Relationship between water content of Cymbidium protocorm like body and growth

To develop a simple growth model of a heterotrophically cultured plant in vitro, the relationship between growth and water content of the plant was investigated with Cymbidium Protocorm like body (PLB) as the model plant. The growth of Cymbidium PLBs with different water contents, which were induced through different glucose concentration media (1 g/l, 10 g/l, 20 g/l), was studied. To analyze the growth, growth rate per unit surface area of contact between PLB and medium (Area Growth Rate; AGR) was used. PLBs with low water content had large AGR by fresh weight and this tendency was most striking from the initial transplanting to day 1. However, AGR by dry weight did not change with water content. A simple growth model for Cymbidium PLB using AGR was constructed. The model was based on the following assumptions: 1) water uptake depended on the water potential difference between PLB and medium, and 2) glucose uptake depended on the glucose concentration in the medium. The growth model could simulate the growth of PLBs with different water contents.