Influence of Manganese and pH on Chemical Composition, Bronzing of Leaves, and Yield of Carrots Grown on Acid Sphagnum Peat Soil
1970
Gupta, Umesh C. | Chipman, E. W. | MacKay, D. C.
Greenhouse experiments were conducted on the direct effects and interactions of pH and Mn on the growth and the Mn and Fe contents of carrots (Daucus Carota L., sativa D.C.) grown on an acid sphagnum peat soil. The highest content of Mn in carrot tops occurred at pH values of 4.4 to 5.0 and the lowest at pH 6.2 and 6.4. However, the Mn content was lower at pH values of 4.0 and 4.1 than at pH 4.4 to 5.0. There was a significant interaction of pH and Mn on the Mn content of tissues. At low pH, high rates of applied Mn increased the Mn content of tissue several times more than it did at high pH. Bronzecolored symptoms on carrot leaves appeared when the Mn content of tops was more than 2,600 ppm. Such symptoms were associated with lower yields of carrots, when Mn content of tops ranged from about 7,100 to 9,600 ppm. This reduction in yield was also related with low pH. The Mn content of roots varied from 133 to 236 ppm. The Fe content of tops was lower at pH 4.1 than at higher pH values.
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