New Zealand Journal of Agricultural Research abstracts

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A closed chamber technique for field measurement of gas exchange of forage canopies

A. GRAU

AgResearch
Invermay Research Centre
Private Bag 50034
Mosgiel, New Zealand

Abstract  A portable chamber and closed system was used to investigate canopy gas exchange of forage species. The polycarbonate chamber encloses a volume of 62.5 l from a 50 x 25 cm open base inserted 3 cm into the soil. Air within the chamber is mixed by two 80-mm fans. Evapotranspiration from potted plants measured with the chamber was 25% higher than gravimetric water loss. Nevertheless, chamber values and actual gravimetric water loss were highly correlated. The chamber was tested in a pilot study comparing different forage species at a high-country site in Central Otago. Individual measurements using the canopy chamber were normally completed in less than 2 min, a speed of operation similar to that achieved with conventional leaf chambers. The chamber system provides a simple and useful tool for rapid physiological comparison of whole canopies under field conditions.

Keywords  canopy gas exchange; photosynthesis; transpiration; water use efficiency; forage; Medicago sativa; Lotus corniculatus; Festuca arundinacea; Dactylis glomerata

New Zealand Journal of Agricultural Research, 1995, Vol. 38: 71-77

0028-8233/95/3801-0071 $2.50/0 (c) The Royal Society of New Zealand 1995

PDF file of entire paper: medium quality (655K); (scanned from paper original: notes about this process)

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