Madison, Wisconsin
February 2, 2009
Over the past decade, two-thirds
of Indiana growers have shifted to planting their soybean crop
earlier because they believe that earlier planting increases
yield. Planting date is probably one of the most important yet
least expensive management decisions that significantly affects
soybean yield. Few scientists, however, have studied the effect
of early-planting dates on soybean yield components and the
impact of early planting on seed composition.
To answer this question, Andrew P. Robinson and colleagues at
Purdue University conducted
a 2-year (2006-2007) study at West Lafayette, Indiana. The
research was supported by the Indiana Soybean Alliance and the
Indiana Crop Improvement Association.
Three soybean cultivars were planted approximately every 2 weeks
starting in late March and ending in early June. Detailed
measurements of soybean yield components (pod number, seeds per
pod, and seed mass), nodes, and reproductive nodes were counted
by hand just before harvest. Oil and protein concentrations were
determined by near-infrared reflectance spectroscopy.
A recent article in the January-February 2009 issue of
Agronomy Journal
gives detailed results from this study. This research was
presented at the American Society of Agronomy annual meetings in
October 2008 at Houston, TX, and at the American Seed Trade
Association, Corn, Sorghum, and Soybean annual meetings in
December 2007 at Chicago, IL.
"The research found that yield was consistently the highest when
planting from April to early May," comments Robinson.
Pods-per-square-meter were a good indicator of yield potential
of early planted soybean, whereas seed mass was a good indicator
of late-planted (late-May and early-June) soybean. Oil
concentration was higher at early plantings and protein
concentration was higher at late planting dates. As the
temperature increased during R6 soybean growth stage (full seed)
oil concentration increased and protein concentration decreased.
"Our research shows that early planting does increase yield, but
can vary by year and cultivar choice. Our research also suggests
that early planting may lead to increased oil concentration of
Midwest soybean. However, early planting may not be for
everyone," warns Robinson. "Further research is needed to
quantify the impact early planting has on seed quality."
The full article is available for no charge for 30 days
following the date of this summary. View the abstract at
http://agron.scijournals.org/cgi/content/full/101/1/131.
A peer-reviewed international journal of agriculture and
natural resource sciences, Agronomy Journal is published six
times a year by the American Society of Agronomy, with articles
relating to original research in soil science, crop science,
agroclimatology and agronomic modeling, production agriculture,
and software. For more information visit:
http://agron.scijournals.org.
The American Society of Agronomy (ASA) www.agronomy.org, is a
scientific society helping its 8,000+ members advance the
disciplines and practices of agronomy by supporting professional
growth and science policy initiatives, and by providing quality,
research-based publications and a variety of member services.
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