Growth and yield response of selected crops to treatment with ComCat

English: A recently commercialized natural bio-stimulant, ComCat®, that contains three active brassinosteroids (BRs) of which two were identified previously, was scrutinized in this study for its potential to be applied in the agricultural industry. Concerning objective (1), seven biotests were employed to quantify the bio-stimulatory activity of ComCat® under laboratory and glasshouse conditions. The product was tested at different concentration levels and the 0.5 mg ℓ-1 application repeatedly emerged as the optimum concentration in terms of contributing towards increases in all of the parameters measured. Treatment with ComCat® had little or no effect on seed germination, but especially root growth of seedlings from different crops was significantly and consistently induced. Concerning objective (2), two cultivars for each of five test crops were treated with ComCat® over two growing seasons under field conditions in order to ascertain their yield response. Some of the test crops, but not all, showed cultivar sensitivity to treatment with ComCat®. However, overall the significant yield increases measured in one or both cultivars of the five different test crops and in one or both seasons confirmed the potential of ComCat® to be applied in agriculture and to contribute to economic prosperity for a farmer. Concerning objective (3), gas chromatographic analyses of a crude extract of the product as well as semi-purified fractions thereof by, using internal BR standards, were employed to identify an unknown BR contained in ComCat®. This was confirmed to be 24-epi-brassinolide. The latter as well as the previously identified 24- epi-castasterone and 24-epi-secasterone are known to be active BRs of the brassinosteroid group. In conclusion, the bio-stimulatory characteristic of ComCat® was confirmed both in vitro and in vivo under laboratory, glasshouse and field conditions in this study. Significant yield increases in all of the test crops over two seasons in some instances, confirmed the potential of ComCat® to be applied sustainably in the agricultural practice. Based on the results obtained in this study, three possible application methods of ComCat® are suggested. These include 1) seed treatment, 2) foliar application or 3) soil application.