利用化感物质防治杂草研究现状及应用前景

简述了国内外利用植物化感物质防治杂草研究的现状以及应用前景。     

杉木根腐解3个月后根化感物质对杉木种子的发芽效应

采用丙酮、乙酸乙酯、蒸馏水(2:2:1)混合提取腐解3个月后的杉木根化感物质,并用杉木种子发芽试验进行生物检测。结果表明:杉木根腐解3个月后.添加氨态N、硝态N素及不加N素处理的杉木根化感物质对种子发芽具有不同的效应。就弱杉性化感物质200 mg·kg~(-1)处理而言,NH_4Cl 100 g、NH_4Cl 50 g、NaNO_3 50 g处理的对杉木种子绝对发芽势抑制作用强于不加N素处理;NH_4Cl 50 g、NaNO_3100 g处理的对胚根长和胚轴长抑制作用强于不加N素处理。就极性化感物质200 mg·kg~(-1)处理而言,NH_4Cl 100 g和NaNO_3100 g处理的对绝对发芽率抑制作用强于不加N素处理,NH_1Cl 100 g、NaNO_3 100 g和NaNO_3 50 g处理的对绝对发芽势抑制作用强于不加N素处理,添加氨态N和硝态N素处理的根极性化感物质对胚根长抑制作用强于不加N素处理。     

化学生态学研究现状和进展(Ⅱ)--植物他感作用和矿质养分化学生态

植物他感作用是化学生态学的重要研究内容,文章概述了植物他感作用的概念、意义、研究现状和进展及目前急需解决的问题.同时,根据分子生态学理论,矿质养分作为环境因子有着重要的生态学作用,因此这方面的研究也已成为化学生态学研究的重要领域,对此方面作者根据本人和前人的研究结果综述了矿质养分的化学生态作用.     

Weed-Suppressing Effect and Mechanism of Allelopathic Rice Accessions

Two allelopathic rice accessions, PI312777 and Allelopathyl, significantly suppressedthe growth of associated weeds in the field. Moreover, their weed-suppressing effectswere correlated with the cultivation patterns. The weed-suppressing effects of throwingand transplanting were more effective than that of direct seeding. Furthermore, theamounts of allelochemicals (resorcinols, flavones and hydroxamic acids) produced andreleased from two allelopathic rice accessions were much higher than that from a non-allelopathic rice variety Hua-Jing-Xian 1, and reached the maximum concentration at the6th leaf stage. Differences in the weed-suppressing effects of rice accessions appear toresult from the accessions producing and releasing different amounts of allelochemicalsin the field. Further research confirmed that in PI312777 plants, allelochemicals weresynthesized by the above-ground parts, and then secreted through the root tissues. Roottissues of PI312777 plants never produced the allelochemicals. Root exudates fromPI312777 could significantly inhibit the growth of E. crus-galli surrounding rice plantsin water culture. However, when activated carbon was added to the culture solution, whichcould absorb allelochemicals from root exudates, the growth of E. crus-galli was nolonger significantly inhibited. Weed-suppressing effects of rice accessions depended onallelopathy, cultivation patterns and other factors in rice fields, while allelopathywas one of important factors. Interestingly, the amounts of allelochemicals produced andreleased from allelopathic rice plants may be induced by the presence of E. crus-galli.This suggests that there is a possible chemical recognition between rice and E. crus-galli.     

人参根际土壤中化感物质鉴定

通过甲醇提取人参根际土壤的生物活性实验,表明人参土壤化感物质分布Ⅰ、Ⅱ和Ⅳ组分。利用GC-MS对甲醇洗脱部分进行物质组成分析,初步确定人参部分化感物质组成为:棕榈酸甲酯等酯类、9,12-十八(烷)酸(Z,Z)-、十五(烷)基酸等酸类、双环(10,8,0)二十烷,(Z)、二十三烷、5,6,-四亚甲基四氢-1,3-嗪-2-硫-4-环己烷和二十五烷等烷类18种物质。     

Rhizosphere isoflavones (daidzein and genistein) levels and their relation to the microbial community structure of mono-cropped soybean soil in field and controlled conditions

Despite an increase in the understanding of the soybean isoflavones involved in root-colonizing symbioses, relatively little is known about their levels in the rhizosphere and their interactions with the soil microbial community. Based on a 13-year experiment of continuous soybean monocultures, in the present study we quantified isoflavones in the soybean rhizosphere and analyzed the soil microbial community structure by examining its phospholipid fatty acid (PLFA) profile. Two isoflavones, daidzein (7, 4′-dihydroxyisoflavone) and genistein (5,7,4′- trihydroxyisoflavone), were detected in the rhizosphere soil of soybean plants, with the concentrations in the field varying with duration of mono-cropping. Genistein concentrations ranged from 0.4 to 1.2 μg g⁻¹ dry soil over different years, while daidzein concentrations rarely exceeded 0.6 μg g⁻¹ dry soil. PLFA profiling showed that the signature lipid biomarkers of bacteria and fungi varied throughout the years of the study, particularly in mono-cropping year 2, and mono-cropping years 6-8. Principal component analysis clearly identified differences in the composition of PLFA during different years under mono-cropping. There was a positive correlation between the daidzein concentrations and soil fungi, whereas the genistein concentration showed a correlation with the total PLFA, fungi, bacteria, Gram (+) bacteria and aerobic bacteria in the soil microbial community. Both isoflavones were easily degraded in soil, resulting in short half-lives. Concentrations as small as 1 μg g⁻¹ dry soil were sufficient to elicit changes in microbial community structure. A discriminant analysis of PLFA patterns showed that changes in microbial community structures were induced by both the addition of daidzein or genistein and incubation time. We conclude that daidzein and genistein released into the soybean rhizosphere may act as allelochemicals in the interactions between root and soil microbial community in a long-term mono-cropped soybean field.     

土壤微生态与花生连作障碍机制的研究进展

连作导致花生产量降低、品质下降,连作障碍已成为我国花生产业发展面临的突出问题。从土壤营养元素失衡、化感物质的自毒作用和微生物区系失衡三个方面综述了花生连作障碍的发生机理,认为花生连作障碍发生的主要原因是根系土壤微生态系统功能失调。从多因素相互作用角度出发,提出关键因子的挖掘是花生连作障碍机制研究的有效途径。     

Ex vitro elimination of seed dormancy and in vitro seedling performance of Cucumis africanus and Cucumis myriocarpus

Cucurbitacins from Cucumis africanus and Cucumis myriocarpus fruits are widely used in various industries. However, propagation of the two Cucumis species had been elusive due to seed dormancy, with seedlings performing poorly. The objective of this study was to determine the kind of seed dormancy under natural conditions and to eliminate the possibility of microbial degradation of inhibitory chemical compounds by germinating treated C. africanus and C. myriocarpus seeds under in vitro conditions. Forty seeds each, grouped as untreated, leached and leached-scarified (LS) batches, were arranged in a completely randomised design, with five replicates. Seeds in Murashige and Skoog medium were germinated under in vitro conditions for seven weeks at 25°C and 50–60% relative humidity. In both Cucumis species, untreated seeds did not germinate, whereas the LS seeds germinated in both species. In addition to the LS seeds, leached seeds in C. africanus germinated, but completely failed to germinate in C. myriocarpus. In all Cucumis species, seedlings from LS seeds outperformed those from leached seeds, suggesting that both chemical and physical dormancies were involved in seed dormancy and poor performance of seedlings in the two Cucumis species.     

植物化感物质对种子萌发的影响及其生态学意义

化感现象作为植物之间的一种相互作用方式,在农林业生产中广泛存在。合理利用植物之间的化感作用,对于生产实践具有重要的指导意义。研究表明,化感物质可促进或抑制不同物种种子的萌发过程,这对于植物的生长发育、植物群落的组成与分布以及生态系统的平衡有着重要影响。本文从化感物质对种子萌发的影响与其生态学意义两个方面进行了综述。一方面,在阐述化感作用影响种子萌发的基础上,进一步总结了化感物质抑制植物种子萌发的生理生化机制。包括:化感物质通过抑制胚根和胚轴的伸长,破坏亚细胞结构,干扰植物激素及活性氧的合成与代谢,造成细胞损伤,从而阻碍种子萌发;抑制种子中储存物质的代谢,阻碍种子萌发过程中的物质以及能量转换,导致种子萌发受阻等。另一方面,本文从化感作用在抑制农田杂草及影响生态系统稳定性两个方面,阐述了化感物质调控种子萌发的生态学意义。讨论了农作物的化感抑草作用,农林业生产中的化感自毒作用以及化感作用造成的生物入侵等,以期为农林业生产提供借鉴。最后,根据目前研究进展,对本领域未来研究方向进行了展望和讨论。     

麦类作物化感作用及其分子生态学研究

本文综述了近年来国际上研究麦类作物化感作用的新进展,着重介绍了小麦和大麦的化感作用种质资源的筛选与评价。在此基础上运用现代分子生物标记技术ISSR,分析了麦类化感作用的遗传多样性,并进一步阐明了小麦和大麦化感物质的研究现状。最后根据当前植物化感作用研究的发展趋势,提出化感作用基因表达与信号调控的分子生态学及根际生物学过程是未来麦类作物化感作用的重点领域。