AUTHOR=Shi Congcong , Yang Fan , Liu Zihao , Li Yueming , Di Xiaolin , Wang Jinghong , Lin Jixiang 

TITLE=Uniform Water Potential Induced by Salt, Alkali, and Drought Stresses Has Different Impacts on the Seedling of Hordeum jubatum: From Growth, Photosynthesis, and Chlorophyll Fluorescence

JOURNAL=Frontiers in Plant Science

VOLUME=Volume 12 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.733236

DOI=10.3389/fpls.2021.733236

ISSN=1664-462X

ABSTRACT=Hordeum jubatum is a halophyte ornamental plant and wildly distributed in the Northeast of China, where the low water potential induced by various abiotic stresses is a major factor limiting plant growth and development. However, little is known about the comparative effects of salt, alkali and drought stresses at uniform water potential on the plants. In the presented study, the growth, gas exchange parameters, photosynthetic pigments and chlorophyll fluorescence in the seedlings of this species under three low water potentials were measured. The results showed that the growth and photosynthetic physiological parameters under these stresses were all decreased except for carotenoid with the increasing of stress concentration, and alkali stress caused most damage effect on the seedlings. The decreased Pn, Gs and Ci values under salt stress were mainly attributed to stomatal factors, while non-stomatal factors were dominate under drought and alkali stresses. The reduced chlorophyll and slightly increased carotenoid contents occurred under these stresses, and also most significant changed under alkali stress. In addition, the Fv/Fm, ΦPSⅡ and qP under the stresses were all decreased, indicating that salt, alkali and drought stresses all increased susceptibility of PSII to photoinhibition, reduced the photosynthetic activity by the declined absorption of light for photochemistry and increased PSII active reaction centers closed. Moreover, the NPQ of alkali stress was different from salt and drought stresses, showing that the high pH of alkali stress caused more damaging effects on the photoprotection mechanism depended on xanthophyll cycle. The above results suggest the Hordeum jubatum has stronger tolerance of salt than drought and alkali stresses, and the negative effects of alkali stress on the growth and photosynthetic performance of this species was most serious.