Research on Crops

Nemarioc-AL and Nemafric-BL phytonematicides, developed from fruits of wild cucumber (Cucumis myriocarpus Naude) and wild watermelon (Cucumis africanus LF.), respectively, are highly effective in suppressing root-knot (Meloidogyne species) nematodes in various crops. Fruits of C. myriocarpus and C. africanus contain cucurbitacin A and B, respectively, as active ingredients in the two phytonematicides. Due to the high incidence of post-harvest decays, chopped fresh fruits have to be dried soon after harvest, but there is scant information on the appropriate drying method. The objective of this study was to determine the comparative effects of four drying methods on concentration of cucurbitacins from fruits of the C. myriocarpus and C. africanus in order to allow for the selection of an appropriate method in initial preparation of inputs for the two phytonematicides. Chopped fresh fruits were subjected to oven-, sun-, freeze-and shade-drying methods. Relative to 52°C oven-drying method, other drying methods reduced the concentration of cucurbitacin A (46 to 81%) and cucurbitacin B (44 to 85%). In conclusion, oven-drying method at 52°C had the highest concentration of both the cucurbitacins in fruits of both plant species and should, therefore, be viewed as the preferred drying method in initial processing stages of inputs for the two phytonematicides.