Growth Monitoring of Healthy and BSR-Infected Oil Palm Seedlings Using Ground-based LiDAR

The most threatening disease to the oil palm is Basal Stem Rot (BSR) disease caused by Ganoderma boninense. Besides matured oil palm trees, palm seedlings are susceptible to BSR disease. Therefore, it is crucial to detect the symptoms of the disease at an early stage so that the infected plants can be treated immediately. This study focuses on growth monitoring to differentiate between the infected (INF) seedlings and non-infected (NONF) seedlings by using ground-based LiDAR. This study used one hundred INF seedlings and 20 NONF seedlings, where the NONF seedlings acted as a control. The parameters measured using LiDAR were the height, stem diameter, and point density of the seedlings, which were measured four times every two-week intervals. The results showed significant differences in mean height and mean stem diameter between INF and NONF seedlings. Results from the LiDAR measurements were consistent with the manual measurements, with more than 86% correlations. In temporal measurements, the mean stem diameter for NONF seedlings consistently increased over the six weeks, while for INF seedlings, it was inconsistent throughout the time. Furthermore, in the last three measurements, the mean point density of NONF seedlings was higher than that of INF seedlings, which indicated better growth of non-infected seedlings than infected seedlings.