Effect of diurnal change of turgor pressure on wood formation

为了建立一种利用应变计测定树木活细胞内膨压日变化的方法，了解膨压与树木次生生长的关系，本研究测定了内树皮切向应变的日变化，结果表明：1、在自然光照条件下，树干内层树皮的切向应变在下午约两时出现最大收缩，其后逐渐扩大，直至晚上。在人工控制光照的生长室中测定的切向应变表明，切向应变的日变化与光照强度的变化相一致。2、切向应变与水分的日变化有很好的相关性，在光照强度为100000时，切向应变的日变化与水分的日变化基本一致。3、切向应变与水分的日变化有很好的相关性。4、切向应变与水分的日变化有很好的相关性。 ...更多信息 在最大干缩条件下观测到的切向应变在摘叶或打顶时突然释放。切向应变收缩对应于较大的水分胁迫，在萎凋过程中，当水势低于-1.5MPa时，即使供水，收缩应变也不能恢复。切向应变的收缩过程分为两个阶段。从以上结果可以清楚地看出，切向应变的日变化是由于蒸腾和吸胀引起的负水压变化所产生的活细胞膨压的变化。根据内树皮的切向应变和杨氏模量计算出活细胞的膨压为0.3-0.4MPa。本研究建立了一种与水势相关的活细胞膨压连续测定方法，为进一步研究木材物理性质的形成过程与细胞壁形成的关系提供了理论依据。少

The aim of this research was to establish a method of detecting the diurnal change of turgor pressure in the living cells of tree by using the strain gage and also to understand the relation between the turgor pressure and the secondary growth of the tree.The diurnal change of the tangential strain in the inner bark was measured, leading to the following results.1, Under the natural light condition, the tangential strain in the inner bark of the tree trunk showed a maximum shrinkage at about two o'clock in the afternoon, expanding gradually later in the afternoon until night-time. The maximum expansion was observed before the daybreak and during the day period a sudden shrinkage was appreciated at the same time when the sunshine started.The tangential strain measured in a growing chamber with controlled artificial lighting made clear that the diurnal change of the strain coincided with the change of sunlight illumination.2, The tangential strain had a high correlation with the water po … More tential measured in the leaves measured with a psychrometer.3, The tangential strain observed under the maximum shrinkage condition, was suddenly released when the leaves were removed or topping was done. Tangential strain shrinks corresponding to large water stress.During the process of withering, the shrunk strain did not recover even after water was supplied once the water potential became less than -1.5MPa. Two steps were recognized in the shrinkage process of the tangential strain. The strain shrunk up to the point when protoplasm separation would be occurred in the cell stops to shrink and start again to shrink by further drying.4, From the above results, it was clear that the diurnal change of tangential strain was due to the change in turgor pressure of living cells generated by the change in negative water pressure induced by both, transpiration and imbibition.5, The calculation made from the data of tangential strain and Young's modulus of the inner bark gave a value of 0.3-0.4MPa as the turgor pressure of living cells. The amount of diurnal change of the turgor pressure was estimated at 16-88Kpa.In this research, a method of continuous measurement of turgor pressure of living cells related to water potential was developed.Further research will enable to understand the generation process of the physical properties of wood in relation to the cell wall formation. Less