Evaluation of salinity tolerance of sugar beet breeding populations and hybrids under greenhouse and field conditions

Soil salinity is one of the most important factors in reducing crop yield around the world, especially in arid and semi-arid regions. Therefore, development of salt-tolerant cultivars such as sugar beet that can grow under stress condition and have economic yield, is one of the most important breeding goals. For this purpose, salinity tolerance evaluation of different sugar beet populations and hybrids based on some physiological, morphological, and biochemical traits was performed in greenhouse and field conditions to select high yield populations and and determining the suitable traits for selection. Two greenhouse environments were used to study physiological, morphological and biochemical traits during establishment and field environment to study physiological traits, yield and its components. Five hybrids and four breeding populations along with three tolerant and susceptible control cultivars were evaluated at two salinity levels of 0 (control) and 16 ds/m in a factorial design based on completely randomized design in greenhouse and in a randomized complete block design in the field in normal (1.2 ds/m) and saline (17.34 ds/m) at Miandoab Research Station, Iran. Several characteristics such as fresh and dry weight of shoot, relative water content of leaves, relative leaf water reduction, specific leaf weight, and proline and nutrients (Na and K) in leaves, root yield and sugar yield, sugar content, Na and K in root were measured in both stress and normal conditions. Under stress condition in greenhouse, proline, dry matter, leaf sodium content and root length increased significantly compared with normal condition, but the values ​​of K, leaf area, relative leaf water content, leaf water reduction and root dry matter decreased. In the field, salinity stress increased the sugar content and potassium and decreased root yield and sugar yield compared with normal condition. In this study, Msc2*FS7 hybrid and FS2 population were found to be superior to other populations in terms of root yield, sugar content, and white sugar yield. Susceptible cultivar Shirin had the lowest ​​ root yield under stress ondition. Based on the results, proline and dry matter traits can be used as criteria for cultivars or populations selection under salinity stress.