Recent Advances in Understanding the Role of Potassium and Magnesium in Mitigating Abiotic Stress in Crops

Keywords: yield security, drought stress, cold stress, yield potential, potassium and magnesium fertilisation

The subject of this paper was expertly covered in a former IFS conference (Cakmak, 2007). However, since this time, not only has agriculture faced an increasingly challenging period of climatic extremes, but several new areas of interest have been discovered about novel mechanisms of potassium (K) and magnesium (Mg) and their effects in plants’ resistance to abiotic stress. For example, the function of K in water management within crops has long been known but recent German research suggests K also has a specific physic-chemical effect on the water-holding capacity of some soils and that K concentration of soils appears to affect the shear strength. Here, we summarise some of the recent advances made in this increasingly interesting subject.

Changing environmental conditions are a major challenge for agricultural crop production in the future. At least in Central Europe, recent years were characterised by severe winters damaging over-wintered crops and a precipitation pattern which frequently did not fulfil crop demand, e.g. hot and dry spells coinciding with periods of high crop growth rates.

Indeed, drought represents the most important abiotic stress factor limiting crop growth on a global scale. It is expected that climatic changes will cause more intense drought conditions, especially in combination with heat and high radiation stress. Recent FAO estimations indicate that water is, and will be one of the most important limiting resources in agricultural production.

In addition to drought stress, frost was another challenge European farmers had to cope with, particularly in recent years. One such example was in parts of Eastern Germany in 2011 where some 70% of winter crops were irreversibly damaged by extreme low temperatures which resulted in costly re-drilling of spring sown crops and a subsequent major shortage of spring seed.

In order to meet the increasing world food demand under increasingly adverse production conditions, a range of novel agronomic strategies are required to improve crop tolerance to various stresses and also to increase the efficiency by which resources such as nitrogen and water are utilised. Among the agronomic factors contributing to improved yields, efficient nutrient management practice (e.g. fertilisation), both through direct growth responses but also in its effect on mitigating abiotic stresses, plays a substantial role. Recent results show that the essential nutrients Mg and K have an increasingly wide range of complex functions in alleviating abiotic stress by influencing important metabolic processes. This paper will focus on the roles of Mg and K in plant growth and yield by paying special attention to their contribution to stress tolerance and resource use efficiency of crop plants.

Andreas Gransee, Hans-Peter König and Hendrik Führs, K+S KALI GmbH, Bertha-von-Suttner-Str. 7, 34131 Kassel, Germany, and

Jerry McHoul, K+S UK & Eire Ltd, Unit 13 Watermark Way, Foxholes Business Park, Hertford, SG13 7TZ, United Kingdom.

24 pages, 12 figures, 8 plates, 47 references.