Effects of Nitrogen Supply on the Root Morphology of Corn and Velvetleaf

ABSTRACT

Root morphology will affect interplant competition for soil nutrients. Research was conducted to assess fine root fraction, mean root radius, specific root length, root length density, and nitrogen (N) uptake per unit fine root biomass of corn and velvetleaf over time and in response to nitrogen supply. Pots containing either corn or velvetleaf were embedded in the ground and received one of three N treatments. Plants were destructively sampled on 10 dates during each of two years and root subsamples analyzed using root scanning software. While corn root morphology was more responsive to N supply than velvetleaf, velvetleaf N uptake per unit fine root length was greater than that of corn at similar biomass. Results suggest that, in lieu of modifying root morphology to increase uptake efficiency when N is deficient, velvetleaf may invest more root biomass to produce a deeper tap root to reach nutrients deeper in the profile.

Keywords:

• maize
• Zea mays L.
• velvetleaf
• Abutilon theophrasti Medic.
• specific root length
• root length density
• biomass partitioning
• ontogenetic drift
• phenology
• optimal partitioning theory
• functional equilibrium
• competition

ACKNOWLEDGMENTS

This research is a contribution of the University of Nebraska Agricultural Research Division, Lincoln, NE. This research was supported in part by funds provided by the Hatch Act and by the State of Nebraska.