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Acta Prataculturae Sinica ›› 2021, Vol. 30 ›› Issue (1): 130-139.DOI: 10.11686/cyxb2020070

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Effects of exogenous melatonin on photosynthetic carbon assimilation and endogenous hormones in tobacco seedlings under drought stress

Dong LI1,2(), Hong-tao SHEN3, Yan-fang WANG1, Yue-hua WANG1, Li-jun WANG1, Shi-min ZHAO4, Ling LIU1()   

  1. 1.College of Agriculture,Henan University of Science and Technology,Luoyang 471023,China
    2.Qiandongnan Branch of Guizhou Tobacco Company,Kaili 556000,China
    3.Technology Center,China Tobacco Henan Industrial Co. ,Ltd. ,Zhengzhou 450000,China
    4.Technology Center,Luoyang Branch of Henan Provincial Tobacco Company,Luoyang 471023,China
  • Received:2020-02-21 Revised:2020-03-23 Online:2021-01-20 Published:2021-01-08
  • Contact: Ling LIU

Abstract:

In order to elucidate the physiological mechanism of exogenous melatonin (MT) application in relieving drought stress on tobacco seedlings growth. The drought-tolerant variety ‘Yuyan No.6’ and drought-sensitive variety ‘Yuyan No.10’ were tested for their response following foliar-spraying with MT at concentration of 0.2 mmol·L-1 under normal water supply and drought stress. Parameters measured included seedlings growth, chlorophyll fluorescence parameters, photosynthetic carbon assimilation enzyme activity, and the contents of carbohydrates and endogenous hormones of the tobacco seedlings. The results showed that drought stress significantly inhibited the seeding growth of both tobacco cultivars, and the inhibiting effects in drought-sensitive ‘Yuyan No.10’ were greater than that in drought-tolerant ‘Yuyan No.6’. Exogenous melatonin application remarkably increased plant height, stem diameter, biomass, reduced the root-shoot ratio, increased maximal PSⅡ quantum yield (Fv/Fm), PSⅡ actual photochemical efficiency (ΦPSⅡ) and photochemical quenching coefficient (qP), decreased non-photochemical quenching coefficient (NPQ), enhanced the activities of sedoheptulose-1,7-bisphosphatase (SBPase) and ribulose-1,5-bisphosphate carboxylase (Rubisco), and increased the contents of soluble total sugar, sucrose, fructose, auxin (IAA), gibberellin (GA) and zeatin nucleoside (ZR), reduced the contents of starch and abscisic acid (ABA) of tobacco seedlings under drought stress. The changes in drought-sensitive ‘Yuyan No.10’ were greater than those in drought-tolerant ‘Yuyan No.6’. The results indicated that exogenous MT played an important role on enhancing the activity of photosynthetic carbon assimilation enzyme, regulating the metabolism of endogenous hormones and carbohydrates, relieving the damage of photosynthetic apparatus caused by drought stress, and strengthening the drought resistance of tobacco seedlings.

Key words: melatonin, drought stress, tobacco seedlings, photosynthetic carbon assimilation enzyme, endogenous hormones, carbohydrates