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During the period 19887-2001, research was carried out into the influence of monoculture and five crop rotations on the yield and quality of flue-cured tobacco. The field trial was set up on the experimental field of the Tobacco Institute Zagreb on luvic semigley soil. Like in tobacco monoculture, tobacco planting folowed after winter wheat (2-crop rotation, 3-crop rotation, 4-crop rotation and 6-crop rotation) and rape (5-crop rotation). Tobacco was planted every year (monoculture), every second (winter wheat and tobacco), every third (maize, winter wheat and tobacco), every forth (maize, soybean, winter wheat and tobacco), every fifth (maize, soybean, winter wheat, rape and tobacco) and every sixth year (red clover, red clover, maize, soybean, winter wheat, rape and tobacco). All crops were repeated four times. A significantly lower yield was obtained after the fourth year of tobacco monoculture compared to tobacco growing in crop rotation. Tobacco grown in crop rotation had higher percent of better quality clesses and a better chemical composition. After fifteen years of continual monoculture, infection with TMV amounted to 27.8 % while it was 3.8 % in the six crop rotation. Tobacco production in monoculture reduced its yield from 2.63 t/ha in the first year (1987) to 1.39 t/ha in the fifteenth year (2001). Tobacco planted in wider rotation was significantly less infected with TMV, had a higher yield and quality. |
