Effects of Prolonged High Salinity Stress on Alfalfa ( Medicago sativa L.) Cultivars and Populations

Background: Alfalfa is a promising crop for improving soil structure and restoring agricultural land, particularly in areas affected by salinity. However, high and continuing salinity in soil and irrigation water can pose a significant challenge to the growth and productivity of alfalfa. The objective of this study was to investigate the effects of prolonged high salinity stress on alfalfa cultivars and populations. Methods: The material used in this study included 16 alfalfa populations and four alfalfa cultivars that exhibit salt tolerance during germination and early seedling development. The materials were exposed to 17.52 dS m-1 saline irrigation water stress for three months. As well as the morphology, survival at three months and crude ash, sodium and chloride ions were measured. Result: Salt-tolerant plants showed a slowdown in growth compared to control conditions, although they were still able to maintain growth. Duration and severity of stress affected the salt tolerance of the genotypes. The survival rates of the materials remained relatively unchanged for the first two months, but decreased significantly by the end of the third month. Furthermore, the survival rate of the materials increased as the amount of sodium and chloride ions absorbed by the plant decreased under high salinity conditions. Genetic material demonstrating long-term high salinity tolerance is crucial for resistance breeding and holds promise for the development of tolerant cultivars that can be grown under field conditions in the future. The properties of this material need to be determined and its long-term performance in field conditions needs to be tested.