Introduction.

Maralfalfa (Pennisetum sp.) stands out for its forage productivity in tropical regions; however, technical evidence regarding its management for propagule production is insufficient. The quality of asexual seed is subject to agronomic factors that determine stem robustness and physiological maturity. Objective. To evaluate the effect of planting density and the number of harvests on the yield and morphometric characteristics of maralfalfa as a seed nursery. Materials and methods. The study was conducted in Huaral, Peru (2018-2019), using a completely randomized design with a 3 × 2 factorial arrangement. Three planting densities (0.50, 0.75, and 1.00 m between plants; 0.80 m between rows) and two harvests (120 days post-planting and 90 days post-cut) were evaluated. Fresh biomass yield (FBY), plant height (PH), stem weight (SW), number of tillers per plant (NTP), stem diameter (SD), and number of stem nodes (NSN) were quantified. Results. No significant interaction between factors was detected (p > 0.05). FBY, SW, and NTP were significantly higher (p < 0.05) in the second harvest, with increases of 45 % (1.45 vs. 1.00 kg/plant), 29 % (564.31 vs. 437.30 g), and 10 % (3.79 vs. 3.45 tillers), respectively. The largest SD was obtained with a density of 1.00 m (3.97 cm; p < 0.05), while a density of 0.50 m produced plants with higher PH (3.80 m; p < 0.05) and NSN (15 nodes; p < 0.05). Conclusions. The second harvest optimized yield and tillering due to the consolidation of the root system. For propagule production, the 1.00 m spacing favored robustness, as reflected in stem diameter, whereas the 0.50 m spacing maximized node availability per unit area, allowing differentiated management according to the objective of the seedbed.