Mepiquat chloride increases the Cry1Ac protein content of Bt cotton under high temperature and drought stress by regulating carbon and amino acid metabolism

The effects of mepiquat chloride(DPC)on the Cry1Ac protein content in Bacillus thuringiensis(Bt)cotton boll shells under high temperature and drought stress were investigated to provide a theoretical reference for Bt cotton breeding and high-yield and-efficiency cotton cultivation.This study was conducted using Bt cotton cultivar‘Sikang 3'during the 2020 and 2021 growing seasons at Yangzhou University Farm,Yangzhou,Jiangsu Province,China.Potted cotton plants were exposed to high temperature and drought stress,and sprayed with either 20 mg L^(-1)DPC or water(CK).Seven days after treatment,the Cry1Ac protein content,α-ketoglutarate content,pyruvic acid content,glutamate synthase activity,glutamic oxaloacetic transaminase activity,soluble protein content,and amino acid content were measured,and transcriptome sequencing was performed.DESeq was used for differential gene analysis.Under the DPC treatment,the Cry1Ac protein content increased by 4.7-11.9% compared to CK.Theα-ketoglutarate content,pyruvic acid content,glutamate synthase activity,glutamic oxaloacetic transaminase activity,soluble protein content,and amino acid content all increased.Transcriptome analysis revealed 7,542 upregulated genes and 10,449 downregulated genes for DPC vs.CK.Gene ontology(GO)and Kyoto Encyclopedia of Gene and Genomes(KEGG)analyses showed that the differentially expressed genes were mainly involved in biological processes,such as carbon and amino acid metabolism.For example,genes encoding 6-phosphofructokinase,pyruvate kinase,glutamic pyruvate transaminase,pyruvate dehydrogenase,citrate synthase,isocitrate dehydrogenase,2-oxoglutarate dehydrogenase,glutamate synthase,1-pyrroline-5-carboxylate dehydrogenase,glutamic oxaloacetic transaminase,amino-acid N-acetyltransferase,and acetylornithine deacetylase were all significantly upregulated.The DPC treatment increased pyruvate,α-ketoglutarate,and oxaloacetate by increasing the operational rate of the glycolytic pathway of the citric acid cycle.It also significantly upregulated the genes encoding glutamate synthase,pyrrolidine-5-carboxylic acid dehydrogenase,glutamate oxaloacetate transaminase,and N-acetylglutamate synthetase,while it downregulated the genes encoding glutamine synthetase.Therefore,the synthesis of aspartic acid,glutamic acid,pyruvate,and arginine increased after treatment with DPC,and the Cry1Ac protein content was increased by regulating carbon and amino acid metabolism.

Effects of mepiquat chloride on yield and main properties of cottonseed under different plant densities

Background:Cottonseed oil and protein content as well as germination traits are major indicators of seed quality.However,the responses of these indicators to plant density and mepiquat chloride(MC)are still uncertain.To investigate plant density and MC effects on cotto nseed yield and main quality parameters,we con ducted a twoyear field experiment including four plant densities(1.35,2.55,3.75 and 4.95 plants·m^-2)and two closes of MC(0 and 135g·hm^-2)in Dafeng,Jiangsu Province,in 2013 and 2014.Results:The application of MC reduced plant height,fruit branch length and fruiting branch number under different plant densities,resulting in a lower and more compact plant canopy.Cottonseed yield showed a nonlinear increase as plant density increasing and achieved the highest value at 3.75 plants·m^-2,regardless of MC application.No significant interactio ns were found between plant density and MC for cotton seed yield and quality parameters.The 100-seed weight,cottonseed oil content and vigor index significantly decreased as plant density increased,while these parameters significantly increased with MC applying under different plant densities.Seed vigor index was positively correlated with 100-seed weight and seed oil con tent across different plant densities and MC treatments.Conclusions:Thus,application of MC could realize a win-win situation between cottonseed yield and main quality parameters under various densities;and plant density of 3.75 plants·m^-2 combined with 135 g·hm^-2 of MC applying is optimal for high cottonseed yield and quality in this cotton production area.

Cotton maturity and responses to harvest aids following chemical topping with mepiquat chloride during bloom period

Early maturity, complete defoliation and boll opening are essential for the efficient machine harvesting of cotton. Chemical topping, involving one extra application of mepiquat chloride(MC) in addition to its traditional multipleapplication strategy, may be able to replace manual topping. However, it is not known whether this chemical topping technique will influence maturity or cotton responses to harvest aids. In this 2-yr field study, we determined the effects of the timing of chemical topping using various rates of MC on boll opening percentage(BOP) before application of harvest aids(50% thidiazuron··ethephon suspension concentrate, referred to as TE), and the defoliation percentage(DP) and BOP 14 days after TE application. The results indicated that late chemical topping(near the physiological cutout, when the nodes above white flower is equal to 5.0) significantly decreased BOP before TE by 5.9–11.2% compared with early(at peak bloom) or middle(seven days after peak bloom) treatments in 2019, which was a relatively normal year based on crop condition. Also, a high MC rate(270 g ha) showed a significantly lower(22.0%) BOP before TE than low(90 g ha) or medium(180 g ha) rates. In 2020, which was characterized by stronger vegetative growth in the late season, the late chemical topping reduced the number of leaves before TE application relative to early or middle treatments, but had lower DP(23.2–27.2%) 14 days after TE application. The high MC rate showed a leaf count before TE application that was similar to the low and medium rates, but it showed the most leaves after TE and much lower(15.0–21.7%) DP in 2020. These results suggest that late timing of chemical topping and a high MC rate decreased the sensitivity of leaves to harvest aids. Further analysis indicated that the late chemical topping mainly affected the leaf drop from the mainstem and fruiting branches where the late regrowth occurred, and the high MC rate reduced leaf shedding from these parts and also from the vegetative branches. In conclusion, chemical topping with MC during the bloom period affected cotton maturity and responses to harvest aids in different ways according to the crop condition. To avoid the risks of delayed maturity and poor defoliation after the application of harvest aids, chemical topping should not be performed too late(i.e., near the physiological cutout) by using MC at more than 180 g ha. The optimum timing of chemical topping probably varies from peak bloom to around seven days later, and the safest MC rates for chemical topping should be less than 180 g ha.

Effects of plant density and mepiquat chloride application on cotton boll setting in wheat–cotton double cropping system

Sowing cotton directly after harvesting wheat in the Yangtze River Valley of China requires early mature of cotton without yield reduction.Boll-setting period synchronisation and more yield bolls distributed at the upper and middle canopy layers are also required for harvesting.The objective of this study is to quantify the individual and interaction effects of plant density and plant growth regulator mepiquat chloride(MC)on temporal and spatial distributions of yield bolls,as well as yield and yield components.During the 2013–2016 cotton growing seasons,the experiments were conducted on a shortseason cotton cultivar CRRI50 at Yangzhou University,China.Various combinations of plant density(12.0,13.5 and 15.0 plants m^(–2))and MC dose(180,270 and 360 g ha^(–1))were applied on cotton plants.The combination of 13.5 plants m^(–2)and 270 g ha^(–1)MC resulted in the greatest boll number per unit area,the highest daily boll setting number and more than 90%of bolls positioned within 45–80 cm above the ground.In conclusion,appropriate MC dose in combination of high plant density could synchronize boll-setting period and retain more bolls at the upper and middle canopy layers without yield reduction in the system of direct-seeded cotton after wheat harvest,and thus overcome the labor-intensive problem in current transplanting cropping system.

Effects of mepiquat chloride and plant population density on leaf photosynthesis and carbohydrate metabolism in upland cotton

Background Mepiquat chloride(MC)application and plant population density(PPD)increasing are required for modern cotton production.However,their interactive effects on leaf physiology and carbohydrate metabolism remain obscure.This study aimed to examine whether and how MC and PPD affect the leaf morpho-physiological characteristics,and thus final cotton yield.PPD of three levels(D1:2.25 plants·m^(-2),D2:4.5 plants·m^(-2),and D3:6.75 plants·m^(-2))and MC dosage of two levels(MC0:0 g·ha^(-2),MC1:82.5 g·ha^(-2))were combined to create six treatments.The dynamics of nonstructual carbohydrate concentration,carbon metabolism-related enzyme activity,and photosynthetic attributes in cotton leaves were examined during reproductive growth in 2019 and 2020.Results Among six treatments,the high PPD of 6.75 plants·m^(-2)combined with MC application(MC1D3)exhibited the greatest seed cotton yield and biological yield.The sucrose,hexose,starch,and total nonstructural carbohydrate(TNC)concentrations peaked at the first flowering(FF)stage and then declined to a minimum at the first boll opening(FBO)stage.Compared with other treatments,MC1D3 improved starch and TNC concentration by 5.4%~88.4%,7.8%~52.0% in 2019,and by 14.6%~55.9%,13.5%~39.7% in 2020 at the FF stage,respectively.Additionally,MC1D3 produced higher transformation rates of starch and TNC from the FF to FBO stages,indicating greater carbon production and utilization efficiency.MC1D3 displayed the maximal specific leaf weight(SLW)at the FBO stage,and the highest chlorophyll a(Chl a),Chl b,and Chl a+b concentration at the mid-late growth phase in both years.The Rubisco activity with MC1D3 was 2.6%~53.2% higher at the flowering and boll setting stages in both years,and 2.4%~52.7% higher at the FBO stage in 2020 than those in other treatments.These results provided a explanation of higher leaf senescence-resistant ability in MC1D3.Conclusion Increasing PPD coupled with MC application improves cotton yield by enhancing leaf carbohydrate production and utilization efficiency and delaying leaf senescence.

Mepiquat chloride priming confers the ability of cotton seed to tolerate salt by promoting ABA-operated GABA signaling control of the ascorbate–glutathione cycle

Background Ensuring that seeds germinate and emerge normally is a prerequisite for cotton production,esp.in areas with salinized soil.Priming with mepiquat chloride(MC)can promote seed germination and root growth under salt stress,but its mechanism has not been fully elucidated.In this study,physiological and biochemical experiments revealed that MC-priming promotes the tolerance of cotton seeds to salt stress by increasing the ability of antioxidant enzymes related to the ascorbate-glutathione(AsA-GSH)cycle to scavenge reactive oxygen species(ROS).Results Results revealed that treatment with inhibitors of abscisic acid(ABA)and γ-aminobutyric acid(GABA)biosynthesis reduced the positive effects of MC-priming.Similarly,MC-priming increased the contents of ABA and GABA under salt stress by stimulating the expression levels of GhNCED2 and GhGAD4 and the activity of calmodulin-binding(CML)glutamate decarboxylase(GAD).Further analysis showed that an inhibitor of ABA synthesis reduced the positive impacts of MC-priming on the content of GABA under salt stress,but the content of ABA was not affected by the GABA synthesis inhibitor.Furthermore,a multi-omics analysis revealed that MC-priming increased the abundance and phosphorylation levels of the proteins related to ABA signaling,CML,and Ca^(2+)channels/transporters in the MC-primed treatments,which resulted in increased oscillations in Ca^(2+)in the MC-primed cotton seeds under salt stress.Conclusion In summary,these results demonstrate that MC-mediated ABA signaling operates upstream of the GABA synthesis generated by GAD by activating the oscillations of Ca^(2+)and then enhancing activity of the AsA-GSH cycle,which ensures that cotton seeds are tolerant to salt stress.

适宜氮肥和缩节胺配合施用显著提高棉花“四桃”种子的播种和营养品质

【目的】研究棉花“四桃”种子品质及其对氮肥和缩节胺(DPC)配合施用的响应,为高质量棉花种子高效生产提供科学依据。【方法】2015—2017年,在郑州市黄河滩区进行双因素裂区设计田间试验。主区为3个氮肥用量,即:不施氮肥(N0)、施用常量氮肥(N1,225 kg/hm^(2))和过量氮肥(N2,450 kg/hm^(2));副区为3个DPC用量,即:不喷施DPC(D0)、喷施常量DPC(D1,75 g/hm^(2))和过量DPC(D2,150 g/hm^(2))。测定了棉花“四桃”种子的播种品质(籽指、发芽势和发芽率)和营养品质(总蛋白、粗脂肪、总淀粉、可溶性蛋白和可溶性糖含量)。【结果】“四桃”种子的播种品质和营养品质差异显著,伏桃和早秋桃的籽指以及发芽势和发芽率没有显著差异,二者均显著高于伏前桃和晚秋桃。伏桃和早秋桃的总蛋白和可溶性蛋白含量显著高于伏前桃和晚秋桃,但总淀粉和可溶性糖含量显著低于伏前桃和晚秋桃,“四桃”的粗脂肪含量差异不显著。施用氮肥与DPC均可显著提升“四桃”种子的发芽品质和营养品质。N1处理“四桃”种子的平均籽指与N2没有显著差异,发芽势和发芽率显著高于N2处理;N1处理的种子总蛋白、可溶性蛋白和粗脂肪平均含量显著高于N2处理,但总淀粉、可溶性糖显著低于N2处理。D1处理的种子平均籽指低于D2处理,平均发芽势和发芽率高于D2;D1处理的种子总蛋白、可溶性蛋白、粗脂肪平均含量高于D2,总淀粉、可溶性糖平均含量低于D2。在氮肥与DPC的9个用量组合中,N1D1组合的发芽势、总蛋白、可溶性蛋白和粗脂肪含量均最高,较其他8个处理组合分别增加了3.35%~40.86%、3.80%~43.01%、13.75%~54.86%和1.11%~13.48%。种子的发芽势和发芽率与总蛋白、粗脂肪和可溶性蛋白含量呈极显著正相关,与总淀粉和可溶性糖含量呈极显著负相关。【结论】在黄河流域棉区,棉花伏桃和早秋桃的种子质量明显优于伏前桃和晚秋桃。适宜氮肥与DPC用量组合可显著提高种子总蛋白、粗脂肪和可溶性蛋白含量,降低总淀粉和可溶性糖含量,进而提升发芽势和发芽率。施用常量氮肥(225 kg/hm^(2))配合常量DPC(75 g/hm^(2)),并采收早秋桃和伏桃有利于提升棉花种子质量。

棉籽中胺鲜酯和甲哌鎓残留的HPLC/MS/MS法检测及其膳食摄入风险评估

建立了胺鲜酯和甲哌鎓在棉籽中残留的HPLC/MS/MS法检测方法,并对棉籽中胺鲜酯和甲哌鎓残留量进行了膳食摄入风险评估。胺鲜酯平均回收率分别为88%~97%,相对标准偏差分别为6.6%~7.3%;甲哌鎓平均回收率分别为84%~92%,相对标准偏差分别为3.6%~9.4%;棉籽中胺鲜酯和甲哌鎓的最低检测浓度均为0.01 mg/kg。按本试验设计进行施药,不同采收间隔期棉籽中胺鲜酯和甲哌鎓的残留量分别为≤0.01 mg/kg和≤0.48 mg/kg。胺鲜酯的普通人群国家估计每日摄入量是0.047 mg,占日允许摄入量的3.3%左右;甲哌鎓的国家估算每日摄入量是0.33 mg,占日允许摄入量的2.7%。认为对一般人群健康不会产生不可接受的风险。

解淀粉芽孢杆菌和其他药剂混配对小麦茎基腐病及产量的影响

本研究旨在寻找针对小麦茎基腐病的有效防控措施。试验采用了3种不同的药剂,包括解淀粉芽孢杆菌(≥100亿CFU/mL)AS、甲哌鎓(5%)AS、噻呋酰胺(240 g/L)SC,并进行不同组合处理以评估其对病害的防控效果,探索该病害的最佳防控途径。试验结果显示,苗期调查的结果显示3种药剂组合能显著增加麦苗的4项评价指标,且能显著降低苗期的病株率;在拔节期各处理都能较好的控制小麦茎基腐病的扩散流行,以处理6防控效果最好,病株率为20.00%;灌浆期调查结果表明3种组合能较好控制小麦茎基腐病,病茎率值为23.33%~24.44%,防效为75%以上;测产结果表明3种药剂组合最优,小麦增产率为21.23%以上。试验结果表明,3种药剂组合后使用对于控制该病害能起到较好的防控效果且能使小麦增产,今后生产上可以采用此药剂组合对该病害进行防控。

Exogenous application of bio-stimulants and growth retardants improve nutrient absorption and fiber quality in upland cotton

Background Natural and synthetic plant growth regulators are essential for plant health,likewise these regulators also play a role in increasing organic production productivity and improving quality and yield stability.In the present study,we have evaluated the effects of foliar applied plant growth regulators,i.e.,moringa leaf extract(MLE)and mepiquat chloride(MC)alone and in combination MC and MLE on the conventional cotton cultivar(CIM 573)and transgenic one(CIM 598).The growth regulators were applied at the start of bloom,45 and 90 days after blooming.Results The application of MC and MLE at 90 days after blooming significantly improved the relative growth rate,net assimilation rate,the number of bolls per plant,and seed cotton yield.Likewise,the combined application of MLE and MC at 90 days after blooming significantly boosted the nitrogen uptake in locules,as well as the phosphorus and potassium uptake in the leaves of both cotton cultivars.The application of MLE alone has considerably improved the nitrogen uptake in leaves,and phosphorus and potassium contents in locules of Bt and conventional cotton cultivars.Similarly,Bt cotton treated with MLE at 90 days after blooming produced significantly higher ginning out turn and oil contents.Treatment in combination(MLE+MC)at 90 days after blooming produced considerably higher micronaire value,fiber strength,and staple length in conventional cultivar.Conclusion The natural growth enhancer,MLE is a rich source of minerals and zeatin,improving the nutrient absorption and quality of cotton fiber in both conventional and Bt cotton cultivars.

植物生长调节剂对中国南瓜杂交种植株生长和雌性性状的影响

为探究南瓜雌花的发生规律,调控南瓜开花顺序,降低南瓜母本第1雌花显花节位,简化南瓜杂交制种过程,以制种南瓜杂交种‘JP56’‘JP57’‘JP58’为材料,在苗期对其进行不同组别或浓度乙烯利、甲哌鎓、增瓜灵处理,统计分析南瓜植株生长和性型分化表达情况。结果表明:对南瓜‘JP56’而言,A3处理(3叶1心期喷施0.3 g/L甲哌鎓+1.06 mL/L乙烯利,5叶1心期喷施0.3 g/L甲哌鎓+1.06 mL/L乙烯利+4.0 g/L增瓜灵)第1雌花节位最低,为第9.22节,节长最短,为37.84 mm,均较清水对照显著降低,雌花数较多,为3.39朵,较对照显著增加,为最佳喷药方法;对南瓜‘JP57’而言,A_(2)处理(3叶1心期喷施0.3 g/L甲哌鎓,5叶1心期喷施0.3 g/L甲哌鎓+4.0 g/L增瓜灵)为最佳喷药方法,较对照可显著降低南瓜第1雌花节位至第6.55节,并显著缩短节长至40.20 mm;对南瓜‘JP58’而言,B3处理(3叶1心期喷施乙烯利1.33 mL/L,5叶1心期喷施乙烯利1.33 mL/L+4.0 g/L增瓜灵)较对照可显著增加SPAD值至45.36,显著降低第1雌花节位至第7.33节和显著缩短节长至46.78 mm,为最佳喷药方法,A3处理较对照可显著增加雌花数至3.59朵。生产上可根据具体需求选择相应植物生长调节剂组合的控制方式。

多效唑、缩节胺和矮壮素对花生化学调控效应的比较研究

【目的】筛选出适宜花生生长的植物生长调节剂及其最佳喷施浓度,为花生生产提供技术指导。【方法】以桂花771为试材,设不同浓度3种植物生长调节剂为处理,分别为多效唑（150、250、350、400mg/L）、缩节胺（200、250、300mg/L）和矮壮素（100、150、200mg/L）,调查花生农艺性状和产量。【结果】3种植物生长调节剂对花生植株生长的抑制程度顺序为：多效唑〉缩节胺〉矮壮素。多效唑、缩节胺和矮壮素分别在400、250和200mg/L时对花生植株生长的抑制程度最大。经多效唑处理的桂花771单株荚果数、单株生产力、产量分别较对照降低。250mg/L缩节胺处理花生单株生产力和产量均高于对照,但差异不显著。200mg/L矮壮素处理花生单株荚果数、单株生产力、产量达到最大值,分别比对照增加了15.7%、23.5%和17.0%。【结论】250mg/L缩节胺和100-200mg/L矮壮素可适当降低花生植株的伸长量,提高花生产量,其中200mg/L矮壮素对花生的化学调控增产效应最好。

乙烯利-甲哌鎓复配剂对夏玉米生育及产量的影响

在玉米大喇叭口期叶面喷施乙烯利 -甲哌复配剂 ,能起到改善株型结构、促进同化物分配转运和提高产量的综合效果。具体表现为 :1)增加气生根数和根系干重 ;2 )缩短节间长度、增加茎粗 ,降低株高和穗位高 ,提高茎粗系数 ;3)促进灌浆初期同化物向根系分配、灌浆中期在地上部营养器官内积累、灌浆后期向产量器官转运 ,并有利于玉米提早成熟 ;4 )提高双穗率、增加穗数 ,减少秃尖、增加行粒数 ,显著提高玉米单产。上述结果表明 ,乙烯利 -甲哌复配剂能起到防止倒伏、提早成熟的作用 。

食品中矮壮素和缩节胺分析方法的研究进展

近年来由于植物生长调节剂使用不当引起的食品安全问题逐渐增多,而吸引了众多研究人员对其检测方法的研究。矮壮素和缩节胺是我国农业上广泛使用的植物生长调节剂,随着人们对其残留危害的日益关注,痕量矮壮素和缩节胺的分析技术也在不断发展。文中综述了近年来食品中矮壮素和缩节胺分析前处理技术和测定方法的研究进展,并着重介绍了固相萃取法及液相色谱-质谱法,为进一步研究食品中矮壮素和缩节胺的分析检测方法以及开展风险评估提供参考。

氮肥和DPC用量对棉花叶片叶绿素含量和SPAD值的影响

在大田条件下研究了氮肥和缩节胺(DPC)用量对中早熟棉花品种豫杂35和早熟品种银山1号叶片叶绿素含量、SPAD值的影响。结果表明,随着施氮量或DPC用量的增加,两个品种的叶片叶绿素含量和SPAD值均呈增加趋势。叶片叶绿素含量和SPAD值呈正相关关系,但生育后期叶绿素含量的下降明显快于SPAD值,表现为吐絮期的叶绿素含量显著低于盛铃期,而吐絮期的SPAD值与盛铃期差异不显著。因此,在DPC化控条件下,仍可使用SPAD值进行棉花叶色诊断,但应注意生育后期SPAD值与叶绿素含量的不同趋势。

黄河流域北部棉区棉花缩节胺化学封顶技术

【目的】探讨黄河流域北部棉区应用缩节胺(1,1-dimethyl-piperidinium chloride,DPC)对棉花进行化学封顶的可行性。【方法】于2012—2014年在河北省河间市瀛州镇国欣科技园和北京市中国农业大学上庄实验站进行,共包括6个独立试验。供试棉花品种为国欣棉3号(GX3)、欣抗4号(XK4)、石抗126(S126)和欣试17(XS17)。DPC化学封顶技术分为单独应用常规DPC化控技术(简称DPC)、将常规DPC化控技术与增效型DPC(简称DPC+)相结合(简称DPC+DPC^+)两种方式,以在常规DPC化控基础上进行人工打顶(简称DPC+MT)为对照。【结果】2012和2013年花铃期(7—8月份)多雨,应用DPC化学封顶技术的棉株较高、新生果枝数较多,其中株高较DPC+MT增加10.6—12.3 cm,果枝数增加5.8—7.9台。2014年花铃期干旱少雨,DPC化学封顶的株高与DPC+MT相比无显著差异,新生果枝数不超过3台。DPC化学封顶对棉花产量的影响不显著,但可发现2012年DPC+DPC^+的产量表现出降低趋势,且上部果枝成铃少、新生果枝成铃多,群体熟期有推迟现象。2013和2014年DPC+DPC^+的产量和熟期则与对照相当或略有增减。DPC+的应用时间(7月中旬至7月底)和剂量(750—1 500 m L·hm^(-2))对棉花株型及产量的影响无显著差异,但应避免在结铃盛期(7月底)应用大剂量DPC+(1 500 m L·hm^(-2)),以防延长后期棉铃的成熟。与DPC+DPC^+相比,单独应用常规DPC化控技术进行化学封顶在多雨年份或高密度下对棉株的控长强度较弱,而且存在减产风险。【结论】应用DPC进行化学封顶在黄河流域北部棉区基本可行,实际应用时需要根据气象因子和种植密度决定单独应用常规DPC化控技术还是将常规DPC化控技术与增效型DPC的应用相结合。

离子色谱法同时测定植物生长调节剂中氯化胆碱、甲哌鎓及N-甲基哌啶

建立了一种离子色谱-抑制电导同时测定植物生长调节剂中主要活性成分氯化胆碱、甲哌鎓以及杂质N-甲基哌啶的快速检测方法。样品经稀释过膜后直接进样分析,采用阳离子交换色谱柱thermo scientific ionpac CG17 (50 mm×4 mm)+CS17 (250 mm×4 mm),以10 mmol·L^(-1)甲烷磺酸溶液等度淋洗,可在10 min内完成以上目标分析物的检测,且常规阳离子(Li^+、 Na^+、 NH_4^+、 K^+、 Mg^(2+)和Ca^(2+))不会干扰对3种化合物的测定。在优化后的最佳色谱条件下,氯化胆碱的线性范围为0.1～500 mg·L^(-1),甲哌鎓的线性范围为0.5～500mg·L-1,N-甲基哌啶的线性范围为0.4～200 mg·L^(-1),3种化合物线性相关系数(r)均大于0.999 4,线性关系良好。3种目标分析物的检出限(信噪比S/N=3)为28.0～112.5μg·L^(-1),定量限(信噪比S/N=10)为93.5～375.0μg·L^(-1),峰面积的相对标准偏差(RSD, n=6)均小于0.47%,表明方法具有较好的重现性。该检测方法简单方便,已成功应用于商品化植物生长调节剂中3种成分质量浓度的测定,实际样品加标回收率为96.0%～103.6%。可应用于相关植物生长调节剂原料及成品的质量控制。

植物生长调节剂甲哌鎓在土壤中的降解及其影响因子

植物生长调节剂甲哌鎓(DPC)主要用于防止棉花徒长,在我国的应用面积每年达400万hm2以上,用量为75～300g·hm-2,明确其在土壤中的降解及其影响因子可为评价其环境安全性提供依据。在实验室恒温培养条件下应用紫外分光光度法研究了DPC在土壤中的降解动态,该方法的线性检测范围为0～3.5mg·kg-1,添加浓度为1.0～2.0mg·kg-1时,回收率在74.5%～88.8%之间,标准偏差为3.1%～3.6%,变异系数为3.9%～4.2%。研究结果表明,DPC在土壤中的降解包括微生物降解和化学降解两条途径,化学降解和化学降解+微生物降解的平均降解率分别为1.93和3.12%·d-1,半衰期(T1/2)分别为13.0和7.2d,降解95%所需时间(T0.95)分别为53.8和33.2d。另外,土壤温度和湿度对DPC降解均有显著影响,DPC降解的适宜温度为25℃,适宜湿度为饱和持水量的60%～70%,此时平均降解率为(3.0￣3.5)%·d-1,半衰期为8d左右,降解95%所需时间(T0.95)为30￣35d。根据《化学农药环境安全评价试验准则》,DPC属于易降解农药,对环境的影响较小、安全性较高。

缩节胺浸种提高棉花幼苗根系活力中的活性氧代谢

以国欣棉3号为材料,研究200 mg L–1缩节胺(DPC)浸种12 h对棉花子叶苗根系活力的影响,并从活性氧(ROS)代谢的角度揭示相关的生理机制。结果表明,DPC浸种显著增强了棉花幼苗的根系活力,根尖部位氯化三苯基四氮唑(TTC)染色光密度为清水对照的1.3倍,TTC法测定的根系活力和呼吸速率分别较对照增加167%和90%,非损伤微测技术(NMT)测定的K+净内流速率(距根尖300μm处)较对照提高36%。吖啶橙染色结果显示,DPC处理根尖伸长区的凋亡细胞数目较对照减少。此外,DPC处理使根系的过氧化氢酶(CAT)、抗坏血酸氧化酶(APX)和谷胱甘肽还原酶(GR)活力显著高于对照,超氧化物歧化酶(SOD)活力则降低;H2O2含量和超氧阴离子(O2-)产生速率较对照分别降低56%和65%,H2O2原位染色结果也显示其根尖部分的褐色较对照明显减弱。根系组织的ROS代谢得到改善可能是DPC浸种提高棉花幼苗根系活力的机制之一。

缩节胺对棉蚜种群繁殖的影响

研究不同质量浓度缩节胺对棉蚜触杀作用、忌避作用、成虫寿命及生殖能力和种群增长的影响。结果表明,缩节胺对棉蚜没有触杀作用。在处理后的同一时间内,随处理质量浓度的升高,对棉蚜的忌避作用增强。400mg.L-1、48h的忌避率为33.3%,25mg.L-1、48h的忌避率为18.2%。在同一质量浓度下,随处理时间的延长,对棉蚜的忌避作用增强。到第7天时,400mg.L-1、48h的忌避率为66.4%,25mg.L-1、48h的忌避率为46.2%。处理第1天,棉蚜成虫寿命和生殖能力均未受到抑制,仅400mg.L-1处理的蚜虫寿命减少。随处理时间的延长,棉蚜成虫寿命和生殖能力逐渐下降,说明缩节胺处理对棉蚜成虫寿命和生殖能力的影响与棉花生长时间有关,同时缩节胺对棉蚜种群有较好的抑制作用。