Abstract
Stress-extension rate (SER) characteristics of frozen-thawed segments from the elongation zone of inflorescence stems of Arabidopsis thaliana measured with the programmable creep meter (PCM) by the ramped sweep method. The SER curves were essentially the same as those of the hypocoytls of cowpea, soybean and cucumber although the maximal rupture tension and extension rate were low (around 16 gf at pH 6.8) and high (up to 25 % h-1 at pH 4.8), respectively. The curve depended strongly on pH indicating that the extension of Arabi cell walls were also facilitated by acids. However, we found that the Lockhart approximation to the Arabi SER-curve was not effective. We defined the differential extensibility and the apparent yield tension and developed an algorism for calculating them. The wall yielding properties of Arabi cell walls were found to be adequately characterized with these new parameters that closely depended on tension.
