Open Access

ARTICLE

Germination and Photosynthetic Responses to Salinity and Alkalinity in Avicenna marina Propagules

by Abdallah Atia^1,2,*, Ahmed Abdallah Hussain^3,4, Barhoumi Zouhaier^3,5

1 Department of Biology, College of Arts and Science Mahayel Asir, King Khalid University, Abha, 61413, Saudi Arabia
2 Research Unit, Nutrition and Nitrogen Metabolism and Stress Protein, Department of Biology, Faculty of Sciences of Tunis, Campus Universitaire El Manar I, Tunis, 1068, Tunisia
3 Department of Biology, King Khalid University, Abha, 61413, Saudi Arabia
4 Faculty of Science, Abu Haraz, Gezira University, Wed Medani, 21111, Sudan
5 Laboratory of Extremophile Plants, Biotechnology Center of Borj Cedria, University Tunis El Manar, Tunis, 1068, Tunisia

* Corresponding Author: Abdallah Atia. Email:

(This article belongs to the Special Issue: Plant Ecophysiology: Recent Trends and Advancements)

Phyton-International Journal of Experimental Botany 2022, 91(5), 1015-1026. https://doi.org/10.32604/phyton.2022.017778

Received 06 June 2021; Accepted 28 October 2021; Issue published 24 January 2022

Abstract

Avicenna marina (Forssk.) Vierh is a halophytic mangrove. The reproductive unit is green and has photosynthetic propagules. Mangroves are naturally exposed to fluctuations in some abiotic factors at the soil surface, including salinity and alkalinity. The objective of this study was to determine the effects of two salts including NaCl and NaHCO₃ on germination processes and discuss the relationships between cotyledon photosynthesis and embryo axis growth in A. marina propagules. These propagules came from Al Birk, located on the shoreline of the Saudi Red Sea. The results showed that the studied salts did not affect neither the final germination percentage nor the embryo axis growth. However, rooting and root growth were delayed by both salts at 300 mM and were strongly inhibited by 600 mM NaHCO₃. Both NaCl and NaHCO₃ reduced the photosynthetic activity. These two salts did not affect the other photosynthetic parameters, including stomatal conductance, net transpiration, and intercellular CO₂. Thereafter, the reduction in net photosynthesis was not related to any limitation of stomatal conductance. The early germination phase was independent of cotyledon photosynthesis, whereas rooting and root growth may be limited by reduced photosynthesis under NaCl and NaHCO₃.

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