GENETIC VARIATION IN SIMAZINE RESISTANCE IN WHEAT, RAPE AND MUSTARD

Summary. The resistance to simazine of a range of varieties of wheat ( Triticum aestivim L.), rape ( Brassica napus L.) and mustard ( Sinapis alba L.) was assessed in glasshouse tests Varietal differences in survival and final weight of survivors were found in all three crops Variability m the time for which individual plants survived was greatest in the two out-breeding crops, rape and mustard. The 1 % of mustard plants that survived 10 oz/a csimazine were allowed to produce seed in a polycross. These progenies showed a very marked increase m resistance over the unselected controls.
There is thus appreciable genetic variation in resistance to simazine both within and between varieties. This is readily available for selection, and could he valuable in extending the selectivity of herbicides.
Variation génétique de la resistance á la simazine chez le blé, le colza et la moutarde     

A comparative study of the species composition of discards from five fisheries from the Algarve (southern Portugal)

Discards from five of the most important fisheries (crustacean trawling, fish trawling, demersal purse seining, pelagic purse seining and trammel netting) in southern Portugal were studied and compared. A total of 236 species of all taxa were discarded, with fish and cephalopods accounting for more than 90% of the discarded biomass, except trammel nets (81%). Although there was some overlapping of species, multivariate analysis using cluster analysis for classification and multidimensional scaling (MDS) for ordination, showed that there were significant differences between the five gears in terms of species composition and biomasses discarded, with the least similarity between crustacean trawling and all other fishing operations. The differences between fisheries were probably as a result of a combination of gear selectivity and depth fished. The results suggest that discarding practices are likely to have different, yet significant impacts on the marine ecosystem, warranting further studies on the fate of discards, the factors influencing discarding and mitigation.     

Composition and properties of poorly ordered minerals in Welsh soils. I. Composition

Eleven horizons of acidic soils in mid-Wales developed from Lower Palaeozoic sedimentary rocks were examined. Selective extraction of Al and Si provided evidence against the occurrence of significant quantities of poorly ordered Al-silicates. Fe₀ was weakly correlated with Al₀, but very closely correlated with Al₀ minus Al extracted by cold 5% Na₂CO₃, implying that poorly ordered Al occurs in part as a substituent in Fe oxide and in part in a form unassociated with Fe oxide. Support for this was obtained by analysis of oxide fractions concentrated from aqueous suspensions by sequential ultracentrifugation and through the examination of synthetic Al-substituted Fe oxides. Fe oxide containing Al substituted at an almost constant level was the dominant constituent of the poorly ordered fraction in four of the five Bs horizons examined. The occurrence of Al in this form is an important mechanism by which Al is retained in aerobic but highly acidic Bs horizons.     

Nonlinear mixed effects pharmacokinetic/pharmacodynamic analysis of the anticonvulsant ameltolide (LY201116) in a canine seizure model

The anticonvulsant ameltolide (LY201116) is a novel potential therapy for the treatment of canine epilepsy. Eight dogs were administered five different oral doses of ameltolide and clinical scoring of the maximal electroshock (MES) induced seizures at 3 and 24 h postdosing were determined in two separate crossover design studies. Plasma ameltolide concentrations were determined at the time of seizures in all dogs and complete plasma concentration‐time profiles were also determined in a separate study. A nonlinear mixed effects PK/PD model was fit to the resulting data. A one compartment open model with first order absorption was determined to best fit the ameltolide pharmacokinetics. An effect compartment with a cumulative logistic regression equation was used to establish the PK/PD relationship. The mean bioavailability normalized volume of distribution and the elimination half‐life were estimated at 1.20 L/kg and 5.46 h, respectively. The fitted model estimated that from 2 to 15 h following a single 3 mg/kg oral ameltolide dose the mean probability of obtaining a 1 unit reduction in the seizure clinical score severity was greater than 0.80. The utilized PK/PD analysis combined with the canine MES model allowed for the rapid and efficient determination of the plasma ameltolide concentration‐anticonvulsant relationship preclinically in dogs.     

外源脱落酸处理对库尔勒香梨抗寒性的影响

为给库尔勒地区香梨安全越冬、稳产和高产的相关研究与栽培实践提供理论依据,以树势健壮、结果正常的库尔勒香梨单株为试验材料,在其生长期(2013年5月6日)第1次对其叶面喷施浓度分别为50、70、90 mg/L的外源激素ABA,之后每隔20天喷施1次,共喷施3次;在其休眠期采集枝条样品,在人工低温胁迫条件下测定其膜透性、丙二醛、脯氨酸、可溶性蛋白质、可溶性糖和淀粉含量等抗寒性指标,并采用隶属函数法对其抗寒性进行了综合评价。结果表明:以50 mg/L的ABA喷施1次的枝条其各生理指标值的平均隶属度0.6,其抗寒级别可划为Ⅱ级;以70 mg/L的ABA喷施1次和2次及以50 mg/L的ABA喷施2次与3次的枝条,其各生理指标值的平均隶属度均大于0.4,这几个处理的枝条均为中抗寒型,其抗寒级别均可划为Ⅲ级;以90 mg/L的ABA喷施1次和2次的枝条,其各生理指标值的平均隶属度均大于0.3,这两个处理的枝条均为低抗寒型,其抗寒级别均可划为Ⅳ级;以70和90 mg/L的ABA喷施3次的平均隶属度均小于0.3,这两种处理的枝条均为不抗寒型,其抗寒级别均可划为Ⅴ级。文中认为,以50 mg/L的ABA叶面喷施1次,库尔勒香梨便能抵抗-24℃的低温。     

Weed problems and their management in rice fields of Malaysia: An overview

The available literature on weed problems and weed control in rice fields in Malaysia is reviewed and suggestions for future research are included. The problem of weed competition with rice is of great economic importance in the country because it causes a 10–35% reduction in grain yield. About US$4.10 million is spent annually on herbicides for rice alone, and this amounts to approximately 7% of the total expenditure on herbicides. The shift in methods of rice culture from transplanting to direct seeding has magnified the weed problem. The problem of weedy rice is particularly acute in the direct-seeding rice areas. Although a number of sulfonylurea herbicides (e.g. cinosulfuron, metsulfuron, bensulfuron and pyrazosulfuron) have been found to be suitable alternatives to the old herbicide 2,4-D, an integrated weed management program must be developed in order to reduce the problem of herbicide resistance in weeds. Weed control methods that are more friendly to the environment and affordable to farmers must be sought. Weed-competitive and allelopathic rice varieties must be produced. The problem of weeds in rice calls for systematic studies on biotechnological methods of control of weedy rice. Detailed studies on the biology and ecology of notorious rice weeds, particularly Oryza sativa L. (weedy rice), Echinochloa spp., Leptochloa chinensis (L.) Nees, Fimbristylis miliacea (L.) Vahl. and Limnocharis flava (L.) Buch. need to be done in order to formulate successful weed control measures.     

The possible effect of soluble silicon on the lepidocrocite content of gley soils from England and Bangladesh

Nine different gley profiles from England and Bangladesh were studied; out of these, four English soils contained variable amounts of lepidocrocite. The amounts of lepidocrocite present in various layers of these soils decreased with increasing concentrations of Si(OH)₄ in the soil solution. The amount of lepidocrocite formed was negatively correlated (r= -0.78) with the atomic ratios of Si/Fe in the citrate/dithionite extracts. Lepidocrocite was absent from the other five profiles, including three surface water gley soils from Bangladesh. These soils contained relatively large concentrations of Si(OH)₄ in soil solution, ranging between 0.7 mm and 1.0 mm. The atomic ratio of Si_d/Fe_d in the citrate/dithionite extracts was higher in these soils. Enborne soil contained maximum amount of citrate/dithionite extracted silicon (2.30 mg g^?1) with no X-ray crystalline iron oxides in the profile.