Influence of nitrogen and duration of weed interference on corn growth and development

Abstract

An improved understanding of the effects of nitrogen (N) on crop-weed interactions is needed for the development of integrated weed management systems where responsible use of N fertilizers is considered. Field experiments conducted in 1999 and 2000 at two locations in eastern Nebraska quantify the effects of N and increasing duration of weed interference on corn growth and development. A naturally occurring population of weeds was allowed to compete with the corn crop for increasing lengths of time and at three rates of N application (0, 60, and 120 kg N ha Ϫ1). Weed interference and withholding applied N increased the time to 50% silking by an average of 3.9 and 2.9 d, respectively. Regardless of treatments, relative growth rates of corn leaf area and biomass were maximized between the V1 and V2 growth stages of corn and increased linearly with N rate but were affected to a lesser extent by weed presence. The improvement in early season corn growth with addition of N resulted in greater leaf area, biomass, and height, which improved the competitive ability of corn against weeds. Reductions in maximum corn leaf area and height due to weed interference usually began earlier and were more extensive at reduced rates of N. Partitioning of biomass to reproductive structures increased with N during reproductive stages, likely contributing to greater harvest indices at the end of the season. Results from this study indicate that the effects of N fertilization on early-season crop growth provided a competitive advantage for corn relative to weeds, thereby increasing the length of time that weeds could compete with a crop before removal was required, but further research is needed to identify mechanisms regarding improved crop tolerance to weeds.

Simulated insect defoliation and duration of weed interference affected soybean growth

“…These findings are similar to those of Evans et al (2003), who reported an increase in PC leaf in weed-free compared to weedy corn. Note.…”

“…It is also important to know how production factors influence the CPWC. Evans et al (2003) reported that the increase in nitrogen level reduced the length of CPWC in corn (Zea mays L.), and narrow row spacing delayed the CTWR in soybean (Knezevic et al 2003a(Knezevic et al , 2003b.…”

Effect of Nitrogen Addition and Weed Interference on Soil Nitrogen and Corn Nitrogen Nutrition

“…), Amaranthus species, and Setaria species at HAL in 1999 and 2000 and at the ARDC in 2000. Pennsylvania smartweed (Polygonum pensylvanicum L.) was an additional dominant weed at the ARDC in 1999 (Evans et al 2003b). …”

The Biology of Invasive Alien Plants in Canada. 3. Amaranthus tuberculatus (Moq.) Sauer var. rudis (Sauer) Costea & Tardif

“…rudis and Abutilon theophrasi Medic. (Evans et al 2003). Results obtained in Iowa have shown that composted swine manure applied at rate of 4000 or 8000 kg C ha -1 reduced the emergence of A. tuberculatus var.…”