Carbon flow from C-labeled straw and root residues into the phospholipid fatty acids of a soil microbial community under field conditions

To better understand how residue quality and seasonal conditions influence the flow of C from both root and straw residues into the soil microbial community, we followed the incorporation of ¹³C-labeled crimson clover (Trifolium incarnatum) and ryegrass (Lolium multiflorum) root and straw residues into the phospholipid fatty acids (PLFA) of soil microbial biomass. After residue incorporation under field conditions in late summer (September), the ¹³C content of soil PLFA was measured in September, October, and November, 2002, and April and June, 2003. Multivariate non-metric multidimensional scaling techniques showed that the distribution of ¹³C among microbial PLFA differed among the four primary treatments (ryegrass straw and roots, clover straw and roots). Regardless of treatment, some PLFA remained poorly labeled with ¹³C throughout much of the study (16:1ω5, 10Me17:0; 0-5%), whereas other PLFA consistently contained a larger percentage of residue-derived C (16:0; 18:1ω9, 18:2ω6,9; 10-25%). The distribution of residue ¹³C among individual PLFA differed from the relative contributions of individual PLFA (mol%) to total PLFA-C, suggesting that a subset of the soil biomass was primarily responsible for assimilating residue-derived C. The distribution of ¹³C among soil PLFA differed between the sampling times, indicating that residue properties and soil conditions influenced which members of the community were assimilating residue-derived C. Our findings will provide the foundation for further studies to identify the nature of the community members responsible for residue decomposition at different times of the year, and what factors account for the dynamics of the community involved.     

应用~(15)N~(32)P示踪技术研究水稻对不同复(混)合肥料中氮磷的吸收

在盆栽条件下几种复(混)合肥料对水稻均有增产作用,与对照相比稻谷增产60.8—77.7％,达到显著水准。但几种复(混)合肥之间无显著差异。用15～(N)示踪法测定水稻对复(混)合肥的氮素利用率:尿素磷铵为44.7％,氯磷铵为44.5％,尿素为44.1％,尿素加普通过磷酸钙(简称普钙)为40.8％,硝酸磷肥为36.4％。说明硝酸磷肥不宜于水稻田施用。用~(32)P示踪法测定水稻对几种复(混)合肥的磷的利用率:硝酸磷肥为22.6％,氯磷铵为22.4％,尿素磷铵为21.1％,尿素加普钙为20.7％,普钙为11.9％。水稻对供试复(混)合肥料磷的利用率均显著高于普钙。     

运用双液相系统进行三氯苯的生物降解

Due to easy volatilization of volatile organic compounds from water,it is difficult to monitor their aerobic biodegradation in the traditional single water system.Whether a two-liquid-phase system(TLPS) could overcome this obstacle and enhance the degradation of volatile contaminants? In this study,a TLPS composed of silicone oil and water was employed to investigate the biodegradation of volatile compounds,trichlorobenzenes(TCBs),by the adapted microorganisms in an activated soil.The degradation and volatilization of TCBs in TLPS and in a single water system were compared.The results showed that due to volatilization losses of TCBs,the mass balance of TCBs in a single water system was very low.In contrast,using TLPS could effectively inhibit the volatilization losses of TCBs and achieved a very good mass balance during the biodegradation process.Meanwhile,the TLPS could increase microbial activity and microbial growth during the degradation process.With TLPS,the TCB degradation was in descending order of 1,2,4-TCB> 1,2,3-TCB>> 1,3,5-TCB,which was related to the exposed concentration of the contaminants in soil.This study showed that TLPS could be employed as an effective tool to evaluate the biodegradation of volatile hydrophobic organic compounds,which could not be achieved with the traditional single water system.     

无机添加剂对复混肥中有效养分的影响

复混肥制作过程中无机添加剂的使用可以导致肥料中有效养分的减少，为了阐明和有效地解决这个问题，选用含有氮、磷、钾3种营养元素的肥料和常用的无机添加剂作为原料，模拟工厂化制作和贮存过程，以分析和探讨无机添加剂对肥料养分有效性的影响。研究结果表明，灰白色膨润土、浅红色膨润土和钙粉对复混肥的有效养分含量均有影响，需根据实际生产需求选取适宜的添加剂。     

复合充种式排种器的研究

设计了一种复合充种、重力清种式排种器，分析了充种过程中种子相对排种盘的运动轨迹，并依此设计了排种盘的型孔。该排种器不需设置清种机构，有效地解决了由此而产生的种子破碎问题，尤其是玉米催芽播种的种子破碎。田间性能测试结果表明：该排种器的各项性能指标均达到了JB/T51017—92中耕作物精密播种机质量分等中的优等品指标。     

氮锌复合作用对单播和混播牧草氮素来源的影响

在亚热带中山草地黄棕壤上研究了氮锌复合作用对单播和混播牧草氮素来源的影响 ,结果表明 :施氮降低了白三叶前期固氮百分数 ,但低水平施氮显著提高了白三叶后期固氮百分数。在各种施氮水平下 ,施锌 6mg kg之处理 %Ndfa最高。施氮显著降低了氮转移的数量 ,低量施锌促进了氮转移 ;施氮促进了牧草对肥料氮的吸收 ,所有施氮水平下 ,单播黑麦草 %Ndff以施锌 6～ 2 0mg kg较高。在施氮 3 0～ 90mg kg,混播黑麦草和混播白三叶 %Ndff以施锌 6～ 2 0mg kg较低 ;单播和混播黑麦草 %Ndfs随施氮水平增加显著下降 ,施锌对单播黑麦草的 %Ndfs影响不明显。在所有施氮水平下 ,施锌 6～ 2 0mg kg减少了混播白三叶和混播黑麦草对土壤氮的吸收     

非浸泡复合酶法预处理改善糙米碾米性能

在糙米碾米过程中普遍存在碎米较多及碾米能耗高的问题,为改善糙米碾米品质,提出以纤维素酶和木聚糖酶的复合酶溶液处理替代常规水加湿方法的酶法预处理工艺。以贮藏期糙米(含水率15%以下)为原料,采用二次正交旋转中心组合设计试验,研究复合酶溶液处理工艺中复合酶配比、酶质量浓度、加液量及酶处理时间对碾米后整精米率和碾米能耗的影响规律,建立了各因素对整精米率和碾米能耗影响的数学模型。结果表明:构建的整精米率、碾米能耗与复合酶配比、酶质量浓度、加液量及酶处理时间之间的回归方程极显著(P0.01),得到优化参数组合为纤维素酶和木聚糖酶质量比1.3∶1 g/g、复合酶溶液质量浓度65 mg/m L、加液量1.25%,酶处理时间102 min,该条件下整精米率为80.07%、碾米能耗为90.72 k J/kg。复合酶溶液处理后整精米率较加湿调质处理提高约3.98%,节约能耗约13.06%;较纤维素单一酶溶液加湿处理后整精米率提高约0.98%,节约能耗约5.48%。并通过微观结构分析证实了糙米皮层粗纤维的局部破损是其碾米性能改善的主要原因。研究结果可为实际生产条件下的酶法糙米预处理工艺提供参考。     

尿素与复合氮肥增效剂配施对水稻氮素利用的影响

采用^15N-尿素进行盆栽和田间试验，研究了复合氮肥增效剂用量、尿素与复合氮肥增效剂配施对水稻生长、籽粒产量和氮素吸收利用的影响。结果表明，适宜用量（施氮量的20％）的复合氮肥增效剂能显著促进水稻幼苗生长发育；尿素全量配施复合氮肥增效剂不影响水稻生长，能显著提高水稻植株Ndff％、氮吸收总量，氮素利用率和^15N的吸收量,尿素减量5％～15％（即减少施氮7．8～23．7kg／hm^2）配施复合氮肥增效剂基本上不影响水稻生长、籽粒产量和吸氮总量，能显著提高氮素的农学效率、生理效率和氮素利用率；植株吸氮总量、净吸收氮量和^15N总吸收量与不施增效剂的处理相当或有所提高。尿素减量达30％以上配施复合氮肥增效剂，对水稻植株生长和氮素吸收利用产生明显不利影响。尿素与施氮量20％的复合氮肥增效剂配施，不影响大田水稻植株生长和单季产量，能提高氮素利用率，节省氮肥投入达15％。     

不同用量腐植酸复合肥对葡萄叶片养分积累及其生理指标的影响

以2年生葡萄为供试作物进行盆栽试验,研究不同用量腐植酸复合肥对葡萄叶片养分积累及其生理指标的影响。结果表明,不同肥料用量对葡萄体内各种生理活动均有明显影响,且与等养分的无机肥相比,腐植酸复合肥表现出明显优势。施肥量低于1.75g/株时,超氧化物歧化酶活性随施肥量的增加显著提高,但当施肥量超过1.75g/株后,超氧化物岐化酶活性开始显著降低;当施肥量为3.50g/株时,过氧化物酶活性达最高,之后再增加肥料用量,腐植酸复合肥处理过氧化物酶活性急剧下降,而无机肥处理过氧化物酶活性变化平缓,对葡萄叶片蒸腾速率的影响与对过氧化物酶活性的影响趋势基本一致;施肥有利于植株叶片养分的积累及吸收利用。     

复合果蔬汁饮料最优配方的筛选

采用L9（3^4）正交试验设计对复合果蔬汁饮料生产的4个主要因素（果蔬汁、海藻糖、柠檬酸和稳定剂）进行处理方案设计,按工艺生产出相应的产品,应用Excel程序建立四元二次多项式方程,并进行效应分析,得出各因素对饮料品质的影响,再运用Qbasic寻优程序进行寻优。试验结果表明,4个因素对饮料品质影响大小顺序为：果蔬汁〉稳定剂〉海藻糖〉柠檬酸;复合果蔬汁饮料的最佳配方为：甜红椒汁25％,枸杞汁7．5％,柠檬汁7．5％,海藻糖10％;柠檬酸0．04％;CMC＋黄原胶0．18％。