NET CARBON DIOXIDE EXCHANGE RATES IN PHASEOLUS VULGARIS L. AS INFLUENCED BY TEMPERATURE, LIGHT INTENSITY, LEAF AREA INDEX, AND AGE OF PLANT
Plants of Phaseolus vulgaris were grown under controlled conditions for 10 to 60 days and then transferred to light intensities of from 0 to 12,000 ft-c at temperatures of 4 to 38 °C for measurement of net carbon dioxide exchange by means of an infrared analyzer. The net carbon dioxide exchange was not markedly influenced by temperature at higher light intensities, particularly with older plants and the greater planting density, but was strikingly influenced by temperature in darkness or low light intensity. The leaf area index affected the rate at which the maximum net carbon dioxide exchange rates were attained. The compensation point increased with aging and with denser planting. The net assimilation decreased at the onset of fruiting. Several features of the experimental method are discussed.