氟噻草胺与氟唑磺隆混配协同作用及在小麦田杂草防治中的应用

本文通过室内生物测定研究了氟噻草胺与氟唑磺隆对小麦及多花黑麦草的活性,田间试验测定了二者混配对阔叶杂草的防效及对小麦分蘖数的影响。室内水培法测定结果表明,氟噻草胺、氟唑磺隆对多花黑麦草有效抑制中剂量(ED50)分别为0.37mg/L和105.91mg/L,氟噻草胺与氟唑磺隆混配比例为8∶2、12∶2、16∶2、20∶2时,共毒系数(CTC)分别为94.3、239.7、198.1、156.5,表明氟噻草胺与氟唑磺隆混用具有相加或增效作用,其中以12∶2、16∶2比例混配对多花黑麦草防治增效最为显著。盆栽试验结果表明,苗前以12∶2和16∶2比例土壤封闭喷施对小麦与多花黑麦草的选择性指数为1.51和1.43;苗后3d及苗后15d茎叶喷施对多花黑麦草与小麦选择性较差,选择性指数低于1。田间测定结果表明,氟噻草胺与氟唑磺隆混配对阔叶杂草荠菜、播娘蒿、婆婆纳防效优于氟噻草胺单独使用,混配条件下株防效为85.45%~100%,鲜重防效为89.57%~100%,对小麦分蘖数无显著影响。     

Direct measurement of paraquat in leaf protoplasts indicates vacuolar paraquat sequestration as a resistance mechanism in Lolium rigidum

Sequestration of paraquat away from its target site in the chloroplast has been proposed as a mechanism of paraquat resistance. However, no consensus has been reached as to where paraquat is sequestered. This study quantifies paraquat in leaf protoplasts of paraquat resistant (R) and susceptible (S) Lolium rigidum. Intact protoplasts were prepared from plants treated with commercial dose of paraquat for 2 h. Paraquat absorbed by the leaf protoplasts was determined by light absorption of reduced paraquat following concentration and purification using a cation-exchange resin. Leaf protoplasts from treated paraquat resistant plants contained 2- to 3-fold more paraquat than leaf protoplasts isolated from susceptible plants. Since paraquat is not metabolised in L. rigidum and paraquat readily enters chloroplasts of both R and S plants, this greater amount of paraquat in leaf protoplasts of R plant must be kept away from the target site (chloroplast). This result indicates that paraquat resistance in L. rigidum is associated with a cytoplasmic mechanism, most likely a greater rate of vacuolar sequestration.     

Phosphorus in agricultural constructed wetland sediment is sparingly plant‐available

Agricultural constructed wetlands (CWs) are intended to retain sediment and phosphorus (P) carried off with runoff and drainage water. The accumulated sediment, with adsorbed P, is often advised to be recycled to agricultural land, but little is known about the fertilizer value of sediment‐associated P. This study examined the effects on P adsorption characteristics and P plant availability of mixing CW sediment into soil. Although the total P content in the sediment was approximately equal to that in catchment soil and the NaOH‐extractable P content was higher to that in catchment soil, in adsorption‐desorption tests sediment P solubility decreased and affinity for P increased with increasing addition rate of CW sediment to soil. Already the lowest sediment addition rate (12.5% of dry weight) decreased the equilibrium P concentration (EPC₀') by 60% on average compared to unamended catchment soil. In a greenhouse pot experiment, Italian ryegrass (Lolium multiflorum L.) yield was largely unaffected by CW sediment application, but P uptake systematically decreased when the rate of sediment application to soil increased. When 12.5% dry weight of sediment was added, plant P uptake decreased by 6–50% in P‐unfertilized pots and by 6–17% in P‐fertilized pots (150 mg P kg⁻¹) compared with P uptake of ryegrass grown in unamended field soil. Our other results suggest that the plant availability of P in CW sediments is very low due to high clay content and high concentrations of aluminium (Al) and iron (Fe) (hydr)oxides in the sediment. Thus, if applied to agricultural fields in large quantities, dredged CW sediment may impair crop P supply.     

Effects of Ozone on Growth of Seven Grass and One Clover Species

Abstract

Seven species of grass and one of red clover were grown at different ozone (O₃) concentrations for about five weeks in growth chambers located in a greenhouse. At an O₃ concentration of 55 compared with 10 nmol mol^?1 during 7 h day^?1 the shoot dry weight decreased by 45% in Phleum pratense, 28% in Dactylis glomerata and Poa pratensis, 23% in Festuca rubra and 16% in Festuca pratensis, while the effects on Agrostis tenuis were not significant. No effect was found at 25 compared with 10 nmol mol^?1O₃. Visible O₃ injury was observed in all six species at 55 nmol mol^?1 and this effect was generally well correlated with the effect on the dry weights. In another experiment no effect was found with O₃ concentrations of up to 62 nmol mol_?1 on Lolium perénne, while the dry weight in Trifolium pratense decreased by 30% at 59 compared with that at 6 nmol mol^?1.     

Differences in winter-hardening between phenotypes of Lolium perenne with contrasting water-soluble carbohydrate concentrations

Carbohydrates are essential for the winter-hardening of temperate grasses, affecting both rate of hardening and level of frost hardiness. The rate and extent of winter-hardening of contrasting phenotypes of two Lolium perenne cultivars targeted for differences in water-soluble carbohydrates concentration were quantified under controlled hardening conditions and standardized freeze testing. The phenotype with the lowest water-soluble carbohydrates concentration had a lower rate of hardening and tolerated less frost than the other phenotypes but the effect of water-soluble carbohydrate concentrations on the hardening processes levelled off at increasing water-soluble carbohydrate concentrations, indicating a threshold. Contrasting responses to freezing were found for survival and for potential for tillering and regrowth. Mortality was little affected by the higher test temperatures, while tillering was negatively affected, even at −5°C. Compensatory regrowth of tillers surviving the lower test temperatures partially compensated for the effects of loss of tillers on regrowth. The hardiest phenotypes had a rapid lowering of LT₅₀ during the first 3 d (−1·65°C d⁻¹), acquiring LT₅₀ values at −15°C or below in 10 d. The hypothesis that rate and maximum level of hardening increase with water-soluble carbohydrates concentrations in stubble is supported by the results.     

Enhancing Seed Germination Rate of Four Turfgrass Genera by Acid Treatments

Turfgrasses are commonly propagated by seeds. In some genera of turfgrasses, the presence of low germination percentage (GP) or rate is the main problem in seed propagation. The present investigation was undertaken to determine the best concentration and duration of sulphuric acid treatment for seeds of the following turfgrass genera: Cynodon dactylon [L.] Pers.; Festuca rubra L. var. rubra‘Shadow’; Lolium perenne L. ‘Barball’ and Poa pratensis L. ‘Merion’. In the first experiment, sulphuric acid was used with concentrations of 0 (control), 25, 50, 75 and 100 % for 10, 15, 20, 25 and 30 min. In the second experiment, effects of light/dark (16/8) or dark conditions on germination rates of different mentioned genera were investigated using the best specific acid treatments. Each treatment was replicated four times with 100 seeds per replicate kept in plastic Petri dishes. The results indicated that in Cynodon, using 50 % acid for 20–25 min had highest GP and mean daily germination (MDG) in light/dark; in Festuca, using 25 % acid for 15 min had highest GP and MDG in light/dark; in Lolium using 50 % acid for 10 min had highest MDG in dark and in Poa, using 50 % acid for 15–25 min had highest MDG in dark. Both Cynodon and Poa had the highest and Festuca had the lowest GPs. Cynodon and Festuca had the highest and lowest MDGs, respectively. This simple procedure, with considerable results, may be replaced to time-consuming and expensive methods such as seed priming.     

中国主要产区何首乌以二苯乙烯苷含量为指标的种质评价

采集我国几大主要产区的野生何首乌及部分栽培品，采用高效液相色谱法(HPLC)对其特征性成分2，3，5，4’-四羟基二苯乙烯-2-O-β-D-葡萄糖苷的含量进行测定，分析了6个野生居群和2个栽培居群以及同一居群同一生长环境不同年限的样品和同一居群同一年限在不同环境条件下生长的样品。实验结果表明：采自广西的一种何首乌药材原植物是何首乌的一个变种棱枝何首乌(P.multiflorum Thunb.var angulatum S.Y.Liu)，而且其中2，3，5，4’-四羟基二苯乙烯-2-O-β-D-葡萄糖苷含量较低；贵州、湖北居群2，3，5，4’-四羟基二苯乙烯-2一O—B—D-葡萄糖苷含量较高，四川、河南较低；另外还发现，种质的不同，年限的差异及不同环境是影响2，3，5，4’-四羟基二苯乙烯-2-O—β—D-葡萄糖苷积累的重要因素。     

Testing the Efficiency of Pollination Bag Materials

Crossing bags manufactured from three grades of polyester and three types of paper bags were tested for their permeability to grass pollen. Bags were placed on L. perenne plants of known PGI isozyme genotype. Any pollen passing through the crossing bag and pollinating the plant was detected by assaying its progeny for PGI isozymes. The results obtained allowed differentiation of the various materials for their suitability for pollen proofing.     

多胺引发对黑麦草种子萌发期耐冷性的影响(英文)

[目的]探讨多胺引发对黑麦草胚生理生化和种子发芽的影响。[方法]以一年生黑麦草(钻石T和牧乐8000)为材料,种子经0.5mmol/L的腐胺(Put)、亚精胺(Spd)和精胺(Spm)引发24h后,在5℃下低温吸胀不同时间(12、24、36和48h),分析Put、Spd和Spm引发对一年生黑麦草种子吸胀中耐冷性和种子发芽能力的影响。[结果]Put、Spd和Spm引发提高了胁迫期间种子胚内过氧化物酶(POD)、过氧化氢酶(CAT)、超氧化物歧化酶(SOD)和抗坏血酸过氧化物酶(APX)活性,以及可溶性蛋白质含量,同时也显著提高发芽率、缩短平均发芽时间。低温吸胀48h后,与对照相比,Put、Spd和Spm处理分别提高一年生黑麦草种子的平均发芽率15.5%和12.0%,分别缩短平均发芽时间1.21和1.14d。在种子吸胀期间的耐冷性牧乐8000强于钻石T。总体而言,Put、Spd和Spm处理能提高一年生黑麦草种子吸胀期间的耐冷性,提高低温胁迫下种子发芽能力。[结论]该研究结果为种子引发技术在一年生黑麦草生产上的应用提供了理论依据。     

填埋场陈垃圾对黑麦草种子发芽的影响

非正规垃圾填埋场的治理和陈垃圾的资源化利用是环保领域一项重要而迫切的任务。选择黑麦草作为试验对象,采用种子发芽的陆生生态毒理方法,研究陈垃圾对植物发芽的影响,以期为陈垃圾利用和非正规垃圾填埋场治理提供一种新的思路。培养基质中陈垃圾的比例分别为20%、80%和100%,使用蒸馏水和土壤作为对照。试验结果表明:陈垃圾的使用能够显著提高黑麦草种子的发芽势和发芽率,但黑麦草种子的发芽势和发芽率随着陈垃圾用量的增加呈现先增大后减小的特征,陈垃圾在培养基质中的最佳比例为80%,与空白和使用土壤作为培养基质相比,发芽率分别提高了34.3%和20.9%,发芽势分别提高了52.0%和24.0%。培养基质中添加陈垃圾有利于黑麦草种子根、芽的发育和生长,在培养基质中陈垃圾的比例为80%的条件下,黑麦草种子的根长、芽长和芽的鲜质量分别比使用土壤时增加了50.0%、46.9%和74.0%。因此,将稳定后的陈垃圾用于草坪种植是可行的,这为陈垃圾的资源化利用提供了一条新的途径。