Development of a Simple Method for the Study of Translocation of Photosynthetic Products in an Elementary School or a Lower Secondary School: Aplication of Sucrose-Test Paper

Abstract

We designed the "dip method" as a simple and efficient method of obtaining sieve-tube exudate to apply the "sucrose-test paper" which was developed to detect easily sucrose. We investigated the leveles of sucrose collected by the dip method. Sucrose contents in the dip solution were measured with invertase-glucoseoxidase method. Two pinnate-compound leaves of the potato Solanum were cut at their petioles. The cut ends of petioles were dipped over night in water for adaptation. The exudation of sucrose into water through the petiole was the maximum during the first night after the adaptation and then daily decreased. The sucrose contents translocated were close to 6.6 μg per 1 cm2 -leaf area and increased proportionally to an increase of leaf area. Such a proportion, however, was not found when the stem bearing more than two pinnate-compound leaves was dipped in water. Thus, immersion of two individual matured leaves of Solanum in 50 ml of water at their petioles for a day and night after over-night adaptation was a sufficient condition to obtain the successful detection of sucrose in water. It is natural that one has to pay attention to the decrease of water resulting from water absorption by plants, light fluence rate given to plants in the daytime, and wilting of plants throughout the experiment. Since no technical difficulties exist in these procedures, we are convinced that the dip method is applicable even for the experiment in an elementary school or a lower secondary school to study the translocation of photosynthetic products in plants.