Maximizing cocoa (Theobroma cacao L.) seedling growth through liquid coconut shell smoke in Ultisols soil

The crucial aspect of cocoa cultivation is ensuring the availability of seedlings with robust growth. Ultisols, a type of soil with potential for cocoa plant propagation, necessitate materials to enhance fertility when used as a growing medium. This includes the application of liquid smoke derived from coconut shells. To further study on this aspect this research aimed to determine the role of liquid coconut shell smoke on the growth of cocoa seedlings in Ultisols soil. The research was conducted in the laboratory and greenhouse of the Faculty of Agriculture, Panca Bhakti University, Pontianak, for 90 days from July to October 2023. The research used a complete randomized block design (CRBD) with four replications. The treatment concentrations of liquid coconut shell smoke (%) consisted of six levels: 0.00, 0.25, 0.50, 0.75, 1.00, and 1.25%. Each replication consisted of three cocoa plant seedling samples, resulting in a total of 72 plants for the entire research unit. The observed parameters included plant height increase (cm), the increase in the number of leaves (leaves), and the increase in stem diameter (mm). The research results found a very significant influence on all observed parameters. The treatment of liquid coconut shell smoke at a concentration of 0.75% yielded the highest results in terms of seedling height increase (29.09 cm), the number of leaves (14.08 leaves), and stem diameter (9.87 mm) compared to the control. This research finding shows that a concentration of 0.75% liquid coconut shell smoke can maximize the growth of cocoa seedlings in Ultisols soil through soil fertility improvement.