水稻化感材料的抑草作用及其机制

Weed-Suppressing Effect and Its Mechanism of Allelopathic Rice Accessions

水稻化感材料PI312777和化感1号在田间能显著地抑制杂草,而且其抑草作用与栽培方式相关,抛秧和移栽方式对杂草的抑制作用明显地优于直播。结果表明,PI312777和化感1号植株产生和释放的化感物质(多酚、黄酮和羟基肟酸)显著高于非化感品种华粳籼1号,而且在6叶期植株中的化感物质含量达最大值。这种不同水稻材料植株在不同生育期产生并释放化感物质量的差异是导致它们在田间抑草效应强弱的重要原因之一。进一步研究发现,PI312777植株由地上部分合成化感物质后经根部分泌到环境中,根组织并不产生化感物质,且稗草能诱导PI312777植株产生和释放更大量的化感物质。在水培条件下,PI312777根分泌的化感物质明显地抑制稗草的生长,但水培液中加入活性碳能使水稻对稗草的抑制作用明显减弱。研究显示,水稻化感材料的抑草效应虽与化感作用、栽培方式和环境等多因素相关,但化感因子起着重要的作用,而且水稻和伴生稗草之间可能存在着化学识别机制。

Two allelopathic rice accessions, PI312777 and Allelopathy 1, could significantly suppress the growth of associated weeds in the field. Moreover, their weed-suppressing effects were correlated with the cultivated patterns. The weed-suppressing effects of the throwing and transplanting were more effective than that of the direct seeding in the field. Furthermore, the amounts of allelochemicals (resorcinol, flavone and hydroxamic acid) produced and released from the two allelopathic rice accessions were much higher than that from the non-allelopathic rice variety Huajingxian 1, and reached the maximum values at the 6th leaf stage. Obviously, the differences of weed-suppressing effects of rice accessions resulted from their different amounts of allelochemicals produced and released in the field. Further research confirmed that allelochemicals of PI312777 plants were synthesized by their above-ground parts, and then secreted through their root tissues. Root tissues of PI312777 plants never produce the allelochemicals. Root exudates from PI312777 significantly inhibited the growth of barnyard grass surrounding rice plants under water culture. However, the culture solution treated with activated carbon, which could absorb allelochemicals from root exudates, the growth of barnyard grass had no longer to be significantly inhibited. Actually, weed-suppressing effects of rice accessions depended on allelopathy, cultivated patterns and other factors in rice fields, while allelopathy was one of the important factors. Interestingly, the amount of allelochemicals produced and released from allelopathic rice plants could be induced by associated barnyard grass. It suggested that there was a possible chemical recognition between rice and barnyard grass.