Genetic Variation in Nitrogen Uptake and Utilization in Spring Rape (Brassica napus L.) and its Exploitation Through Selection

Field and controlled environment studies revealed significant genetic variation in nitrogen uptake and utilization within an F2 population of spring rape. However, narrow-sense heritabilities of measures of these characters were consistently low, and were less than that of seed yield in the field. Flowering time in the field had a much higher heritability than seed yield and the expected yield response to selection for this character was 34 % greater than the response to direct yield selection. An even greater yield response was expected from selection based on an index combining measurements of flowering time, nitrogen uptake and nitrogen utilization. The expected yield response to selection for an index incorporating these characters and seed yield was SI % greater than that for direct yield selection.