A simple apparatus is described for the collection of root exudates at different intervals without disturbing the root system of the seedling.
Root exudate studies have achieved singular importance during the last few years because they have been shown to have stimulatory as well as inhibitory influence on several pathogenic fungi. Different methods have been evolved by various workers to collect root exudates 1 2 a 4 5 6. However, each of these methods have one or the other limitations. They include (a) contamination of plants with microfungi and bacteria during germination period; (b) difficulty in separating out the root, leaf and seed exudates; (c) difficulty in obtaining exudates at different intervals of growth of the same seedling and (d) difficulty encounter in sterilising the entire apparatus. To avoid most of these limitations an apparatus has been designed, the details of which are given in Fig. 1.
The bottle A 9 ร 5 cm, fitted with a rubber cork and having a basal opening Q at the bottom; a Tube T 20 ร 2.5 cm, having a narrow basal opening O of 1.0 cm in diameter was introduced in such a manner that it touched the sterilised water contained in the bottle A. Glass wool was inserted at the basal end of the tube T. This assembly was connected by tube 'C' of 0.5 cm diameter to another graduated bottle 'B' 5 ร 2.5 cm, containing sterilised water.
The opening M of the tube 'T' and the opening 'N' of the bottle 'B' have been plugged with non-absorbent cotton. The whole assembly was sterilized at 15 lb pressure for 25 minutes.
Sterilised seeds of which the exudate was needed, were introduced under the asceptic condition. They were then allowed to germinate. The desired amount of root exudate was removed when necessary through the basal opening Q of the bottle A in sterilised flask and stored in a refrigerator. A known quantity of water again poured in the bottle 'A' from the bottle * A part of the Ph.D. thesis submitted by the senior author to the Aligarh Mushm University, Aligarh (U.P.), India.