Suitability of CMS-based Interspecific Eggplant (Solanum melongena L.) Hybrids as Rootstocks for Eggplant Grafting

Aims: The objective of the study was to determine the suitability of five newly developed CMS-based interspecific eggplant hybrids as eggplant rootstocks.

Place of Study: This study was conducted in an experimental field of the Hellenic Agricultural Organization “Demeter” (HAO “Demeter”), in Thessaloniki, Greece.

Methodology: In the grafting experiment the Greek eggplant cultivars ‘Langada’ (L), ‘Emi’ (E) and ‘Tsakoniki’ (T) were used as scions. The interspecific rootstocks viz., F1(cmsLxSI), F1(cmsExSI), F1(cmsTxSI), F1(cmsExSG) and F1(cmsTxSG) were previously developed after crossing the respective CMS eggplant lines (cmsL, cmsE and cmsT) to the wild species S. integrifiilum (SI) and S. gilo (SG). Self-grafted plants of the three eggplant scions were used as controls. For each of the 18 scion/rootstock combinations nine plants were grafted by using the cleft grafting technique and plant survival rate was recorded. The grafted plants were transplanted in the field and arranged according to the completely randomized experimental design. The number of early and total fruits and weight of early and total yield as well as some important fruit characteristics (weight, length and diameter, ratio of length to diameter, penducle length, number of penducle prickles) were recorded on per plant basis. In addition, some aspects of external fruit morphology (color, shape, presence of stripes) were also recorded.

Results: Plant survival in the hetero-grafting combinations was high (94.0%) and comparable to the self-grafted controls (96.3%). While early production was not affected by grafting, total production was improved by certain rootstocks. F1(cmsTxSI) and F1(cmsExSG) had an overall positive effect on all scions and increased total fruits by 41.4% and 31.0%, respectively, and total yield by 36.8% and 35.8%,respectively. F1(cmsLxSI) combined well with cv. ‘Langada’ increasing total fruits by 34.3% and total yield by 53.8%. Interestingly, both self- and hetero-grafting resulted in morphological alterations of the fruit which varied with respect to the scion/rootstock combination.

Conclusion: The grafting compatibility between the eggplant scions and the interspecific rootstocks was very high. A differential response to grafting of each eggplant cultivar was apparent for most of the studied yield and fruit characteristics with possible underlying scion x rootstock interactions. From a practical point of view, F1(cmsTxSI) and F1(cmsExSG) indicate high potential as eggplant rootstocks and may be considered for further evaluation.