The influence of humus acid on the respiration of plant roots

Abstract

Humus acid (Humussäure Riedel de Haen AG. Seelze Hannover) in 0·01% concentration increases the respiration intensity of plant roots grown in water cultures both as regards O2 consumption and CO2 production, while RQ (CO2:O2) is only very slightly increased. The plants used in these experiments were the winter wheat Pyšelka (Triticum vulgare Vill.), maize Zaj íček's “Český koňský zub” (Zea mays L.) and the gourd Veltrusská velkoplodá (Cucurbita maxima L.). O2 consumption and CO2 production were determined on separated root tips by the direct Warburg method. It was found that the effect of humus acid is not only to increase respiration intensity in the roots of the experimental plants, but also their lengths and dry weights (for all experimental plants); for maize and gourd the dry weights of overground parts were also increased, which indicates that increased respiration intensity was linked with more intensive growth of the plants.