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All Journal Journal of Tropical Crop Science
Supijatno Supijatno
Department of Agronomy and Horticulture, Faculty of Agriculture, IPB University, Indonesia
Agriculture, Biological Sciences & Forestry

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The Identification of Potential Stress in Oil Palm Using Sentinel-2A Satellite Imagery Approach and Laboratory Tests Bagus Arfanda; Sudradjat Sudradjat; Supijatno Supijatno; Harry Imantho
Journal of Tropical Crop Science Vol. 13 No. 02 (2026): Journal of Tropical Crop Science
Publisher : Department of Agronomy and Horticulture, IPB University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29244/jtcs.13.02.430-444

Abstract

Oil palm (Elaeis guineensis Jacq.) is a valuable source of vegetable oil for various industries, such as food and cosmetics. Global climate change, driven by global warming, has the potential to shift climate conditions and trigger extreme events, such as prolonged droughts. Extreme climate phenomena will impact plant conditions, causing plants to become stressed. A study was conducted from June 3 to October 31, 2023, at the Oil Palm Education and Research Plantation of IPB University in Jonggol, Bogor, West Java. The study aimed to determine the Palm Oil Stress Index (POSI) to identify stress in oil palm plants. The identification process included analyzing Sentinel-2A satellite images, testing soil water availability, and measuring leaf proline content. The study utilized the Leaf Water Content Index (LWCI) and Enhanced Vegetation Index (EVI) values as models to determine the POSI from the satellite images. Furthermore, soil physics analysis and proline values from the 17th leaf sample were used to assess the plants’ water availability and stress levels. The satellite images showed signs of potential stress in October; observation blocks in October had a pF value of 4.2 between 14.93%-16.77% compared to the water content, which ranged from 13.79%-15.09% supported by decreased soil water levels and increased proline accumulation occurred in October a value of 0.0382-0.0391 mg/g, compared to June, which is 0.0143-0.0159 mg/g. All areas were healthy from June to August; however, potential stress, as indicated by POSI values, their formulation, and color changes, was present in September and October.
Optimizing Potassium Fertilization for Precision Nutrition: Effects on Growth, Physiology, and Seed Potassium Content of Two Soybean Varieties Ratu Fatkhunnisa; Supijatno Supijatno; Edi Santosa
Journal of Tropical Crop Science Vol. 13 No. 02 (2026): Journal of Tropical Crop Science
Publisher : Department of Agronomy and Horticulture, IPB University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29244/jtcs.13.02.335-349

Abstract

Potassium is an essential macronutrient that supports major physiological processes in plants and strongly influences soybean productivity. This study aimed to evaluate the effects of different potassium fertilization levels on plant physiology, yield performance, and seed nutritional composition in two soybean varieties, ‘Dena 1’ and ‘Denasa 1’.The research employed a factorial completely randomized group design with five potassium fertilizer levels (0, 15, 30, 45, and 60 kg K2O/ha) and two soybean varieties (‘Dena 1’ and ‘Denasa 1’), with three replications. The results showed that the potassium dose significantly affected plant height and leaf number but did not influence photosynthetic rate or stomatal conductance. The ‘Dena 1’ variety exhibited better growth, greater leaf greenness, and faster generative development than ‘Denasa 1’. The optimal potassium dose of 45 kg/ha improved yield components, resulting in a 30.7% increase in seed weight and a 45.8% increase in the number of filled pods compared with the control. A positive correlation was found between plant potassium content and key physiological traits, such as photosynthesis and transpiration rates. Seed nutrition analysis showed that soybean varieties significantly influenced nitrogen and phosphorus levels at the R7 and R8 stages, whereas the potassium fertilization dose had no significant effect on seed nutrient concentrations. Nutrient levels increased from R6 to R7 before declining at R8, reflecting nutrient redistribution during seed filling. Overall, the results suggest that applying 45 kg K2 O/ha is an effective fertilization rate for enhancing soybean physiological performance and yield, while varietal characteristics remain the primary factor shaping seed nutritional composition.
Co-Authors Bagus Arfanda Edi Santosa Harry Imantho Ratu Fatkhunnisa Sudradjat Sudradjat