Evaluation of Some Morpho- Physiological Responses of Citrus Genotypes to Salinity Stress

To identify salinity tolerant citrus genotypes, two international tolerant (Cleopatra mandarin) and sensitive genotypes (Troyer Citrange), and some screened citrus genotypes for salinity tolerance from citrus research center of Ramsar and Darab research station (total 28 genotypes) were evaluated under glasshouse conditions. Three levels of salinity stress including; zero (control), 40 and 90 Mm sodium chloride were applied on eight months seedlings of citrus genotypes. In 12th week after the application of salinity stress morpho- physiological characteristics including; leaf area, specific leaf area, growth rate, stem diameter, leaf thickness, fresh and dry weight, leaf necrosis and loss, leaf relative water content (RWC), sodium and potassium content, and potassium : sodium ratio were measured and studied. The studied genotypes showed different responses for all traits, except for specific leaf area. Salinity stress caused significant reduction in leaf area, growth rate, stem diameter, leaf thickness, fresh and dry weights and RWC. Furthermore, significant increase of leaf necrosis and loss, and leaf sodium and potassium concentration were observed. Study of stress tolerance score (STS) showed that two Iranian landraces including G25 and G8 and tolerant genotype (Cleopatra) had high salinity tolerance. G8 and Cleopatra were selected as the tolerant genotypes based on physiological traits and STS. In condusion, considering horticultural characteristics, these two genotypes can be recommended as rootstock in areas with saline soil and water.