秋茬生菜深水栽培氧的需求规律

以意大利耐抽薹生菜为试验材料,研究了深水栽培条件下不同生长发育阶段营养液中的溶氧量和单株吸氧量的变化。结果表明,生菜的不同生长阶段营养液中溶存氧的日变化和植株单株吸氧量有所不同,生长初期,氧需求量和吸收量均较少,只需补充少量的氧就可满足正常生长的需要;生长中期氧的需求和吸收量均较高,生长末期氧需求量减弱,吸收量也明显下降。生产管理上应注意增加和补充生长中期的充氧时间和充氧量,适当减少生长末期的充氧量。     

铝盐对厌氧微生物产甲烷活性的影响研究

废水中铝盐含量增高以及铝盐的生物毒性使其对废水生物处理工艺中微生物产生的危害引起了人们的关注。本文以产甲烷活性为指标，通过投加氯化铝测定其对颗粒污泥的产甲烷毒性来研究铝盐对厌氧菌的危害。结果表明，铝盐使厌氧颗粒污泥的活性明显降低，但其毒性可以驯化，且清除铝盐后厌氧颗粒污泥的活性可以恢复。     

长链脂肪酸对厌氧颗粒污泥产甲烷活性的影响及其相互作用研究

采用间歇培养实验研究了辛酸、癸酸和月桂酸等三种长链脂肪酸对UASB反应器厌氧颗粒污泥产甲烷活性的毒性，以及癸酸对辛酸和月桂酸抑制作用的影响。结果表明，辛酸、癸酸和月桂酸对UASB反应器厌氧颗粒污泥的产甲烷活性有严重抑制，对厌氧颗粒污泥最大比产甲烷活性产生50%抑制的浓度(IC     

旱区覆膜滴灌棉田N 2 O排放对化肥减量有机替代的响应

覆膜滴灌条件下,采用静态箱-气相色谱法研究了不同施肥策略:CK(不施肥)、CF(N 300 kg/hm~2;P2O590 kg/hm~2;K2O 60 kg/hm~2)、60%CF+OF(普通有机肥6 000 kg/hm~2)、60%CF+BF(生物有机肥6 000 kg/hm~2)对棉田土壤N_2O排放的影响,旨在明确滴灌棉田连续不同施肥策略下土壤N_2O的排放特征。结果表明,棉花生育期N_2O排放通量表现为施肥处理大于不施肥处理,滴灌施肥后第3/4天N_2O排放通量顺序为CF60%CF+OF60%CF+BFCK,而滴灌后第7/8天N_2O排放通量则表现为有机肥处理高于化肥处理,滴灌施肥结束后表现与之相同;生育期的N_2O排放总量以100%化肥处理(CF)最高,与其相比,60%CF+OF和60%CF+BF处理分别降低3.75%和8.37%,N_2O排放系数则分别降低1.39%和73.8%;相关及通径分析均表明,与土壤NH+4-N相比,NO-3-N与N_2O排放的关系更密切。     

电控发动机的氧传感器波形分析

通过汽车示波器对氧传感器的信号电压波形测试,介绍了氧传感器的标准信号电压波形、氧传感器波形分析法诊断发动机故障的一般流程及其具体应用。     

博落回急性及亚慢性毒性试验

博落回对小鼠经口急性毒性和对大鼠腹腔注射慢性毒性试验结果表明：博落回生物碱硫酸盐对昆明系小鼠的急性毒性为：水溶液ＬＤ５０＝９００ｍｇ·ｋｇ＾－１，水混悬液ＬＤ５０＝１０４３ｍｇ·ｋｇ＾－１，均属低毒级。博落回注射液对Ｗｉｓｔａｒ大鼠亚慢性毒作用的靶器官主要为肝，长时间或大剂量接毒引起肝细胞变性，增生，使雄性动物肝／体比明显增高，而血清谷－丙转氯酶下降。     

Use of ammonia electrode for total nitrogen determination in plants

Abstract

An ammonia electrode was evaluated as a means of determining ammonium concentration in semi‐micro Kjeldahl digests of plant samples. Results of the ammonia electrode determination agreed closely with distillation and titration results. Advantages of the electrode method include speed, precision, increased safety, simplicity and the fact that only a small aliquot of the digest is used.     

Sulfur content of plant material: A comparison of methods of oxidation prior to determination

Abstract

Procedures for S determination involving digestion of plant material with HNO₃/HClO₄ mixtures gave lower values than those using oxygen flask combustion. Tests on a range of S compounds showed that the HNO₃/HClO₄ procedure underestimated S present in methionine, cysteine and glutathione but S in sulfate and the glucosinolate, sinigrin, was not underestimated.

Low recoveries using HNO₃/HClO₄ digestion procedures can be due both to incomplete oxidation of certain compounds and to gaseous losses during the vigorous boiling stage of digestion.     

Effect of high rates of zinc on several crops grown on an irrigated plainfield sand

Abstract

A field experiment was conducted to determine whether Zn applied for pathogen control could accumulate to a level which would be toxic to snapbeans, cucumbers, or corn. Zinc sulfate (ZnSO₄) was applied at rates varying from 0 to 363 kg Zn/ha on a Flainfield loamy sand to approximate 3, 9, 27 and 81 years of fungicidal treatment.

Even at the high rate of Zn, yields of snapbeans, cucumbers, or corn generally were not reduced. As rates of applied Zn increased, there was a corresponding increase in the level of Zn in the leaf tissue of all crops grown. At the high Zn rate, snapbean and cucumber leaf tissue accumulated over 350 ppm Zn. Available soil Zn was extracted with 0.1N HCl, EDTA, or DTPA. Highly significant correlations were observed between the Zn removed by each extractant and plant tissue Zn, thus, indicating that the various extractants were equally effective in predicting Zn uptake.

Very little downward movement of Zn was observed. Two and one‐half years after application, the Zn had leached to a depth of only 30 cm in the soil profile at the higher Zn rates.

These data indicate that application of Zn‐containing fungicides and bactericides should not cause a Zn toxicity problem on the Plainfield sand in the foreseeable future.