Effect of different levels of salinity on morpho-physiological cCharacteristics of wood Sage (Salvia nemorosa L.)

Salinity is one of the abiotic stresses that severely curtails the growth and production of agricultural products. Water scarcity makes the use of salty waters for agricultural products not only inevitable but also economically efficient. Salvia nemorosa is a perennial plant that belongs to Lamiaceae family. Given the medicinal value Salvia of plants, this study was performed to assess the effects of sodium chloride salinity on the physiological and morphological properties of Salvia nemorosa.

The study was a randomized block design and was conducted in 2018 using pots at the greenhouse of the Research Center no.1 of the City of Isfahan’s Parks Department. The randomized block design had 4 levels of salinity: 12(control), 50, 75, and 100 mM of sodium chloride and was repeated 5 times. The morphological properties of the plants such as the length and width of the leaves, the plants’ height and the length of the corymbs were measured by a ruler. The number of leaves and corymbs in each bush and the number of flower and seed in each corymb was measured manually. Aerial parts of the plants, under both wet and dry conditions, were measured by a digital scale. In order to measure chlorophyll the method of Li et al. was used. Measuring Prolin leaf was done by the method of Bates et al. and the total phenol was measured by Folin-Ciocalteu. Statistical analysis was done by SAS and the means were compared using the Least Significant Difference (LSD) with alpha levels of 1% and 5%.

The ANOVA results showed significant effect of salinity on the height, the number and the width and length of leaves, the length of corymbs and their number in each bush, the number of flowers in corymbs, the wet and dry weight of the root, the level of chlorophyll a and b and the total chlorophyll and these properties at the level of salinity of 100mM were respectively: 20.56% , 68.95%, 54.41%, 27.97%, 9.19%, 82.85%, 41.45%, 62.31%, 60.47%, 53.84%, 23.13%, 34.09%, 66.66%, 62.5% and 64.7% reduction in comparison with the control sample. Salinity had also a significant effect on the level of Prolin and total phenol and in the sample of 100mM sodium chloride, it showed an increase of 62.5% and 96.17% respectively in comparison with the control sample.  Since the dry weight is an appropriate measure for photosynthesis and growth in plants, the decreasing of the dry weight of the aerial parts and the root of the plant as salinity stresses increase, shows that the plants photosynthesis and growth have decreased in the plants. Accumulation of harmful ions like sodium chloride leads to a decrease in the wet weights of the aerial parts and causes disorder in the metabolism of nutarians.  Reduction of the leaves chlorophyll in salinity stresses is caused by decomposing enzymes. Decreasing of the leaf area can be considered as a defense mechanism in the plant in order for it to reduce the level of transpiration and avoid salinity. Increasing the level of salinity also increases the rate of falling of leaves and decreases the rate of the production of new leaves. Meanwhile, higher salinity causes a decrease in the level of calcium and potassium in the plant, which in turn, results in a decline in growth.  Salinity stress decreases the number of corymbs through disturbing the photosynthesis process in the plant, which in turn, reduces the production of photosynthetic material that is supposed to feed the growing parts of the plants. This reduction will eventually cause the plant to not to achieve its genetic potentials with respect to the number of corymbs. The reduction in the rate of germination leads to a lower number of flowers. Phenolic combinations are parts of the non-enzymatic and antioxidant defense system which inhibit the free radicals. Soil salinity increases the total phenol in some plants which is an advantage in medicinal plants. These plants use Prolin to keep the osmotic pressure and protect the plant against salinity.

Salvia nemorosa combats salinity by osmotic adjustment via increasing of Prolin amino acid and by increasing total phenol and oxidative stress.Therefore it can be concluded that the this plant on salinity levlels up to 50 mM (6.5 ds/m) can tolerate sodium choloride and is sensitive to higher levels of salinity.