BERMUDAGRASS CARBOHYDRATE-LEVELS AS INFLUENCED BY POTASSIUM FERTILIZATION AND CULTIVAR

Stored nonstructural carbohydrates are a primary source of reserve ene rgy in vegetative organs of warm-season grasses, Research is needed co ncerning the influence of potassium on carbohydrate levels in turfgras ses. Four K rates ranging from 24 to 390 kg ha(-1) per growing month w ere applied twice monthly from 1992 to 1994 to 'Tifdwarf' and 'Tifway' bermudagrasses [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt Davy] field grown on Uchee loamy sand (loamy, siliceous, thermic Aren ic Hapludult) and sand-peat (9:1 by volume) medium, Root + rhizome and shoot + stolen samples were evaluated monthly for total non-structura l carbohydrate (TNC) concentrations by means of near infrared reflecta nce spectroscopy. TNC concentrations varied among cultivars, plant par ts, and time of year. Tifdwarf produced 30% greater root + rhizome TNC concentration and 55% greater shoot + stolen concentration than Tifwa y, Higher K rates either did not influence or reduced root + rhizome T NC concentrations compared to low K rates, Correlation analysis indica ted that root + rhizome yields and TNC concentrations were negatively influenced by temperature, Carbohydrate and root + rhizome yield respo nses suggest there is no benefit to applying K at rates beyond those t hat provide sufficient K levels for normal growth.