不同化感潜力水稻品种对低钾的生理与分子响应

选择国际公认的化感水稻品种“P1312777”和非化感水稻品种“Lemont”为材料,在K元素为5mg·L^-1（低K）和40mg·L^-1（正常K）2个水平的营养液中培养,通过水稻形态学指标（根长、株高、根冠比和生物量）、生理生化指标（SOD、POD、CAT、根系活力及植株中N、P、K含量）,评价不同化感潜力水稻品种对低K胁迫的生理响应,并采用实时荧光定量PCR（Realtime Fluorescent Quantitative PCR,FQ-PCR）,分析了低K胁迫下水稻根和叶中与N、P、K吸收利用相关的12个关键酶的基因表达差异。结果表明,低K促进了化感水稻“P1312777”根的生长,根冠比加大,生物量增加,但对株高的影响不显著;而该条件下非化感水稻“Lemont”的上述指标均受到不同程度的抑制。低K对两种水稻的保护酶系（SOD、POD、CAT）和根系活力均有一定程度的抑制作用,植株中N、P、K含量降低,但非化感水稻“Lemont”受抑制的程度远大于化感水稻“P1312777”。FQ-PCR检测结果表明,低K胁迫下两种水稻根、叶中的12个关键酶的基因均呈现上调表达,而化感水稻“P1312777”的基因表达上调倍数均明显大于非化感水稻“Lemont”。低K胁迫下两种水稻品种的形态学差异、生理与分子响应均表明,化感水稻“P1312777”比非化感水稻“Lemont”具有更强的适应K匮乏的能力。     

不同供氮水平下间甲酚对玉米的化感作用

通过发芽和管栽试验研究了不同供氮水平下,小麦根系分泌物间甲酚对玉米的化感作用。结果表明,间甲酚对玉米幼苗根系产生的化感作用较弱,对地上组织的化感作用较强,其中苗高受间甲酚的影响最明显。氮素与间甲酚对玉米生物产量和根重均存在显著的互作作用,施氮量与间甲酚对成熟期玉米生物产量产生的化感作用呈显著负相关,施N量为300mg·kg^-1（土）时,浓度为300×10^-6mol·kg^-1（土）的间甲酚对玉米生物产量表现为化感抑制作用,但施N量为150mg·kg^-1（土）时,相同浓度的间甲酚对玉米生物产量表现为促进作用。间甲酚可增大玉米的根重,施氮可显著提高间甲酚增加根重的作用。农田生态系统中,当存在化感物质时,选择适宜的施肥水平十分重要。     

化感小麦种质资源的筛选与评价

以国内外90份不同小麦为材料,采用土壤-琼脂三明治法和田间杂草调查法,对不同小麦种质资源进行化感潜力评价,筛选出具有较强化感潜力的小麦品种。土壤-琼脂三明治法测试结果表明,不同小麦品种的化感潜力存在明显差异,对莴苣根长抑制率IR在10．1％和69．1％之间;筛选出“115／青海麦”、“92L89”、“百泉3199”、“81-214”和“92H31”5个强化感潜力的小麦品种,其对莴苣根长抑制率依次为69．1％、68．5％、68．7％、69．1％和65．2％,筛选出“抗10103（80）”和“A246”2个弱化感潜力的小麦品种,抑制率IR依次为10．1％和12．2％;田间杂草调查评价和土壤-琼脂三明治法表现出相似趋势,检测结果也得到了琼脂迟播共培法的佐证,表明采用土壤-琼脂三明治法筛选化感小麦种质资源是可行的。这为小麦化感作用研究提供了重要的种质资源,也为化感小麦种质资源的筛选提供方法借鉴。     

银杏凋落叶对生菜生长及生理特性的影响

采用盆栽试验,通过向土壤中施加不同量(0、2.5、5.0、7.5、10.0 g/kg)的银杏凋落叶,研究银杏凋落叶对生菜生长及生理特性的影响。结果表明:在土壤中施用银杏凋落叶后显著抑制了生菜的生长,其根长、茎粗和株高均显著下降,地上部鲜物质量较对照分别减少了11.38%、22.54%、32.37%、34.82%;各处理生菜叶片中叶绿素含量较对照均显著减少,且随凋落叶施用量的增多呈现降低趋势,10.0g/kg银杏凋落叶处理下的叶绿素a、叶绿素b、总叶绿素以及类胡萝卜素含量分别比对照减少45.24%、56.25%、47.72%以及38.08%;生菜叶片中超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、过氧化氢酶(CAT)活性较对照均有所增强,且各处理中后两者酶活性均显著高于对照;各处理生菜叶片丙二醛(MDA)含量均小于对照,且随凋落叶施用量增多呈增加趋势。研究认为,银杏凋落叶对生菜生长及抗性生理产生化感作用,综合表现为抑制作用。     

Sorption of benzoic acid onto soil colloids and its implications for allelopathy studies

The fate of allelochemicals in the soil environment largely determines the expression of allelopathy in the natural environment. In allelopathy research, the sorption of allelochemicals onto soil particles has been less well studied than their degradation. A study was carried out to evaluate the growth of cucumber (Cucumis sativus var Marketmore 76) and radish (Raphanus sativus var Crimson giant) in soil amended with 1, 5, 10 and 20 mg l^–1 benzoic acid as model allelopathic substance. Growth of both cucumber and radish was not inhibited in soil amended with benzoic acid. A labeled study indicates that sorption of benzoic acid onto soil particles increases with concentration. Benzoic acid isotherms of both soils were non-linear, with an N value of 0.875 for a garden soil and 0.891 for a garden soil + sand, and they may explain the reason for the limited allelopathic effect of benzoic acid at concentrations often recorded in natural soil.     

An allelopathic substance isolated from Zanthoxylum limonella Alston fruit

Bioassay-guided fractionation of the ethyl acetate extract of the Zanthoxylum limonella Alston fruits led to the isolation of a phenolic compound named xanthoxyline. The allelopathic effects of xanthoxyline were evaluated on Chinese amaranth (Amaranthus tricolor L.) and Barnyardgrass (Echinochloa crus-galli (L.) Beauv.) under laboratory conditions. At a concentration of 2500 μM, xanthoxyline completely inhibited seed germination and growth of Chinese amaranth, while this compound showed a significantly inhibitory effect on seed germination of Barnyardgrass by 43.59% and inhibited shoot and root length by 71.56% and 87.48%, respectively. To determine the mechanism through which xanthoxyline exerts its toxicity, the cytogenetic bioassay was conducted. Roots of Allium cepa L. (onion) were treated with a series of concentrations, ranging from 15.625 to 125 μM for 18 h. Cytogenetic studies of onion roots showed a decrease of the mitotic index in the exposed roots dependent on the concentration of xanthoxyline. Likewise, the mitotic phase index was altered in onion incubated with xanthoxyline. Analyses of the abbreviation types showed spindle disturbances at late prophase, sticky metaphase, c-mitosis, non-oriented chromosome at metaphase, sticky anaphase, delayed anaphase and diagonal at telophase for the onion roots exposed to xanthoxyline.     

多裂骆驼蓬水浸液对多年生黑麦草的化感作用与生理生化表现

为探讨多裂骆驼蓬(Peganum multisectum (Maxim.) Bobr.)对多年生黑麦草(Lolium perenne L.)的化感效应,采用溶液培养和盆栽土培法研究了不同浓度多裂骆驼蓬水浸液对多年生黑麦草种子萌发和幼苗生长的影响及其生理生化表现。结果表明,多裂骆驼蓬水浸液显著抑制多年生黑麦草萌发种子的α-淀粉酶和ATP酶活性及根尖细胞的有丝分裂,提高吲哚乙酸氧化酶活性,使种子萌发率和萌发指数及幼苗根长、株高和干重下降,这种抑制效应随水浸液浓度提高而增强,并与多年生黑麦草的种植密度呈负相关。在多年生黑麦草植株生长过程中浇灌多裂骆驼蓬水浸液提高了其叶片的超氧阴离子(O₂^·-)、H₂O₂和丙二醛(MDA)含量;超氧化物歧化酶(SOD)、过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)活性及抗坏血酸(ASA)含量随着水浸液浓度提高先升后降,过氧化氢酶(CAT)活性升高,谷胱甘肽(GSH)含量及光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)降低,胞间CO₂浓度(Ci)升高。叶绿素荧光动力学资料显示,叶片初始荧光(Fo)随多裂骆驼蓬水浸液浓度提高而增加,最大荧光(Fm)、PSⅡ潜在光化学效率(Fv/Fo)、最大光化学效率(Fv/Fm)、光合电子传递量子效率(ΦPSⅡ)和光化学狡灭系数(qP)降低,非光化学狡灭系数(NPQ)先升后降,表明叶片光合机构受到伤害。     

三裂叶蟛蜞菊对水稻化感作用的初步研究

三裂叶蟛蜞菊（Wedelia trilobata L.）是华南地区的重要杂草和园林绿化植物。本文研究了三裂叶蟛蜞菊水提液对水稻（Oryza sativa L.）种子萌发和植株生长过程中一些生理过程的影响。结果表明,三裂叶蟛蜞菊各水提液浸种显著抑制了水稻萌发种子的α-淀粉酶活性和过氧化物酶活性,提高了质膜透性,进而使其活力和呼吸速率显著     

Effect of Mulch from Selected Multipurpose Trees (MPTs) on Growth, Nitrogen Nutrition and Yield of Maize (Zea mays L.)

Leaf extracts and mulch from 14 multipurpose trees were used to test their effects on maize germination, growth and yield. Maize germination was significantly reduced by leaf extracts of all species with increasing extract concentration. The most drastic reductions were caused by Gliricidia sepium , Tetrapleura tetraptera , Lonchocarpus sireceus , Senna siamea and Leucaena leucocephala . Terminalia superba , Tetrapleura tetraptera , Pithecelobium dulce , Gliricidia sepium and Senna siamea significantly reduced maize root growth at the lowest extract concentration, while shoot length was most significantly reduced by Gliricidia sepium , Leucaena leucocephala , Alchornea coordifolia , Pithecelobium dulce , Terminalia superba , and Tetrapleura tetraptera at all concentrations. Growth of maize in pots and yield in the field were controlled by nitrogen supply and uptake. Fast-decomposing leaf material rich in nitrogen promoted growth and yield of maize. Thus Leucaena leucocephala and Gliricidia sepium , both nitrogen-fixing legumes with high nitrogen contents and fast-decomposing leaf materials, significantly increased maize growth and yield. This suggests that the negative effects of leaf extracts observed in the laboratory are ecologically irrelevant in the field.     

作物化感作用研究现状及前景展望

作物化感作用研究是一个相对较新的研究方向，尽管2000年前就有关于植物间克生现象的描述，化感作用在农业生产实践中的应用很有潜力，从化感作用的概念着手总结了近20年来的研究成果，包括化感作用物质研究，作用机制研究，种质资源，生物检测方法和遗传特性研究等，并阐明了作物化感作用的研究意义，研究存在困难以及应用途径与前景。