Multidimensional screening and evaluation of morpho-physiological indices for salinity stress tolerance in wheat

Soil salinity is one of the major constraints to crop production worldwide. The multifaceted nature of salinity tolerance traits complicates plant screening and the identification of salt-tolerant germplasm to be used for the genetic advancement of corps. Many screening criteria have been suggested to distinguish between genotypes. Most of these were applied under controlled environmental conditions and limited to one developmental stage of plants. As a result, most of the reported tolerance could not be validated under field conditions. This study employed a membership function value (MFV) to assess NaCl tolerance of eight wheat (Triticum aestivum) genotypes measured at germination, vegetative and reproductive stages, as an integrative tool for the overall plant performance. Salt stresses had an adverse effect on plant physiological (residual transpiration, stomatal density, chlorophyll fluorescence characteristics; leaf N, Na+ and K+ content) and agronomical (plant height; biomass; root and tiller number; grain) characteristics. Based on this assessment, plants were divided into three contrasting groups: salt tolerant, moderately salt tolerant and salt sensitive. Although genotypes did not show the same degree of tolerance in germination, glasshouse and field experiments, the variety Yu-07 showed consistently better performance in all trials, whilst Aus19720 was most sensitive in glasshouse and field experiments. These contrasting genotypes could be of a potential value for further studies to uncover the genetic mechanisms governing salt stress response in wheat.