北京地区杂交油葵适宜密度、水分管理、除草剂试验研究

研究表明：在北京地区夏播的条件下，杂交油葵适宜密度一般为52500株／hm^2，适宜的除草剂为33％除草通（施田补）乳油2250～3300mL／hm^2对水375～450kg／hm^2喷洒地面。油葵种植应保证底墒水和现蕾水充足，有利于北京地区杂交油葵的生长，提高产量。     

丹参干燥工艺参数的研究

丹参是重要的中药材,为了保证丹参的加工质量,对丹参根采收后的干燥进行了试验研究。通过正交试验,研究了风温、风速和物料层厚度对丹参色泽、气味和干燥时间的影响。通过研究可知,当风温取70℃,风速取0.7m/s时,丹参色泽和气味较好;当风温取70℃,风速取1.0m/s时,丹参干燥最快,总干燥时间约210min。     

柠檬酸铁作为发色剂对改善羊排色泽的研究

通过L8(23)正交试验,研究了不同浓度条件下的柠檬酸铁、柠檬酸和L-抗坏血酸钠对羊排的发色作用。影响羊排发色效果的因素依次为柠檬酸铁与柠檬酸的共同作用、柠檬酸铁单独作用、柠檬酸铁与抗坏血酸钠的共同作用、柠檬酸的单独作用和抗坏血酸钠的单独作用。当柠檬酸铁、柠檬酸和L-抗坏血酸钠的的质量比为2∶1∶2时的发色效果最佳,且当柠檬酸铁的质量分数为0.05%,柠檬酸的质量分数为0.025%,L-抗坏血酸钠的质量分数为0.05%时的发色效果好于试验中的其余组。     

新疆小麦Psy-A1、Ppo-A1、Ppo-D1、TaLox-B1等位变异对面粉色泽的影响

利用已开发的面粉色泽相关性状基因的分子标记,检测了182份新疆小麦品种(系)的Psy-A1、Ppo-A1、Ppo-D1、Ta Lox-B1等位变异,并结合表型鉴定结果,分析不同等位变异对面粉色泽的影响。结果表明,单基因等位变异对面粉色泽的影响不同,其中4个基因等位变异L*值的差异均不显著;对a*值的效应,Psy-A1a高于Psy-A1b(P0.01),Ppo-A1b高于Ppo-A1a(P0.05),Ta Lox-B1a高于Ta Lox-B1b(P0.05);Psy-A1a基因型的b*值高于Psy-A1b基因型(P0.01);Psy-A1a基因型的Wht值低于Psy-A1b基因型(P0.01)。说明Psy-A1是影响面粉色泽(红度、黄度和白度)的重要基因,而Ppo-A1和Ta Lox-B1基因的等位变异只对面粉红度有显著影响。4个检测基因共有12种等位变异组合,对a*、b*和Wht值有显著效应(P0.01),但对L*值影响不显著(P0.05);Psy-A1b/Ppo-A1a/Ppo-D1b/Ta Lox-B1b组合具有最高的Wht值和最低的a*、b*值,Psy-A1a/Ppo-A1a/Ppo-D1b/Ta Lox-B1a组合具有最低的Wht值和最高的a*、b*值。182份品种的Wht值平均为86.86,其中审定品种平均为86.87,冬小麦品种为86.42,春小麦品种为87.32。青春5号具有优良的基因型和较高的面粉白度,应加强利用。总体来看,改良新疆小麦面粉的白度,应重点加强对Psy-A1基因的选择,提高Psy-A1b比例。     

Seed Color Inheritance in Brassica carinata A. Braun, Cultivar S-67

The inheritance of seed color was studied in the brown seeded Ethiopian mustard (Brassica carinata A. Braun), cultivar S-67. Seed color was controlled by a single gene pair. The heterozygous condition resulted in light yellow-brown set-d indicating incomplete dominance [semidominance] of brown over yellow. The homozygous recessive condition resulted in yellow seed. The significance of these findings in relation to seed color inheritance in other Brassica species is discussed.     

Genetic control of irregular striping, a new phenotype in Cucurbita pepo

Longitudinal striping of the fruit exterioris a common trait in Cucurbita pepo(pumpkin, squash, gourd). Striping occursas ten pairs of alternating dark and lightstripes that are regularly situated inaccordance with the ten sub-epidermalcarpellary vein tracts. Usually, the darkstripes occur in the central areas betweenthe vein tracts, with the light stripesoccupying the remainder of the fruitsurface. A new phenotype is described inwhich dark spots or streaks occur in thecentral areas between the vein tracts;these are usually accompanied by darkstreaks or stripes that occur adjacent toand over part or all of the length of someor all of the ten carpellary vein tracts. The inheritance of this irregular stripingpattern was studied by crossing anaccession that bred true for this phenotypewith a near-isogenic line havinglight-colored fruits. The resultsindicated that irregular striping isdominant to light coloration and isconferred by a single gene. Testcrossesfor allelism with regular striping wereprepared by crossing the irregularlystriped accession with near-isogenic lineshaving broad stripes, l-1 ^BSt/l-1 ^BSt, and narrowstripes, l-1 ^St/l-1 ^St. The testcross results revealed thatirregular striping is conferred by anallele at the l-1 locus, designatedl-1 ^iSt. The l-1 ^iStallele is dominant to light-colored (l-1), recessive to dark-colored (L-1), and can be co-dominant or recessiveto broad-striped (l-1 ^BSt) andnarrow-striped (l-1 ^St),depending on whether or not it is fullyexpressed. Dominance relationships at thel-1 locus can, therefore, berepresented as L-1 > (l-1 ^BSt > l-1 ^St) l-1 ^iSt > l-1.     

The critical N dilution curve for linseed (Linum usitatissimum L.) is different from other C3 species

The objective was to determine the critical N dilution curve of linseed, which is the minimal total N concentration in shoots necessary to produce the maximal shoot dry matter, and to explain possible differences with other C3 species. One main experiment was carried out in 1998/1999 on winter linseed with four levels of fertilizer N. Two plant densities were also studied, the recommended one (600 seeds m⁻²) and the minimum for canopy closure (150 seeds m⁻²), in order to investigate the stability with plant density of the critical N dilution curve. Shoot dry weights (W_S) and shoot N contents expressed in percentage (N_S) were measured for the determination of the critical dilution curve, along with organ N percentages and relative weights. The results of four other experiments were used to validate the critical N dilution curve. Three of these four trials were conducted on winter linseed (one in 1996/1997 and two in 1997/1998) with five levels of fertilizer N, and one on spring linseed in 1999 with six levels of fertilizer N.

The critical N dilution curve of linseed was different from those of other C3 species. The curve was steeper, indicating a greater decrease in the critical shoot N concentration (N_SC) as the critical shoot dry weight (W_SC) increased. This linseed curve determined with the data of the main experiment was relevant when compared to the data of the four other experiments. Organ weight ratios and N concentration of organs were investigated in a fertilizer N treatment resulting in N_S close to the critical N values, N_SC. In this treatment, the decrease in N_S was the result of both a decrease in the N percentage of all organs and a decrease in the leaf weight ratio. The difference between linseed and other C3 species was mainly due to an acceleration of the dilution of N when leaf emission stopped and the flower bud emission began. At this stage of development, the leaf weight ratio of linseed was less than that of wheat, resulting in lower N_S. For a given W_S, no significant differences in N_S, organ N percentages nor organ weight ratios were observed between the two plant densities. This indicates that the difference between linseed and other C3 species could not result from very high plant densities in linseed. Hence, it is concluded that the linseed N accumulation in shoot is different from other C3 species.     

土壤微生物多样性研究方法综述

Soil microorganisms play a central role in decomposing organic matter, in determining the release of mineral nutrients, and in nutrient cycling. Recently, extensive studies have focused on soil microbial diversity. However, understanding the diversity of this complex microbial community in the soil environment is a challenging task. Thus, it is important to master and comprehend appropriate methods for studying soil microbial diversity. Concepts of soil microbial diversity and major methods of study are briefly introduced in this paper. Then, the application of biochemical-based and molecular-based techniques in this area, and their advantages and disadvantages are evaluated. Based on recent related research, perspectives for studying microbial diversity in soils are presented.     

适宜共混速度改善低密度聚乙烯/竹粉复合材料力学与流变性能

该文主要研究共混速度对(low density polyethylene,LDPE)/竹粉木塑复合材料、流变性能和吸水率的影响。采用熔融共混方法制备LDPE/竹粉复合材料,通过旋转流变仪、扫描电镜(scanning electron microscope,SEM)和材料试验机等详细研究了共混速度(40,75和100 r/min)对LDPE/竹粉复合材料的复合材料动态力学性能、形态、吸水率和力学性能的影响。在LDPE/竹粉复合材料,LDPE、增容剂马来酸酐接枝聚乙烯(maleic anhydride grafted polyethylene,MAPE)和竹粉的质量比控制在65∶5∶30。共混温度和时间分别设定为170℃和10 min。结果表明,添加竹粉可有效增强LDPE的力学性能。LDPE/竹粉复合材料的拉伸强度和弯曲强度随着共混速度的增加而呈现下降趋势,但是与纯LDPE相比,LDPE/竹粉复合材料(40 r/min)的拉伸强度和弯曲强度分别增加了28%和115%;弯曲模量从48.45 MPa降低到40.75 MPa。与LDPE相比,LDPE/竹粉复合材料(40 r/min)的弯曲模量最高增加了238%;缺口冲击强度则从12.8 k J/m2提高到18.27 k J/m2,但仍低于纯LDPE。在相同频率下(1.0 Hz),随着共混速度的增加,LDPE/竹粉复合材料的储能模量和复数黏度也逐渐下降,加工性能得到了改善;同时复合材料的吸水率也从0.89%(40 r/min)下降至0.59%(100 r/min)。SEM结果表明,竹粉能均匀分布在LDPE中,提高共混速度使得竹粉表面被大量树脂覆盖,改善了界面性能,使得材料断裂面产生大量的塑性形变,提高了材料韧性和冲击强度。试验结果证实共混速度为100 r/min时,LDPE/竹粉复合材料具有较好的冲击强度和较低的吸水率,这为木塑复合材料力学性能和吸水率的改善提供有意借鉴。     

毛乌素沙地苔藓结皮的野外人工培育技术

[目的]探索影响毛乌素沙地人工培育苔藓结皮的关键因子及其最优组合,为该区土地荒漠化的治理提供理论支持。[方法]利用正交试验设计方法,考虑遮阳、覆膜、营养液、浇水频率4个因子,分析不同因子对苔藓结皮株密度和生物量的影响。[结果](1)除Knop营养液外,遮阳、覆膜、浇水频率对苔藓结皮株密度、生物量有显著影响。(2)遮阳、覆膜、营养液、浇水频率4个因素对不同指标的影响顺序不同。(3)就株密度而言,野外培养最优条件为遮阳、不覆膜、Knop营养液和高频率浇水。就生物量而言,苔藓结皮野外培育最优因素组合为遮阳、覆膜、Knop营养液和高频率浇水。[结论](1)在野外苔藓结皮培育过程中遮阳、覆膜、浇水频率对结皮生长都有显著影响。(2)在提供适宜的生长条件的前提下,在干旱半干旱地区进行苔藓结皮人工培育是可行的。