Weight-Change Patterns in Cut and Intact Rose Shoots I. Beta-Ray Gauging for Assessing the Foliar Contribution: Technical Aspects and Considerations

Abstract

Summary Beta-gauging was applied in two modalities: 1. long-term monitoring of one leaf per plant, and 2. discontinuous short measurements, at critically chosen moments, on as many leaves per plant as practicable, in conjunction with total plant weight determination. It was established that in our plant material (own-rooted, single-stem rose plants) all leaves behaved basically in the same way. Consequently, representative values of specific leaf weight (i.e., fresh weight per unit leaf area) could be obtained, so that with known leaf area total foliage weight could reliably be estimated and followed in time, with the plants remaining intact. Comparison with simultaneously determined total plant weight enabled the relative contributions of flower and foliage to be estimated in the patterns of weight change observed during the vase life of cut roses. Some preliminary results are presented: 1. Leaves on intact plants showed characteristic and persistent patterns of change in specific weight during consecutive light/dark cycles, and continued to increase in weight for a considerable period of time. 2. Upon cutting, this rapid rise in leaf weight abruptly stopped, whether the roses were placed in water or in a sugarcontaining solution, but the diurnal patterns thus obtained were widely different. 3. The patterns of change in total shoot weight during vase life were caused mainly by the flower, with a relatively minor but constant contribution of the foliage.