Physical–Mechanical Properties of Tomato Seedlings for the Design and Optimization of Automatic Transplanters

This study was based on the hypothesis that the hybrid type and its physical&ndash:mechanical properties significantly influence the operational efficiency of transplanting systems. Understanding these properties is essential for optimizing the performance of semi-automatic and automatic transplanters. To test this hypothesis, a completely randomized design was implemented to evaluate the physical&ndash:mechanical properties of tomato seedlings. A total of 1350 seedlings from three F1 hybrids&mdash:Natalie (H1), CID (H2), and Gavil&aacute:n (H3)&mdash:cultivated in central Mexico, were analyzed. The statistical analyses included mean comparisons using Tukey&rsquo:s test and multiple linear regression to estimate the center of mass (CM). The results indicate that H2 was notable for its total height (ht = 311.76 mm), canopy development in X, Y, and Z axes (170.24 mm, 106.84 mm, and 98.14 mm, respectively), stem diameter (ds = 3.65 mm), total weight (wt = 11.92 g), de (78.36 mm) and dp (233.40 mm) distances, and oscillation period (T = 0.88 s). H1 had the highest stem height (hs = 53.18 mm), wt = 11.76 g, and root ball (RB) moisture content (MC) (77.36%). H3 had the largest ds = 3.70 mm, as well as the highest MC in the stem (94.51%) and the remaining foliage (92.92%). Regarding mechanical properties, the average adhesion force (AF) was 4.606 N (H1), 7.470 N (H2), and 3.815 N (H3). The average root ball punching force (RBPF) was 0.36, 0.48, and 0.25 N, respectively. The lowest static friction coefficient (SFC) on a galvanized steel sheet was 0.936. The drop test (DT) revealed an average residual substrate mass of 0.148 g at a height of 500 mm. It can be concluded that the interaction between hybrid type, transplanting age, and MC plays a critical role in the efficient design of semi-automatic and automatic transplanting equipment. This interaction enables process optimization, ensures operational quality, reduces seedling damage, and ultimately enhances and increases the long-term profitability and sustainability of the equipment.