Pot Method

a laboratory method of studying plants by growing them in pots kept in greenhouses. The pot method is used to study the physiological role of nutrients and their intake by plants, the significance of the reaction of the medium (pH) and the watering rate, and the reaction of plants to the concentration of the nutrient solution, temperature (frost resistance), moisture (drought resistance), light (photoperiodism), chemical protective agents, herbicides, and so forth. The pot method is used mainly to compare different kinds of fertilizers added to soil. To determine the significance for plants of various chemical elements or their salts, the pots are filled with quartz sand or distilled water instead of soil, and the compounds under study are added.

Plants grown in pots must be protected from accidental injury and atmospheric precipitation, which disrupt the particular conditions created in the pots, and from other factors. A serious shortcoming of the pot method is that there is a limited amount of soil in which to grow the plants. Therefore, the roots are more crowded in the pots than in the field. The small amount of soil in the pots also explains why plants growing in pots respond much more sharply to a lack of one element or another than plants grown under field conditions. Therefore, the data obtained by the pot method on fertilizer requirements are often exaggerated. Another major shortcoming of the pot method is that the soil structure is destroyed when the soil is dried and sifted before it is packed into the pots. Thus, the results of pot method experiments must be regarded as preliminary and extrapolated very cautiously to field conditions.

The pot method has been most fully worked out in the studies of the Russian scientists P. S. Kossovich, D. N. Prianishnikov, and K. K. Gedroits. An enthusiastic exponent of the pot method was K. A. Timiriazev, who organized a demonstration of the method at the All-Russian Exhibition in Nizhnii Novgorod (the modern city of Gorky) in 1896.