Autumn growth and development of different winter oilseed rape variety types at three input levels

The autumn growth and development was studied in three types of winter oilseed rape varieties (line, hybrid and genetically modified hybrid) at three technologies (intensity, standard and low input). Technologies were different by soil preparation before sowing, sowing rate, chemical treatment levels, growth regulation and fertilisation. It is evident from the autumn period 1999-2002, that the yield of biomass and roots in the autumn period was influenced by the technology and year conditions (water soil condition). The occurrence of surface soil clods influenced negatively the creation of root and aboveground biomass irrespective of the soil cultivation (ploughing or cultivation without ploughing). Also the excessive soil moisture negatively influenced the root and aboveground biomass and increased the differences among variants. The low input variant was substantially worse than intensity and standard. The dry mass of aboveground and root biomass was statistically different (alfa = 0.05) in the intensive and standard variant in comparison with the variant without ploughing (low input). No statistically significant differences were found in the mass of aboveground and root biomass (alfa = 0.05). The percentage of dry mass in aboveground and root biomass was statistically significantly higher (alfa = 0.05) in intensity of growth regulator application tebuconazole (Horizon 250EW) + chlormequat-chloride (Retacel Extra R68) compared with standard and low input. The diameter of root neck, length of roots and number of leaves was statistically the highest (alfa = 0.05) in the intensive variant. Statistically the values differed from the standard and low input variants. Substantially lower differences were found in the varieties in the same characters. GM hybrid showed a lower heterosis effect and the studied characters did not reach the level of unmodified hybrid level.