PHENOLICS IN TWO Alternanthera SPECIES RESIDUES AFFECT THE GERMINATION AND EARLY SEEDLING GROWTH OF RICE (Oryza sativa)

ABSTRACT Alternanthera species are invasive aquatic/semi-aquatic weeds posing a serious threat to agro-biodiversity in several countries in the world. The present study was conducted to assess the phytotoxic effects of Alternanthera philoxeroides and A. sessilis residues on emergence and early seedling growth traits of rice (Oryza sativa). Soil was prepared with 4% (w/w) Alternanthera species residues separately and allowed to decay for 0, 15 and 30 days. Rice emergence was significantly decreased but increase in mean emergence time and time to 50% emergence was observed in soils modified with Alternanthera species residues compared with seed sown in unmodified soils. Rice emergence was reduced to 50-67% and 52-75% by A. sessilis and A. philoxeroides, respectively. A significant reduction in rice root, shoot length, and biomass was also noted with Alternanthera-infested soil. Total phenolics increased with increasing residue decay time in both species thereby showing their direct interaction with emergence and seedling traits of rice. The phenolic compounds identified were namely Quercitin, Chlorogenic acid, P-Coumeric acid, Trans-4-hydroxy3-methoxy, Cinamic acid, Caffeic acid, Syringic acid, Sinapic acid, Vanillic acid, 4-hydroxy-3-methoxy benzoic acid.

摘要：莲子草属（Alternanthera）物种为入侵性水生/半水生杂草，对全球多个国家的农业生物多样性构成严重威胁。本研究旨在评估水花生（Alternanthera philoxeroides）与莲子草（Alternanthera sessilis）残体对水稻（Oryza sativa）出苗率及幼苗早期生长性状的植物毒性效应。分别以4%（质量分数w/w）的莲子草属植物残体掺入土壤中，并设置0、15、30天的腐解时长。与未掺入残体的对照土壤相比，掺入莲子草属残体的土壤中水稻出苗率显著降低，但平均出苗时间及达到50%出苗的时间均有所延长。莲子草与水花生分别使水稻出苗率降至50%~67%和52%~75%。经莲子草属残体处理的土壤还会显著抑制水稻根系、地上部的长度及生物量。两种莲子草残体中的总酚类物质含量均随腐解时长增加而升高，表明其与水稻出苗及幼苗性状存在直接相互作用。本次研究鉴定出的酚类物质包括槲皮素（Quercitin）、绿原酸（Chlorogenic acid）、对香豆酸（P-Coumeric acid）、反式-4-羟基-3-甲氧基肉桂酸、肉桂酸（Cinamic acid）、咖啡酸（Caffeic acid）、丁香酸（Syringic acid）、芥子酸（Sinapic acid）、香草酸（Vanillic acid）及4-羟基-3-甲氧基苯甲酸（4-hydroxy-3-methoxy benzoic acid）。