Seed Germination Techniques in Halophyte Plants

Dear Colleague,

Halophyte plants grow better in the presence of salts in the soil and/or irrigation water; however, like glycophyte plants, the germination process of halophyte seeds can be negatively affected by the presence of salts in the environment that surrounds them. Seed germination is the first step required to produce halophyte plants for their use for both ecological (producing vegetation cover) and agronomic (saline agriculture) purposes. In saline environments, the germination of seeds usually occurs in the spring or during seasons featuring high precipitation levels because such conditions contribute to the reduction of soil salinity levels, creating a more favorable environment for the germination process. Numerous research investigations have indicated that the seeds of numerous halophyte species exhibit dormancy when subjected to low water potential. However, seed dormancy in halophytes can be effectively overcome through various methods, such as physical treatments like scarification (the elimination of the seed coat) and seed stratification (cold pre-treatment), or through the application of chemical treatments. These approaches have been found to significantly reduce the negative impact of salinity on the germination of halophytes.

The germination response of halophyte populations plays a crucial role in their success, especially in temperate conditions. Soil salinity in areas where halophytes typically thrive increases due to the rapid evaporation of water, particularly in the summer period, resulting in higher soil salinity and water potentials at the soil surface. In arid and semi-arid regions, seed germination typically takes place after rainfall, which helps reduce surface soil salinity.

There is a significant amount of variation in how halophytes respond to increasing levels of salinity and other environmental factors during germination. The available information on the germination of halophytic seeds is still incomplete. Of the approximately 2500 – 3000 reported species, data are only sporadically available for a few hundred species. Various factors, such as salinity, temperature, light, habit, life form, habitat, and water, play roles in determining the germination responses of halophytic seeds. It would be intriguing to identify any germination patterns that may exist due to these factors. Moreover, numerous research investigations have indicated that the seeds of numerous halophyte species exhibit dormancy when subjected to low water potential.

The presence of salts in irrigation water and soils is a major abiotic component for agricultural operations on a global scale, affecting plant growth and productivity, especially in arid and semi-arid areas. Additionally, it is estimated that the world’s population will grow to nearly 10 billion by 2050, which implies an increase in agricultural and livestock production to feed these increasing populations. However, according to forecast estimates, less fresh water and less arable land will be available. On the other hand, the salinization of soils and groundwater is a growing problem worldwide, leading to a situation that could force farmers to use salt-tolerant plants and/or agronomic management capable of overcoming salinity in order to produce food (biosaline agriculture). In that regard, the use of a halophyte-based management may be a possibility that would allow production in salinized soils. To achieve this, two related strategies are proposed: (1) mixed cultivation of halophytic plants and plants of agronomic interest (intercropping) and (2) growing plants of agronomic interest in monoculture where halophytic plants had previously been grown (crop rotation). These practices require the continuous availability of halophyte plants. Therefore, developing techniques to improve seed germination is of great importance, including priming and in vitro approaches.

The aim and scope of this Special Issue entail the investigation of research works and/or reviews that delve into methodologies aimed at improving the germination rate of seeds derived from halophytic plants, including priming techniques and the utilization of in vitro culture approaches.

This Special Issue is dedicated to the publication of research works and/or reviews that explore the physiological, biochemical, and molecular changes that take place during the germination of halophyte seeds, with a particular focus on the utilization of omics and metabolomics approaches.

This Special Issue on “Seed germination techniques in halophilic plants” has as its main objective to promote the publication of research on the germination of halophytic seeds and early seedling growth with the aim of using them in saline soil remediation processes enabling the production of crop plants by applying saline agriculture.

Dr. José Antonio Hernández Cortés
Dr. Pedro Diaz-Vivancos
Dr. Gregorio Barba-Espín
Guest Editors

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• saline agriculture
• halophyte
• seed germination
• seed priming techniques
• in vitro culture

Title: Seed priming as an effective technique for enhancing salinity tolerance of halophytes: mechanistic insights and prospects for saline agriculture
Authors: Abdul Hameed1; Sadiq Hussain1 and Aysha Rasheed1
Affiliation: Institute of Sustainable Halophyte Utilization, University of Karachi, Karachi-75270, Pakistan
Abstract: Seed priming is an easy, low-cost, and effective pre-sowing technique that enables plants to better tolerate abiotic stresses, including high soil salinity, which is a major limiting factor in the productivity and establishment of halophytes for saline agriculture. This article attempts to provide an overview about the physio-chemical and molecular processes including the induction of priming/stress memory, which enhance salinity tolerance of halophytes following seed priming. This review will also cover the aspects of reactive oxygen species (ROS), nitric oxide (NO), and hormonal signaling(s) that are activated as a result of seed priming. Finally, the prospect of seed priming to enhance agronomic potential of halophytes for saline agriculture will be discussed.