How to Choose the Right Rootstock for Grafting Eggplant
Disease resistance in grafting depends mainly on the disease resistance of the rootstock. Based on years of research and application results by experts at home and abroad, the excellent rootstocks now widely used in production are mainly Japanese Red Eggplant, CRP, and Torubamu.
(1) Japanese Red Eggplant. Also known as Ping Eggplant or Red Eggplant, it is a rootstock variety used relatively early in foreign countries. The excellent characteristics of Japanese Red Eggplant as a rootstock are high resistance to Fusarium wilt, moderate resistance to Verticillium wilt, a well-developed root system, and relatively thick and sturdy stems. The internodes are shorter, and there are thorns on the stems and leaf surfaces, with relatively many thorns. The seeds are white, shaped like chili seeds, coarsely kidney-shaped, 4mm long and 3mm wide. They germinate very easily; after soaking for 24h, the germination rate is 23% at 2d, 28% at 3d, and 93% at 4d. The seedling growth rate is the same as that of ordinary eggplant. When Japanese Red Eggplant is used as a rootstock, it needs to be sown 7d earlier than the scion, and the grafting method can be cleft grafting or slant grafting. Because the disease resistance spectrum of Red Eggplant is relatively narrow, it is not suitable for use as a rootstock in fields with severe Verticillium wilt.
(2) CRP. CRP is also a wild eggplant, named after its place of origin. This variety has more thorns on stems and leaves, so it is also called Thorny Eggplant. It is the newest excellent rootstock variety for eggplant grafting. CRP is highly resistant to eggplant Verticillium wilt, and it is now an excellent rootstock variety widely promoted and applied in northern China.
The 1000-seed weight of CRP seeds is 2g; they are brown and nearly round, with a diameter of about 3mm. The seed germination rate is 7.4%, 65.6% at 6d, and 93.44% at 8d.
CRP is resistant to damping-off at the seedling stage, but is susceptible to Rhizoctonia rot. It is relatively tolerant to low temperatures, making it suitable as a rootstock for eggplant cultivation in protected facilities in autumn and winter.
In some places in Liaoyang City, CRP is used as a rootstock for grafting eggplant with very good results. After 4 years of continuous cropping, soilborne diseases have never been observed. With 2500 plants planted per 667 sq m, the taller plants reach 1.8-2.0m, and an average of 35 eggplants are harvested per plant, with a yield of up to 1.5 million kg per 667 sq m, significantly increasing production and making it very popular.
(3) Torubamu. The Torubamu variety comes from Japan. This variety is highly resistant or immune to Verticillium wilt, Fusarium wilt, bacterial wilt, and root-knot nematode disease and other soilborne diseases, and is known as the "four-resistant" eggplant rootstock variety. It has a well-developed root system, extremely strong aboveground plant growth, relatively long internodes, few thorns on stems and leaves, and very small seeds, with a 1000-seed weight of about 1g. Under normal conditions, the seeds do not germinate easily and need to be sprouted.