ISHS Acta Horticulturae 379: International Symposium on Quality of Fruit and Vegetables: Influence of Pre- and Post- Harvest Factors and Technology
BETANINE AND NITRATE CONTENTS IN TABLE BEET CULTIVARS AS A FUNCTION OF GROWTH PERIOD AND MANNER OF NITROGEN FERTILIZATION |
| Authors: | B. Michalik, D. Grzebelus |
| Abstract:
The objective of the research was to determine how the length of vegetation period and intensity of nitrogen fertilization influence chemical composition of beet roots. In the first field trial plants were harvested after 100, 120 and 140 days of vegetation. In the second trial, plants were supplied with nitrogen by three different dressing manners. All cultivars exhibited the same reaction to extending the vegetation period from 100 up to 140 days: less betanine (ca. 99 to 84 mg/100 ml of sap), more nitrates (ca. 2200 to 2660 mg KNO3/kg fresh weight) and decreased dry matter contents (on average from 15.1% to 14.6%). The roots of cultivar Okragly Ciemnoczerwony attained the highest nutritional value: 98 mg of betanine in 100 ml of sap, the lowest amount of nitrates (1740 mg KNO3/kg fresh weight), 16% of dry matter and over 9% of sugars. Top-dressing with ammonium nitrate caused a high rise in the nitrate contents of the roots. When the fertilizer was applied prior to sowing, nitrate contents averaged 1660 mg KNO3/kg fresh weight, in the case of top-dressing to reach 60 or 90 mg N-NO3/1 of soil, nitrate contents increased to 2460 and 3330 mg KNO3/kg fresh weight, respectively. Medium dose of ammonium nitrate used as top-dressing brought about the highest betanine contents, which fell to medium when no top-dressing was applied and to low when a higher nitrogen rate was used as top-dressing (82, 70 and 63 mg/100 ml of sap, respectively). The cultivars reacted differently to top-dressing with nitrogen compounds. | |
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