Biochar enhances root development and aloin content of mature leaves in containerized Aloe arborescens Mill

The leaves of the medicinal plant Aloe arborescens Mill. Asphodelaceae) contain significant amounts of bioactive metabolites, including aloin (a mixture of the two diastereoisomers, aloin A and aloin B), aloesin, isoaloeresin D, and aloenin A. The presence of these metabolites varies considerably depending on the plant’s growth conditions, including the used growing substrate. In recent years, there has been growing interest in using biochar for potted plants cultivation. However, there is currently no available information regarding the suitability of biochar for the containerized cultivation of A. arborescens. A pot experiment was conducted with the hypothesis that biochar could influence the growth and phytochemistry of A. arborescens. The growing medium was supplied with increasing proportions of biochar (1: 100% commercial substrate; 2: mixed 50%(v/v) substrate; 3: 100% conifers wood biochar). Over the course of three years, the plants were closely monitored, and several key growth parameters were measured, including plant height, stem diameter, number and weight of leaves, and the number of suckers. After the first year, the content of selected active metabolites wasassessed. This evaluation also involved a comparison of the respective levels in the leaves taken from the apical, median, and basal sections of the stem. The leaves collected from the median section of plants were found to be larger and exhibited the highest percentage of spikes, epidermis, and gel on fresh weight. As a general trend, it was observed that in plants cultivated within the highest amount of biochar, the leaves collected from the intermediate stem portion contained the highest quantity of secondary metabolites.