Analysis of physiological traits in the response of Chenopodiaceae, Amaranthaceae, and Brassicaceae plants to salinity stress

Soil salinity is one of the main factors affecting plant growth. Dissection of plant response to salinity into physiological traits may result a simple approximation than the overall response that may influence many aspects of the plant. In the present study two factors were considered to evaluate the correlation of different physiological variables in the plant response to salinity. The first factor was the species, with four levels (Atriplex halimus, Salicornia fruticosa, Cakile maritima, and Brassica rapa), and the second was the salinity (0, 100, 200, and 300 mM NaCl). Thus, the interrelationships of distinct physiological traits - leaf succulence, minerals (micronutrients and macronutrients), plant water relations (osmotic potential, water potential, and hydraulic conductivity), protein content, catalase, and unsaturated fatty acids - were analyzed by Discriminant Canonical Analysis (DCA). Additional information supplied by the interaction between the variables provided a multivariate response pattern in which the two factors (species x salinity) influenced the relationship between responses rather than affecting a single response. Such analysis allows to establish whether the selected trait was associated to each other for helping to define the best set of parameters in relation to the response of new genotypes to salinity. Thus, plant growth was influenced by leaf succulence adaptation to salt stress whereas it was not determined by water relations. The Na ion prevailed over K as the element with the highest variability in the response to salinity in A. halimus and S. fruticosa, whereas in C. maritima and B. rapa, Ca, S, and P stood out more. Patterns of ion accumulation together with the protein and unsaturated fatty acid ratios could be used in discriminating plant response to salt stress may be positioned in interrelated groups. The results highlight new evidences in the response to salt stress associated to a specific interrelationship of a set of physiological parameters.