A mathematical relationship was developed which shows environmental influences of light and nitrate nutrition on growth and nitrate uptake kinetics. Growth chamber experiments provided data for model development and validation. Ion-specific macroelectrodes determined nitrate depletion from recirculating solutions in short-term kinetic tests. Lettuce (Lactuca sativa, cv. Ostinata) was grown under three light levels and three nutrient solution nitrate contents which represented a range of adequate and inadequate environments. Larger, faster-growing plants should have a larger demand for nitrate and hence larger uptake rates than smaller, environmentally stressed plants. Results showed higher sustained levels of nitrate uptake by larger plants. Neither the severity of stress under which a plant was grown nor the plant size were the sole determinants of maximum potential uptake behavior, however. Increased light level was related to an increased ability to transport nitrate on a short-term basis. Increased light level was associated with increased maximum nitrate uptake rates (V(max)) as described by the Michaelis-Menten relationship. The effects of environmental light and nitrate levels on nitrate uptake was incorporated into a power relationship where the maximum uptake velocity was determined in relation to the shoot growth rate.
|Original language||English (US)|
|Number of pages||9|
|Journal||Transactions of the American Society of Agricultural Engineers|
|State||Published - May 1 1998|
All Science Journal Classification (ASJC) codes
- Agricultural and Biological Sciences (miscellaneous)