The effect of habitat height on the diversity of structural, functional traits and ploidy levels in Sicilian wheatgrass Elymus tauri (Boiss. & Balansa) in northwest Iran

Wheatgrass Elymus tauri (Boiss & Balansa) is a drought- and cold-resistant species that grows on rocky, stony slopes with steep slopes in Azerbaijan, Alborz and some parts of Zagros, Iran. It is a perennial plant. It has a strong root and is resistant to excessive livestock grazing. It is one of the delicious species of pasture for livestock grazing. The genetic diversity of grasses is affected by various factors such as human activities, the environment, pollination system, genetic drift, and population size. Therefore, ecogeographical factors are also important influencing factors in the populations’ structure and genetic diversity. The aim of this study was to investigate the effect of habitat height and ploidy level on the diversity of structural and functional traits of Elymus tauri populations in the northwest of Iran.

 The experimental materials included the seeds of 12 native populations of E. tauri, which were mainly collected from the pastures of East Azerbaijan and Ardabil provinces. At the time of collection, the altitude and geographical coordinates of locations were recorded using GPS. The collected seeds were sown in a research farm using a randomized complete block design in four replications in the northwest of Tabriz city, Iran, at 1350 m above sea level and on the edge of the Aji Chai River. The region’s climate is semi-arid, the texture of the station's soil is light loamy and sandy, and the amount of soil organic matter and chemical elements (NPK) was weak to moderate. The electrical conductivity was measured as EC=6.2 millimos per square centimeter. Soil pH (pH=7.55) was alkaline. Each plot contains four 6m lines. The distance between lines was 40 cm, and the distance between plants on each line was 40 cm. Irrigation was made during the plant growth period. The number of 10 plants from the two middle rows of each plot was randomly selected, and yield and morphological traits were measured and recorded. Genotypes were grouped based on habitat altitude and ploidy levels. A statistical analysis (T-test method) was made between two groups for habitat altitude.

The results of the T-test analysis between the two altitude ranges showed there were significant differences between the two altitudes in terms of the tillers number, the length of the second leaf, the fresh and dry weight of the plant, the number of fertile tillers, the number of infertile tillers, the length of the spike, the length of the flag leaf and number of spikelets (P<0.05). The means of populations in the upper areas were higher than those in the lower areas. Grouping based on altitude showed that populations at altitudes less than 1600 m above sea level were diploid, while populations at altitudes higher than 1700 m were tetraploid. The cluster analysis and principal component analysis (PCA) results confirmed the grouping of populations based on habitat altitude and ploidy levels. Also, the biplot of PC1 vs. PC2 confirmed the grouping of cluster analysis.

This plant had better adaptation in high altitude habitats, so it has grown better in cold conditions than in mild temperate and plain areas. The higher mean values of many traits in the tetraploid populations confirmed the correction of the grouping. Considering that this species grows more in cold regions, it was suggested to use polyploid populations from higher altitude areas to improve breeding varieties.