珍珠梅和榆叶梅茎直径微变化及其原因

Stem diameter micro-changes of Sorbaria sorbifolia and Prunus triloba and the causes

晴好天气下,测定2种蔷薇科植物珍珠梅(Sorbaria sorbifolia A.Br)和榆叶梅(Prunus triloba Lindl.)茎直径、木质部直径、韧皮部直径、木质部含水量、叶水分亏缺和蒸腾速率日变化.结果表明,珍珠梅和榆叶梅茎直径呈现白天收缩,傍晚、夜间恢复或者膨胀的变化过程.珍珠梅和榆叶梅木质部直径变化趋势与茎直径变化趋势一致,而韧皮部直径无明显变化;相关分析表明木质部直径变化与茎直径变化呈现极显著正相关,说明木质部直径的变化是引起茎直径变化的主要原因.珍珠梅和榆叶梅木质部含水量与其木质部直径呈现极显著正相关;茎直径与叶水分亏缺呈现极显著负相关性,与水分代谢有密切关系.说明珍珠梅和榆叶梅的茎直径变化是由体内水分平衡决定的.

The diurnal variations of plant stem diameter,xylem diameter,phloem diameter,water content of the xy-lem,leaf water deficit and transpiration rate of Sorbaria sorbifolia and Prunus triloba were measured on sunny days.The correlations among these variations were analyzed in order to understand the causes of micro-changes of plant stem diameter.The results showed that the stem diameters of S.sorbifoliaand P.trilobashrank in daytime and returned to the original size at night.The xylem diameters of the plants also presented the same trend,but the phloem diameters had no significant change.Correlation analysis indicated that the change of stem diameter showed a highly significant positive correlation with the xylem diameter change,so the xylem diameter change played a main role in the stem diameter changes.The stem diameter of S.sorbifoliaand P.trilobahad a highly significant nega-tive correlation with the leaf water deficit,and the changes of stem diameter had a close relationship to the water me-tabolism.These results suggested that the stem diameter changes of S.sorbifoliaand P.triloba were determined by the water balance of plant.