Morphological Responses and Seedling Quality of Areca Nut (Areca catechu L.) Varieties Batara and Saluang to Areca Husk-Based Liquid Organic Fertilizer in Peat Soil

This study evaluated the effects of areca husk liquid organic fertilizer (LOF) concentrations and areca nut varieties (Batara and Saluang) on seedling morphological responses in peat soil media. The experiment was conducted using a factorial completely randomized design with five LOF concentration levels (150, 300, 450, 600, and 750 mL L⁻¹) and two areca nut varieties, replicated four times. The results showed that there was no significant interaction between LOF concentration and variety on plant height and stem diameter; however, both factors independently affected these parameters. The optimum plant height and stem diameter were observed at LOF concentrations of 150–300 mL L⁻¹, while higher concentrations reduced growth performance, indicating that excessive application may reduce nutrient uptake efficiency.Significant interaction effects were observed for shoot–root ratio and seedling quality index (SQI). The highest SQI was obtained in Batara seedlings at 150 mL L⁻¹, while Saluang showed the highest shoot–root ratio at 300 mL L⁻¹. All treatments produced SQI values above 0.09 (3.33–4.49), indicating that all seedlings were suitable for field transplantation.Plant dry weight was highest at 150–300 mL L⁻¹, with Batara showing slightly higher biomass than Saluang. The improvement in growth performance was attributed to better nutrient availability and uptake efficiency at moderate LOF concentrations. The integration of LOF with half-dose NPK fertilizer reduced inorganic fertilizer use by 50% while maintaining seedling quality.The beneficial effects of LOF were associated with its nutrient content as well as plant growth regulators such as auxin (52.20 ppm), cytokinin (18.31 ppm), and vitamin B1 derived from rice washing water. These components enhanced root development, shoot growth, and stress tolerance. Additionally, microbial activity in LOF contributed to organic matter decomposition and improved nutrient availability in peat soil. Overall, LOF derived from areca husk combined with reduced NPK fertilizer application can improve seedling growth and quality while reducing dependence on chemical fertilizers.