Abstract
Thirteen different inbred lines in relation to the type of grain and life cycles were characterized by testing for osmotic stress associated with salinity. The identification of tolerant genotypes would be an effective strategy to overcome the saline stress. Osmotic stress reduces immediately the expansion of the roots and young leaves which determine a reduction in the size of the plant. A completely randomized design was adopted to test seedlings under controlled conditions of light and temperature. Two treatments were used: 0 mM NaCl (as control) and 100 mM NaCl. After 15 days of complete salinization, the seedlings were harvested and several morphological traits were measured. The morphological traits of growth were leaf growth (Ar1, Ar2, Ar3 and Ar4), dry masses of shoot and root (SDM and RDM, respectively). Also, traits associated with water economy were registered: leaf water loss (LWL) and relative water content (RWC). The morphological traits were expressed in relative terms, while the traits associated with the economy of water were expressed in absolute terms. Uni and multivariate techniques were applied to identify genotypes with divergent behaviors to osmotic stress tolerance. Also, a Tolerance Index was employed to identify superior genotypes. Four clusters were obtained after applying a Cluster Analysis and Principal Component Analysis (PCA). The genotypes were compared to each other with a test of DMS. The results obtained with different statistical techniques converged. Some variables presented a differential weight classification of genotypes. The morphological traits like RDM, SDM, Ar3, Ar4 and Ar5 were the most discriminating. Tolerance Index allowed to classify genotypes, thus SC2 and AD3 lines were that reached highest value of the index and therefore would be tolerant lines, while AF3 and LP3 had a low index and were seen as sensible.
Highlights
Saline soils are abiotic factors with great negative effect exerted on world agriculture [1]
The aims of this study were: (a) to assess the effects of salinity on growth and water economy traits in seedlings of maize, as a way to identify the presence of osmotic tolerance and b) to explore the presence of genetic variability for such a mechanism; with the purpose of identifying genotypes of contrasting behavior useful for gene effects’ studies and for breeding programs
The application of least significant difference (LSD) Test revealed the presence of differences in the behavior of the tested genotypes
Summary
Saline soils are abiotic factors with great negative effect exerted on world agriculture [1]. The identification of crops tolerant would be an effective strategy to overcome the saline stress. Salinity affects some physiological and biochemical processes of the plants and reduces significantly the yield. Photosynthesis is the most important process affected by salinity; this may be due, among other things, to the closure of the stomata. It reduces the ability of the plant to use water, which causes a decrease in the rate of growth [2]-[4]. A two-phase model to explain the inhibition of the growth under salinity conditions was proposes. The first phase is known like osmotic phase, where the decrease of the water potential of the soils is produced by the salt accumulation [5]
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