Sulfate Boosts Ability of Plants to Handle Dry Conditions

Plants absorb the mineral sulfate from soil water. An international research team led by scientists from Heidelberg University has uncovered how sulfate controls the production of the drought stress hormone ABA in plants and thus contributes to their drought-resistance. These findings improve scientists' understanding of how the drought-stress signal travels from the roots to the leaves. The studies in Heidelberg were carried out at the Centre for Organismal Studies (COS).

Plants take in carbon dioxide for photosynthesis through pores in their leaves. When rainfall is low, however, these openings spell disaster for the plants because strong sunlight and active photosynthesis draw a lot of water through the open pores. Without fresh water from the roots, the plants wither and ultimately die. The hormone ABA [abscisic acid] controls how far the pores open in order to regulate the water loss of the plant.

Last year the researchers uncovered that the nutrient sulfate accumulates in the water transport pathways of the plants when the soil begins to dry out. Now the team led by Dr Markus Wirtz and Prof. Dr Rüdiger Hell has shown that the mineral actually known as sulfate plays a critical signalling role in supplying water to the plant. “Even we were surprised how efficiently sulfate triggers the synthesis of ABA and thus controls closure of the pores,” states Prof. Hell.

“The extremely dry European summer of 2018 was a preview of the imminent effects of global warming on the growth of plants and nutrient production,” stresses Dr Wirtz. “To be able to cultivate food crops that are more resilient during periods of water scarcity and drought, we need to understand how environmental factors regulate the formation of the hormone ABA”.

The results of the study were published in the journals “The Plant Cell” and “Plant Physiology” in late 2018.

The implications for turf could be most intriguing too and if your also add in the known effects of potassium on cell wall strengthening under dry conditions, could this explain or partially suggest an improved role for use of potassium sulfate as a summer fertiliser, or use of more complex mixes including slow release nitrogen?

Potassium sulfate is an often favoured means of supplying potassium and considered much superior to some alternate and cheaper forms, but is the real benefit the potassium or the sulfate in boosting drought resilience in many summer growing warm season turf grasses, especially in water deficit and /or hot stress conditions?  Do similar issues arise if using potassium sulfate in hydroponics in hot conditions [ it is commonly used in hydroponic cultivation] ?

It is an intriguing outcome of the research.......with no doubt more to come.

[ some material used from a press release by COS]