Effects of switches in nutrient levels during the life cycle of spring wheat

Accumulation of cations in roots and shoots and influx of K⁺(⁸⁶Rb⁺) and Ca²⁺(⁴⁵Ca²⁺) into the roots were investigated in spring wheat (Triticum aestivum L. cv. Svenno). Plants were sampled at four main developmental stages: tillering, shooting, heading and grain filling. The effects of switches between a high and a low supply of nutrients were characterized. Growth of the shoots and roots was affected by the switches. A high supply of nutrients at the seedling stage and towards tillering supported a high growth rate, while a further high supply of nutrients increased vegetative growth and delayed grain filling. An early high supply of nutrients followed by a low supply at shooting, heading and grain filling accelerated root growth and growth of the main culm. Switches of the mineral supply gave only small changes in concentration of Mg in the plants. Generally, the K⁺(⁸⁶Rb⁺) influx into the roots decreased during ontogenesis, while Ca²⁺(⁴⁵Ca²⁺) influx increased more or less independent of the switches between nutrients levels.