Study on promotive effects of rice on seed germination of Potenderiaceae paddy weeds

假鸭舌草车前草和异型花是危害严重的稻田水生杂草。近年来，它们在日本成为更严重的问题，其中杂草的数量通过移植的方法增加：本研究通过水稻种子、秧苗、谷壳和稻草对杂草种子萌发的影响，结果表明：水稻种子、稻草、谷壳和稻草均能促进甜菜夜蛾的出苗，和麸皮。水稻种子、谷壳和稻草在黑暗条件下均能促进紫云英种子的萌发。水稻种子、谷壳和稻草也能促进泥藻的萌发和出苗，而稻草、谷壳和谷壳的水浸提物在黑暗条件下能促进紫茎泽兰种子的萌发。兴奋剂似乎已经取代了光。从稻草中分离得到氨基酸（23个化合物）和磷酸作为刺激剂的候选化合物。氨基酸与磷酸混合后，在黑暗条件下能诱导种子萌发。然而，混合物不诱导灭菌种子的萌发。这些结果表明，稻草产生的刺激物可能通过促进微生物的生长来诱导种子萌发，微生物在种子萌发中起重要作用。尿素和水稻种子协同增加幼苗的数量和生长阶段。类胡萝卜素生物合成抑制剂氟立酮和氟草酮，促进了阴道支原体的出现。这些化合物能打破种子的休眠，阻止种子进入休眠，从而减少种子库中的种子数量。

Monochoria vaginalis var. plantaginea and Heteranthera limosa are very serious aquatic weeds in paddy fields. In recent years, they became a more serious problem in Japan where the number of the weeds was increased by the method of transplanting : direct-seeding and infant-seedling culture.This study was conducted to determine the effects of rice seeds, seedlings, hulls and straw on the germination of the weed seeds, and the following results were obtained.The emergence of M.vaginalis was promoted by the rice seeds, straw, hulls, and bran under submerged condition. The germination of the M.vaginalis seeds was stimulated in the dark by rice seeds, hulls and straw regardless of the cultivars tested. The germination and emergence of H.limosa were also promoted by rice seeds, hulls and straw.The aqueous residues extracted from rice straw, bran and hulls stimulated the seed germination of M.vaginalis in the dark. The stimulants seem to have replaced light. Amino acids (23 compounds) and phosphoric acid were isolated from rice straw as the candidate compounds for the stimulants. When the amino acids and phosphoric acid were mixed, they induced the seed germination in the dark. However, the mixture did not induce the germination of the sterilized seeds. These results suggest that stimulants produced by rice straw induce the seed germination possibly through enhancing the growth of microbes, which may play important roles in the seed germination.The emergence of M.vaginalis was promoted by urea and ammonium-nitrogen. Urea and rice seeds synergistically increased the number and growth stage of the seedlings.Fluridone and norflurazon, carotenoid biosynthesis inhibitors, promoted the emergence of M.vaginalis. They broke the seed dormancy and prevented the seeds from entering dormancy, thus these compounds can be usefull in decreasing the number of seeds in the seed bank.