عنوان مقاله [English]
Background and Objectives
Spearmint is perennial, it has creeping and underground stems, belong to the labiatae family. After drought, salinity is the second most common environmental agent that restricts agricultural production. Glycine betaine is the most commonly used organic solution and is known for its quadrature ammonium compounds, which is the largest and most abundant compound in response to stress. The purpose of this experiment was to investigate the effect of glycine betaine on some quantitative and qualitative properties of mint under salinity stress.
Materials and Methods
A factorial experiment based on randomized complete block design with three replications was conducted in 2017-18. Experimental factors: 1. Salinity stress (4 levels, 7 (control), 30, 60 and 90 mM NaCl) and 2. Glycine betaine (at 3 levels, 0, 100 and 200 mM). In the present study, some growth traits, height of plant, fresh weight and dry weight of shoot, root volume, fresh and dry weight of root, photosynthetic pigments (chlorophyll a and b and total), protein, proline and soluble sugars were measured.
The results showed that the salinity stress was significant for all characteristics, So that by increasing levels of salinity, all of traits was reduced except chlorophyll b, total chlorophyll, proline and soluble sugars. Salinity due to decrease plant height (29.47%), fresh weight of shoot (49.56%), dry weight of shoot (56.87%), root volume (47.89%), fresh weight of root (52.15%), dry weight of root (43.92%), photosynthetic pigments (a) (18%) and (b) (29.41%), protein content (17.79%), proline (30.98%) and soluble sugars (3.58%). Application of glycinebetaine reduced the negative effects of salinity stress, but it caused reduced height (9.16%) and chlorophyll b (26.31%) compared to control. Also, interactions between salinity stress and foliar application of glycinebetaine had significant for shoot fresh weight, shoot dry weight, root fresh weigh, root dry weight, proline, protein (p<0.01), root volume and soluble sugars (P<0.05). The highest values of the studied traits were obtained for the interaction between 7 mM NaCl and 200 mM glycinebetaine.
Salinity stress reduced the growth of plants through osmotic stress, ion toxicity and nutritional imbalance. But glycine betaine, as an important osmolite in plants, increases the osmotic potential and improves the water relations and increases the activity of photosynthesis and the production of hydrocarbon materials. In this way, glycine betaine can protect against the stress of salinity by increasing the mechanisms of tolerance to salinity, will provide better conditions for plant growth in a saline environment.