مشخصات پژوهش

Plants respond differently to water-deficit stress conditions in the soil. In order to study different irrigation regimes and plant growth regulators/plant growth promoting bacteria effects on some physiological characteristics and inulin content in chicory plants, experiments were conducted as a factorial based on randomized complete block design with five replications at the greenhouse of Agricultural Faculty of Azarbaijan Shahid Madani University, Tabriz, Iran in 2017−2018. Experimental factors were different irrigation regimes: ((i) irrigation at the 55 %; (ii) irrigation at the 30 %; and (iii) irrigation at the 10 % of total available water capacity in the soil) and plant growth regulators including methyl jasmonate, uniconazole, chlormequat chloride and the solution containing plant growth promoting bacteria. Results indicated that the lowest relative water content, membrane stability index, chlorophyll a, b, total chlorophyll, carotenoids; soluble sugars and inulin in the roots; and the highest thiobarbituric acid reactive substances, proline, and soluble sugars in the leaves were related to severe water-deficit stress in the soil. Relative water content, membrane stability index, chlorophyll a, b, total chlorophyll, carotenoids, proline (except of plant growth promoting bacteria), soluble sugars and inulin increased, whereas thiobarbituric acid reactive substances decreased by the application of exogenous plant growth regulators/plant growth promoting bacteria compared with control plants. Interaction effects revealed that plant growth regulators/plant growth promoting bacteria could diminish water-deficit stress adverse effects in chicory plants at a physiological level by regulating endogenous phytohormones and antioxidant enzymes. In general, exogenous plant growth regulators especially uniconazole and plant growth promoting bacteria, improved inulin content in chicory plants compared with control plants.