferred to test tubes containing sterile distilled water and rooting hormone. M.piperita plantlets were transferred to plastic pots containing sterile vermiculite. After 9 days, the plants were inoculated with PGPR strains B. velezensis GB03 and P. simiae WCS417r. For drought stress determination, two treatments were applied: moderate stress MS (deprivation of water 10 days before harvest) and severe stress SS (deprivation of water 20 days before harvest); and control (C): irrigated 2 times per week, until the end of the assay (36 days). Plants were grown in a growth chamber with controlled conditions of light (16/8 h light/dark cycle), temperature (22 ± 2ºC), and relative humidity (~70%). Inoculated plants without stress showed significant differences with control (non inoculated)(p