Application of Humus substances to overground organs of plants

Abstract

The authors studied the effect of the application of humus substances to the leaves ofBegonia semperflorens Link etOtto. For spraying they ušed a dialysed extract of garden soil containing sodium humate with admixture of fulvic acid in total concentration of 300 mg/l. Doses of 2 ml. were applied twice a week during the period of the main growth phase. It was found that humus substances applied to the leaves cause a leng-thening of plant organs and increase of their fresh and dry weights. The chloro-phyll content and the amount of expired carbon dioxide are increased. The final result depends on the time when spraying was carried out and on the concentration used. It can be assumed that these effects are the result of direct influence by the humus substances and are not due to the action of stimulated soil or root microflora nor to improvement of the physicochemical character of the soil environment. In conclusion we may say that humus substances applied to the leaves cause lengthening of the plant organs and increase in their fresh and dry weights. Chlorophyll content and the amount of expired carbon dioxide are also increased. The final effeet depends on the period of spraying and on the concentration used. In view of the fact that these effects do not differ from the effects caused by humus substances given as a part of root nutrition, we may assume that they are the result of direct action of humus substances and not of the action of stimulated soil or root microflora, nor to the improve-ment of physical or physico-chemical character of the soil environment. A prerequisite for the practical utilization of humus sprays is, however, the extension of experiments to a greaternumber of plant species, the determination of their sensitivity, suitable concentrations of the solutions and the most suitable time of application.