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Acta Prataculturae Sinica ›› 2021, Vol. 30 ›› Issue (3): 137-157.DOI: 10.11686/cyxb2020416

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Effects of complex saline-alkali stress on seed germination and seedling physiological characteristics of Achnatherum inebrians

Ya-qi CHEN(), Kai-qi SU, Tai-xiang CHEN, Chun-jie LI()   

  1. State Key Laboratory of Grassland Agro-Ecosystems,College of Pastoral Agricultural Science and Technology,Key Laboratory of Grassland Livestock Industry Innovation,Ministry of Agriculture and Rural Affairs,State Key Laboratory of Engineering Research Center of Grassland Industry,Ministry of Education,Center for Grassland Microbiome,Western China Technology Innovation Center for Grassland Industry,College of Pastoral Agriculture Science and Technology,Lanzhou University,Lanzhou 730020,China
  • Received:2020-09-14 Revised:2020-10-26 Online:2021-03-20 Published:2021-03-09
  • Contact: Chun-jie LI

Abstract:

Saline-alkali land currently has limited options for cultivation and development. This project investigated seed germination, physiological characteristics and antioxidant enzyme activities of Achnatherum inebrians in order to better understand the adaptation to saline soil environments exhibited by this species and provide information to aid future breeding selection and cultivation. A set of 20 different alkali-saline stress conditions were stimulated by mixing two neutral (NaCl and Na2SO4) and two alkaline (NaHCO3 and Na2CO3) salts with soil in different proportions (A: NaCl∶Na2SO4=1∶1; B: NaCl∶Na2SO4∶NaHCO3=1∶2∶1; C: NaCl∶Na2SO4∶NaHCO3∶Na2CO3=1∶9∶9∶1; D: NaCl∶Na2SO4∶NaHCO3∶Na2CO3=1∶1∶1∶1; E: NaCl∶Na2SO4∶NaHCO3∶Na2CO3 = 9∶1∶1∶9) and at concentrations of 50, 100, 150, and 200 mmol·L-1. These soil mixtures were used to grow seedlings of endophyte-infected (E+) and endophyte-free (E-) drunken horse grass, and analyze the general salt tolerance of drunken horse grass accessions at the germination and seedling growth stages were analyzed. The seed germination rate, germination vigor, germination index, energy index and shoot length, root length, root-shoot ratio, and shoot tissue antioxidant enzymes peroxidase (POD) and superoxide dismutase (SOD), malondialdehyde (MDA) and proline were evaluated and analyzed data explored by subordinate function analysis. It was found that the germination rate, germination potential, germination index and vigor index of both E+ and E- drunken horse grass were decreased under the five different saline-alkali stresses. Germination was significantly inhibited with increase in saline-alkali stress concentration (P<0.05). The radicle length and root-shoot ratio were also significantly decreased with increased salt concentration. Except for treatments C and E, physiological indexes (POD, SOD and CAT activities, MDA and proline levels in shoot tissue) of drunken horse grass were reduced at higher salt concentrations. Subordinate function analysis and the multivariate analysis of salt tolerance indicated that the order of salt tolerance across treatments was A>D>B>C>E. In conclusion, saline-alkali stress significantly inhibited seed germination and seedling growth of drunken horse grass (P<0.05). Among the alkaline salts tested (NaHCO3 and Na2CO3), Na2CO3, especially, had a stronger inhibitory effect on seed germination and growth. Vigor index, root length, POD, SOD, and proline were found to be the most useful indicators to evaluate the salt tolerance of drunken horse grass. The salt tolerance of E+ drunken horse grass was found to be better than that of E-. Epichlo? endophytic fungi can improve the osmotic adjustment and scavenging of reactive oxygen species of drunken horse grass, thus reducing the membrane lipid peroxidation, and improving the salt tolerance of A. inebrians.

Key words: mixed saline-alkali stress, drunken horse grass, endophytic fungi, physiological property, salt tolerance