INFLUENCE OF THE NATURE OF THE CULTURE SUBSTRATE AND OF ALGEA EXTRACTS ON PLANT GROWTH AND DIFFERENTIATION.

The physical properties of the culture substrate as well as its chemical composition play an important role in the developmental patterns and in the growth rate of plants. The use of liquid culture medium or of the medium the physical texture of which was modified either i) by different concentrations of gelifying agents (agar, gelrite…..) or ii) by introducing solid materials such as glass beads leads to changes in the morphogenetic programs (flowers, roots, vegetative buds or callus) and to different intensities of organogenesis.

Hydroponic culture when proven appropriate versus culture using solid substrates-offers the advantages of modifying the chemical composition of the culture medium as can be done in in vitro conditions, but in field conditions for agronomic crops. There are several chemical compounds which could improve plant growth and development. Among them are minerals, organic compounds, growth substances, vitamins, etc.

We report here on the importance of i) the physical nature of the in vitro culture substrate and ii) a group of compounds which allowed high yield in several agronomic crops tested: cereals and vegetables and which enhanced flowering and fructification. These compounds were brown algea aquous extracts (marketed as "Goemar GA 14" and "CL 142") which were prepared according to a Goemar patented method. They can be supplied to the plants either by pulverization or added to the hydroponic culture in order to improve the yield of agronomic crops.

The low concentration used suggested that these products do not act through N / P / K fertilizer-like supply but maybe through specific mechanisms which are under study in our laboratories.