Effect of nitrogen fertilization and harvest age on the morphological characteristics and agronomic performance of tree marigold (Tithonia diversifolia) ecotype INTA-Quepos.

Abstract

Morphological and agronomic performance variables of the tree marigold ecotype INTA-Quepos were evaluated at different doses of nitrogen fertilization (0, 100 and 200 kg N/ ha/year) and at 2 harvest ages (40 and 60 days). The experiment was carried out in the Central Pacific of Costa Rica, at an altitude of 15 meters above sea level and in a soil of the order Inceptisol; the evaluated period comprised both rainy and dry seasons, during 2019. The experimental design corresponded to a 3x2 factorial, with a total of 24 plots of 4 m² distributed in 4 blocks. The differences found in the morphological variables of leaf:stem relationship, leaf area, plant height and yield were explained by the interaction between age and the level of nitrogen applied. The yield showed an increasing effect regardless of the harvest age evaluated due to fertilization; this effect is expected to be greater with a uniform rain pattern. Regarding the morphological variables (leaf area and plant height), significant differences were found between the different treatments, being the treatment of 60 days of harvest and 200 kg N/ha/year the one that obtained the highest values ​​(102 cm² and 84 cm, respectively). It is concluded that the tree marigold (ecotype INTA-Quepos) is a plant with excellent potential for production in areas such as those of the present study, in addition, with a response to nitrogenous doses that improve characteristics of interest.