# Behavior of Different Grafting Strategies Using Automated Technology for Splice Grafting Technique
## 2 Materials and Methods  
### Device Description  
To understand the influence of the different seedling grafting strategies on the success of the grafting process, an automated experiment was designed to harmonize the work processes and thereby avoid variation in the obtained results, as far as possible.  
The rootstock and scion are cut to a precise angle of 60\({}^{\circ}\); this ensures greater splicing graft success [45]. The cutting is performed using two simple devices, in which the seedling stems are placed in a slit that guarantees verticality. Once the seedlings are set in place, a pneumatic actuator advances a blade that makes the cut with a dry shock movement against the seedling, causing a clean stem bisection and ensuring cutting angle accuracy. The seedlings are placed into the grafting device by two Kuka industrial robotic arms (Agilus model R6 900 developed by KUKA Roboter GmbH). Each robot operates independently in handling each of the seedlings, one responsible for holding the rootstock and the other for the scion.  
The grafting equipment on which the various splicing strategies were tested cuts each of the flexible plastic clips from a continuous reel, and then positions the grafting clip, thus ensuring the union between the rootstock and the scion (Figure 3). The process consists of two basic operations: (1) Preparation of the grafting clip by making a custom cut and (2) clamping the clip for optimal opening and placing it on the seedling to be grafted [47].  
(1) In the first phase, the device makes a grafting clip from a continuous roll of plastic tube tape through the coordinated and sequential action of several pneumatic actuators and a blade cutting system. To do this, the first microcylinder (SMC CJPB10-5) clamps the continuous tube tape against a second cylinder (SMC CXSM15-15), which vertically pushes through the exact length required for the grafting clip. Finally, the tube is cut by a blade attached to the second cylinder (SMC CXSM15-15), with a clean dry shock cut.  
(2) In the second phase, the grafting clip is clamped by a rotary actuator (Festo DM-6-90-P-A), which acts on a lever mechanism that presses the clip's side wings, thus opening the clip to its maximum. As a last step, once the clip is on, a cylinder (SMC CXSM25-70) horizontally scrolls the clip to align with the union point of the two graft seedlings. Once the graft is complete, the rotary actuator (which holds the clip open) releases the clip and removes itself from the union point, returning to its resting position.  
A passive fitting device is located at the meeting point of both seedlings and the grafting clip, which ensures correct seedling positioning. The seedling stems may suffer slight deviations or inclinations due their natural variability and search for a light source as they grow. The passive device is designed to correct these small deviations. It has two openings, one on top for the scion and one below for the rootstock, which guarantee the correct placement and housing of the seedlings. Both openings are connected by a channel, allowing sufficient space to fit both seedlings and the graft clip and to ensure that both seedlings are perfectly matched up.  
Once the clip is positioned, the robot holding the scion graft releases and withdraws while the robot holding the rootstock graft stem likewise withdraws from the grafting point, so that the post-graft healing phase can begin.  
The graft clips used in the test were taken from a continuous roll of flexible translucent plastic, equipped with a lateral opening; the 3.00 mm internal diameter is slightly oval to provide better grip and closure when the rootstock and scion stem diameters are not the same, and it is also equipped with side wings for opening and placement. These types of clips, widely used in splice grafting, can be purchased on continuous reels for automation purposes. They can be cut to different lengths, are easy to handle and adapt as the callus heals and the stems thicken, and they eventually fall off by themselves.