Einfluß von konstantem und abnehmendem Nährstoffangebot auf Aufnahme und Verteilung von K,Ca und Mg bei Sonnenblumen

Influence on the uptake of K, Ca and Mg in sunflowers with a constant and a diminishing supply of nutrients. . In a model-test with sunflowers it was investigated how the K-, Ca- and Mg-content in the plants is reacting when (a) a nutrient solution maintained constantly at the same level is given as in a ?good soil”? with a constant supply of nutrients, compared to (b) a solution with diminishing as in a highly fertilized soil but which hardly supplies nutrients itself. It was shown that, if the offer of the nutrient was constant, the cation content in the leaves could be maintained at the same level (the relation of cations is also maintained at the same time). Contrary to this with a diminishing nutrient solution due to removal of nutrients out of the solution without replenishing nutrients and the differentiated nutrient translocation the result was a lesser and lesser content of the nutrients inside the plant and more evident changes in the relation of cations, even before the insufficient supply was noted in a decreasing crop. Only in the leaves the relation of cations was nearly constant (K:Ca:Mg = 6:3:1). From these results it can be concluded that, through a high single supply of nutrients the effect of a constant flow of nutrients from the soil to the plant concerning the mineral contents of the plant cannot be compensated.