Word Alert allelopathy
By: Charles Geddes
between crops and weeds begins sooner than most of us think!
are all too familiar with the impact of weeds on their farm. Crop and weeds
compete for essential resources, like water, nutrients or sunlight; which can
have a direct effect on crop yields. We call this resource direct competition
and it is the most well-known mechanism of yield loss.
less-well understood are the impacts of resource indirect competition. With the
large impact weeds can have on net farm income through crop yield reduction,
research into this is valid and warranted.
Resource indirect plant competition results when a neighboring weed impacts the
crop without depleting essential resources. Research in this field is growing
and scientists are beginning to understand some of the mechanisms of indirect
weed competition. There are a few mechanisms of indirect competition that can
result in crop yield loss. One mechanism is allelopathy, which I will address
in a subsequent article.
mechanism results from a plant’s ability to sense its immediate environment.
On-going research suggests that plants can sense the quality of light reflected
off of neighboring plants, the soil surface or even surface residue. Incoming
light reflects off neighboring plants including weeds. By sensing the change in
light quality a crop plant can know whether it might have to compete with a
neighboring weed in the near future.
crop plant can sense weeds even when they are too small to have a significant
impact on resources available to the crop. When a plant senses its neighbor, it
can have a shade avoidance response. Shade avoidance results in an alteration
of crop morphology, usually observed as an increase in plant height (among
other changes) in anticipation of competition with a neighboring weed. This
alteration of crop morphology can use energy that would commonly go towards
producing seed, resulting in a yield reduction.
loss can result from direct or indirect plant competition, however the
contribution of each mechanism in the field is still under investigation.
Created November 21, 2019 | Category: Pest Management