Effect of salt stress and nitrogen supply on seed germination and early seedling growth of three coastal halophytes

Abstract

Due to high salinity and low nutrient concentrations, the coastal zone is considered as one of the most vulnerable of the earth’s habitats. Thus, the effect of salt and nitrogen on growth and development of coastal halophytes has been extensively investigated in recent years, but insufficient attention has been paid to the crucial stages of plant establishment, such as seed germination and seedling growth. Thus, we carried out a field experiment to evaluate the effects of salt stress (6, 10 and 20 g/kg NaCl) and nitrogen supply (0, 6 and 12 gm−2year−1) on seed germination and seedling growth of three coastal halophytes (including two dominant herb species Glehnia littoralis and Calystegia soldanella, one constructive shrub species Vitex rotundifolia) from September 2020 to June 2021. The results of our experiment showed that seeds of G. littoralis exhibited an explosive germination strategy in the early spring of 2021 with 70% of the seeds germinating. Conversely, the seeds of V. rotundifolia exhibited slow germination in the late spring of 2021 with only 60% of the seeds germinating. C. soldanella seed germination exhibited two obvious peak periods, but only 6% of the seeds germinated, which means that most seeds may be stored in the soil by stratification or died. All three halophytes showed greater sensitivity to nitrogen than salt stress during the seed germination stage. Nitrogen supply significantly delayed seed germination and reduced the cumulative germination percentage, particularly for G. littoralis. Despite the large impact of nitrogen on seed germination, nitrogen had a larger impact on seedling growth suggesting that the seedling growth stage of halophytes is more vulnerable to changes in nitrogen supply. Moreover, nitrogen supply significantly reduced the individual biomass of G. littoralis, C. soldanella and V. rotundifolia, with greater decreases seen in the dominant species than in the constructive species. Conversely, nitrogen supply increased underground biomass allocation of G. littoralis and C. soldanella, suggesting that the constructive species were less sensitive to nitrogen and exhibited a stronger anti-interference ability than the dominant species. Therefore, increasing nitrogen supply may firstly affect the seed germination and seedling growth of the dominant species, but not the constructive species.

Effects of Salinity and Drought of Germination Parameters of Seeds of <i>Triticosecale</i>

“…The analysis of the obtained data showed that the increase in sucrose concentration (pressure) in the medium leads to a decrease in the indicators of seed germination. As a result of the study of the germination parameters of Eremosparton songoricum (Fabaceae), Elymus nutans and Portulaca oleracea seeds under drought conditions, it was noted that the germination of seeds decreased by 35-80% inversely proportional to the increase in the level of drought in these plants (Li et al, 2013, Pham et al, 2023, Long et al, 2023. These data confirm the validity of our results regarding the effect of drought on seed germination of triticale cultivars.…”

“…Water deficit affects the activity of internal enzymes in seeds, cell division and other physiological metabolic processes. At the same time, water deficit can cause seeds to lose viability due to their inability to absorb enough water at the same time, which affects seed germination (Long et al, 2023;Tursunov et al, 2023). Triticale -Triticosecale is…”