University of Central Florida Undergraduate Research Journal - Creating a Multi-Berry Shrub via Cross Grafting
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Creating a Multi-Berry Shrub via Cross Grafting

By: Alexa Laurent | Mentor: Dr. Rani Vajravelu

Methods

This study uses methods and materials easily available to assist everyday growers in replicating our experiment and using our research to graft their own plants.  For our plants, we used two species from the rosaceae family—rubus fruiticosus (blackberry) and rubus idaeus (raspberry).  We started with three dormant r. fruiticosus shrubs and three dormant r. idaeus (Figure 1). The plant on the right is r. fruiticosus and the one on the left is r. idaeus.

Figure 1: Test Plants in Greenhouse. Photo credit Chelsea Schuler

Both plants were under a year old at the beginning of the experiment and were kept in the University of Central Florida’s public greenhouse.  They were watered by a sprinkler system that rained water down onto the plants at set intervals.  Because the greenhouse was a public greenhouse, the temperature and humidity changed depending on how long someone had the door open at a time.  The grafting method used was cleft grafting—where an incision is made in a branch of the rootstock and the scion is inserted into the incision.  In total, we grafted six branches between the six plants.  To prepare the rootstock, we used a razor blade to cut a branch from each r. fruiticosus  plant and each r. idaeus plant.  The scions were then placed in water while unattached to a plant, and a 2.54cm incision was made in the branch of the rootstock.

At the end of each scion, the outer tissue was sheared off to create a smooth, tapered end that was inserted into the cleft in the rootstock.  One r. idaeus scion was attached to a corresponding r. fruiticosus rootstock and each r. fruiticosus scion was attached to a r. idaeus rootstock.  Once the cambiums (the cellular tissue of the plant) of the scion and rootstock were aligned, the scion was inserted and the wound was sealed with wood glue before being wrapped in electrical tape (Figure 2).  The wood glue and the electrical tape were placed over the wound to prevent water from entering the open graft. 

Figure 1: Week one Hades Graft. Photo credit Chelsea Schuler

The scions were all the same length, about 10cm long, and placed toward the end of the rootstock’s branch.  When choosing the scions, we cut branches that were at the end of a side branch of each plant to ensure similar characteristics with the same chances for growth.  The wounds were covered for three weeks, during which the height and welfare of the integument of the rootstock and scion were observed and recorded twice a week.  After the three-week healing time, the grafts were uncovered, and the rate of healing and new tissue growth was evaluated.  After the tape was removed, the health of the rootstock and the scion were monitored for an additional four weeks.

Results >>