January 9, 2001
Information from 2000 Missouri Rice Research Update, February 2001.
Using Chlorophyll Meter and Plant Area Board to Monitor Plant Nitrogen
Status on Cocodrie
Gene Stevens, David Dunn, Keith Birmingham, Chris Moylan, and Alan Sheckell
Abstract
An experiment was performed at the Missouri Rice Farm near Glennonville to form
calibration curves for Cocodrie and Drew rice varieties using a chlorophyll
meter and an area board.
Introduction
The use of the chlorophyll meter and area board can prove to be valuable tools
in monitoring the growth and development of rice plants. In developing the
calibration curve, the chlorophyll meter was used to determine the N levels of
the plants, since a primary component of chlorophyll is N (see University of
Missouri Extension Bulletin MP 729). The area board was used to determine
average plant height and width.
Materials and Methods
Cocodrie and Drew rice were drill seeded on May 8, 2000. Due to problems
during planting, Drew had to be abandoned from the test. Cocodrie was tested
at preflood application rates of 0, 30, 60, 90, 120, 150, and 180 lb/acre.
Half included midseason applications of 30+30 lb/acre. The other half only
included the first application. The experimental design was a randomized
complete block with four replications. Chlorophyll meter and area board
readings were taken before applying mid-season N to help determine the effects
that the mid-season application would have on the rice.
Results
Yield results from the experiment showed that in Cocodrie the highest yields
occurred with 120 to 150 total lb N/acre. A preflood application of N along
with a mid-season application resulted in an average of 15 bu/acre increase in
yield over preflood application only (Table 1).
In 1999, Drew yields were higher in the plots where the mid-season application
was included, averaging 9 more bu/acre than those with only a single
application.
Conclusion
This experiment illustrates the importance of carefully monitoring the growth,
development, and fertilizer needs of different rice varieties. Without such
knowledge, a producer may be inclined to use the same fertilizer strategy on
all his rice, giving too much to some varieties, resulting in wasted money and
greater susceptibility to disease; and not giving enough N to other varieties,
resulting in unrealized yield potential. Chlorophyll meters and area boards
provide relatively quick and accurate results when trying to obtain this data.
This experiment funded by the Missouri Rice Research and Merchandising Council.
Table 1. Rice yields from chlorophyll meter/plant area board calibration test.
Variety Preflood Midseason Yield bu/acre
------lb N per acre-------
Cocodrie 0 30+30 103
Cocodrie 30 30+30 84
Cocodrie 60 30+30 161
Cocodrie 90 30+30 160
Cocodrie 120 30+30 142
Cocodrie 150 30+30 161
Cocodrie 180 30+30 155
Cocodrie 0 0 109
Cocodrie 30 0 118
Cocodrie 60 0 114
Cocodrie 90 0 109
Cocodrie 120 0 146
Cocodrie 150 0 146
Cocodrie 180 0 163
Chlorophyll meter readings were made before applying midseason N.
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