Boron Deficiency in Oil Palm

Weng Kee Ch’ng, Regional Sales Manager, Southeast Asia, U.S. Borax

Functions and symptoms of boron deficiency in oil palm trees

Boron (B) is the most frequently deficient micronutrient in oil palm cultivation. This deficiency is intensified in regions with sandy soils and those subject to high rainfall volumes. Cultivation areas with high productivity and that are normally well supplied with adequate doses of other nutrients such as nitrogen (N), phosphorus (P), potassium (K), and magnesium (Mg), have high rates of vegetative growth. These areas also see high boron demands and will require a frequent supply of the micronutrient.

Round leaf. Image courtesy of Fabiano Silvestrin

Boron plays important roles in oil palm cultivation, including:

• Structural and metabolic processes, such as structuring cell walls, transporting carbohydrates in phloem vessels, and forming complexes with sugars

• Functions related to floral biology, such as pollen grain germination and pollen tube formation

• Fundamental biological processes that act directly on cluster productivity and consequent oil yield

Hook leaves. Image courtesy of Weng Kee Ch’ng

From a structural point of view, boron is an essential constituent of membranes and plant cell walls, acting directly in the formation of new tissues (meristems) of the aerial part and roots of the oil palm plant. In situations where severe deficiency occurs, there is complete inhibition of the development of new leaves, due to the disintegration of non-expanded leaf primordia.

Crinkle new leaf. Image courtesy of Fabiano Silvestrin

Palm plants are very sensitive to low concentrations of boron in the soil, and the onset of symptoms occurs very quickly on leaves, roots, and entire plants. Leaves with symptoms of boron deficiency show irregular expansion and malformations. Due to its low mobility in the phloem vessels of these plants, boron deficiency results in the manifestation of symptoms first in young and growing leaves, with the leaflets in the distal section being the most affected.

A more intense green often appears in symptomatic leaves that may also have a wrinkled appearance and shape— showing rigidity and eventually brittleness. Boron deficiency greatly affects reproductive growth because the synthesis of cytokinins—phytohormones that promote cell division—is repressed. The germination of pollen grains associated with poor formation of pollen tubes prevents proper fertilization and embryonic formation.

Crinkle new leaf. Image courtesy of Weng Kee Ch’ng

Boron deficiency increases auxin levels, which can induce increases in the enzyme auxin-oxidase, affecting root formation and loss of the apical domain. It can also cause supra-optimal levels of auxins, which can inhibit cell division and increase the enzyme auxin-oxidase in the formation of tertiary and quaternary roots and loss of the apical domain. This causes a reduction in the differentiation of lateral roots that do not fully develop, forming clusters of short and thick roots.

These effects on the root system can reduce palm tree uptake of water and other nutrients, which will certainly impact crop productivity. As a way of monitoring adequate levels of boron in the crop, we recommend periodic analysis of the plant tissue, accompanied by assessments of the soil’s nutrient content. In addition, frequent field checks to check for deficiency symptoms in the leaves and roots will help determine any issues with boron in oil palm.

The most commonly visible symptoms of boron deficiency in

oil palm are:

• Little leaves

• Fishbone leaves

• Hook leaves

• Crinkled pinnae

• Blind fronds

• Leaves with white stripes

• Frond shatter

Lack of boron can lead to parthenocarpic fruitlets with no kernel and poor development or with no seed resulting in small fruit. This leads to a small fresh fruit bunch (FFB) and a significant loss of yield. Lack of boron can also cause significant root growth reduction in oil palm.

White stripe leaf. Image courtesy of Weng Kee Ch’ng

Borates in the field

A study conducted in Malaysia demonstrated that the application of 100g of U.S. Borax’s Fertibor® per palm per year increased the production yield of the palms for two different age groups at two different plantations. Fertibor® helps to increase the bunch weight per fresh fruit bunch and also the number of

bunches per palm per year.

How much boron is enough for oil palm?

For seeding, we recommend doing a spray test on several seeds to find out the appropriate dosage of fertilizers before application on all plants in the nursery:

• In general, 13.6 g of U.S. Borax’s Solubor® (20.5% B) in 100 L of water is the recommended concentration for spraying

• Solubor® can also be mixed with insecticides or fungicides commonly used in nurseries

• Divide into three to four applications during periods of spraying insecticides or fungicides

• A preventative application of boron can be carried out during the fourth, eighth, and tenth months after germination

When planting, keep in mind that oil palm removes significant amounts of boron from the soil each year. Fertilizer dosage rates for immature and mature oil palm depend on the soils and yield goals:

• In general, the standard application for immature palms is 50 g per palm per year of Fertibor®, increasing to 100-200 g per palm per year up to four to six years

• Always consult your local Department of Agriculture to check the proper dosage of fertilizers

Your U.S. Borax boron fertilizer options for oil palm

• Granubor® is an ideal material for dry blends for soil application.

• Fertibor® works in direct soil applications and fertilizer mixtures.

• Solubor® allows you the most flexibility for applying boron in solution. It can be dissolved alone in water or liquid fertilizer and/or pesticides and then applied to the soil or directly onto the palms.

• Boric acid is not recommended for foliar applications.

References

• boron deficiency in the oil palm (Elaeis guineensis Jacq.) in Costa Rica. Agronomía Mesoamericana. 24(2): 441-449.

• Rajaratnam, J. 1973. “Application, Absorption, and Translocation of Boron in Oil Palm: I. Methods of Application and Types of Boron Fertilizer.” Exper Ag, 9(2), 129-139.

• Viégas IJM; Müller AA editors. 2000. A cultura do dendezeiro na Amazônia brasileira. Belém: Embrapa.

• Von Uexkull, HR; Fairhurst, TH. 1991. IPI Bulletin No. 12: Fertilizing for high yield and quality THE OIL PALM. Bern, Switzerland: International Potash Institute.