Changes in yield, vegetative, physiological and biochemical characteristics of strawberry cv. Aromas under effect of electrical conductivity of nutrient solution caused by sodium chloride

The most regions of Iran are arid and semi-arid and electrical conductivity of irrigation water in these regions is high and often is salty. The improvement of saline water and soils is costly and time-consuming and it is practically impossible. Therefore, it is necessary to evaluate the tolerance of various plant species and cultivars to salinity for cultivation in these areas. Strawberry is one of the small fruits which has a high demand in the market due to high nutritional value and favorable taste. Strawberry has various cultivars with different yield and sensitivity to stress. Therefore, this research evaluated the sensitivity of "Aromas" cultivar to different levels of electrical conductivity of the nutrient solution.

In order to evaluate the effect of different levels of electrical conductivity of nutrient solution on morphological, yield, physiological and biochemical characteristics of "Aromas" cultivar of strawberry, an experiment was performed as pot based on the completely randomized design in the Research Center of Strawberry Breeding and Improvement of the University of Kurdistan. The culture media was cocopeat perlite with equal ratio and the nutrient solution was modified Hoagland. Different levels of electrical conductivity of a nutrient solution (0.7, 2, 3, 4 and 5 dS/m) were prepared by adding sodium chloride. Frozen leaf samples were used for physiological and biochemical evaluations. Then, at the end of the experiment period, the functional characteristics of plants were measured and the obtained data were analyzed by SAS software and mean comparison was done by the LSD method.

The results of variance analysis showed that the electrical conductivity of the nutrient solution had a significant effect on all of the measured traits. The highest mean number of leaf, leaf area, leaf dry weight, root volume, root dry weight, number of crown, crown dry weight, dry weight of whole plant, number of fruit, single fruit weight and total fruit yield belonged to control plants (irrigated with nutrient solution with electrical conductivity of 0.7 dS/m) and with increasing electrical conductivity of nutrient solution, the amount of mentioned factors decreased. Moreover, the highest relative water content of leaf, membrane stability index, total soluble proteins, chlorophyll, carotenoids and potassium of leaf belonged to 0.7 dS/m treatment. While the highest total soluble carbohydrates, proline, hydrogen peroxide, the activity of peroxidase and superoxide dismutase enzymes, malondialdehyde and sodium of leaf were observed in plants that received a nutrient solution with electrical conductivity of 5 dS/m. The slope of yield loss was 49.02 for each unit of electrical conductivity of nutrient solution and the salt tolerance threshold of this cultivar was less than 2 dS/m based on total fruit yield and biomass.

Overall, based on the findings of this research, the "Aromas" cultivar was strongly influenced by the electrical conductivity of the nutrient solution and its morphological, physiological, biochemical and yield properties changed significantly. Based on the observations, it seems that Aromas cultivar is not able to withstand high electrical conductivity of the nutrient solution and to achieve optimal performance of this cultivar, nutrient solutions with electrical conductivity of less than 2 dS/m should be used.