Water Culture

the raising of plants in a liquid (aqueous) nutrient medium.

The science of water culture, which was developed in the 1870’s by the German biologists J. Knop and J. von Sachs, is used in the study of plant feeding, growth, and development, as well as in manufacturing. Growing crops in water makes it possible to regulate the volume, composition, concentration, osmotic pressure, and reaction of the nutritive solution. With the introduction of water and sand culture methods into physiological and agrochemical research, new elements were established as indispensable for plant nourishment and development, and the importance of microelements in the life of plants was clarified.

Water culture was first used in Russia by K. A. Timiriazev in 1872; it was further developed in the works of D. N. Prianishnikov. Water culture is used in studying the ingestion, assimilation, and metabolization of salts by plants. All agricultural crops grow well in water culture, including root and tuber crops.

The water culture medium is a solution in distilled water of nutritive mixtures whose composition depends on the research task and the type of crop being studied. The vessels containing the water culture are placed in a greenhouse. Water culture makes possible the observation of the root system’s development in experimental plants and the systematic analysis and periodic replacement of the nutrient solution. Previously sprouted seeds are secured with cotton to lids that cover the vessels and have openings for the roots. A glass tube that reaches to the bottom of the container is placed through one of the openings to supply the roots with oxygen. To prevent overheating of the containers and the growth of algae, double covers are placed on the vessels: the inner cover is black, and the outer cover is white.

The essential disadvantage of water culture is the variation in the reaction of the nutrient solution, with sharp jumps toward acidity or alkalinity as a result of the physiological acidity or alkalinity of the nutrient salts used. This often leads to the development of diseases such as chloroses in the plants. In these cases it is necessary to add sodium hydroxide or sulfuric acid (until a stable reaction is produced), or sometimes iron citrate. Periodic changes of the nutrient solution are also helpful.