Development of a simple method for measuring resistance to water transport in crop plants.

即使作物在充足的土壤水分条件下生长，在晴朗的午后，气孔导度和光合速率也会降低，此外，由于水分不足，有时会发生严重的叶片萎蔫和叶片死亡。植物体内水分运输阻力的增加是植物水分亏缺的原因。为了研究水分亏缺的原因和培育抗旱植物，需要估计植物各部位对水分运输的阻力。本研究旨在建立一种简单的方法来测定作物特别是根和茎的抗性，因为抗性被认为是可变的.为了估计茎阻力，（1）在茎段的切割端施加低静水压力（P），（2）测量茎段另一切割端的渗出率（E），（3）通过等式（1）计算茎段中的水运输阻力（Rs）。楼梯底部的阻力 ...更多信息 严重萎蔫的黄瓜植株和白色穗干枯的水稻植株的穗基部的m和m分别显著增加，这与其它可靠的测量结果一致。RS=P/E（1），Rr=Pr/Er（2）2。为了估算根系阻力，（1）在茎基部测量渗出速率（Er）和根压（Pr），并通过方程（1）计算从根到茎基部的阻力。（二）、这种阻力可以认为是根系主动吸水的阻力。在强蒸腾作用下，主动吸水的根系阻力远大于被动吸水。然而，据推测，在主动和被动吸水阻力之间存在密切的相关性，即主动吸水阻力越高，被动吸水阻力也越高。结果表明，在强蒸腾作用下，根系被动吸水阻力可以通过测定根系主动吸水阻力来进行比较。少

Even though crop plants are growing under sufficient soil moisture conditions, stomatal conductance and photosynthetic rate decrease in the afternoon on a clear day and, moreover, severe leaf wilting and leaf death sometimes occur due to water deficits. Increase of resistance to water transport in plants is responsible for the plant water deficits. It is required to estimate resistance to water transport in various parts of a plant for investigating the cause of the water deficits and for breeding drought-resistant plants. This investigation was to develop a simple method for measuring the resistance in crop plants especially in roots and stem of which resistance is thought to be variable.1. For estimating stem resistance, (1) low hydrostatic pressure (P) was applied on the cut end of a stem segment, (2) exudation rate (E) from the other cut end of the segment was measured and (3) resistance to water transport in the segment (Rs) was calculated by Eq(1). Resistance of the base of a ste … More m and of the panicle base increased markedly in the severely wilted cucumber plant and in the rice plant with desiccated white head, respectively, which agrees with the results obtained from other reliable measurements. It was concluded that this method can be employed for estimating stem resistance.Rs=P/E (1), Rr=Pr/Er (2)2. For estimating root resistance, (1) exudation rate (Er) and root pressure (Pr) were measured at the base of a stem and the resistance from roots to the base of a stem was calculated by Eq. (2). This resistance can be thought to be root resistance in active water uptake. Root resistance in active water uptake was far larger than that in passive water uptake under intense transpiration. However, it was supposed that there is a close correlation between the resistance in active and passive water uptake, that is, the higher the resistance in active water uptake, the higher, the resistance in passive water uptake. It was concluded from these results that root resistance in passive water uptake under intense transpiration could be compared by measuring the resistance in active water uptake. Less