水位和氮浓度对三江藨草幼苗生长和生物量分配的影响

以莫莫格国家级自然保护区常见植物三江藨草(Scirpus nipponicus)为研究对象,设置低(5 cm)、中(35 cm)、高(65 cm) 3个水位和低(4 mmol·L-1)、中(8 mmol·L-1)、高(12mmol·L-1) 3个氮浓度交互的室内控制实验,探究不同水位和氮浓度对湿地植物三江藨草幼苗生长及生物量分配的影响。结果表明:水位对三江藨草幼苗生长、生物量及其分配均产生显著影响(P<0.05),随着水位的升高,三江藨草株高增加,分株数、球茎数及根生物量降低,根茎、球茎、地下、地上和总生物量均呈先增加后降低的趋势;植株地上生物量分配增加,地下(包括根和球茎)生物量分配降低;氮浓度仅对植株株高、球茎数以及地下与地上部分的生物量分配有显著影响(P<0.05),对分株数及生物量的累积均无显著影响(P>0.05);综合三江藨草幼苗的生长特征和生物量累积,认为其生长的最适宜水位为35 cm;且低水位有利于植株对氮的吸收,高水位和高氮浓度限制植株的生长。     

养分对入侵植物大狼耙草和近缘本地植物狼耙草竞争的影响

为探讨大狼耙草的入侵特性,采用盆栽试验,研究了不同养分条件对入侵植物大狼耙草(Bidens frondosa L.)和近缘本地植物狼耙草(B.tripartita L.)竞争的影响。结果表明,大狼耙草的竞争响应随着养分的增加而降低,而本地种狼耙草的竞争响应随着养分的增加而升高,低养分下大狼耙草的竞争响应大于狼耙草的竞争响应,高养分下则相反。低养分下,竞争显著降低大狼耙草的生长,而高养分下,竞争显著降低本地植物狼耙草的生长,说明了养分的增加提高了入侵植物大狼耙草的竞争能力,同时降低了本地植物狼耙草的竞争能力。人类活动使生境中的养分增加,会提高大狼耙草对狼耙草的竞争能力,促进其入侵。     

几种除草剂对薇甘菊的防控效果

【背景】薇甘菊是一种外来入侵的恶性杂草,对当地农、林业造成了严重的危害。【方法】研究了草甘膦、氨氯吡啶酸、甲嘧磺隆、噻吩磺隆、苯磺隆、百草枯、五氟磺草胺、单嘧磺隆和单嘧磺脂9种除草剂对薇甘菊的化学防治,调查各药剂对薇甘菊的植株鲜重抑制率、叶片覆盖度和抑花率。【结果】氨氯吡啶酸25～100gai.hm-2、草甘膦1538～2306gai.hm-2、甲嘧磺隆100～400gai.hm-2、百草枯750、1125gai.hm-2、五氟磺草胺125gai.hm-2、噻吩磺隆11.25～33.75gai.hm-2和单嘧磺脂15～60gai.hm-2对薇甘菊营养生长控制效果较好。其中,百草枯短时间有效,草甘膦、五氟磺草胺、单嘧磺脂、单嘧磺隆、氨氯吡啶酸和甲嘧磺隆对薇甘菊的抑花率较高,苯磺隆和单嘧磺隆基本无效,且9种药剂对橡胶树均未表现出药害。【结论与意义】适当降低氨氯吡啶酸、甲嘧磺隆、草甘膦、五氟磺草胺、噻吩磺隆和单嘧磺脂的浓度可以保持薇甘菊营养生长而扼制种子蔓延。本研究首次发现五氟磺草胺、噻吩磺隆和单嘧磺脂对薇甘菊有良好的抑制效果。     

矮壮素对苦草矮化特征及生理指标的影响

沉水植物生长过高引起水体污染问题受到人们高度重视。本文在实验室模拟条件下,研究了0(CK)、0.01、0.02、0.10、0.20、0.50、0.75、1.00和1.25g.L-1共9个不同浓度矮壮素对苦草(Vallisnerianatans)矮化特征及生理指标的影响。结果表明:不同浓度处理30d后苦草株高具有显著差异性(P<0.05),且浓度越高矮化效果越显著;矮壮素使苦草叶宽增加、根长缩短,其中浓度在0.02～0.20g.L-1时苦草根冠比增加,浓度在0.01～0.50g.L-1时苦草株数增加明显;矮壮素浓度在0.10～0.50g.L-1时,苦草湿重增加61%～123%,将从水中或底泥中吸收更多N、P等营养物质,增强其净化水质的能力;当矮壮素浓度为0.02g.L-1时,不仅苦草矮化的效果较好,占据空间相对较小,而且苦草根长生长较长,根冠比较大,叶绿素含量增加,SOD、POD酶活性升高,苦草抗逆性增强,延缓植株衰老。因此,0.02g.L-1浓度矮壮素对苦草矮化较为适宜。     

不同除草剂的田间杂草防效及对糜子生长发育的影响

筛选糜子适宜除草剂来防范农田药害,是糜子高效安全生产和改善生态环境亟待解决的关键问题。本研究以粳性糜子品种‘榆糜2号'为材料,探究22种除草剂对糜子田间杂草的防除效果及对糜子生长发育的影响。结果表明: 1)喷施土壤封闭型除草剂谷友、丁草胺、莠去津、苄嘧·丙草胺和茎叶型除草剂苯唑·二甲钠、阔世玛、藤净、陶氏·优先、阔菲后,基本无药害作用,糜子幼苗生长正常,其余除草剂均对糜子有不同程度的药害影响;2)参试的22种除草剂在糜子田中对杂草均表现出一定的防除效果,总体而言,土壤封闭型除草剂的杂草防效相对优于茎叶型除草剂,但所有参试除草剂对糜子株高、功能叶片叶绿素含量、单株穗重均造成不同程度的影响;3)与人工除草相比,参试除草剂均导致糜子产量有不同程度的下降;但与不除草对照相比,部分除草剂有明显的增产增效作用。土壤封闭型除草剂中,谷友、丁草胺、莠去津、苄嘧·丙草胺的杂草防效较好,较不除草对照增产60%以上;茎叶型除草剂中,阔世玛、苯唑·二甲钠的杂草防效较好,较不除草对照增产50%以上。因此,在糜子出苗前可用38%莠去津或44%单嘧磺隆进行土壤封闭处理,或在出苗后喷施茎叶型除草剂3.6%二磺·甲碘隆或55%苯唑·二甲钠,农田杂草防效较好,且对糜子生长发育的负面影响较小。     

13种茎叶处理除草剂对不同生育期白花鬼针草的生物活性

[目的] 白花鬼针草是一种恶性外来入侵杂草,近年来已侵入农田,对农业生产及生态系统带来严重危害。为筛选防治白花鬼针草的有效除草剂,分析评价了13种常见茎叶处理除草剂对幼苗期和成株期白花鬼针草的防治效果。[方法] 采用整株盆栽法,在白花鬼针草幼苗期（2~3对叶期）和成株期（6~7对叶期）分别进行茎叶喷雾处理,每种除草剂设置3个剂量。[结果] 供试的13种除草剂中,灭生性除草剂草甘膦、草铵膦和敌草快对幼苗期和成株期的白花鬼针草防效达到100%。选择性除草剂中,麦草畏和辛酰溴苯腈对幼苗期和成株期的白花鬼针草均有较好的防效,三氯吡氧乙酸、乙羧氟草醚和氯吡嘧磺隆在高剂量下对幼苗期的白花鬼针草有较好的防除效果,但对成株期的白花鬼针草防效较差,氯氟吡氧乙酸、乳氟禾草灵、灭草松、二氯吡啶酸、乙氧氟草醚对幼苗期和成株期白花鬼针草防效均较差。[结论] 白花鬼针草对多种化学除草剂具有较强的耐药性,生育期对除草剂防除白花鬼针草的效果有较大影响。灭生性除草剂草甘膦、草铵膦、敌草快及选择性除草剂辛酰溴苯腈和麦草畏适用于防除白花鬼针草。     

百草枯和草甘膦对多刺裸腹溞的毒性效应

采用急性毒性实验方法研究了两种常见除草剂百草枯和草甘膦对多刺裸腹溞(Moina macrocopa)的48hLC50值,应用生命表实验方法研究了亚致死浓度的百草枯(0、0.01和0.04mg·L-1)和草甘膦(0、0.4和1.6mg·L-1)对多刺裸腹溞生命表统计学参数的影响。结果表明:百草枯和草甘膦对多刺裸腹溞的48hLC50值分别为0.626和26.287mg·L-1;百草枯浓度对多刺裸腹溞的生命期望、世代时间、净生殖率和种群内禀增长率有显著影响(P<0.01),草甘膦浓度对多刺裸腹溞的生命期望、世代时间和种群内禀增长率有显著影响(P<0.01),百草枯和草甘膦的交互作用对多刺裸腹溞的世代时间和种群内禀增长率有显著影响(P<0.01)。多重比较显示:当忽略草甘膦的影响时,0.01mg·L-1的百草枯使多刺裸腹溞的生命期望显著延长,而0.04mg·L-1的百草枯则相反,0.04mg·L-1的百草枯使多刺裸腹溞的净生殖率显著降低;当忽略百草枯的影响时,0.4和1.6mg·L-1的草甘膦均使多刺裸腹溞的生命期望显著缩短;与空白对照组相比,0.01mg·L-1的百草枯和1.6mg·L-1的草甘膦混合液使多刺裸腹溞的世代时间显著延长;而0.04mg·L-1的百草枯和0、0.4、1.6mg·L-1的草甘膦混合液均使多刺裸腹溞的世代时间显著缩短,种群内禀增长率显著降低。随着草甘膦浓度的升高,0.04mg·L-1的百草枯对多刺裸腹溞的毒性显著降低,表现出明显的拮抗作用。     

2,4-二叔丁基苯酚对番茄叶霉病及幼苗生长的影响

采用室内试验和田间试验相结合方式,研究了不同浓度(0、0.01、0.05、0.10、0.50和1.00 mmol·L-1)2,4-二叔丁基苯酚对番茄叶霉菌及番茄种子萌发幼苗生长的影响.结果表明:2,4-二叔丁基苯酚在叶霉菌培养的前阶段极显著地抑制了菌丝的生长,培养7d时,0.1 mmol· L-1的抑制作用最大,抑制率为40％;在田间抗病性调查期间各浓度处理均提高了番茄幼苗的抗病性,其中以0.1 mmol· L-1处理抗病性最好,病情指数比对照降低了54％;低浓度2,4-二叔丁基苯酚促进了番茄种子的萌发,增加了幼苗的株高、茎粗、地上和地下部鲜质量、叶绿素含量、根系活力和幼苗体内保护酶活性,随着浓度增大,促进作用减弱甚至表现出抑制作用;而低浓度的2,4-二叔丁基苯酚降低了叶片丙二醛(MDA)含量和细胞相对电导率,且随浓度增加作用强度增大;浓度为0.1 mmol·L-1时,抑制作用最强.综合分析表明,2,4-二叔丁基苯酚对番茄植株及叶霉病具有调控作用,可以确定0.1mmol·L-1为田间施加最适浓度.     

草甘膦对草鱼、鲢鱼和鲫鱼的毒性

【背景】草甘膦是一种灭生性除草剂,对防治多年生杂草效果明显。近年来,草甘膦被广泛用于防治鱼塘水生杂草,其对鱼类的安全性逐渐受到关注。【方法】采用半静态法测试了草甘膦对草鱼、鲢鱼和鲫鱼的急性毒性,并计算出其对草鱼、鲢鱼和鲫鱼的安全浓度。【结果】随着受试鱼苗在药液中暴露时间的延长,LG50值逐渐减小;草甘膦对草鱼、鲢鱼和鲫鱼的96h LC50值分别为0．2518、0．2588和0．2599mg·L^-1;草甘膦对草鱼、鲢鱼和鲫鱼的安全浓度分别为0．0252、0．0259和0．0260mg·L^-1。【结论与意义】草甘膦对草鱼、鲢鱼和鲫鱼高毒,该结果对指导淡水养殖区杂草防除时科学使用草甘膦具有重要的实践意义。     

棉隆熏蒸处理对平邑甜茶幼苗生长和生物学特性及土壤环境的影响

本试验以苹果砧木平邑甜茶幼苗为试材,通过温室与露地盆栽两种方式,研究不同浓度(0、0.1、0.2、0.4 g·kg^-1)棉隆熏蒸对连作土壤微生物环境和平邑甜茶幼苗生长的影响。结果表明:不同浓度的棉隆熏蒸均能促进连作土壤中平邑甜茶幼苗的生长,其中以0.2 g·kg^-1处理的效果最显著。0.2 g·kg^-1棉隆熏蒸下,平邑甜茶幼苗在温室和露地条件下的株高、地径、地上部干质量、地下部干质量分别比连作对照提高了192.9%和91.8%、72.8%和60.1%、196.8%和195.0%、138.5%和130.7%;幼苗根系相关指标(根长、根面积、根体积、根系呼吸速率)也明显优于其他处理;幼苗根系的超氧化物歧化酶、过氧化物酶、过氧化氢酶活性分别比连作对照提高了114.6%和118.5%、123.5%和107.6%、164.6%和175.6%;幼苗根系的丙二醛含量也显著低于其他处理。随着棉隆施用浓度的增加,土壤细菌含量、真菌含量、尖孢镰孢菌基因拷贝数、土壤酶活性均显著降低,连作土壤真菌群落结构也发生了不同程度的改变。综上,0.2 g·kg^-1棉隆熏蒸可以提高连作平邑甜茶幼苗生物量,改善土壤环境,有效缓解平邑甜茶的连作障碍。在苹果老果园重茬建园时,可以优先考虑0.2 g·kg^-1的棉隆熏蒸处理。     

Chemical weed management in wheat at higher altitudes

To evaluate the effect of different herbicides for controlling weeds in wheat (variety Fakhr-i-Sarhad),at higher attitude, an experiment was conducted at Agriculture Research Station, Chitral during Rabi season 2003-04, using Randomized Complete Block Design, keeping four replications. The experiment, sown in November comprised of eight treatments, viz; seven herbicides and a weedy check. Each treatment consisted of 5 rows each 30 cm apart and 5 m long thus giving a total size of 5 m x 1.5 m. The herbicides used included; terbutryn + triasulfuron at 0.16 kg, 2,4-D at 0.7 kg, fenoxaprop-P-ethyl at 0.93 kg, clodinafop at 0.05 kg, bromoxynil + MCPA at 0.49 kg, carfentrazon-ethyl at 0.02 kg and isoproturon at 1.0 kg a.i ha(-1). The data were recorded on weed kill efficiency (%), fresh weed biomass (kg ha(-1)), plant height (cm), spike length (cm), number of tillers m(-2), number of grains spike(-1), thousand grains weight (g), biological yield (kg ha(-1)), grain yield (kg ha(-1)) and harvest index (%). The data recorded on weed kill efficiency, weed biomass (kg ha1), grains yield (kg ha(-1)) and harvest index (%) were significantly affected by the different herbicidal treatments. Statistically isoproturon treatment exhibited the best performance, with maximum weed kill efficiency (48.26%) and minimum fresh weed biomass (433.3 kg ha(-1)) as compared to weedy check (6 %) and (1102 kg ha(-1)), respectively. Similarly, the spike length (8.34 cm), number of tillers (427 m(-2)), number of grains spike(-1) (38.0), thousand grains weight (39.85 g), biological yield (8475 kg ha(-1)), grain yield (2530 kg ha(-1)) and harvest index (31.3%) were the highest in isoproturon treatments as compared to weedy check having (7.64 cm), (356 m(-2)), (34.1), (37.12 g), (6858 kg), (1913 kg ha(-1)) and (27%), respectively.     

Synergistic effect of the herbicides glyphosate and MCPA on survival of entomopathogenic nematodes

The survival and infectivity of the infective juveniles of two species of entomopathogenic nematodes, Steinernema feltiae (Rhabditida: Steinernematidae) Heterorhabditis bacteriophora (Rhabditida: Heterorhabditidae), were determined after exposure for 72 h to two concentrations of the herbicides glyphosate and MCPA, as well as to the combination of the two herbicides (glyphosate + MCPA). For all herbicide treatments, concentrations and exposure times, S. feltiae was more tolerant to the herbicides than H. bacteriophora. The exposure of entomopathogenic nematodes to glyphosate + MCPA caused significantly higher mortality (26.33–57.33%) than glyphosate (0.67–15%) or MCPA (2.33–19%) alone. These results confirm the synergistic effect of the glyphosate + MCPA combination on the mortality in these nematodes. Nematode infectivity of Galleria mellonella larvae in response to the herbicides presence was evaluated in Petri dish assays containing sterile sand. Nematode infectivity was not significantly reduced by exposure to herbicides in S. feltiae but H. bacteriophora was less tolerant. Synergistic effect was obtained in the nematode mortality test but no synergistic effect was observed in the nematode infectivity assay. Our results suggest that possible synergistic effects of agrochemicals on survival of nematodes should be tested before mixing with entomopathogenic nematodes.     

The influence of form of deposit on the phytotoxicity of MCPA, paraquat and glyphosate applied as individual drops

MCPA, paraquat and glyphosate were applied as individual drops (200–400 μm) to pot-grown plants of radish (Raphanus sativus) or wild oat (Avena fatua), using concentrations appropriate to very low volume applications of these herbicides. For a given dose per plant, herbicide activity was unaffected by concentration of MCPA or paraquat but was enhanced as the concentration of glyphosate was increased. The activity of all three herbicides on both species was affected by variation of the site of application but not by drop size. On radish the greatest activity resulted when paraquat was applied to the cotyledons, glyphosate to the interveinal areas of true leaves and MCPA to the veins of true leaves. This is discussed in relation to herbicide mobility and local toxicity following applications at high concentration.     

Use of a model and toxicity data to predict the risks to some wild plant species from drift of four herbicides

The dose responses of 14 wild plant species (two grasses, two legumes, one annual and nine perennial dicotyledons), not usually recognised as weeds, to four herbicides (asulam, glyphosate, MCPA and mecoprop) were measured in glasshouse experiments. Glyphosate was the most toxic; seven of the species tested had EDu, values (measured as shoot dry weight) of < 1.0 μg/plant, compared with only one species for MCPA and mecoprop. Asulam was the least toxic. Results were used to indicate the risk to each species from drift damage. A model of spray drift, based on that developed by Thompson & Ley (1982) for evaporating droplets, was rescaled to allow for field application rates and used to predict the distances travelled by given doses of herbicide. This gave acceptable agreement with reports for drift damage in the field, and predicted that only glyphosate sprayed at the highest recommended concentration might be unsafe to some of the species examined. The two herbicides sometimes used as volatile formulations (MCPA and mecoprop) did not cause damage at the small doses likely to result from exposure to vapour in the field.     

除草剂对莲草直胸跳甲存活与繁殖的影响

【背景】除草剂应用是目前防治空心莲子草的主要措施之一,但其可能对空心莲子草的重要天敌昆虫莲草直胸跳甲的存活、发育和繁殖产生不利影响;为了协调应用化学除草剂和莲草直胸跳甲联合控制空心莲子草的防治措施,本研究探明了除草剂对莲草直胸跳甲的安全性。【方法】采用空心莲子草叶片喷施除草剂后饲喂莲草直胸跳甲的方法,测定了使它隆、农达和稻杰3种除草剂对莲草直胸跳甲成虫和3龄幼虫的取食和存活、幼虫化蛹和成虫产卵的影响。【结果】使它隆对莲草直胸跳甲成虫产卵量的影响较小,喷施农达则显著降低莲草直胸跳甲的产卵量,稻杰的影响居中。连续取食除草剂处理的叶片5d,莲草直胸跳甲成虫取食量均显著降低,3种除草剂的影响为使它隆〉农达〉稻杰。农达对莲草直胸跳甲幼虫的取食量影响较大,取食高浓度农达处理的叶片3d后,其幼虫停止取食;稻杰影响较小。除草剂对莲草直胸跳甲雌虫影响较小,存活率较高。【结论与意义】3种供试除草剂中,稻杰对莲草直胸跳甲最安全,以0.9L.ha-1浓度最佳,在空心莲子草的综合治理中可与莲草直胸跳甲协同应用。     

The effect of some herbicides on lactate dehydrogenase activity

The effect of herbicides N-(phosphonomethyl)glycine (glyphosate), 2-methyl-4-chlorophenoxyacetic acid (MCPA), 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine (atrazine) and the respective commercial preparations “Round-up”, “Aminex”, and “Zeazin”, on the activity of lactate dehydrogenase isolated from germinating soybean seeds and beef heart were compared. The main aim of the work was to compare the effect of the herbicides on lactate dehydrogenase isolated from animal and plant material. Simultaneously the effect of herbicides and the respective commercial preparations was compared. Substantial differences resulting from the two comparisons indicate differences in the structure of active centres of lactate dehydrogenase isolated from animal and plant material, and also a considerable effect of additives and surfactants in commercial preparations.     

水分亏缺和施氮对冬小麦生长及氮素吸收的影响

利用管栽试验研究了不同生育期,水分亏缺和施氮对冬小麦生长及氮素吸收的影响.结果表明：任何生育期水分亏缺都会影响冬小麦的株高、叶面积、干物质累积及对氮素的吸收.冬小麦对水分亏缺的敏感期为拔节期,其次为开花期、灌浆期和苗期.苗期干旱后复水对后期生长有显著的补偿效应,开花期适度干旱后复水对生物量形成和氮素吸收有一定的补偿作用,拔节期干旱对小麦的生长影响明显.相同氮肥处理下, 与不亏水处理比较, 苗期水分亏缺、拔节期水分亏缺、开花期水分亏缺、灌浆期水分亏缺的根系氮素积累量分别平均降低25.82%、55.68%、46.14%和16.34%,地上部氮素积累量分别平均降低33.37%、51.71%、27.01%和2.60%.在相同水分处理下冬小麦含氮量、累积吸收氮量都表现为高氮处理（0.3 g N·kg^-1FM）>中氮处理（0.2 g N·kg^-1FM）>低氮处理（0.1 g N·kg^-1FM）.水分逆境条件下施用氮肥对冬小麦植株生长和干物质累积及氮吸收具有明显的调节效应.