1Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100094, China.
2Institute of Cereal and Oil Crops, Hebei Academy of Agricultural Sciences, Shijiazhuang, 050031, China.
3Research Center, Agriculture and Agri-Food Canada, Lethbridge,T1J4B1, AB, Canada.
Crabgrass (Digitaria ciliaris) is major weed in corn (Zea mays) in China. Laboratory and field studies were conducted to determine the effects of winter wheat (Triticum aestivum L.) residues on the germination and growth of this weed. Under laboratory conditions, aqueous extracts of wheat shoots and roots markedly reduced its germination. The germination was inhibited more by extracts from shoots than roots and by the extracts from young seedlings than mature wheat plants. The inhibitory effects on weed germination varied with wheat cultivars. In corn field, crabgrass density and biomass decreased with increase in the quantity of wheat residues. Wheat residue at 0.75 kg/m2 reduced the weed density by 87.3 to 96.4% and biomass by 77.7 to 81.0% over the two years. Reductions in weed density and biomass in the field were likely due to the combined effects of physical suppression and allelopathy. Although germination, plant height and biomass of corn seedlings were slightly reduced in the wheat residue mulched plot, but corn yield was similar to control. These findings may lead to the improvement in current weed management programme for corn in the wheat-corn rotation in China.
Allelopathy, crabgrass (Digitaria ciliaris), integrated weed management, stubble mulch, weed suppression
