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Measuring the whole-plant corn carbon balance
Abstract
Photosynthesis and respiration are physiological processes which influence plant productivity and growth. Methods of measuring these processes have evolved for over 100 years. This dissertation details a method developed for measuring the fluxes of carbon into and out of a growing corn plant. A novel gas exchange system was developed for measuring net photosynthesis, shoot respiration, and root respiration. A methodology for controlling the CO$\sb2$ concentration in a commercially-available plant growth chamber was devised using a CO$\sb2$-free air injection system and a computer-based control system. Three separate experiments were conducted in which sixteen corn plants were grown for 40 days. Carbon exchange rates of corn plants were measured and used to predict carbon accumulation. Actual carbon accumulation, estimated by destructive sampling, was compared with predicted carbon accumulation. In each experiment, actual and predicted carbon accumulation rates were similar. Gas exchange experiments also provided data which were used to calculate the growth and maintenance coefficients of respiration. Two experiments were conducted to evaluate the effects of high (1000 $\mu$mol m$\sp{-2}$ s$\sp{-1}$) and low (250 $\mu$mol m$\sp{-2}$ s$\sp{-1}$) irradiance on plant respiration. In the low irradiance treatment, calculated shoot and root growth coefficients were 0.13 and 0.40 (g DM (g DM)$\sp{-1}$), respectively. These data indicate that root growth had a higher respiratory demand than shoot growth. In the low irradiance treatment, calculated shoot and root growth coefficients were 0.14 and 0.41 (g DM (g DM)$\sp{-1}$), respectively. These data indicate that the growth respiration requirements of these plants were independent of the irradiance level under which the plants grew. Calculated maintenance coefficients of shoots and roots in the low irradiance treatment were 0.037 and 0.045 (g DM (g DM)$\sp{-1}$d$\sp{-1}$), respectively. The maintenance coefficients of shoots and roots increased in the high irradiance treatment to 0.072 and 0.061 (g DM (g DM)$\sp{-1}$d$\sp{-1}$), respectively. These data indicate that both shoot and root maintenance requirements increased with increasing irradiance.
Subject Area
Agricultural engineering
Recommended Citation
Storlie, Craig Alan, "Measuring the whole-plant corn carbon balance" (1990). ETD collection for University of Nebraska-Lincoln. AAI9030156.
https://digitalcommons.unl.edu/dissertations/AAI9030156