The first project we did this semester in SAFS 680 was grafting cucumbers!! Grafting is the process of joining the rootstock from one species with the scion of another species to create a plant that has the most desirable traits from both sections. Grafting first originated in Japan in the 1920s and has a long history in fruit trees throughout Asia and Europe. There are many benefits to grafting including resistance to disease/pathogens, vigor, stress tolerance, precocity, size along with other desirable traits.
For our cucumbers, we chose the squash Cucurbita ficifolia for the rootstock and Cucumis sativus var. ‘Socrates’ for the scion. The rootstock variety was chosen because of its cold hardiness. Cucumbers are generally a warm-temperature summer crop and so this rootstock will hopefully allow for successful cucumber production in the fall in the heated high tunnel. The scion was chosen for its fruit quality, cold tolerance, as well as it being parthenocarpic so pollinators are not necessary for fruit set in the high tunnel.
There are many different ways to graft but we chose to use the single cotyledon method. This consisted of first removing the root system from the rootstock. Removing the roots stimulates the plant to put out more adventitious roots which leads to an overall healthier plant. Then, the apical meristem of the rootstock and one cotyledon are removed so that the rootstock does not grow new vegetative leaves. The scion is then cut above the soil and both cotyledons are cut in half to limit water loss through transpiration during the healing process. An angled cut is then made on the stem of the scion and lined up with the removed meristem section of the rootstock. A grafting clip is used to hold the two sections together. The newly grafted plant is misted with water and then placed in a cell filled with wetted potting mix.
The bottom trays were then filled with water to encourage root growth and the plants were misted and covered with a plastic dome to maintain high relative humidity. The tray then experienced a 24 hour dark period inside the healing chamber followed by exposure to an LED light with red and blue wavelengths. The light intensity increased over the several weeks in the chamber as the plants began the healing process. During their stay in the greenhouse in the healing chamber, the temperature was kept between 80-90 F through a bottom heat mat.
After the healing process was complete, the plants were slowly acclimated to the greenhouse light and then ready to be sowed in the high tunnels!!
Stay tuned on social media for updates on the growth of our grafted cucumbers!!