Einfluß der P-Aufnahme und P-Remobilisierung in der Kornfüllungsperiode auf den Ertrag von Sommerweizen

Influence of P-uptake and P-remobilization during the grain-filling period on the yield of spring wheat Experiments were performed with spring wheat in hydroponics using labelling with ³³P and ³²P to investigate the influence of high (0,5 mM) or low (0,05 mM) P-concentration in the solution on the distribution and remobilization of the nutrient as well as on crop yield. With low P-supply the yield was reduced, not only due to a considerable decrease of tillers but also in consequence of lowering the thousand grain weight and the number of grains even in apparently still fully developed ears, as well as significantly depressing the P-concentration in the grain. Flowering and maturity commenced much earlier than in the case of plants supplied with a relatively high level of phosphorus. When the P-concentration in the medium was only dropped from a high to low level after the end of flowering, the yield of the plants, which had a comparable number of tillers to the control, was slightly but significantly reduced, too. In spite of an enormous enhancement of the retranslocation of P deposited in the plant before flowering the P-concentration of the grain was also deminished. The experiments have shown that the intensified P-retranslocation during the grain-filling period and a still continuing P-uptake and translocation into the leaves and particularly the grain proceeded simultaneously under the experimental conditions. Besides, the effective P-retranslocation based on the labelling was substantially greater than indicated by the net P-retranslocation. The possible function of phosphate during the storage phase of cereals is discussed.