|Lokhande, Suresh - FOREST SVC INTNTL PRGMS|
|Yang, Yang - U OF MD,QUEENSTOWN, MD|
Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: March 20, 2008
Publication Date: N/A
Technical Abstract: A study was conducted to evaluate the effects of potassium nutrition on growth, development and various other physiological processes and the spectrum characteristics of corn. Corn seeds were shown in sand culture using 3.8L pots in SPAR chambers with day/night temperatures of 30/220C and Carbon Dioxide concentration (CO2) of 400 or 750 ppm. The CO2 and temperature treatments were imposed at emergence of the seedlings, whereas potassium treatments of 0%, 5%, 20%, 40% and 100% (control) of full strength Hoagland solution potassium levels were imposed at 15 days after emergence. Weekly or twice weekly measurements were made on growth and developmental rates, photosynthetic pigments, potassium and other major nutrient concentrations. Stomatal conductance, and hyperspectral reflectance of the top most fully expanded leaf were also measured during the experiment. The results of the experiment showed that the potassium concentration decreased as the plants developed, and that the overall potassium concentration of the treatment plants was lower than that of the control plants under both ambient and enhanced CO2 environment. The overall leaf potassium content of the control plants was relatively stable, while that of the treatment plants decreased as the plants developed and was lower than that of the control plants. There was no significant difference in leaf nitrogen concentration/content under either CO2 environments. The difference in potassium status during the experiment did not result in difference in the development and growth rate of the corn plants. However, leaf level stomatal conductance rate of the treatment plants was higher than that of the control plants late in the season. The increase in stomatal conductance was correlated to the decrease in potassium concentration. In fact, when we compared the trend of change in leaf potassium concentration and stomatal conductance, an exponential decay function between leaf potassium concentration and stomatal conductance was obtained. As the plants matured, the position of the red edge inflection point (REIP defined as the maximum first derivative of the reflectance spectrum in the 680 nm to 750 nm region) in both treatment and control group shifted towards longer wavelength, but the magnitude at REIP of the treatment plants was higher than that of the control plants.