Silicon uptake and distribution in agropyron smithii as related to grazing history and defoliation

Abstract

A controlled environment experiment was performed on plants from 2 Agropyron smithii Rydb. (western wheatgass) populations to determine how defoliation at 1-week intervals and graxing history affected total silicon accumulation in shoots, and how Si was distributed within the plant. Plants were collected from a heavily grazed, 10-year-old prairie dog colony and an ungrazed, 40-year-old exciosure at Wind Cave National Park, South Dakota. After 18 weeks, the total amount of Si accumulated in shoots was similar in plants from both populations, regardless of whether or not the plants were clipped. However, the Si concentration in shoots was greater in nondefoliated than defoliated plants of both populations because of Si dilution resulting from greater shoot production in defoliated pIants. In both populations, roots and leaf blades had the highest Si concentrations, rhizomes had the lowest concentrations, and sheaths, crowns, and belowground stems had intermediate concentration.