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