Residues of glyphosate in irrigation water

In investigations to determine the extent of contamination from typical spray applications of glyphosate, a conservative fluorescent tracer was used to predict the theoretical upper limit in channels carying flowing water. Polarographic and bioassay estimations of glyphosate showed reasonable correlation with these predictions for samples collected immediately downstream of the spray zone. The current desirable criteria of 0.1 g m^?3 for drinking water in Australia, and 0.2 g m^?3 approved for irrigation in the United Kingdom would be exceeded, except in sprayed channels of highest cross-sectional area. Only about 7–17% of the glyphosate applied entered the water when a foam spray was routinely directed with a hand-gun on to a marginal growth of Paspalum paspalodes (Michx.) Scribn., and it was calculated that this technique could reduce concentrations in the spray zone to less than 0.1 g m^?3 in many situations. Tributary dilution, dispersion, and adsorption processes also attenuate the contamination downstream. The impact of dispersion processes on dissipation of the glyphosate concentration was relatively small, but the glyphosate concentration was reduced by 63% as a result of adsorption during transport downstream through 2 km of drainage channel containing deep silty sediments.     

Residues of dalapon and TCA in sediments and irrigation water

When dalapon and TCA are used for the management of aquatic weeds in irrigation distribution systems, they are often applied to established stands of Typha spp. and Phragmites australis in autumn or early winter, after draining water from the system. It has been assumed that the herbicides would dissipate from the sediments within 6 weeks, so that water supplies could be safely restored. In field experiments the decay of dalapon and TCA in sediments followed the classical pattern for a microbially mediated process, with a slow lag-phase, followed by a rapid phase of decline, but not to completion. Particularly for TCA, there was a final slow phase in which residues were sufficient to contaminate eluting water at concentrations much greater than the legally prescribed tolerance, even when the interval between herbicide treatment and water re-supply was more than 6 weeks. Although the overall pattern of dissipation in the sediment was similar for the two herbicides, concentrations of TCA were higher than those of dalapon in the elution water, probably reflecting differences in herbicide mobility and elution efficiency. Dye tracers were used in three field experiments to investigate the efficiency of herbicide elution and carryover of contaminated water when canals were filled to capacity, drained and refilled. Together with the rate of dissipation from sediments, canal topography and draining efficiency determined the safety of the elution process in removing surplus residues before re-supply of water for irrigation. In large-scale management operations, where the dissipation interval was only 17-19 days, the TCA was eluted from the sediment into flowing water in proportion to the square root of time, giving average concentrations over 3 days of discharge of more than 0.4gm^?3. Ideally, the interval between spraying and water re-supply should be extended beyond 6 weeks. Alternatively, herbicide use should be restricted, or provision made for elution of surplus residues and disposal of contaminated water to waste, or onto tolerant crops or fallow land.     

水、肥、气耦合滴灌对温室番茄生长和品质的影响

以温室番茄为对象,采用地下滴灌的供水方式,设置施氮量（低氮和常氮）、掺气处理（非曝气和循环曝气）和灌水量（低水量和高水量）3因素2水平随机区组试验,研究水、肥、气耦合滴灌对温室番茄生长与品质的影响。结果表明：循环曝气、高水量和常氮处理可有效促进番茄生长,表现为叶绿素含量增加和净光合速率增强,番茄地上部鲜重、产量提高和品质提升。其中株高和叶绿素含量曝气处理较非曝气处理平均增加9.81%和8.63%（P<0.05）,高水量处理较低水量处理平均增加18.14%和11.44%（P<0.05）,常氮处理较低氮处理平均增加6.58%和8.20%（P<0.05）。就地上部鲜重和产量而言,曝气处理较非曝气处理平均提高14.93%和22.91%（P<0.05）,高水量处理较低水量处理平均提高27.10%和41.19%（P<0.05）,常氮处理较低氮处理平均提高24.89%和40.87%（P<0.05）。株高、叶绿素含量、净光合速率与产量均呈极显著正相关（P<0.01）。可溶性固形物、Vc含量、可溶性蛋白质含量,曝气处理较非曝气处理平均提高16.73%、12.13%、11.59%,总酸含量平均降低11.44%（P<0.05）;高水量处理较低水量处理平均提高16.09%、17.60%、18.99%,总酸含量平均降低16.38%（P<0.05）;常氮处理较低氮处理平均增加12.65%、41.81%、28.03%,总酸含量平均降低7.97%（P<0.05）。本试验中,常氮高水量循环曝气处理（施氮量为180 kg·hm^-2,灌水量为1 237 m³·hm^-2,掺气比率为15%）是促进温室番茄生长和品质提升的适宜水、肥、气组合方案。     

旱区“环状毛细芯渗灌”对葡萄生长发育和果实品质的影响研究

"环状毛细芯渗灌"是利用毛细现象的原理,在已有的毛细直芯基础上增加一个毛细环,通过毛细芯浸润方式给植物根部供水的节水渗灌方法。试验在宁夏自治区永宁县玉泉营农场的红地球(Vitis vinifera L.cv.red globe)葡萄园内进行,灌溉方式为环状毛细芯渗灌与常规沟灌(CK);毛细芯渗灌的灌水次数分为一次和两次,每次灌满一桶水(100L),水由毛细芯慢慢渗出,常规沟灌的灌水次数为两次;环状毛细芯的埋藏深度分为两种:30cm深和土壤表面(0cm深)。试验结果表明,处理0*1(环状毛细芯表面渗灌、一次灌水)下副稍增长量最大,与常规沟灌存在显著差异(P0.05)。在相同灌水量下,处理0*1副稍增长量高于处理30*1(地下30cm深的环状毛细芯渗灌、一次灌水)。处理0*2(表面渗灌、两次灌水)叶中脉长势最好。处理0*2、0*1相比于其它处理果实粒径增长量最大,处理0*1横径增长速度比CK提高了55.6%,这说明环状毛细芯渗灌有效促进了葡萄果实的增长。在相同灌水量下,表面渗灌下葡萄粒径的长势明显好于30cm深的渗灌。处理30*2(地下30cm深的环状毛细芯渗灌、两次灌水)百粒重比相同灌水量下的CK提高了30%。常规沟灌下脯氨酸含量最高,处理30*2脯氨酸含量最低;在相同灌水量下,表面渗灌下脯氨酸含量高于30cm深的渗灌,这说明30cm深的毛细芯渗灌能较好地减轻植物的水分胁迫。处理30*2与30*1的可溶性固形物较高,处理30*1的糖酸比最高;在相同灌水量下,30cm深的渗灌下葡萄糖酸比高于表面渗灌。从最终产量和果实品质的角度看,处理30*2是旱区葡萄着色期~成熟期最好的组合。     

不同基质下咸、淡水灌溉对番茄生长和品质的影响

设置草炭(P)、草炭+蚯蚓粪(PE)、草炭+生物炭(PB)3种栽培基质,以及微咸水灌溉(b)和淡水灌溉(f)两种灌溉水质,共6个处理,分析栽培基质和灌溉水质对番茄植株生长、光合荧光特性、果实品质和产量的影响。结果表明,各基质处理在淡水和微咸水灌溉下株高和茎体积相对生长率均无显著差异。与草炭处理相比,在淡水灌溉下PE_f显著增加果实可溶性糖11.17%以及可溶性固形物19.84%,PB_f处理显著增加总生物量32.01%和地上部干物质量32.21%;在微咸水灌溉下PE_b、PB_b均显著增加总生物量和地上部生物量,分别为49.41%、63.59%和54.04%、61.27%,且PE_b显著增加光合速率13.2%和气孔导度381.75%,PB_b显著增加光合速率、气孔导度、WUE、qP、ETR,分别为32.69%,71.94%,23.27%,58.87%、14.35%。在相同基质下,PE_b相对PE_f显著增加蒸腾速率49.29%、气孔导度222%和Fm 5.6%,PB_b相对PB_f增加果实Vc含量37.43%和可溶性糖6.25%。在微咸水灌溉下各基质处理产量低于淡水处理,但是相比草炭处理,草炭添加生物炭产量增加32.26%。综合分析表明,在相同基质下,P_b和PB_b相对于淡水灌溉显著降低了综合得分,提高了PE_b的综合得分,且微咸水灌溉下相对P_b处理,PE_b、PB_b均增加了综合得分。因此草炭添加生物炭和蚯蚓粪均有利于缓解微咸水胁迫,提高作物生物量,但根据隶属函数综合排名,在淡水和微咸水灌溉下,草炭添加生物炭处理对番茄生长效果均为最优。     

河谷区地下水人工回灌试验研究

河谷区采用现场坑灌和井灌试验,通过测定回灌量衰减和渗透系数的变化来分析回灌效果.坑灌回灌量中期衰减24%,后期衰减40%,在整个回灌过程中区域水位上升1.1～1.3 m,实际形成水丘规模很小,反映出试验层水平渗透能力强.井灌初期回灌量衰减33%,在后期基本稳定,但总趋势仍在衰减,含水层渗透系数以主孔为中心,由远到近渗透...     

尾菜再生水灌溉对土壤酶活性与重金属含量的影响

为探究尾菜再生水灌溉对土壤酶活性和重金属含量的影响，采用室内土柱模拟试验，分别以尾菜再生水(VW)和自来水(TW)为灌溉水，设置充分灌溉(90%田间持水量，09FC)和非充分灌溉(70%田间持水量，07FC)2个灌水水平，以18 d为1个灌水周期，累计灌溉16期，分别在第72、144、216、288 d进行分层取样，测定土壤过氧化氢酶(CAT)、脲酶(UE)、蔗糖酶(IA)、碱性磷酸酶(ALP)活性及重金属(Pb、Zn、Cr、Cd、Cu)含量的时空变化特征，并对各处理进行相关性分析和潜在生态风险评价。结果显示，与TW-07FC处理相比，长期再生水非充分灌溉0～20 cm土层土壤UE、IA活性分别显著提高了31.36%和6.55%;与TW-09FC处理相比，再生水充分灌溉ALP活性显著提高了15.63%,CAT活性无显著性变化；随着灌溉次数的增加，再生水2个灌水水平均会增加土壤Pb、Cr、Zn含量，但增加效果不显著，土壤Cd含量与自来水灌溉相比无显著变化(P>0.05),土壤Cu含量有降低的趋势；由相关性分析可知，CAT活性与Cu、Zn含量呈极显著正相关关系(P<0.01);...     

紫茎泽兰化学防除试验

为探究低毒、低残留、高效的药剂防除紫茎泽兰的方法,选用50%特丁赛草隆、75%苄.草苷、41%草甘膦异丙胺盐、50%草甘膦等4种药剂,在紫茎泽兰生长期和非生长期实施叶片正反面喷施试验。结果表明,以41%草甘膦异丙胺盐水剂、50%草甘膦可湿性粉剂效果较好。41%草甘膦异丙胺盐水剂150 mL＋水125 00 g（浓度为1.16%）株防效达100%,50%草甘膦按50 g＋洗衣粉10 g＋水12 500 g株防效达75.33%。同种药剂生长期较非生长期防除效果好,41%草甘膦异丙胺盐水剂在生长期浓度达1.16%时株防效达100%,而在非生长期浓度为1.6%时株防效仅达62.6%。     

Factors affecting glyphosate activity in Imperata cylindrica (L.) Beauv. and Cyperus rotundus L. II: effect of shade

Imperata cylindrica and Cyperus rotundus were grown under three different light regimes; unshaded, 50% shade, and 75% shade and no shade plus 75% shade before and after spraying, (temporary shade) in a heated greenhouse. Six weeks after the start of the experimenis, glyphosate was applied to the plants at 0·2, 0·4 and 0·8 kg/ha (for Imperata) or 0·3, 0·6 and 1·2 kg/ha (for Cyperus). Glyphosate toxicity was enhanced as shade increased. In Imperata, all shade regimes at all rates of glyphosate eaused greater damage to the plants than the unshaded regime. The reduction in shoot dry weight, rhizome dry weight and total carbohydrate content of Imperate rhizotties at 75% continuous and temporary shaiie conditions, with the lowest rate of glyphosate, was almost twice as much as the reduction in the same features m the unshaded plants caused by the highest rate of glyphosate. In Cyperus. glyphosate at the intermediate and highest rates decreased the shoot dry weight at 75% continuous shade by 79% and 98% respectively. Plants in 50% shade were significantly affected only at the highest rate of glyphosate. Sprouting ability of the tubers al 75% continuous shade was inhibited when the tubers were replanted for recovery. Enhanced toxicity of glyphosate in reduced light intensity was attributed to the morphological changes in the nature of the leaves caused by shade.     

Fate of glyphosate in soil and the possibility of leaching to ground and surface waters: a review

The very wide use of glyphosate to control weeds in agricultural, silvicultural and urban areas throughout the world requires that special attention be paid to its possible transport from terrestrial to aquatic environments. The aim of this review is to present and discuss the state of knowledge on sorption, degradation and leachability of glyphosate in soils. Difficulties of drawing clear and unambiguous conclusions because of strong soil dependency and limited conclusive investigations are pointed out. Nevertheless, the risk of ground and surface water pollution by glyphosate seems limited because of sorption onto variable-charge soil minerals, e.g. aluminium and iron oxides, and because of microbial degradation. Although sorption and degradation are affected by many factors that might be expected to affect glyphosate mobility in soils, glyphosate leaching seems mainly determined by soil structure and rainfall. Limited leaching has been observed in non-structured sandy soils, while subsurface leaching to drainage systems was observed in a structured soil with preferential flow in macropores, but only when high rainfall followed glyphosate application. Glyphosate in drainage water runs into surface waters but not necessarily to groundwater because it may be sorbed and degraded in deeper soil layers before reaching the groundwater. Although the transport of glyphosate from land to water environments seems very limited, knowledge about subsurface leaching and surface runoff of glyphosate as well as the importance of this transport as related to ground and surface water quality is scarce.     

A target-site mutation is present in a glyphosate-resistant Lolium rigidum population

Annual ryegrass (Lolium rigidum) is the only weed species to have evolved resistance to the broad‐spectrum herbicide glyphosate in Australia. A population that had failed to be controlled by glyphosate was collected from a vineyard in the Adelaide Hills region of South Australia. Dose–response experiments on this population (SLR 77) showed that it was glyphosate resistant, with an LD₅₀ that was 1.9–3.4 times higher than that of a susceptible population (VLR 1). The movement of radiolabelled glyphosate within SLR 77 plants showed that this population did not have the differential glyphosate translocation mechanism of resistance common to several other Australian glyphosate‐resistant populations. Subsequent analysis of shikimic acid accumulation within the plant after glyphosate treatment showed that this population accumulated significantly less shikimic acid than a susceptible population, but more than a glyphosate‐resistant population with the translocation mechanism, indicating the possible involvement of another mechanism of resistance. Sequencing of a portion of the SLR 77 5‐enolpyruvylshikimate‐3‐phosphate synthase gene was carried out and a mutation causing an amino acid change at position 106 from proline to threonine was identified. This mutation is likely to be responsible for glyphosate resistance in this population, as mutations in this position have been found to be responsible for glyphosate resistance in goosegrass (Eleusine indica) from Malaysia. This paper represents the first report of target‐site glyphosate resistance in L. rigidum and provides evidence that this species has at least two mechanisms of glyphosate resistance present in Australia.     

根据气象信息指导南疆棉花膜下滴灌的试验研究

为了探索利用气象信息指导膜下滴灌棉花科学灌溉的可行性,在南疆阿拉尔布设田间试验,根据自动气象站采集的气象信息计算作物蒸发蒸腾量（ET_c）,当蒸发蒸腾量与降水量的差值累计达到30 mm时即进行灌溉。试验设置3个灌水定额处理,T1：24 mm,T2：30 mm,T3：36 mm,分别为水分亏缺量的0.8,1.0和1.2倍,同时设置1个当地生产中的常规灌溉处理作为对照（T4）,重复3次。试验过程中,对不同处理棉田的土壤水分动态变化、植株生理指标、籽棉及皮棉产量、灌溉水利用效率和田间水利用效率进行了监测与分析。结果表明：根据气象信息指导灌溉的处理生育期耗水量在361.8~435.2 mm,且灌水定额越大,全生育耗水量越多,但均显著低于常规灌溉处理522.1 mm的总耗水量。根据气象信息确定灌溉时间的处理,籽棉产量与灌水定额呈显著的正相关关系,T3处理籽棉产量7 072.05 kg·hm^-2与T4对照处理7 245.28 kg·hm^-2的籽棉产量无显著差异,但灌水量却减少了164 mm;灌溉水利用效率随着灌水定额的增加而减小,但均显著高于对照处理。综合灌水量、产量及水分利用效率等因素考虑,认为当棉田作物蒸发蒸腾量与降水量的差值累计达到30 mm灌溉+灌水定额36 mm的组合,可以在保证棉花不减产的条件下,显著提高灌溉水利用效率和田间水利用效率,适用于南疆地区根据气象信息指导膜下滴灌棉花的灌溉管理。     

Management of submerged aquatic macrophytes with terbutryne: availance, phytotoxicity and persistence

In ideal conditions (static assay with long exposure time) several species of submerged weeds (Myriophyllum propinquum A. Cunn, Potamogeton tricarinatus F. Muell and A. Benn, and Vallisneria gigantea Graebner) were controlled by terbutryne at initial concentrations of <0·2 g m^?3. However, since water management practices in irrigation systems limit the contact time which can be imposed, the availance (concentration-time integral required for effectiveness) was further investigated, using Elodea canadensis Rich., which is dominant and widespread in the irrigation systems of south-eastern Australia. In many experiments in irrigation channels, where control was poor, contact times were probably inadequate. Other factors may also contribute to inefficiency, including poor penetration of the weed beds after surface application, protection by high loadings of aufwuchs (periphyton, bacteria, detritus and associated particulate matter) on the leaves in the autumn, and inhibition of photosynthesis in an unfavourable light climate. Weed control was improved by injecting the herbicide into Mowing water, before ponding the treated water in the channels in spring or summer for at least 11 days. Terbutryne residues in the water decreased with a first order half-life of about 9–20 days. Therefore, terbutryne is unsuitable for pulse injection treatment of flowing water in summer. Instead, effective control might be achieved by ponding the treated water in the channels in spring before the period of great water demand for summer crops. Contaminated water would be discarded onto tolerant crops or fallow land or retained in the system for about 7 weeks to ensure degradation of terbutryne before reuse.     

Occurrence and mobility of the insecticide permethrin in rivers in the Southern Humber catchment,UK

The synthetic pyrethroid insecticides cis‐ and trans‐permethrin are widely used, particularly in sheep‐dips and for mothproofing within the textile industry. This study aims to establish the concentrations and mobility of permethrin within rivers in the Humber catchment, which contain some of the highest densities of wool‐scouring activity in the world. Our approach was to utilise three different surveys: (a) weekly and storm‐responsive sampling of ‘whole waters’ in the rivers Aire, Ouse, Don, Trent and Calder; (b) intensive sampling of ‘whole waters’ and suspended sediments in the rivers Aire (0.5 h) and Calder (1 h); (c) a bed‐sediment survey of the River Calder. Sediments were extracted by supercritical fluid extraction and all samples were analysed by gas chromatography with mass spectrometry. Results demonstrated the presence of permethrin in ‘whole waters’ and sediments, particularly in the rivers Aire and Calder, and at concentrations in the bed‐sediment likely to cause ecotoxicological effects to benthic macro‐invertebrates. Mass‐balance calculations indicated some loss of permethrin from the water column during transport, with the greatest losses at low river‐discharge. Isomer ratios (trans:cis) give retention times of permethrin in different components of the system as ‘whole water’ < suspended sediments < bed‐sediments, with estimates of 4–26 days for suspended sediments and a maximum of 103–125 days for surface bed‐sediments. © 2000 Society of Chemical Industry     

Fate of glyphosate in Agropyron repens (L.) Beauv. growing under low temperature conditions

Absorption, translocation and distribution of ¹⁴C-glyphosate were examined in Agropyron repens (L.) Beauv. plants growing under field conditions in the autumn. Glyphosate absorption did not increase beyond 3 days after application, whereas translocation to the rhizomes continued up to 7 days after application. The translocated glyphosate accumulated more in new rhizomes than in older parts of the rhizomes. Ten per cent of the glyphosate translocated out of the treated shoot was recovered in younger shoots 7 days after application. Plants harvested the following spring contained less than 20% of the glyphosate originally applied. Although a growth cabinet experiment indicated that 34% of the glyphosate in the rhizomes of treated plants could be remobi-lized into new aerial shoots, considerably less was recovered in new, aerial shoots in the spring in the field-grown plants. Freezing experiments showed that glyphosate translocation to the rhizomes was only prevented when cold treatment caused visible damage to A. repens foliage.     

“超纤渗灌”对摩尔多瓦葡萄生长与果实品质的影响研究

“超细纤维”渗灌是一种通过纤维毛细作用，将水分从超细纤维毛细芯传递到植物根部土壤的节水灌溉方式。试验在宁夏永宁县玉泉营农场的摩尔多瓦（Vitis vinifera L.cv. Moldova）葡萄园中进行，灌溉方式分为环状超细纤维表面渗灌（A*0）、埋深10 cm的环状超细纤维渗灌（A*10）和常规沟灌（CK），每株单次灌水量为30 L，灌水周期为1个月。结果表明，在相同的灌水量下，A*10和A*0的土壤含水量变化较CK更稳定，叶水势总体上高于CK，说明“超细纤维”渗灌能够维持较为稳定的水分状态，延缓了葡萄所遭受的水分胁迫。A*10和A*0的副梢生长量比CK分别提高了92%和57%；A*10的粒重比CK提高了8.1%，且A*10的产量比CK提高46.8%，说明“超细纤维”渗灌对葡萄的生长起到了促进作用。A*0和A*10的果粒可滴定酸和可溶性固形物水平与CK差异不大。成熟期A*0和A*10的果粒脯氨酸含量低于CK，是由于“超细纤维”渗灌能够缓解葡萄所受到的水分胁迫；A*0和A*10的花色苷含量高于CK，分别比CK提高了5.2%和14.3%，表明A*10供水均匀连续，有利于花色苷的累积。收获时，A*0和A*10的可溶性蛋白含量高于CK，其中A*10比CK高29%。，说明“超细纤维”渗灌有助于葡萄可溶性蛋白的合成。因此，“超细纤维”渗灌不仅比沟灌水分利用效率高，且能在一定程度上提高葡萄品质。     

Surfactant and salt affect glyphosate retention and absorption

The influence of nonylphenoxy surfactants and glyphosate salt formulation on spray retention, phytotoxicity and [¹⁴C]glyphosate uptake was investigated in wheat (Triticum aestivum L). and Kochia scoparia L. The amount of spray retained, and uptake of [¹⁴C]glyphosate increased with increasing hydrophilic-lipophilic balance (HLB) value of surfactants. The volume of spray delivered to the plant treatment area and retained by wheat and K. scoparia plants increased with increasing surfactant HLB values, but this only partly accounted for the higher spray retention. Spray retention by leaves of plants was not affected by calcium chloride, either alone or with ammonium sulphate in the glyphosate spray solution. [¹⁴C]Glyphosate absorption by wheat and K. scoparia was reduced by calcium chloride alone, but not in mixtures with ammonium sulphate, regardless of surfactant. Phytotoxicity and uptake of glyphosate salt formulations for wheat was: isopropylamine > ammonium > sodium > calcium; these results indicate that the surfactant selected is important to maintain glyphosate efficacy and that sodium and calcium cations antagonize glyphosate by forming salts that are absorbed less than commercial isopropylamine formulations.     

滴灌水钾一体化对猕猴桃光合特性的影响

为探明不同滴灌水钾一体化管理对猕猴桃光合特性的影响,以8 a生金艳猕猴桃为试材,设置对照处理CK（在果实膨大期即III期、果实成熟期即IV期灌水量分别为31.2、26.4 m³·667m^-2,施钾量分别为6.0、7.8 kg·667m^-2）,在III、IV期分别设置3个亏水水平（即轻度、中度、重度水分亏缺,记为LD、MD、SD,灌水量分别为CK的80%、60%、40%）和2个施钾水平（即低钾、高钾,记为LK、HK,施钾量分别为CK的60%和80%）。结果表明：果实膨大期、果实成熟期不同滴灌水钾一体化处理的光合指标日变化趋势相似;LD处理下叶片净光合速率（Pn）、蒸腾速率（Tr）、气孔导度（Gs）、瞬时水分利用效率（WUEi）、羧化速率（CE）均随施钾量增加而增大,果实膨大期LDHK处理的Pn、CE较LDLK处理分别高15.71%、16.80%,果实成熟期LDHK处理的Pn、Gs较LDLK处理分别高6.07%、12.76%,差异达显著水平（P<0.05）;SD处理下,除胞间CO₂浓度（Ci）外各光合指标均较CK显著下降（P<0.05）;MD处理下,除Ci、WUEi外各光合指标均较CK显著下降（P<0.05）;施钾量一定时,除Ci、WUEi外各指标均随灌水量增加而显著增大（P<0.05）,增幅为11.42%~64.40%;与CK处理相比,果实膨大期LDHK处理Pn提高11.38%（P<0.05）,WUEi提高3.06%,CE提高10.83%;IV-LDHK处理Pn提高0.96%,WUEi提高2.00%。综合比较采用果实膨大期LDHK处理及果实成熟期LDHK处理,可在相应生育期节水节肥20%,日光合能力较强,是猕猴桃较适宜的滴灌水钾一体化管理模式。     

The effect of the herbicide glyphosate on non‐target spiders: Part I. Direct effects on Lepthyphantes tenuis under laboratory conditions

We examined the toxic effects of glyphosate to adult female Lepthyphantes tenuis (Araneae, Linyphiidae), a common spider of agricultural habitats. The overspray technique was used to investigate the effect of the herbicide on forty individuals in each of six glyphosate treatments (2160, 1440, 1080, 720, 360 and 180 g ha^?1) and a distilled water control. Spiders collected from the wild were individually placed in exposure chambers and checked every 24 h over a 72‐h experimental period. Mortality of L tenuis remained at less than 10% in all treatments at 24 and 48 h after spray application, and only increased marginally (to 13%) after 72 h. These results support other limited data which suggest that glyphosate is ‘harmless’ to non‐target arthropods. More extended laboratory testing to investigate any side‐effects of glyphosate on the life history of L tenuis and other non‐beneficial invertebrates is required. © 2001 Society of Chemical Industry     

Measurement and modelling of glyphosate fate compared with that of herbicides replaced as a result of the introduction of glyphosate-resistant oilseed rape

BACKGROUND: Crops resistant to glyphosate may mitigate the increasing contamination of the environment by herbicides, since their weeding requires smaller amounts of herbicides and fewer active ingredients. However, there are few published data comparing the fate of glyphosate with that of substitute herbicides under similar soil and climatic conditions. The objectives of the work reported here were (i) to evaluate and compare the fate in soil in field conditions of glyphosate, as used on glyphosate-resistant oilseed rape, with that of two herbicides frequently used for weed control on the same crop, albeit non-resistant: trifluralin and metazachlor, and (ii) to compare field results with predictions of the pesticide root zone model (PRZM), parameterized with laboratory data. Dissipation and vertical distribution in the soil profile of glyphosate, trifluralin and metazachlor were monitored in an experimental site located in Eastern France for 1 year. RESULTS: Herbicide persistence in the field increased as follows: metazachlor < glyphosate < trifluralin, contrary to laboratory results showing glyphosate to be least persistent. The main metabolite of glyphosate-aminomethylphosphonic acid (AMPA)-was more persistent than glyphosate. AMPA and trifluralin had the largest vertical mobility, followed by metazachlor and glyphosate. PRZM underestimated the dissipation rate of glyphosate in the field and the formation of AMPA, but its predictions for trifluralin and metazachlor were correct. The simulation of herbicides and AMPA distribution in the soil profile was satisfactory, but the mobility of trifluralin and metazachlor was slightly underestimated, probably because PRZM ignores preferential flow. In general, data from the laboratory allowed an acceptable parameterization of the model, as indicated by goodness-of-fit indices. CONCLUSION: Because of the detection of AMPA in the deep soil layer, the replacement of both trifluralin and metazachlor with glyphosate might not contribute to decreasing environmental contamination by herbicides. PRZM may be used to evaluate and to compare other weed control strategies for herbicide-resistant as well as non-resistant crops.