Abstract 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.

中文翻译：

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外源植物生长调节剂/植物生长促进细菌在生理水平上减轻菊苣 (Cichorium pumilum Jacq.) 缺水胁迫中的作用

摘要 植物对土壤缺水胁迫条件的反应不同。为了研究不同的灌溉制度和植物生长调节剂/植物生长促进细菌对菊苣植物某些生理特征和菊粉含量的影响，在农业学院温室进行了五次重复的基于随机完全区组设计的析因实验。 2017-2018 年在伊朗大不里士的阿扎拜疆沙希德马达尼大学。实验因素是不同的灌溉制度：（(i) 55 % 的灌溉；(ii) 30 % 的灌溉；和 (iii) 土壤总可用水容量的 10 % 的灌溉）和植物生长调节剂，包括甲基茉莉酸、咪康唑、氯化草铵膦和含有植物促生长菌的溶液。结果表明，相对含水量、膜稳定性指数、叶绿素a、b、总叶绿素、类胡萝卜素最低；根中的可溶性糖和菊粉；叶中硫代巴比妥酸活性物质、脯氨酸和可溶性糖含量最高，与土壤严重缺水胁迫有关。相对含水量、膜稳定性指数、叶绿素a、b、总叶绿素、类胡萝卜素、脯氨酸（植物促生长菌除外）、可溶性糖和菊粉增加，而硫代巴比妥酸活性物质因施用外源植物生长调节剂/植物而减少生长促进细菌与对照植物相比。相互作用效应表明，植物生长调节剂/植物生长促进剂可以通过调节内源性植物激素和抗氧化酶，在生理水平上减少菊苣植物缺水胁迫的不利影响。一般而言，与对照植物相比，外源植物生长调节剂，尤其是氟环唑和植物生长促进细菌，提高了菊苣植物中的菊粉含量。