Abstract

Since the medicinal plants mainly are cultivated in marginal areas, are exposed to environmental stresses such as salinity, more than other plants. Salt stress causes damage to photosynthetic process, carbohydrates assimilation and photosystem I and II. However, recently, the role of fungi coexistence and polyamines in plants tolerance to saline conditions are pronounced. Therefore, the present study was conducted to evaluate the effects of endophyte symbiosis and spraying of polyamine spermidine (Spd) on chlorophyll fluorescence parameters of stevia (Stevia rebaudiana Bertoni) medicinal plant under irrigation with saline water. Treatments included non-inoculation (Control) or co-inoculation of Piriformospora indica + Trichoderma virens (Pi + Trich), foliar application of Spd (0 and 0.75) and three salinity levels of Caspian sea water (0, 6 and 12 dS m^–1). Seedlings of stevia were transplanted in field conditions and were sprayed with Spd solutions after 9 weeks of planting. Seven days later, the plants were irrigated with three saline treatments for two weeks. The results showed that the foliar application of Spd had a positive effect on F_m, F_v and F_v/F_m and negative effect on Y(NO). Irrigation of plants with saline water had an adverse effect on fluorescence parameters. However, fungi inoculation markedly increased F_m, F_v, F_v/F_m and Y(II) while decreased F_o, Y(NPQ) and Y(NO) in all levels of salt stress. Fungal inoculation and Spd application with 0.75 mM remarkably enhanced Fm. Generally, inoculation of endophytic fungi and Spd spraying improved the chlorophyll fluorescence parameters and adjusted adverse effects of salinity stress in stevia plants.

中文翻译：

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咸水灌溉下甜叶菊（Stevia rebaudiana Bertoni）光系统II光化学对真菌共生和亚精胺施用的响应。

摘要

由于药用植物主要种植在边缘地区，因此比其他植物更易受到盐分等环境压力的影响。盐胁迫会破坏光合作用，碳水化合物吸收以及光系统I和II。然而，近来，真菌共存和多胺在植物对盐条件的耐受性中的作用是明显的。因此，本研究旨在评估内生菌共生和喷洒多胺亚精胺（Spd）对甜菜菊（Stevia rebaudiana Bertoni）药用植物在盐水灌溉下的叶绿素荧光参数的影响。治疗包括不接种（对照）或共同接种印度梨形孢子菌+绿木霉。（Pi + Trich），Spd的叶面施用（0和0.75）和里海海水的三个盐度水平（0、6和12 dS m ^–1）。甜菊的幼苗在田间条件下移植，并在种植9周后喷洒Spd溶液。7天后，用三种盐水处理将植物灌溉两周。结果表明，叶面喷施Spd对F _m，F _v和F _v / F _m具有正效应，而对Y（NO）则具有负效应。用盐水灌溉植物对荧光参数有不利影响。但是，真菌接种显着增加了F _m，F _v，F _v / F _m和Y（II），而在所有盐胁迫水平下F _o，Y（NPQ）和Y（NO）均降低。0.75 mM的真菌接种和Spd施用显着增强了Fm。通常，接种内生真菌和Spd喷雾可改善甜叶菊植物中的叶绿素荧光参数并调节盐度胁迫的不利影响。