Effects of base selenium on the herbage yield and agronomic characteristics of alfalfa at different growth stages

A field experiment was conducted to determine the effects of different levels of selenium on the herbage yield and agronomic characteristics of alfalfa at different growth stages. The results of this study showed that application of selenium increased the herbage yield, accumulation rate of dry matter, plant height and leaf/steam at different growth stages to some extent. The 0.45 kgha-1 selenium had the highest herbage yield, accumulation rate of dry matter and plant height at the branching stage, bud stage and early flowering stage, in which the herbage yield increased by 32.67%, 24.78% and 37.93%, respectively, and the plant height increased by 10.01%, 14.00% and 10.51%, respectively, and the leaf/steam increased by 6.43%, 8.00% and 12.80%, respectively. The accumulation rate of dry matter with application of 0.45, 1.05 and 0.75 kgha-1 selenium was the highest at the branching stage, bud stage and early flowering stage, respectively. The growth peak of alfalfa without selenium fertilization was found at the bud stage and its accumulation rate of dry matter decreased at the early flowering stage, but the alfalfa with selenium fertilization continued to grow.