Study of relationship between some agro-physiological traits with drought tolerance in rapeseed (Brassica napus L.) genotypes

Drought is one of the most important abiotic stresses that causes great damage to crops and orchards in the world, especially in Iran, which is considered as an arid and semi-arid country. Due to water limitation and low rainfall, ۵۰% of the area under cultivation of crops is dedicated to rainfed agriculture. Rapeseed (Brassica napus) is one of the most important oilseeds in temperate regions and has a relatively wide range of climatic adaptations. Rapeseed oil has high nutritional quality because it contains unsaturated fatty acids and no cholesterol. Due to the high consumption and import of edible oil in Iran and most of the agricultural lands of Iran are cultivated in the dry season, the production of drought-tolerant cultivars of rapeseed is important. In order to evaluate some agro-physiological traits for identification of drought tolerance in rapeseed, fourteen different rapeseeds genotypes differing in yield performances were evaluated using an RCBD design with three replications under two different environments (irrigated and rain-fed). Stress Tolerance Index (STI), Proline amino acid Concentration (PC), Cell Membrane Stability (CMS), Relative Water Content (RWC), Excised Leaf Water Retention (ELWR), Relative Water Loss (RWL), Relative Water Deficit (RWD) and SPAD were determined in order to find out whether these physiological traits could be used as the indicators of drought tolerance. The result of combine analysis of variance exhibited highly significant difference among years, genotypes and significant differences between genotypes × years interaction for most of the traits. Correlation analysis indicated a positive and strong association between STI, grain yield and oil yield in both conditions. Also, a highly significant correlation was observed between RWC and RWD.

Keywords:

Brassica napus , Drought tolerance , Physiological traits , RWC