Abstract
The aim of this research was to evaluate the salinity tolerance in prairie grass populations at the seedling stage quantifying the variability and the influence of physiological traits related to it. Salinity tolerance, in Bromus catharticus Vahl (prairie grass) populations collected in different environments of the Pampean Phytogeography region (Argentine) was evaluated at the seedling stage, using controlled condition of temperature and light. It was adopted a completely randomized design using 3 plots with three plants each one per population and two levels of treatment: 0 mM and 100 mM NaCl. Morphological, biomass and membrane stability root and shoot traits were studied. A factorial ANOVA with interaction was estimated. Then one way ANOVA for all seedling traits in both treatments allowed estimating variance components, coefficient of genotypic determination (CGD) and variation index (VI). Comparisons between populations were made using Tukey test (at 5% of probability). Phenotypic correlations among traits were calculated and then a path coefficient analysis separated direct and indirect effects at 100 and 0 mM NaCl. No significant interactions “Population × Treatment” were found for any character. The saline stress caused a pairing in the population means for the most traits. Coefficients of variation were mainly higher when the seedlings grew without stress (0 mM) because it allowed a greater potential genotypic expression. The absence of significant interactions denotes a good homeostatic capacity of the prairie grass facing that abiotic stress. Leaf length, shoot length and root dry matter were the variables with the largest direct and indirect effects. Our results showed an increase for them at salt and demonstrated intraspecific variation, possibly in relation with the origin sites. Plants under stress showed a marked resilience, in order to quickly restore the same biomass allocation patterns that occur in non-stress environment.
Highlights
In recent years an agricultural process has happened due to the high demand for grains with a strong price increase
The ANOVAS per treatment showed that the populations differed significantly for RMS, Shoot length (SL), Leaf 3rd length (LL), Shoot dry mass (SDM) and Root dry mass (RDM) when they grew without salt stress (0 mM NaCl), even if at 100 mM Cl Na only differed for RMS, SL and LL (Table 3)
Even though the used saline concentrations were much lower, our results showed an increase for leaf and shoot length at salt. [31] investigated the growth patterns of cheat-grass (Bromus tectorum L.) and demonstrated that plants collected from saline sites, accumulated leaf and root area at nearly twice the rate from no saline sites, even in the control group
Summary
In recent years an agricultural process has happened due to the high demand for grains with a strong price increase. It has led to a redistribution of beef cattle to marginal areas where soils have low aptitude and excess soluble salt. This situation will tend to worsen in places where climate change alters the precipitation/evapotranspiration balance and where agricultural practices lead to secondary salinization [1]. Abiotic stress soils limit growth, biomass accumulation and productivity in most crops and forage around the world. Salinity affects biomass production and alters the partition of photo assimilates between different parts of plants. This behavior could be due to osmotic, toxic and nutritional effects. Other costs are related to poor stand establishment and/or mature plants and plant’s ability to resist a second stress as biotic ones [10]
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