Rootstock and scion anatomical parameters in grafted eggplant seedlings, influencing growth and fruit production

Abstract

Background: The use of vegetable grafting has proven to be effective not only in providing stress resistance but also improving fruit yields. There have been no studies on grafted vegetables' effects on the vascular systems, specifically xylem vessels. This study tested the effects of two groups of rootstocks, Solanum spp., and Solanum lycopersicum, on seedling growth, anatomical parameters, and further plant growth and yield of eggplant cv. Madonna. The experiment was arranged in a completely randomized design with four replications and five plants in each replication.

Results: The results showed that seedling growth parameters including height, and stem diameter were significantly different between grafted and non-grafted eggplant plants. In terms of roots, cv. Optifort rootstock had the longest roots, while Solanum spp. rootstocks had the largest root volume. The radial widths of rootstock collenchyma and phloem were significantly greater in SG-self-grafted than in SR-self-rooted and in other rootstocks. Rootstock xylem area was higher in Solanum spp. than in self-rooted seedlings and cv. Emperador rootstock. Correlation analysis showed that rootstock anatomical traits, including xylem width and cortex parenchyma cell number, had significant positive correlations with yield (r = 0.40 and r = 0.58, respectively). Rootstocks such as ST (Solanum torvum) and A (Solanum integrifolium) which had wider xylem and more cortex cells, exhibited higher yields.

Conclusion: Rootstocks with larger xylem widths and higher cortex cell numbers, such as ST and A, promoted greater yield in grafted eggplant. These results emphasize the importance of selecting rootstock-scion combinations with favourable anatomical traits for optimal productivity.

Keywords: Eggplant rootstock; Growth; Xylem; Yield.

Fig. 1

Cross-section (median portion) of Solanum lycopersicum cv. Emperador. Length-related and area-related anatomical measurements are highlighted with red and blue, respectively. Measured anatomical parameters are radial width of collenchyma (col), radial width of phloem (ph), radial width of xylem (x), pith area (pi), frequency and average area of cortical parenchyma (par) cells. In case of parenchyma measurements, cell frequency per unit cross-sectional area and average size were determined in four identical-sized segments of the cross sections. Scale bar = 500 μm

Fig. 2

Root’s growth and development of grafted eggplant cv. Madonna onto different rootstocks at 45 DAG. The values represent the mean of four replications (5 plants in each replication) ± SD. Different letters within the same column are significantly different between means according to Tukey's multiple range test at P < 0.05. SR = self-root; SG = self-grafting, SH = Solanum grandifolium × Solanum melongena, ST = Solanum torvum, SI = Solanum melongena × Solanum integrifolium, A = Solanum integrifolium; E = Emperador, O = Optifort

Fig. 3

Effect of grafting combinations on rootstock-anatomical parameters of grafted eggplant seedlings at 45 DAG. Abbreviations: par – parenchyma; ph – phloem; x – xylem; pi – pith. Scale bars = 500 μm. SR = self-root; SH = Solanum grandifolium × Solanum melongena; SG = self-grafting

Fig. 4

Effect of grafting combinations on scion-anatomical parameters of grafted eggplant seedlings at 45 DAG. Abbreviations: par – parenchyma; ph – phloem; x – xylem; pi – pith. Scale bar = 500 μm. ST = Solanum torvum; SH = Solanum grandifolium × Solanum melongena, E = Emperador, O = Optifort; SG = self-grafting

Fig. 5

Effect of different rootstocks on accumulated total fruit yield of eggplant cv. Madonna. SR = self-root; SG = self-grafting, SH = Solanum grandifolium × Solanum melongena, ST = Solanum torvum, SI = Solanum melongena × Solanum integrifolium, A = Solanum integrifolium; E = Emperador, O = Optifort

Fig. 6

Correlation heatmap matrix of rootstock and scion anatomical traits with yield