确定经济合理施氮量的新方法:基于施氮量与稻米产量效应函数

  【目的】  探究实现水稻高产、优质和氮肥高效的密度与施氮量协同组合。  【方法】  于2018—2019年,在黑龙江省五常市龙凤山乡辉煌村进行田间试验。采用裂区试验方法,以‘五优稻4号’为供试品种。以密度为主区,设置15穴/m2 (D1)和24穴/m2 (D2);以施氮量为副区,设施氮(N）量为0、75、105、135 kg/hm2 4个水平,分别表示为N0、N75、N105、N135处理。在水稻成熟期,测定了植株地上部干物重、稻谷产量、精米产量、精米率、蛋白质含量、直链淀粉含量、食味值等指标;比较了稻谷产量与精米产量确定的施氮量差异。  【结果】  在D1、D2两个密度下,随着施氮量的增加,稻谷产量、地上部干物重、精米产量都呈先升高后降低的趋势,均在N105达到最大值。除D1密度下N105处理的稻谷产量与N135处理差异不显著外,其余均显著高于其他处理,而N135处理的稻谷产量与N75处理无显著差异,但2018年地上部干物重却显著高于N75处理。随着施氮量的提高,精米蛋白质含量呈现增加趋势,精米率和食味值却呈降低趋势。与N0相比,N135处理精米蛋白质含量平均提高了7.58%,精米率和食味值分别平均降低了8.81%和10.24%。N105处理的氮素回收率显著高于N75和N135处理,农学效率、氮肥生理利用率和偏生产力均显著高于N135处理。D2密度下精米蛋白质含量低于D1密度处理,而精米率和食味品质高于D1密度处理,D2密度下的稻谷产量、氮积累量和精米产量均高于D1密度处理,氮积累量和氮肥偏生产力比D1处理平均提高了40.35%和 40.31%,两个密度间氮肥回收率、农学效率和氮肥生理利用率无明显差异。农户直接出售优质米使经济效益提高了7428元/hm2,D2密度使经济效益额外增加了4229元/hm2。施氮量与稻谷产量、精米产量均呈二次曲线关系,依据施氮量与稻谷产量效应函数,确定经济最佳施氮量为96.4～123.7 kg/hm2;依据施氮量与精米产量效应函数,确定的适宜施氮量为76.2～105.9 kg/hm2。  【结论】  适度密植(24穴/m2)有利于稻谷产量、氮素吸收量的提高,而不影响食味值和精米率。在本试验水稻适宜密植条件下,基于施氮量和精米产量效应函数确定的适宜施氮量为76.2～105.9 kg/hm2,该施氮量的确定方法有利于协同实现稻米高产优质和氮肥减施增效。     

A new method for determining ferrous iron in paddy soils

Introduction

To make clear the chemical behavior of free iron compounds in paddy soils, it is necessary to find an accurate and rapid method for determining ferrous iron in waterlogged paddy soils. Several methods^1,2,3) have been proposed for this purpose, most of which use dilute acids, such as sulfuric and hydrochloric acid, as extracting reagents. According to the writers' experience, however, these methods seem to be inadequate. The reason is that the acid solutions extract not only ferrous iron, but also ferric iron and reducing substances from soils, and the latter two react immediately in the extract to produce ferrous iron, thus we obtain larger value for ferrous iron than the one actually existing in soils. The writers have found that acetate buffer of pH 2.8 is a very suitable extractant for ferrous iron, and they have been able to establish a new method for the determination of ferrous iron in soils using this buffer. The experimental details will be given in this paper.     

A new method for determining mineral weathering rates in soils

Abstract

A new procedure based on measuring the amounts of H⁺ consumed when a pulse of acidic artificial soil solution is passed through a soil column was used to determine mineral weathering rates of a soil (Humo‐Ferric Podzol) from Roundtop Mountain near Sutton, Quebec. The method allows for quantification of H⁺ consumption due to weathering and H⁺ consumption due to cation exchange. Initial experiments yield a soil mineral weathering rate of 0.263 kmol ha^‐1 yr^‐1. This value is well within the range of results obtained by other workers in similar ecosystems. Multiple soil samples can be analysed in a relatively short time, allowing for better quantification of vertical and horizontal variation of H⁺ consumption within a site.     

A new method for determining free iron in paddy soils

For pedological or edaphological study, it is very important to find a suitable method for determining free iron in soils. The removal of free iron also facilitates the identification and determination of minerals present in soils and clays by X-ray and thermal analysis and microscopic observation. Up to the presnt time many methods have been proposed for the removal or the determination of free iron in soils and clays. With some exceptions these methods are all based on the principle that the free iron compounds existing mainly as ferric iron in soils are reduced to ferrous iron and extracted with suitable reagents. A short historical review is as follows.     

Quantitative determination of nitrogen content in plant tissue by a colorimetric method

Abstract

This study was to evaluate the applicability of a colorimetric method in measuring the nitrogen (N) concentration in samples of vegetable origin. In order to do this, the same samples were analyzed with a colorimetric, and macro‐ and microKjeldahl methods. The colorimetric method has been used successfully in the determination of N in nutritional studies with rats and humans. The present procedure has the advantage of eliminating the distillation and titration steps of the Kjeldahl method and it is practical for nutritional studies, since many samples can be run in a single day. The N concentration was measured in leaves of two tropical grasses: Paspalum fasciculatum Willd. ex Flugge and Hyparrhenia rufa (Nees) Stapf, and a Standard Reference Material (SRM 1547 Peach Leaves). In all cases, there were no significant difference (P>0.05) in N concentration in these plant materials using the colorimetric, and micro‐ and macroKjeldahl methods. There was a good agreement between the N concentration of Peach leaves determined by the colorimetric method (2.94%) and the certified N concentration (2.94%). Hyparrhenia rufa, the African grass, and P. fasciculatum, the native species, showed very low N concentration in their leaves, respectively. These results indicate that the colorimetric method, with some light adjustments, is capable of determining the N concentration in plant samples of diverse origin and in very low N levels. The low N concentrations of the grass species suggest the strong limitation imposed by the low soil fertility for the growth and establishment of forage species in tropical savannas.     

Video image method compared to a hand method for determining root lengths

Root lengths are much more sensitive to treatment effects than root weights. Therefore, root length measurements are essential to research concerning rhizosphere effects on plant roots. A video image analyzer method was compared to a hand method for determining the root length of sorghum [Sorghum bicolor (L.) Moench] seedlings resulting from nutrient solution experiments. Initial root lengths were not significantly different, thus only final lengths were recorded. T‐tests for differences between hand and instrument values showed that although absolute values were often significantly different, there were much fewer significant differences in normalized data. Normalized instrumental root length data were well correlated with hand data (r > 0.96) and slopes of the regressions were equal to 1.00. Intercepts were higher than zero. Thus, although the normalized instrumental values for root length were somewhat higher than for hand root lengths, the instrument lengths were very precise in indicating relative differences among treatments.     

Determination of aluminum in plant tissue digests using a catechol violet colorimetric method

Abstract

A procedure is described for the colorimetric determination of Al in acid digests of plant tissue using catechol violet as the chromogenic reagent. Components of plant tissue digests were examined for interference in the determination of Al using the described procedure. For highest accuracy, Al standards should contain macroelements, microelements, and acid at concentrations generally typical of those present in acid digests of the plant tissue being analyzed. Using the described procedure, recovery of Al added prior to digestion was 99.1% and 97.1% for National Bureau of Standards SRM 1571 (orchard leaves) and SRM 1572 (citrus leaves), respectively.     

Development of a new methanethiol quantification method using ethanethiol as an internal standard

Development of a new method to quantify methanethiol in which ethanethiol was employed as an internal standard is reported. Recovery yields for methanethiol from an aqueous model system and a soy protein concentrate (SPC) aqueous slurry determined with this method ranged from 97 to 107% and from 103 to 121%, respectively. The methanethiol content of two commercial SPCs and two commercial soy protein isolate (SPI) samples, on a dry basis, ranged from 835 to 1190 times greater than the odor threshold for methanethiol. Relative standard deviations for quantifying methanethiol with the method from these samples were <5%, indicating its good reproducibility in quantifying methanethiol from soy protein products. Also investigated in the current study was the feasibility of using 5',5-dithiobis(2-nitrobenzoic acid) (DTNB, Ellman's reagent) to determine the concentration of methanethiol in the aqueous solutions used to prepare the standard curve for quantifying methanethiol from soy protein products. The concentrations of methanethiol obtained from Ellman's reagent method were comparable with those from a weighing method and theoretical calculation.     

全波长扫描式多功能读数仪-靛酚蓝比色法测定水样铵态氮含量

全波长扫描式多功能读数仪(酶标仪)是一种多通道光学系统的分光光度计,将靛酚蓝比色法与酶标仪相结合,建立了酶标仪-靛酚蓝测定水中铵态氮的方法,方法检出限为0.046 mg/L。方法的加标回收率在90.7%~101.8%之间,该方法与连续流动分析仪-水杨酸分光光度法相比,两者测定数据之间回归直线方程为Y(连续流动分析仪-NH_4~+-N)=1.052 4X(酶标仪-NH_4~+-N)-0.009,相关系数R=0.976 1**(n=32,P0.01)。5个水样重复6次测定,测定结果的相对标准偏差均小于3%。全波长扫描式多功能读数仪(酶标仪)结合靛酚蓝比色法测定重现性好,结果准确,快速方便,可用于水样中铵态氮含量测定。     

农用地分等中最高单产和最高产量-成本指数确定方法

为提高农用地分等中最高单产和最高产量-成本指数确定方法的科学性和合理性,该文以土地报酬递减理论为基础,应用河南省农用地分等的小麦投入产出调查数据,将样点小麦单位面积产量(kg/hm~2)作为土地报酬递减曲线中的总产量(纵坐标),将样点小麦单位面积投入(元/hm~2)作为土地报酬递减曲线中的总投入(横坐标),从而使土地报酬递减理论中的平均产量(kg/元)与产量-成本指数具有相同的内涵。依据边际产量曲线的变化,分2种情况最高单产的确定:1)边际产量曲线表现为下降趋势,但没有与横坐标轴相交即边际产量仍大于0,这时单产曲线最右端的产量为最高单产;2)边际产量曲线向下与横坐标轴相交即边际产量递减为0时,边际产量曲线与横坐标轴相交点对应的产量为最高单产。依据产量-成本指数和边际产量2条曲线间的关系可以确定最高产量-成本指数:产量-成本指数曲线向上与边际产量曲线相交点的产量-成本指数为最高产量-成本指数,并建立了异常产量-成本指数的修正方法。采用研究数据和验证数据确定的最高单产和最高产量-成本指数分别相差0.12%、0.50%,表明该研究方法确定的区域最高单产和最高产量-成本指数具有相对稳定性。该研究为确定最高单产和最高产量-成本指数提供了理论依据,丰富了土地利用系数和土地经济系数的内涵。     

Surface-bound phosphatase activity in ectomycorrhizal fungi: a comparative study between a colorimetric and a microscope-based method

For the quantification of surface-bound phosphomonoesterase activity (SBPA) of fungi, roots, or mycorrhiza, a colorimetric method based on p-nitrophenyl phosphate (pNPP) is widely used. Unfortunately, this method does not reveal information about the localization of the surface-bound phosphomonoesterase (SBP). We introduce a method that localizes and quantifies SBPA in living hyphae of ectomycorrhizal fungi using confocal laser scanning microscopy of the hydrophilic substrate enzyme-labelled fluorescence (ELF-97) and compare it to the pNPP assay. ELF-97 turns into a strongly fluorescent precipitate upon activation by SBPA and forms bright fluorescent centres on the outer cell wall of the hyphae. Our data show that the enzymatic reaction is not substrate-limited during an incubation period of 15 min in fungal hyphae of Pisolithus tinctorius, Cenococcum geophilum, and Paxillus involutus. Image-processing routines determined the total intensity and the average number of the fluorescent ELF-97 centres per micrometre fungal hyphae of C. geophilum and Paxillus involutus. ELF-97 and pNPP detected similar variations of the SBPA at different pH values (3–7) during the measurement and different phosphorus (P) concentrations during the growth period of the fungi. The ELF-97 method revealed that C. geophilum and Paxillus involutus adapt in different ways to the variation of the P concentrations during the growth period by varying the number, the activity, or both properties of the SBP centres. The phosphatases show peak activities at different pH values, so the response of the fungal mycelium to varying P concentrations in soils is pH selective. In conclusion, ELF-97 is a promising substrate to reveal SBPA and adaptation strategies on a structural–physiological level.     

Simple colorimetric method for determination of thiamine hydrochloride in pharmaceuticals

A simple colorimetric method is described for the determination of thiamine hydrochloride (vitamin B1) in dosage forms. The method is based on measurement of a yellow complex formed when thiamine HCl is treated with p-methylaminophenol sulfate (Metol) under alkaline conditions. Compounds such as vitamins A, B2, B6, B12, C, D, and E, and niacinamide, citric acid, liquid glucose, calcium pantothenate, biotin, liver extract, and folic acid do not interfere in the reaction. Extracting the complex into chloroform before quantitation enhances the stability of the reaction product and removes interference of water-soluble colored constituents in syrup samples. Statistical validation shows that the method is precise and accurate. Results agree well with those obtained by other methods in the literature.     

Simple colorimetric method for determination of metaproterenol sulfate in pharmaceuticals

A simple colorimetric method is described for the determination of metaproterenol sulfate (orciprenaline sulfate). The method is based on measurement of a colored species formed when metaproterenol sulfate is treated with diazotized dapsone, p-nitroaniline, or benzocaine at room temperature, followed by treatment with an aqueous solution of trimethylamine in the case of benzocaine. Compounds such as starch, talc, and common excipients do not interfere in the reaction. Statistical validation showed that the method was precise and accurate. The results agree well with those obtained by other methods reported in the literature.     

Development of a chemiluminescent ELISA for determining chloramphenicol in chicken muscle

An indirect competitive enzyme-linked immunosorbent assay (ELISA) with chemiluminescent (CL) detection for chloramphenicol (CAP) in chicken muscle was developed. CAP-specific polyclonal antibody was raised in rabbit with a CAP-succinate derivative conjugated with bovine serum albumin. Luminol solution was used as the substrate of horseradish peroxidase. The detection limit was 6 ng/L. The CL-ELISA was 10 times more sensitive compared to the colorimetric-ELISA. When CAP was spiked in chicken muscle at levels of 0.05-5 microg/kg, recoveries ranged from 97 to 118% with coefficients of variation of 6-22%. In an actual residue study, the results obtained by CL-ELISA correlated well with those obtained by gas chromatography with microcell electron capture detector. The residue levels of CAP in treated chicken decreased with time and dropped rapidly after the first 6 h from around 50 to 10 microg/kg. After 3 days, CAP was not detected in chicken muscle. The developed method is therefore suitable for screening of CAP in chicken muscle samples.     

新型尿素缓释剂对作物产量的影响

尿素缓释剂不使用HQ(氢醌),而是采用多种化合物复配成的具有复合抑制功能的新型脲酶抑制剂。培养试验结果表明,尿素缓释剂对土壤脲酶活性有一定的抑制作用,可提高尿素肥效,使土壤中有效氮贮存量提高20 4%。田间试验结果表明,使用尿素缓释剂添加到尿素中,比普通尿素有明显的增产作用,粮食作物可增产14 5%,蔬菜可增产19 5%,且可省掉追肥的工序。     

Simple colorimetric method for determination of terbutaline sulfate from pharmaceutical preparations

A simple colorimetric method is described for the determination of terbutaline sulfate. The method is based on measurement of a colored species formed when terbutaline sulfate is treated with diazotized dapsone and p-nitroaniline at room temperature. Compounds such as starch, talc, and common excipients do not interfere in the reaction. Statistical validation showed that the method was highly precise and accurate. The results agree well with those obtained by other methods reported in the literature.     

A microscale method for colorimetric determination of urea in soil extracts

Abstract

The diacetyl monoxime colorimetric method of determining urea in soil extracts was modified for microplate format. A 100‐μL aliquot of extract was treated with color reagent in a disposable plastic microtiter plate (96 wells/plate), and color was developed by heating the plate in a low‐temperature oven at 87°C for 55 min. After cooling for 20 min at ambient temperature, absorbance measurements were simultaneously performed on all 96 wells using a microplate reader. The microscale method was faster and more convenient than the conventional method; moreover, the volume of waste was markedly reduced. Studies to compare the two methods showed very little difference in accuracy, precision, or sensitivity.