Shen-Miller J, Hinchman R, Gordon S A
Division of Biological and Medical Research, Argonne National Laboratory, Argonne, Illinois 60439.
Plant Physiol. 1968 Mar;43(3):338-44. doi: 10.1104/pp.43.3.338.
The magnitude of acceleration required to induce growth responses in Avena seedlings grown in the absence of tropic response to earth gravity has been investigated. For this purpose, a clinostat was developed that imposes accelerations from about 10(-9) g to 3 g upon the seedling; simultaneously, it nullifies, or compensates for, response to the directional component of the gravitational-force vector by rotating the seedling on a horizontal axis. When accelerations less than 10(-3) g are applied in either the acropetal or the basipetal direction, the growth in length and weight of the various organs is not materially different from that of compensated seedlings to which no longitudinal force is applied. At accelerations between 10(-3) and 10(-2) g, differences in growth become highly significant. When the centrifugal forces are transverse to the seedling during compensation, the threshold acceleration range for geoperception, as manifest by shoot reorientation, is again between 10(-3) and 10(-2) g. Geotropic reorientation of the root becomes apparent after exposures between 10(-4) and 10(-3) g.
对在无向地性反应条件下生长的燕麦幼苗诱导生长反应所需的加速度大小进行了研究。为此，开发了一种回转器，它能对幼苗施加约10^(-9)g至3g的加速度；同时，通过使幼苗绕水平轴旋转，消除或补偿对重力矢量方向分量的反应。当向顶或向基方向施加小于10^(-3)g的加速度时，各器官的长度和重量增长与未施加纵向力的补偿幼苗相比没有实质性差异。在10^(-3)至10^(-2)g的加速度下，生长差异变得非常显著。当在补偿过程中离心力与幼苗垂直时，以茎重新定向表现出的对地感知阈值加速度范围再次在10^(-3)至10^(-2)g之间。在10^(-4)至10^(-3)g的暴露后，根的向地性重新定向变得明显。
