Effect of salinity on root characteristics and ionic distribution of six bread wheat cultivars (Triticume aestivum L.)

Introduction Salinity is a major abiotic stress limiting growth and productivity of plants in many areas of the world due to increasing use of poor quality of water for irrigation and soil salinization. The over increasing salinity of land and water resources is one of the most important problems in Iran’s agriculture. A key characteristic of plant development is its plasticity in response to various changing environmental conditions. Roots are important to plants for a wide variety of processes, including nutrient and water uptake, anchoring and mechanical support, storage functions, and as the major interface between the plant and various biotic and abiotic factors in the soil environment. Congregated information on wheat root system as influenced by saline condition is meager. Materials and methods In order to investigate the effect of salinity on some root characteristics and ion distribution, a research was carried out in a three-replicate split factorial with two salinity levels 2dsm-1 (control) and 16dsm-1 (salinity) on six wheat cultivars (Atrak , Pishtaz, Chamran, Roshan, Ghods and Shiraz) and in two levels of harvest (two weeks and three weeks after planting) in greenhouse. The traits of root dry weight, shoot dry weight, shoot dry weight/root dry weight ratio, root length, total volume, sodium, potassium and potassium / sodium ratio in root and shoot, number of main root and number of first and second- order lateral roots were measured. Results and discussion The results showed that salinity in the second and third week reduced the dry weight of root, shoot, length, root volume and root number in all cultivars. Regarding the reduction and amount of root and shoot dry weight, Qods cultivar is susceptible and Roshan cultivar is tolerant. Also, Chamran and Roshan cultivar had a high ability to produce root and shoot in the control treatment, respectively. Qods cultivar under salt stress in the second and third week showed the highest reduction in total root length compared to control treatment and also, it had the least root length in salinity treatment compared to other cultivars. In the second and third weeks, Qods for root production (main, first and second-order lateral root) produced a high root count in the control treatment. However, as a result of salinity, the number of first and second-order lateral roots was significantly reduced, and in this trait it was the most sensitive cultivar. Under salinity Shiraz cultivar maintained in the third week of rooting process and showed the lowest reduction in the number of first and second-order lateral roots. In Roshan and Qods cultivar, there was no significant difference in the level of sodium ion in root in control and salinity treatments in the second and third weeks. This indicates that the accumulation of sodium ion in the root is not affected by salinity. The Roshan cultivar in saline treatment was able to maintain potassium ion in roots and shoots every two weeks. Shiraz and Pishtaz cultivars at the beginning of stress are able to avoid its negative effects by not absorbing sodium, although they are affected by ionic effects by continuity of tension and sodium absorption.