Biomarkers monitor potassium use in oil palms
Palm oil is one of the world’s most widely used edible vegetable oils and comes from the African oil palm(opens in new window). Its main uses are for food manufacturing, cosmetics and as a feedstock for biodiesel production. However, the clearing of tropical rainforest in countries such as Indonesia and Malaysia for oil palm plantations has resulted in significant ecological impacts. Therefore, the greatest challenge facing oil palm cultivation is to meet global food demands while respecting the environment. To achieve this goal, it is crucial to ensure the efficient use of fertilisers, in particular potassium. Oil palm requires high levels of potassium both for fruit production and because it is typically grown in naturally potassium deficient regions. In most plantations, potassium in the form of muriate of potash(opens in new window) is applied uniformly and often exceeds the needs of the tree. This leads to considerable losses to the environment, adversely impacting other agricultural systems and nearby water tables, and potentially causing hypocalcaemia(opens in new window) in cattle and humans.
Reading the leaves
The EU-funded iPALMS project supported by the Marie Skłodowska-Curie Actions programme(opens in new window) used metabolomics to investigate the link between potassium conditions and oil palm metabolic efficiency. The aim was to identify metabolites as biomarkers for the efficient application of fertiliser and reduce input costs and negative ecological impacts. “Monitoring potassium levels based on soil alone is difficult because soil properties vary and can affect the nutrient's availability to the plant. Furthermore, the correct application rate of potassium is complicated by many variables. These include the specific type of oil palm being grown and the interaction with other nutrients,” says project coordinator Emmanuelle Lamade from the French Agricultural Research Centre for International Development(opens in new window). To help fine-tune potassium fertilisation during cultivation, researchers studied leaf biomarkers in addition to leaves minerals, which indicate changes in metabolic activity. “By analysing the metabolic compounds within the plant's leaves, we were able to identify the unique signatures that indicate a potassium deficiency or potassium excess,” Lamade explains.
Increasing sustainability
Researchers exploited the use of ‘omics’(opens in new window) to identify biomarkers, especially metabolites capable of identifying more accurately the oil palms’ nutritional status. The intention is to create a ‘toolbox’ for a wide range of users, from small farmers to plantation managers, capable of testing mineral and metabolic indicators directly in the field. According to Lamade: “Through a series of easy-to-apply tests, farmers will know precisely the level of nutrition deficiency of their palm trees. They will also learn what they must do to overcome this deficiency, or alternatively what is in excess”. “The next step is to use fresh sap instead of leaf samples in dry powder form. The development of a website and an application derived directly from the iPALMS results will also be created, helping farmers diagnose the overall nutrient palm status of their trees,” adds Lamade. “By combining use of omics for monitoring potassium input with other sustainable cropping practices like reducing pesticide use through biological control we can lower the environmental impacts of oil palms. This approach can also be applied to European oil crops such as sunflowers, rapeseeds and castor beans,” Lamade concludes.
