Abstract
For floret development and final grain number ear elongation in wheat (10–17d before anthesis) is the most sensitive period to adverse growth conditions. Sugars are supposedly the main factor determining floret numbers and grain set, and play next to potassium a significant role in establishing turgor pressure in young tissues. In view of this osmotic function, the influence of K on the concentration of water soluble carbohydrates (WSC, total of sucrose and reducing sugars), Ca and Mg was investigated in pot experiments. Further, the osmotic potential of sap extracted from young ears was determined and compared to sap extracted from the leaf blade. Plants supplied with low amounts of K (moderate K-deficiency) had a considerably lower K concentration in the press sap of the flag leaf and the ear than plants well supplied with K. Concentrations of WSC, Ca and Mg were higher in press sap of the flag leaf in K deficient plants than in plants adequately supplied with K. This indicates a substitution of K in its osmotic role. In press sap from ears, however, WSC, Ca and Mg were not influenced by the K application. Therefore, substances other than those measured must have been responsible for the osmoregulation in the young ear. WSC and the osmotic potential increased (more negative) independently on K supply during ear elongation, while K, Ca and Mg concentrations decreased. Whereas grain number was not influenced by the treatment, single grain weight at maturity was reduced by low K availability in the soil.
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Krumm, M., Moazami, V. & Martin, P. Influence of potassium nutrition on concentrations of water soluble carbohydrates, potassium, calcium, and magnesium and the osmotic potential in sap extracted from wheat (Triticum aestivum) ears during preanthesis development. Plant Soil 124, 281–285 (1990). https://doi.org/10.1007/BF00009273
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DOI: https://doi.org/10.1007/BF00009273