The Strategy of the Wheat Plant in the Production of Grains at Reduced Nitrogen Availability

Abstract

The wheat plant somehow sense and adapt its production of grains to prevailing nutrient conditions. The mechanisms of this acclimation process to limiting nutrient availability is however poorly investigated. To be able to distinguish between broad environmentally imposed responses and fine-tuned genetically derived responses we need to culture plants under fully defined and reproducible conditions. Culturing in soil gives only marginal control of the flow of nutrients to the root surface and the amounts of nutrients available for the plant. Culturing in hydroponics with external concen- tration of nutrients as driving variable is as inadequate as soil culturing in this respect. Unless the external concentration of nutrients is kept constant, extremely low and under full control, there are only two options in concentration controlled cultures; optimal supply or acute deficiency. Neither conditions are relevant in mimicking field culturing of cereals where there is a more or less continuous but usually growth limiting flow of nutrients to the root surface. Growth and grain production is then acclimated to the changes in nutrient availability that occurs over the season.