Abstract:

Research has shown that rice-duck farming systems can effectively control weed infestations in rice paddy fields, but it remains elusive how this type of system influences the dynamics and density of weeds in wheat fields. In order to explore the diversity of weeds in wheat field seed banks, we conducted a long-term experiment (13 consecutive years) to observe changes in weed seed bank diversity in rice-wheat rotated wheat fields in Danyang, Jiangsu Province. Results showed that the density of weed seeds in wheat field seed banks decreased continuously. The seed density of 18 weed species, including Alopecurus aequalis, Mazus japonicus, and Cardamine hirsuta, all decreased gradually with some annual fluctuations, and the overall rate of decrease for seeds of all weed species was 97%. Furthermore, rice-duck and wheat rotation farming decreased the richness, diversity, and evenness of weed species in wheat fields. Ecological indices implied a gradual change, which included fewer species, lower density, and lower diversity after adopting rice-duck and wheat return farming. The same conclusions could be drawn from both Jaccard’s similarity indices and Bray-Curtis coefficient of weed communities in wheat fields. Consecutive implementation of rice-duck and wheat rotation farming can significantly decrease both density and biodiversity of weeds in the seed bank of these ecosystems.

Key words: rice-duck farming, straw returning, organic rice-wheat cropping, weed seed bank dynamics, species diversity, weed community similarities, integrated weed management