ROOT-GROWTH OF SUGAR-BEET UNDER SPECIAL C ONSIDERATION OF WATER RELATIONS

In 1992 and 1993 nearby Gottingen field trials were conducted to exami ne root growth and water relations of sugar beet. In both years the ro ot density was much higher in top soil (0-30 cm) than in deep soil. In 1993 the root density reached a higher level than in 1992. The maxima l root depth exceeded in both years 2 m. The total root length in 1992 was 10.2 km/m2 and in 1993 15 km/m2. Few precipitation in 1992 led in opposite of 1993 to continuous use of soil water supply up to 150 cm. The water uptake rate decreased during the growing season and especia lly in 1992 was higher in deep soil than in top soil. The coefficient of evapotranspiration has been calculated as about 220 1 H2O/kg dry ma tter. Basing on these field trials, the growth of sugar beet is charac terised by a high total dry matter combined with a low total root leng th, a low coefficient of evapotranspiration and a high water uptake ra te of roots.