INFLUENCE OF NITROGEN SUPPLY ON WATER-CONSUMPTION AND DRY-MATTER PRODUCTION OF SUGAR-BEET IN POT EXPERIMENTS

This paper describes the influence of nitrogen on water consumption, dry matter production and water use efficiency (WUE) of sugar beet. The experiments, conducted in 1988 and 1989 using sand culture in pots, included five nitrogen levels from 2 to 16 g/pot. Beet roots were heaviest where the N-supply was 8 g/pot. Top weight increased considerably up to 16 g N/pot. Therefore plant dry weight was greatest where the N-supply was maximum. Overall, in 1989 dry matter production (g/pot) was 20 % greater than in 1988 because the beet roots were heavier. Water consumption increased with nitrogen supply. At the largest N-doses water consumption was 1101 (1988) and 1401 (1989). This was three times the amount used at the smallest N-supply. Over the whole season WUE was greatest at 4 g N/pot and lower at both extremes of N-supply. Independently of N-supply, production of plant dry matter per litre of water consumed was between 4.9 and 6.0 g. For root dry matter, equivalent values were 3.7 and 4.6 g/l, and for white sugar yield they were 2.3 and 3.1 g/l.