Potassium nutrition in oil palm: The potential of metabolomics as a tool for precision agriculture

Abstract

Oil palm (Elaeis guineensis Jacq.) is the major oil-producing crop in the world, with a global annual production of about 75 Mt (FAO 2018). Low potassium (K) availability is a major concern on tropical soils where oil palm is cultivated since they are often naturally poor in exchangeable cations such as K + (Ollagnier & Ochs, 1973). In addition, oil palm growth is highly K-demanding. In effect, optimal leaflet K elemental content is quite high (≈1%) while N is about 3% (Foster, 2003; Ochs, 1965; Ollagnier et al., 1987) although there are some variations with seasons, locations and oil palm crosses (Foster & Chang, 1977; Ollagnier & Ochs, 1981). Also, fruit bunch harvesting removes substantial amounts of K from oil palm agrosystems. For example, typical fruit harvesting of 30 tons FFB (fresh fruit bunches) ha −1 y −1 represents a loss of up to 160 kg K/ha y −1 , that is, 75% of K fertilization input (reviewed in (Corley & Tinker, 2016)). Oil palm plantations are thus heavily fertilized with K (typically using potassium chloride, KCl) up to 200 kg K/ha y −1 , leading to an annual cost of about $1 billion at the global scale. However, the efficacy of applied K depends on leaching, the efficiency of K absorption by roots (including the antagonism between K and other cations, mostly Ca and Mg), K allocation within the tree and the response of yield to K availability in the variety (cross) of interest (Goh et al., 2003). Quite understandably, intense efforts have been devoted for decades to improve fertilization strategies and monitor K requirement accurately.

Plant low‐K responses are partly due to Ca prevalence and the low‐K biomarker putrescine does not protect from Ca side effects but acts as a metabolic regulator

“…Putrescine addition is costly (≈$1 g −1 ) and does not suppress the strong effect of low K on respiratory efflux (Figure 2). Therefore, monitoring plant K status using new technologies such as metabolomics (Cui, Chao de la Barca, Lamade, & Tcherkez, 2021), and sustainable K fertilization might be better options to ensure optimal K nutrition for crops in the field.…”

Plant low-K responses are partly due to Ca and the low-K biomarker putrescine does not protect from Ca side effects but acts as a metabolic regulator

“…2). Therefore, monitoring plant K status using new technologies such as metabolomics (Cui et al , 2021), and sustainable K fertilization might be better options to ensure optimal K nutrition for crops in the field.…”