In Morocco, a large number of aromatic and medicinal species are endemic. It is therefore essential to work towards preserving and protecting them from massive and irrational exploitation, especially with the emergence of the "Bio" label. Domestication of these plants is therefore the best option to alleviate the pressure they are under. In addition a large part of Moroccan agricultural regions are affected by the soil salinisation process. Currently, almost 5% of lands are already affected by salinisation at different levels. In response to the magnitude of this problem, it is necessary to select species capable of developing in saline areas. The present work aims to evaluate the substrate effect on Rosemary morphophysiological behaviour (Rosmarinus officinalis L.) under a saline constraint. This was done with the purpose of elaborating a tolerance thresholds classification to saline stress, an important criterion in the choice of species to be retained in an enhancement program of the salinity affected areas. The trial is conducted using an experimental design in block. Rosmary is planted in plastic pots of 9 cm diameter and 11 cm height. The used substrates are: arenosols, sea sand and vertisols. The pots were irrigated with 40 ml of sodium chloride each 72 hours, with a concentration of 6 g.l-1, 9 g.l-1, 12 g.l-1, in addition to the control. The measured parameters are: length of aerial and root parts, root volume, water content (WC), soluble sugar content (SS). Each treatment is repeated 10 times.
Another test was added, which corresponds to pots filled with sea sand. A plastic film is placed under the pots to limit drainage and placed in a vegetable garden, in order to study the interest of the drainage percentage on the plant growth maintenance. The obtained results show that saline treatments cause significant changes on root morphological parameters than on aerial morphological parameters. Plants cultivated in vertisols grow poorly, in contrast to those planted in sandy substrates, which shows the drainage importance to minimise the salt stress effect. The salt effect on the plants physiological characteristics is reflected in a significant reduction in the plants water content (P= 0.041), which leads to an increase in the soluble sugar content. The depressive effect of saline stress above 6 g/l and in the long term in vertisols induces a significant reduction of water content (P=0.032) and a significant increase of soluble sugars (P=0.018). Therefore, under salt stress, an arenosols has optimal characteristics for rosemary germination.
Index Terms- Domestication, Morphophysiological characteristics, Rosmarinus officinalis L., Saline stress, Sea sand.