Exploring temperature and salinity effects on seed germination in North African pastoral grasses: A halo-thermal modeling approach in the context of climate change

Abstract

Understanding how plant species respond to temperature and salt stress is crucial for ensuring successful seed germination and crop production. The ongoing effects of global climate change, such as temperature fluctuations, can have serious consequences for seed germination. This study aimed to investigate the impact of salinity (NaCl) and temperature (T), individually and in interaction, on the germination responses of four North African pastoral grass species Stipagrostis (S. ciliata, S. pungens, S. obtusa, and S. pulmosa) and the potential impact of climate change scenarios on their seed germination. Significant effects of NaCl, T, and their interaction (NaCl × T) were observed on both germination percentage and germination rate across the four species. The halotime and halothermal time models successfully predicted germination time courses for the four species (R2 > 0.86). The base T (Tb), optimum T (To), and ceiling T (Tc) were 13, 9.8, 9.0, and 10.7 °C; 25, 29, 28, and 27 °C; and 34, 35, 38, and 34 °C for S. ciliata, S. obtusa, S. pungens, and S. pulmosa, respectively. The predictions indicated that higher temperatures associated with climate change caused shorter germination times (i.e., 42 h for S. ciliata and 23–24 h for S. pulmosa, S. pungens, and S. obtusa) suggesting potential shifts in germination behavior in response to changing environmental conditions. Furthermore, the study assessed germination recovery after salt stress, revealing species-specific responses to both T and NaCl variations. The results highlighted the resilience of the studied grass species, as seeds were capable of recovering germination after exposure to salt stress. Therefore, the research provides comprehensive insights into the intricate relationships between T, NaCl, and germination in North African pastoral grasses. The findings contribute to our understanding of how these grasses may respond to changing environmental conditions, particularly under climate change scenarios.