Nakamoto T
Faculty of Agriculture, University of Tokyo, Japan.
J Plant Res. 1995 Mar;108(1089):71-5. doi: 10.1007/BF02344308.
The growth of the primary seminal root of maize (Zea mays L.) is characterized by an initial negative gravitropic reaction and a later positive one that attains a plagiotropic liminal angle. The effects of temperature and water potential of the surrounding soil on these gravitropic reactions were studied. Temperatures of 32, 25, and 18C and soil water potentials of -5, -38, and -67 kPa were imposed and the direction of growth was measured for every 1 cm length of the root. The initial negative gravitropic reaction extended to a distance of about 10 cm from the grain. Higher temperatures reduced the initial negative gravitropic reaction. Lower soil water potential induced a downward growth at root emergence. A mathematical model, in which it was assumed that the rate of the directional change of root growth was a sum of a time-dependent negative gravitropic reaction and an establishment of the liminal angle, adequately fitted the distance-angle relations. It was suggested that higher temperatures and/or a lower water potential accelerated the diminution of the initial negative gravitropic reaction.
玉米（Zea mays L.）初生胚根的生长特点是最初有负向重力性反应，随后是正向重力性反应，并达到斜向重力性临界角。研究了周围土壤温度和水势对这些重力性反应的影响。设置了32、25和18°C的温度以及-5、-38和-67 kPa的土壤水势，并对每1厘米长的根测量其生长方向。最初的负向重力性反应延伸至距籽粒约10厘米处。较高温度降低了最初的负向重力性反应。较低的土壤水势在根出现时诱导向下生长。一个数学模型假设根生长方向变化率是随时间变化的负向重力性反应和临界角确立的总和，该模型很好地拟合了距离-角度关系。研究表明，较高温度和/或较低水势加速了最初负向重力性反应的减弱。
