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

Results

After three weeks of evaluation, the total growth rate of each plant and the health of the scions were evaluated (Figure 3).  The table shows the overall vertical height of each base plant and any buds that sprouted on the plant on branches without the graft.  Of the rootstocks, the r. idaeus had a greater total height increase, but the r. fruiticosus plants experienced budding on their non-grafted branches (Figure 3).  These buds were measured because, as they prospered, we saw the scion of the plant wither and dry out.  Also, while the r. fruiticosus plants did not show a significant height increase, they did experience growth in new buds, causing their width to increase.  This result provided evidence that while a scion was failing and dying, it was not due to the rootstock’s health or lack of nutrients.

Figure 3: Rootstock Vertical Growth.

When the grafts were evaluated after three weeks, the scions showed new tissue growth at the site of the union on the r. fruiticosus rootstocks, but not on the r. idaeus rootstocks.  Also, the scions on the r. idaeus plants were in much poorer health. We observed that the r. fruiticosus scions on the r. idaeus rootstocks did not have new tissue growth surrounding the initial cut.  One branch did not even keep the scion in the cleft, and we could see the dried out inner tissue of the scion where it was sticking out of the cleft.

The r. idaeus scions on the r. fruiticosus, while still drooping and of a pale green color, did have new tissue growth surrounding the sight of the union (Figure 4). 

Figure 4: Week seven Hades Graft. Photo credit Chelsea Schuler

The scions on the r. fruiticosus rootstocks were also still soft to the touch on the leaves, unlike the scions of the r. idaeus base plants. One of the r. idaeus rootstocks lost its graft early in the healing process, for the side branch the graft was adhered to was found in the plants’ soil after a night. 

As the plant had dropped inefficient branches before, it is possible that the plant dropped the grafted branch as it did not provide enough benefit to the plant as another branch.  Similarly, the graft on the r. fruiticosus plant, Dionysus, did not take to the rootstock, possibly due to the new growth the plant experienced in its new buds (Figure 3).  The remaining two r. idaeus stocks did not exhibit new tissue growth around the incision point when the tape was removed, whereas the remaining r. fruiticosus rootstocks showed new tissue growth surrounding the incision site.  The scions on the r. fruiticosus rootstocks also exhibited healthier tissue along their stems, remaining a brown or green color similar to the rootstocks’ branch color, while the scions on the r. idaeus rootstocks had turned brown, had shriveled, and had become brittle, losing most of if not all of their leaves.

These results are based on visual observations made throughout the experiment.  During the first few weeks of the experiemnt, we saw the scions drooping on each of the plants and the leaves losing their vibrant green color from before the grafting process.  During the healing process, in the second month of the experiment, we found that while the scions on the r. idaeus rootstocks were turing yellow or brown and becoming brittle, the scions on the r. fruiticosus plants were still showing signs of life though a soft, green hue.  The scions on the r. fruiticosus rootstock were also found to be limp in support, but less dried out and brittle than the scions on the r. idaeus plants.

Discussion >>