Paul Hodgen1, Fernando Solari1, J. S. Schepers2, R. Ferguson1, and John Shanahan2. (1) Univ of Nebraska, 1132 N 45th St, Lincoln, NE 68503, (2) USDA-ARS, 120 Keim Hall, East Campus, Lincoln, NE 68583
There has been increasing
work done on measuring and fertilizing individual corn plants. There has been extensive research using a
Minolta 502 SPAD meter to estimate chlorophyll content in various crops and to
use this information to make more informed nitrogen (N) fertilizer
decisions. The purpose of this study was
to determine the variability in yields and N status of individual plants in the
high yielding irrigated area of the Central
Platte Valley
in Nebraska. SPAD meter readings were taken on strips of
rows of approximately 30 meters in length, for two years on an experiment
station and surrounding farmer fields.
There were 5 SPAD meter readings taken per plant at V16 and R1 on either
the upper most expanded leaf or on the ear leaf depending on the growth stage
at the time of data collection. Each
plant was then hand harvested at physical maturity and the grain shelled and
recorded. Data indicate that a SPAD
meter can be used to detect differences in individual plant yields. The variability in observed grain yields
varied from 0 to nearly 250 g plant-1, while the SPAD meter readings
varied from approximately 30 to 65 units.
SPAD meter readings explained nearly 55 % of the variability of over
1500 individual plant yields. These data
may be helpful in the use of a 502 SPAD meter to make fertilizer
recommendations in corn cropping systems.