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9 United State.
\\,\6J} Department of
Agriculture
National
Agricultural
Statistics
Service
Research and
-
Applications
Division
NASS Staff Report
Number SRB-87-06
July 1987
Effect of Harvest
Delays on
Sunflower
Yield Estimates
Ralph V. -Matthews
Douglas C. Bond
EFFECT OF HARVEST DELAYS ON SUNFLOWER YIELD ESTIMATES by Ralph V.
Matthews and Douglas C. Bond, Research and Applications Division
and Estimates Division, National Agricultural Statistics Service,
u.S. Department of Agriculture, Washington, D.C.
20250, July
1987. Staff Report No. SRB-87-06.,
ABSTRACT
The National Agricultural Statistics Service conducts sunflower
objective yield surveys to forecast and estimate the yield and
production of the oil-type sunflower crop.
Survey procedures
require the harvest of sample plots for yield estimation no more
than 7 days before the farmer harvests
the sample field.
Experiments were conducted in 1984 and 1985 at North Dakota State
University to determine the effect of a delay in harvest of 10,
20, or 30 days. No significant differences were detected among
the harvest dates in either year due to large standard deviations
of approximately 10 and 17 percent of the overall mean in 1984
and 1985, respectively.
Covariance analyses with either stalk
number or head number as the covariate were very similar in 1985.
Differences between years in the average yield and the residual
mean squares precluded 'a combined, 2-year analysis.
KEY WORDS: sunflower objective yield, yield estimation, analysis
of variance, covariance analysis, power
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This paper was prepared for limited distribution to*
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the research community outside the U.S. Department of
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ACKNOWLEDGMENTS
Al Schneiter,
Professor
of Agronomy,
North Dakota
State
University, conducted the field experiments and supervised the
lab work. Bob Battaglia, Fatu Bigsby, Ron Steele, and Ron Fecso
made suggestions which clarif