*3.1. Grafting Success and Plant Biometric Parameters*

Rootstock significantly affected grafting success, number of leaves at 50 DAT and aboveground biomass (Table 1).


**Table 1.** Year and rootstock effects on grafting success and plant biometric parameters of 'Scarlatti' F1 scion.

DAT, days after transplanting. Values within a column and a year followed by the same letter are not significantly different at *p* ≤ 0.05 (Tukey HSD Test). The significance is designated by asterisks as follows: \*, statistically significant differences at *p*-value below 0.05; \*\*, statistically significant differences at p-value below 0.01; \*\*\*, statistically significant differences at *p*-value below 0.001; NS = not significant.

The tube grafting method proved highly efficient with success percentages that ranged from 89.1 to 99.6% among the materials used (Table 1). No significant differences were found in terms of success rate among Scarlatti , *S. torvum*, and *S. melongena* × *S. aethiopicum* gr. *gilo* hybrid rootstocks, which showed percentages of graft success ranging from 99% (*S. melongena* × *S. aethiopicum* gr. *gilo* hybrid) to 99.6% ( Scarlatti ). In contrast, *S. aethiopicum* gr. *gilo* (accessions 1 and 2) had a significantly lower percentage of success (93.6 and 89.1%, respectively) with respect to the other rootstocks (Table 1). No visible disaffinity signals at the grafting zone were observed for any rootstock–scion combination.

The mean number of leaves at 50 DAT varied between 17.5 and 27.3 leaves per plant for the Scarlatti ungrafted and *S. aethiopicum* gr. *gilo* (accession 1) rootstock, respectively (Table 1). Scarlatti scions grafted onto *S. melongena* ( Scarlatti ) and *S. aethiopicum* gr. *gilo* (accession 1) rootstocks had a higher number of leaves at 50 DAT than those ungrafted or grafted onto *S. aethiopicum* gr. *gilo* (accession 2). However, eggplant plants grafted onto *S. torvum* and *S. melongena* × *S. aethiopicum* gr. *gilo* hybrid did not significantly differ from those grafted onto the other rootstocks tested.

Aboveground biomass produced ranged from 5.1 kg for Scarlatti grafted on *S. torvum* rootstock to 3.7 kg for those grafted on *S. aethiopicum* gr. *gilo* (accession 1) rootstock (Table 1). Plants grafted onto *S. torvum* rootstock did not significantly differ compared to those grafted onto *S. melongena* (self-grafted plants), whereas the lowest aboveground biomass values were collected from eggplant plants grafted onto *S. aethiopicum* gr. *gilo* (accessions 1 and 2) (3.7 and 4.0 kg).

Regardless of the rootstock, the second trial (2015) gave the shortest time of first flower formation (50.6 DAT), whereas, irrespective of the year, plants grafted onto *S. melongena* × *S. aethiopicum* gr. *gilo* hybrid and *S. torvum* gave the shortest time of first flower formation (49.3 and 49.0 DAT, respectively). 'Scarlatti' ungrafted had the longest first flower formation (53.1 DAT) (Table 1).

Rootstock significantly influenced plant height at 50, 80, and 110 DAT (Figure 1).

Plants grafted onto *S. aethiopicum* gr. *gilo* (accession 1) had the highest plant height, whereas plants grafted onto *S. aethiopicum* gr. *gilo* (accession 2) had the lowest values (Figure S2).

At 80 DAT, no significant differences were found in plant height among 'Scarlatti', *S. torvum*, *S. aethiopicum* gr. *gilo* (accession 1), and *S. melongena* × *S. aethiopicum* gr. *gilo* hybrid rootstocks. *S. aethiopicum* gr. *gilo* (accession 2) had a significantly lower plant height value with respect to the other rootstocks (Figure 1). However, plant height at 50 and 110 DAT, in 'Scarlatti' F1 grafted onto

*S. melongena* × *S. aethiopicum* gr. *gilo* hybrid rootstocks did not significantly differ from those grafted onto *S. aethiopicum* gr. *gilo* (accession 2).

Rootstock significantly influenced root collar at 50, 80, and 110 DAT (Figure S3). Plants grafted onto *S. aethiopicum* gr. *gilo* (accession 2) and *S. melongena* × *S. aethiopicum* gr. *gilo* hybrid rootstocks had the lowest root collar values, whereas plants grafted on *S. aethiopicum* gr. *gilo* (accession 1) had the highest value (Figure S3).

**Figure 1.** Mineral elements of 'Scarlatti' eggplant fruits produced from ungrafted, self-grafted, and grafted onto *S. torvum*, *S. aethiopicum* gr. *gilo* (accession 1), *S. aethiopicum* gr. *gilo* (accession 2), and *S. melongena* × *S. aethiopicum* gr. *gilo* rootstocks. Bars with different letters are significant by Tukey HSD Test (*p* < 0.05).
