中文摘要：

关于冬种黑麦草（Lolium multiflroum Lam．）使后作水稻增产的机理，以往的研究着重于冬种黑麦草对稻田土壤理化和生物学性状的改善方面。本研究旨在证明黑麦草根茬腐解物中存在促水稻生长活性物质的的假设。实验结果表明，黑麦草根茬腐解液可显著地促进水稻幼苗的生长，水稻的根、苗和植株的干物质质量分别比对照增加41．9％，42．6％和42．3％。腐解液的乙酸乙酯和正丁醇萃取物对水稻幼苗的生长也有显著的促进作用。对腐解液的有机成分进行初步分离，发现了4个具促水稻生长活性的洗脱组分。由此可以推断，黑麦草根茬腐解物中确实存在能刺激水稻生长的活性物质。

英文摘要：

As regards the mechanism of yield increase of subsequent rice brought by Italian ryegrass winter cropping, previous studies laid strong emphasis on the improvement of the physical, chemical and biological properties of paddy soil due to the Italian ryegrass cultivation. In order to prove that some rice stimulators may present in the decaying Italian ryegrass residues, a series of bioassays have been proceeded in the present study. The results showed that the decomposition products of Italian ryegrass residue significantly promoted the growth of rice seed- lings. Comparing with control, average dry weight of root, shoot and the whole plant of rice seedlings treated with water extract of decaying Italian ryegrass residues were increased by 41.9%, 42.6% and 42. 3%, respectively. The ethyl acetate and the n-Butyl alcohol extract of the decomposition product of those residues also possessed significant stimulative effects on the elongation of root and shoot of rice seedlings. Soil microorganisms play important role in the bioactivity of those extracts. Furthermore, four fractions with stimulative effect on rice growth were isola- ted from the decomposition product of Italian ryegrass residues by a method of column chromatography. It is therefore deduce that some rice stimulators are present in the decaying Italian ryegrass residues.