Basal stem rot caused by Ganoderma boninense is the main disease of oil palm plantations. The disease decreases yield, causes plant death, shortens economic life, and accelerates replanting. The purpose of this study is to compare the development of this disease in third-generation oil palm plantations in peat soil and mineral soils. Observations were made to verify secondary census data for 4 years on affected (endemic) rotten stems. Observations were made on each of the 3 blocks for peat soil and mineral soil with palm oil planting year 2011-2012. The results showed that stem base rot develops faster with a higher severity in peat soil than yellow-red podsolic soil. The availability of organic matter in both soil and oil palm plant residues becomes an important source of nutrients for pathogenic fungi in completing the cycle of disease in plantations.

Oil palm plantations in Indonesia are cultivated on various types of land, ranging from very suitable to unsuitable types. This cultivation method is increasingly vulnerable to drought caused by climate change. Climate change due to global warming negatively affects the management of oil palm plantations in the long term. The upper-temperature limit for efficient photosynthesis in oil palm leaves is >38 °C. The increase in temperature (2°C above the optimum) and rainfall by 10% is projected to cause a yield decline of up to 30%. The water shortage is also a major limiting factor for palm oil production. Such vulnerability is predicted to worsen, and thus its negative effects should be explored. The purpose of this study is to reveal the role of organic matter applied as empty bunches (EFB) and the management of Nephrolepis bisserata vegetation in reducing the adverse effects of rainfall on palm oil production on sandy soils. The survey method and observations were carried out for over 3 years on plants aged 14-16 years on blocks. Empty fruit bunches (EFB) of 40 tons/ha/year was applied to each block, and Nephrolepis biserrata was used as ground cover which planted in path. The parameters observed included the number and average weight of fresh fruit bunches (FFB). The relationship between fluctuations in the conditions of monthly rainfall intensity on oil palm production was determined through regression analysis. Rainfall strongly influenced the number of FFB, whereas the average weight of FFB remained relatively constant. The application of EFB and management of Nephrolepis biserrata vegetation facilitates the reduction of drought impacts and increase in oil palm production (15%) as shown in bunch weight and bunch number. EFB and Nephrolepis biserrata vegetation can increase soil organic matter content and improve soil water holding capacity.

Jika faktor genetik, tanah dan teknik budidaya bukan merupakan faktor pembatas, maka fluktuasi hasil panen dipengaruhi oleh faktor iklim atau lingkungan. Penelitian ini bertujuan untuk mengetahui pengaruh ketersediaan air (defisit air, curah hujan dan hari hujan) terhadap sex ratio termasuk model hasil panen kelapa sawit. Penelitian telah dilakukan pada bulan November 2016 hingga Oktober 2017 di wilayah Wilmar International Plantation Kalimantan Tengah. Analisis menggunakan regresi berganda dan uji korelasi termasuk uji asumsi klasik (uji normalitas, multikolinieritas dan heteroskedastisitas) untuk analisis statistik dalam penelitian ini. Hasil penelitian menunjukkan bahwa curah hujan dan hari hujan berpengaruh nyata terhadap perkembangan sex ratio selama 23 bulan sebelum panen (MBH), saat defisit air berpengaruh nyata terhadap sex ratio pada 24 MBH. Estimasi distribusi produksi bulanan, anggaran produksi dan produksi aktual menunjukkan bahwa tidak signifikan. Estimasi distribusi produksi bulanan, anggaran produksi dan realisasi produksi menunjukkan bahwa tidak signifikan, dapat digunakan keakuratan distribusi produksi bulanan kelapa sawit. Kata kunci: sex ratio, curah hujan, hari hujan, defisit hujan, bunga betina

The same rainfall can cause different degrees of water stress depending on soil type, so the production response shown by plants can be different. This study is essential for growers, especially in predicting oil palm production based on water deficit for each soil type. The study was conducted on oil palm plantations in Central Kalimantan, Indonesia, with four soil types in 1,446.15 ha (40 blocks). The source of data collected from oil palm plantations included bunch number, average bunch weight, rainfall, and soil physical and chemical properties for the last 15 years (2007 - 2021). This experimental study used a two-stage cluster sampling method. The results showed that the best productivity, bunch number, and average bunch weight were found on Ultisols. The four soil types tested showed the same annual production distribution dynamic, but the response rate from each soil type showed differences. Entisols and Spodosols were more prone to drought stress due to water deficit than Ultisols and Histosols because of the differences in soil texture. Water deficit causes a decrease in oil palm productivity by 5 - 22% in the first year (Ultisols 12 - 22%; Entisols 12 - 22%; Spodosols 7 - 19%;  Histosols 5 - 15%) and 1 - 8% in the second year (Ultisols 3 - 7%; Entisols 2 - 4%; Spodosols 5 - 8%; Histosols 1 - 5%) compared to previous years production. A decrease in oil palm productivity occurs at 3 - 5 months (bunch failure phase), 1 year (abortion sensitive phase), and 2 - 2.5 years (sex differentiation phase) after a water deficit appears.

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