Free space uptake and influx of Ni2+ in excised barley roots

The effects of switches between high and low nutrient supplies on growth and mineral nutrition of winter wheat ( Triticum aestivum L. cv. Martonvásári-8) were followed in four main developmental phases: tillering, shooting, heading and grain filling. Growth of the shoots was significantly affected by switches. Under low nutrient supply the life cycle was shortened. Root growth was only slightly affected by switches, but an early high nutrient supply followed by low nutrient supply gave an impetus for root development. In general, the growth data indicate that the nutrient status of the plants is determined by the nutrient level supplied during shooting. A high level of nutrients during shooting leads also to high vegetative growth, whereas the best grain yield was obtained by a high dose of nutrients during tillering followed by low nutrient conditions during the shooting stage and later. K⁺(⁸⁶Rb) influx in the roots decreased with age. The potential for K⁺ (⁸⁶Rb) influx was low in plants of high-salt status, but it became high in response to switching to low supply at shooting, whereas later switches had no influence on this function in high-salt plants. The highest K⁺(⁸⁶Rb) influx was found in plants starting with high nutrient supply followed by low-salt conditions; this plant group was outstanding also with respect to its high grain yield.