The role of seed size in the performance of Ceiba aesculifolia seedlings subjected to foliar damage

In tropical forests, herbivore damage is one of the main causes of seedling mortality. However, along with seed size, the resources herbivores provide are an important factor in a seedling's response to selection pressure. The objective of this study was to evaluate the role of seed size and artificially-induced herbivory on the functional traits of Ceiba aesculifolia seedlings. To do this, we established four levels of foliar damage: 10%, 25%, 50%, and 75% (n = 270), and a control treatment (no damage; n = 60). Foliar damage treatments were conducted 60 days after germination. These treatments were applied to seedlings developing from seeds of three different sizes. The response variables were growth, some foliar traits, and seedling biomass. Seedlings from small seeds showed higher growth rates in terms of height (0.44 ± 0.02 cm month−1), diameter (0.24 ± 0.01 mm month−1), and foliar production (9.1 ± 0.19 leaves), as well as higher total dry weight (8.5 ± 0.03 g) and larger leaf area (49.3 ± 1.9 cm2) than those from medium and large seeds. Seedlings from large and medium seeds showed higher root:stem ratio values than seedlings from small seeds (p < 0.05). Foliar damage was found to have an effect on dry weight. The total biomass of seedlings with 75% damage was considerably smaller than that of seedlings with 10% damage. Chlorophyll content was found to be related to the interaction between seed size and foliar damage, and it was lower in seedlings from medium seeds and 50% damage than in those from small seeds with the same level of damage and large seeds with 75% damage. In short, seed size had a significant effect on growth traits. Contrary to our expectations, seedlings from small seeds showed the best performance in terms of height, biomass, number of leaves, and foliar area.