The Effects of NPK Fertilizer and Coconut Husk Ash as Ameliorant on Growth and Photosynthetic Rate of Oil Palm Seedlings in Peat Media

Abstract

This study aimed to investigate the effects of NPK fertilizer and coconut husk ash as an ameliorant on growth and photosynthetic levels of oil palm seedlings in peat soil growth media. A Completely Randomized Design (CRD) was used with two factors, NPK 12:12:17:2+TE including control, 30 g, 60 g, and 90 g per plant. Coconut husk ash includes control, 40 g, 80 g, and 120 g per plant. The data were statistically analyzed using ANOVA, and any observed significant difference led to Duncan's test at p<0.05. The combination of 90 g of fertilizer dose and 80 g of coconut husk ash produced the tallest plant height of 104.53 cm. The highest increase in stem girth was 6.01 cm. The photosynthetic rate was 39.11 μmol CO2 m-2 s-1, and the highest stomatal conductance was 0.21 H2O m-2 s-1. The highest internal CO2 and Water Use Efficiency was 177 μmol CO2 mol-1 and 16.15, respectively, while the best transpiration rate was 2.94 mM H2O m-2s-1. Additionally, the photosynthetic rate positively correlated with seedling height and stem diameter, with a R2 0.25 and 0.44 coefficient, respectively. Stomatal conductance was positively correlated with stem diameter, namely R2 0.04. Meanwhile, transpiration rate was negatively correlated with seedling height (R2 17%) and seedling stem diameter (R2 6.9%). Intracellular CO2 was negatively correlated with plant height but positively correlated with stem diameter. The results of this study are expected to be used in increased growth and photosynthesis.