Earthworms Increased Rape Seed Yield and Colza Oil

A field experiment was conducted to investigate the effects of earthworms (Metaphire guillemi) on the seed yield and oil production of winter oilseed rape (Brassica napus L. cv. Zhongshuang No. 9), which was included inoculated with (E) or without (CK) earthworms treatments in three replicates. The result showed that earthworms significantly increased the seed yield of winter oilseed rape by 23.9% for individual plant and by 30.2% for whole plot levels, which might be due to earthworms significantly increased the pod numbers per plant (42.9%) compared with CK. The present study also showed that, although the seed oil content was significantly decreased by 4.8%, the oil production of winter oilseed rape was significantly increased at both the individual plant (18.1%) and whole plot (24.2%) levels since the increase in seed yield over-rode the decrease in oil content due to earthworm presence. The increased of plant growth and nitrogen (N) accumulation during the vegetative growth stages, and the increased translocation of N to seed during the maturation stages, because earthworms, might be responsible for the increased seed yield and oil production of winter oilseed rape.