Response of Germination and Seedling Development of Cotton to Salinity under Optimal and Suboptimal Temperatures

Abstract

The objective of the study was to investigate the effects of salinity stresses (50, 100, 150, 200 and 250 mM of NaCl) on germination and early seedling growth of six cotton varieties (Lydia, Carisma, Flash, BA151, BA525 and ST468) under optimum (25 degrees C) and low temperature (18 degrees C) conditions. Germination percentage, mean germination time, germination index, germination stress tolerance index, seedling length, vigor index, seedling fresh and dry weight of cotton varieties were investigated. Results showed that low temperature led to decreasing in germination and seedling growth, and caused retardation of mean germination time. Under suboptimal temperature, germination percentage reduced from 86.3% to 77.8% and seedling length decreased from 12.02 cm to 5.36 cm. Each increase in salinity levels higher than 50 mM resulted in decreasing in germination and seedling growth parameters of cotton varieties. No seedling growth was observed at 250 mM of NaCl at 18 degrees C. Cotton varieties showed different tolerance levels to salinity, while they could tolerate it up to 100 mM. It was concluded that Flash and ST468 varieties exhibited better performance under salinity stresses both at optimal and suboptimal temperatures.