Yield from small plots or subsampled yield from larger plots can be determined by directly harvesting plant material from a known area. A known area can be harvested within an inexpensive frame made of PVC or wood, or along a measured linear distance for row crops. A sickle mower or rechargeable or manual clippers can be used to harvest plant material from small plots. The tissue can then be weighed and yield calculated from the weight and harvest area. Grain plots also can be harvested by hand and a representative sample of heads or ears shelled by hand. The total cost of equipment to measure yield from small plots can be under $1,000.
Chlorophyll meters have been used to rapidly assess the green color of leaves of various plant species (Peryea & Kammereck, 1997; Varvel et al., 1997; Bullock & Anderson, 1998). Relationships between meter reading and nutritive status or yield have been developed for certain plants; however, universal calibration curves relating meter readings to tissue nutrient (e.g., nitrogen or iron) content have not been developed. Chlorophyll meter data may be useful for comparing treatments such as nitrogen or iron rates. Readings may also be related to yield to develop localized data for routine use of the meter during field monitoring.
Munsell Plant Tissue Color Charts 49.pdf
A simple visual rating scale (1=yellow through 9=green) has been used extensively to monitor turfgrass color and response to nitrogen or iron treatments (Wehner & Haley, 1990). A similar four-point scale also has been adapted to evaluate tree leaf color in response to iron treatments (Messenger, 1984). Color index scales may be improved by using standardized colors from sources such as the Munsell color chart for plant tissues (Wilde & Voigt 1952; Harrell, Pierce, Mooter, & Webster, 1984).
Rapid analysis of plant sap using portable meters or test strips (Prasad & Spiers, 1984) has been related to traditional colorimetric methods with some success. Use of quick test methods should be preceded by further research into the method to determine whether it has been successfully used for the specific situation. 2ff7e9595c
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