Distribution Characters of Absorption Nitrogen in Oilseed Rape (Brassica Napus L.) at Different Growth Stages

Abstract

Two winter oilseed rape varieties grown in sand culture were labeled with ¹⁵Nitrogen (¹⁵N) at different growth stages to show the route of nitrogen (N) absorption, distribution, and transfer in oilseed rape (Brassica napus L.). Averaged over the two varieties, 84% of the N absorbed at the seedling stage, and 67% of the N absorbed at the stem elongation stage were distributed into the leaves. Of the N absorbed at flowering stage, 43% was distributed into the leaves and 36% into stems. However, 42.4% of the N absorbed at siliquing stage was directly found into the silique. The proportion of the N redistributed from vegetative organs into reproductive organs was 34%, 44%, 41%, and 32%, at seedling, stem elongation, flowering, and siliquing stages, respectively. The amounts of N transferred were 203, 326, 218, and 82 mg per plant, respectively. This corresponded to 65% of the total in the grain. The proportions of N lost after absorption were 24%, 11%, 12%, and 7% at the four growth stages, respectively. The amounts lost were 142, 79, 43, and 16 mg per plant, respectively. N absorbed at early growth stages in oilseed rape was mainly distributed to the leaves first, and then redistributed to the reproductive organs later. This route provided most of the N for the reproductive organs.

Keywords:

• oilseed rape
• N efficiency
• absorption
• distribution
• transfer