Effects of nitrogen fertilization in leafy spurge root architecture

Abstract

There is a dearth of information concerning the degree to which the amounts, periodicity, and spatial patterns of N applications can be manipulated to alter the rooting strategy of leafy spurge, and thus make it more susceptible to chemical and biological controls. This study was designed with the following objectives: (1) determine the effect of patchy N fertilization on shoot and root biomass, root distribution by depth, root plasticity, and the ratio of coarse vs. fine roots of leafy spurge; and (2) determine how leafy spurge scales root biomass to root lateral spread and root surface area, as well as how these scaling patterns are affected by N fertilization. The root architecture, plasticity, and response to patchy N fertilization was evaluated in 3 separate experiments conducted in large containers. Patchy fertilization did not alter the morphological characteristics of leafy spurge roots, but did cause a reduction in root biomass and a drastic change in the distribution of the root surface area within the plant's rooting volume. Fertilization both doubled the percentage of roots located in the top 10 cm of soil and shifted it toward the fertilized patches.