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Sucrose accumulation and osmotic potentials in sugar beet at increasing levels of potassium nutrition
Author(s) -
Beringer Helmut,
Koch Klaus,
Lindhauer Meinolf G.
Publication year - 1986
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740370303
Subject(s) - sucrose , potassium , sugar beet , chemistry , sugar , zoology , horticulture , botany , food science , biology , organic chemistry
In a pot experiment sugar beet Beta vulgaris L. ssp. vulgaris , cv. Kawetina, was grown on alluvial soil (21 mg exchangeable K 100 g −1 ) containing 0 (K 1 ), 20 (K 2 ), 40 (K 3 ) and 60mg fertiliser K 100 g −1 soil (K 4 ). The plants were sown on 15 March 1983 and harvested on 23 June, 14 July and 30 August 1983. At final harvest root dry weight/plant had reached 269 g in K 1 and between 304 and 310 g in K 2 ‐K 4 . Sucrose values were 15% (K 1 ) and 17.3–17.7% of root fresh weight (K 2 ‐K 4 ) respectively. The osmotic potential of the storage root decreased with increasing K nutrition and time. At final harvest ψ, was between −1.83 (K 1 ) and −2.26 MPa (K 4 ), 75–79% thereof being contributed by sucrose. Sucrose concentrations in press sap increased from 340–400 mM on 23 June to 475 (K 1 ) and 540–570 mM (K 2 ‐K 4 ) at the end of August. In the same period K concentrations declined from 40–100 to 10–35 mM K + . The sucrose, K and Mg concentrations measured in the press sap were lower than those calculated from sucrose, K, Mg and moisture content of the storage root. This indicates that press sap from thawed storage root tissue is not fully representative. Betaine, analysed only at final harvest, significantly increased with increasing K concentrations in the storage root ( r =0.83) and a significant linear regression was found between betaine and sucrose accumulation ( r =0.57). This is consistent with the role of betaine as a cytosolic osmoticum for sugar beet storage tissue. Other solutes in the cytosol may also contribute to osmoregulation as sucrose accumulates in the vacuoles.