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

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

Soil salinity is a well-known abiotic factor affecting the germination and seedling growth of various plant species. Therefore, we evaluated the effects of different chloride salts (NaCl, KCl and MgCl2) and sulfate salts (Na2SO4, K2SO4 and MgSO4) on the seed germination and early seedling growth of two important ethnomedicinal shrubs of North Africa and the Mediterranean basin (Ballota hirsuta and Myrtus communis). Seeds of these species were subjected to five salinity levels (0-100 mM) and incubated at 20 °C under a light regime (12 h photoperiod). Both species demonstrated their highest germination percentage under control conditions (i.e., without salinity). However, as salinity levels increased, the germination percentages for both species decreased, regardless of the type of salt used. Cations appeared to be more determinative than the anions in regulating the seed germination of both species. M. communis seeds displayed greater sensitivity to sodium (Na+) salts, especially when accompanied with chloride (Cl-) anions. At the higher salt concentrations (75 and 100 mM), Na+ salts had a more pronounced inhibitory effect on M. communis seedling growth compared to potassium (K+) and magnesium (Mg2+) salts. Conversely, Mg2+ salts were more detrimental to seedling growth in B. hirsuta. Based on our results, it can be concluded that both of these species are able to tolerate a moderate level of salinity. Overall, B. hirsuta may be a promising choice for rehabilitating the soils dominated by chloride salts, while M. communis could be utilized for restoring sulfate-dominated soils.

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

Remotely sensed soil moisture products showed sensitivity to vegetation cover density and soil typology at regional dryland level. In these regions, drought monitoring is significantly performed using soil moisture index and rainfall data. Recently, rainfall and soil moisture observations have increasingly become available. This has hampered scientific progress as regards characterization of land surface processes not just in meteorology. The purpose of this study was to investigate the relationship between a newly developed precipitation dataset, SM2RAIN (Advanced SCATterometer (SM2RAIN-ASCAT), and NDVI (eMODIS-TERRA) in monitoring drought events over diverse rangeland regions of Morocco. Results indicated that the highest polynomial correlation coefficient and the lowest root mean square error (RMSE) between SM2RAIN-ASCAT and NDVI were found in a 10-year period from 2007 to 2017 in all rangelands (R = 0.81; RMSE = 0.05). This relationship was strong for degraded rangeland, where there were strong positive correlation coefficients for NDVI and SM2RAIN (R = 0.99). High correlations were found for sparse and moderate correlations for shrub rangeland (R = 0.82 and 0.61, respectively). The anomalies maps showed a very good similarity between SM2RAIN and Normalized Difference Vegetation Index (NDVI) data. The results revealed that the SM2RAIN-ASCAT and NDVI product could accurately predict drought events in arid and semi-arid rangelands.