Determining the rate of wilting of a grafted seedling in an acclimation process using a machine vision system

摘要

It is important to understand the characteristics of grafted seedlings during the acclimation process, especially the moisture content (m.c.) inside the scion, which depends on the balance between transpiration and supply from the stock. To evaluatethe joining rate between the scion and the stock, the m.c. inside the scion has to be measured with a non-destructive method. This can be done effectively by measuring the wilting rate of a grafted seedling. However, wilting depends not only on the m.c.of a seedling, but also on its rigidity and size. To obtain an index of the seedlings' rigidity, a rigidity measuring system was used to measure the resistance force when the stems were cut. Wilting rate was measured with a video camera. A mechanical model for predicting wilting of a seedling was developed. The wilting behaviour of the seedings was non linear. An attempt was made to model this behaviour after the balance equation of a spring-mass system, using a synthetic spring coefficient as the variable. The m.c. of a seedling was calculated from the wilting data after evaluation of the model parameters using the apparent synthetic spring coefficient. The wilting behaviours of different seedlings were successfully characterized with this model.