Allelopathic effects of decaying Italian ryegrass (Lolium multiflorum Lam.) residues on rice.

摘要

Italian ryegrass - rice rotation system that cultivates Italian ryegrass (Lolium multiflorum Lam.) in paddy field during the winter season as the preceding crop of early rice has been widely accepted in Southern China. However, in the early stages, the growth of rice was decreased after Italian ryegrass cultivation. Allelopathic effects of the decaying Italian ryegrass residues on rice and its allelopchemicals were investigated in this study. A greenhouse experiment showed that incorporation of Italian ryegrass residues in the soil significantly inhibited the tillering of rice. The highest inhibitions of rice tillers were 44.3% and 36.7% for incorporation in-situ and ex-situ treatments, respectively. In a bioassay, both the aqueous leachates and organic solvent extracts of decaying Italian ryegrass residues inhibited the root growth of rice seedlings. Allelochemicals were isolated and identified from the aqueous leachates of decaying Italian ryegrass residues. One of the allelochemicals was identified as benzenepropanoic acid based on MS, 1H NMR and 13C NMR data. Benzenepropanoic acid significantly inhibited the elongation of rice seedling roots at the concentrations >=0.1 mM, whereas restrained the shoots only when its concentration reached 1 mM.