Salt and Drought Effect on Germination and Initial Growth of Lavandula stoechas: A Potential Candidate for Rehabilitation of the Mediterranean Disturbed Coastal Lands

Abstract

Information relating to germination and seedling emergence of a plant aids in determining the species spatiotemporal distribution and also facilitates in designing appropriate plant management strategies within an ecosystem. Lavandula stoechas L. (Lamiaceae), a naturally occurring shrub, is particularly used in pharmaceutical and cosmetic industries. This species, indeed, has the potential for rehabilitation of degraded costal lands. However, various aspects of its seed biology have not yet been recognised. Here, we aimed to assess the effects of different soluble salts (NaCl, CaCl2, MgCl2 and Na2SO4) and drought (as simulated by polyethylene glycol, [PEG]6000) on seed germination patterns and early seedling growth responses. Seeds treated with five iso-concentration (0–100 mM) salinities and five PEG6000 (0 to −1 MPa) levels were incubated in a controlled germinator set at 20°C. The preliminary results revealed that seeds of L. stoechas lacked primary/innate dormancy and they germinated abundantly (89.2% germination) and fast (7.4% day−1) in the absence of stress. Regardless of the kind of salt applied, the germination percentage (GP) and germination rate index (GRI) fell significantly with increasing salinity, and germination ceased completely at 100 mM Na2SO4. In fact, the salinity tolerance index (STI) showed that, among all salts tested, Na2SO4 appeared to have more inhibitory action on germination. In addition, L. stoechas was found to be tolerant to moderate salty stress (<50 mM) in early growth phase. The salt solution parameters (i.e. concentration, electrical conductivity [EC] and salt content) were best correlated with seed/seedling metrics. pH was not a good predictor for salt effects at the germination/seedling stages. Overall, this species seems to be sensitive to drought at the germination and initial growth phases. The germination recovery potential of L. stoechas in both stresses stipulates that this species can be regarded as a promising candidate in the rehabilitation of Mediterranean disturbed coastal habitats.

Study of Drought Effects on Three Medicinal and Aromatic Plants Using Field Spectroscopy

“…Considering the total of precipitation received six months before July 2021 and March 2022 (423 mm-195mm, respectively), it can be deduced that L.stoechas leaf structure was impacted by the lack of water content in its growing period; this is in line with the study by Nogués and Alegre (2002) which concluded that the effects on L.stoechas were only observed in relative leaf water content and water potential. Dadach's team reported that L.stoechas germination rate and water deficit are inversely proportional, which give it limited tolerance to water stress (Dadach et al, 2021).…”

“…North Africa is located in one of the hotspots of global warming, making it one of the most drought-prone and thus water-stressed regions in the world (Bzioui 2005). In the Mediterranean areas, water deficit has destructive impacts on plant physiology (Dadach et al, 2021); furthermore, aridity causes reduction in soil water potential that retards plant emergence (Krichen et al, 2014). The present climate tends towards drier status in the northwestern region of Morocco with a diminution in mean annual precipitation caused by negative trends in winter and spring seasons (Driouech et al, 2021).…”

New Investigation and Challenge for Spatiotemporal Drought Monitoring Using Bottom-Up Precipitation Dataset (SM2RAIN-ASCAT) and NDVI in Moroccan Arid and Semi-Arid Rangelands

“…Overall, the rangeland species seem to be sensitive to drought at the germination and initial growth phases. Th e germination recovery potential of stressed species can be regarded as a promising candidate in the rehabilitation of Mediterranean disturbed coastal habitats (Dadach et al, 2021). In fact, Faisal et al (2019) emphasized that the eff ects of drought depend not only upon the degree and length of water scarcity, but also upon the plant growth phase.…”

Effects of Chloride and Sulfate Salts on Seed Germination and Seedling Growth of Ballota hirsuta Benth. and Myrtus communis L.

“…Moreover, this species is very aromatic due to the high essential oil content in its leaves, and it is mainly utilized in the production of perfume and cosmetic products [28]. Evidence shows that various factors such as soil salinity, prolonged drought and land-clearing activities are severely affecting the growing area of M. communis [15].…”

“…Furthermore, it has been documented that various salt agents may have differing effects during the germination and seedling establishment stages, and these effects can vary depending on the species. For example, Lavandula stoechas seeds exhibited better tolerance to MgCl 2 compared to other dissolved salts [15]. On the other hand, Artemisia herba-alba seeds displayed greater susceptibility to MgCl 2 when compared to NaCl, CaCl 2 and Na 2 SO 4 [6].…”