SMITH II, JAMES L.*, ADOLFO E. GARCIA, and THOMAS A. MAYER. La Sierra University, Biology Department, 4700 Pierce St., Riverside, CA, 92515. - Reduced height and pre-mature mortality of Brassica rapa (Brassicaceae) grown in a pressurized environment.
Few studies have investigated the effects of slightly elevated air
pressure (>1 to 3 atmospheres, atm., absolute pressure) on plant
growth. We used 2-liter soda bottles as inexpensive pressurized growth
chambers to investigate the effects of increased air pressure on plant
growth. Fifteen Brassica rapa plants were grown in each bottle
and there were two bottles for each of the following treatments: the
cap loose, cap tight, cap tight with bottle pressurized and
immediately depressurized, or cap tight with bottle pressurized (3
atm.). Plants in the bottles subjected to pressure germinated and grew
as well or better than the others initially. However, by the sixth day
the growth rate, measured as increase in heighth, of the pressurized
plants began to lag behind the others. Plants kept at 3 atm. became
very pale and began to shrivel up. By the 11th day nearly all of these
pressurized plants were dead, while plants growing in the other three
conditions appeared healthy. The potential causes for this
pressure-induced mortality need to be further investigated. The use of
a “real” pressurized plant growth chamber would facilitate research
into the effects of various air pressures on plant growth and
physiology.
Key words: air pressure, Brassica rapa, Brassicaceae, growth chamber, growth rate, mortality