Influence of top removing on root quality, studied on sugarbeets [Beta vulgaris] cultivated in a field used for long in succession cropping of sugarbeet.
1989
Imura E. | Hayasaka M.
Using a field in Higashimokoto, Hokkaido, being in the tenth year of successive sugar beet cropping, trials were started setting continuous top-removing plots and control plots in 1984 and through 1986. In top-removing plots, tops were removed from fields, while in the control plots, tops were ploughed into land in a usual manner. Effects of top-removing were surveyed through analysis of various factors. The results obtained are as follows: 1) Nitrogen absorbed by tops in the top-removing plots declined sharply from 193kg/ha for 1985 to 176kg/ha for 1986, while in the control plots, the nitrogen content was almost stable. 2) The sugar content of roots in the top-removing plots in 1986, i.e. after two top-removing years, was as high as 16.27% as compared with 15.77% for the controlled. 3) the figures surveyed for the trial plots were compared with those for the control plots by computing the yearly average for the trial plots in percent of the yearly average for the control plots. By top-removing, the root yield declined 3.9% in 1985 and 3.8% in 1986, both from the control pest. On the other hand, sugar content in the top-removing plots increased 8.0% in 1985 and 9.1% in 1986. Accordingly, the sugar yield in the top-removing plots increased over the control plots by 3.4% and 4.3% in 1985 and 1986, respectively. In the top-removing plots, the quality of root was improved, sugar content increased over the control plots while content of both K and Na declined.
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