Increased growth and uptake of nutrients by corn plants treated with low levels of simazine

Abstract

Simazine applications of 1.5 p.p.m. to soil in pots in a glasshouse increased dry matter yields and uptake of nitrogen in corn only when additional nitrogen was applied to the soil. The proportions of protein and non-protein nitrogen in the topgrowth were not affected. Application of simazine at this rate without addition of nitrogen resulted in increased leaf area but did not significantly affect yield. Simazine provided a stimulus to the plant early in its life and enabled it to grow faster than the control plant. When the supply of available nitrogen was exhausted the simazine effect decreased. When incubated with soil, simazine did not increase mineralization of soil organic nitrogen, nor did it have any effect on immobilization of mineral nitrogen. Simazine applied at 0.06 p.p.m. in solution culture increased the yield of corn tops by 36%, the uptake of nitrogen by 37%, phosphorus by 25%, magnesium by 24%, and potassium by 41 %. It had no effect on the yields of roots. The results suggest that simazine increased plant growth by a direct effect on plant metabolism and not through any interaction with the soil.