Top grafting compatibility of three robusta coffee superior clones as scion and a local robusta coffee clone as rootstock

Grafting is a plant propagation technique in the form of combining two different parts of a plant in such a way that they become one whole unit and grow as one plant after tissue regeneration occurs at the joint scar or link. Many factors affect the success of top grafting to improve coffee plant growth, including the condition of the rootstock, and the age level of the entres. The study aimed to obtain high compatibility of top grafting results between 3 scion clones with robusta coffee rootstock segments. The research was conducted in the Coffee Plant Practicum Garden of Lapung State Polytechnic. The research started from May 2023 to October 2023. The research used Factorial Randomized Group Design (RBD) with 2 factors and 3 replications grouped by replication. The treatments tested consisted of 3 robusta coffee clones clone 1 (BP534), Clone 2 (SA203), and clone 3 (BP939) as the scion and rootstock of robusta coffee clone BP42 in the second internode and third internode. Observations were made after the top grafting connection was 3-4 weeks old, which was marked by the growth of shoots. The results showed that all treatments had high top grafting compatibility. Only in the A1R1 and A1R2 treatments the top grafting success was 66.67%. The growth of new shoots is expected to improve the good properties of coffee plants. Plant growth resulting from top grafting is used for plant rejuvenation or replacing branches of old coffee plants that have few fruits.