Investigations into factors influencing growth and yield of oilseed rape in North-East Scotland
Detailed field and container experiments over 3 years were conducted in North-east Scotland to study factors influencing plant growth and yield in autumn-sown oilseed rape in an attempt to find ways of minimising the adverse effects of late sowing on autumn growth, plant survival and yield. Both seed selection on the basis of vigour and a new commercial chemical seed treatment did not seem to improve field emergence of seedling growth in autumn. A new phenomenon, termed one-leaf disorder, which appeared in plants in the autumn was found to reduce overwintering ability, plant vigour and seed yield. The disorder was associated with certain genotypes, being prevalent in Bienvenu and a number of breeding lines under test. Evidence indicated that the disorder was not caused by seed production or chemical seed treatments but was possibly associated with low temperatures after sowing. The application of a new triazole plant growth regulator in spring reduced height, increased branch number and on some occasions increased yield. The possibility that lack of assimilates to fill increased seed numbers was the reason for inconsistent yield effects, was examined. Delayed sowing reduced total height, especially vegetative height (ground to lowermost branch), branching, pod number and final yield. Both autumn fungicides and increased sowing rates were investigated as possible ways of improving the growth and yield of late sown crops. Using container grown plants, the new triazole growth regulator was used in spring to try and increase the branching of late sown plants. None of these approaches seemed to have potential for improving either branching or final yield of late sown oilseed rape crops in North-east Scotland.