不同烤烟基因型根际钾营养和根系特性研究

以3个烤烟基因型农大202、K326和NC89为材料,采用土培和砂培试验,研究了烤烟根系阳离子交换量(CEC)及根际和非根际土壤速效钾、缓效钾含量的变化,以及根系分泌物、根际微生物数量对土壤钾的活化效应。结果表明,各基因型烤烟根际和非根际土壤速效钾含量不同,依次为农大202>K326>NC89;3个基因型烤烟根系分泌物对土壤钾素均有活化作用,农大202活化能力最强,各基因型间差异达极显著水平;与烤烟非根际相比,各基因型烤烟根际真菌数量增加。农大202根际真菌数量较大,极显著的高于K326和NC89,K326和NC89两基因型间差异不显著。3个烤烟基因型根际细菌数量差异达到极显著,而放线菌数量差异不显著。农大202根系阳离子交换量(CEC)高于NC89和K326的,但K326和NC89两基因型间的差异不显著。选育富钾烟草品种,应注重根系生理特性。     

植物对土壤高量硝酸钙积累的反应与温室生理障碍机理浅析

硝酸钙在土壤中累积导致植物生长异常是温室栽培中常见的问题之一。高量硝酸钙何以会引起生长异常尚不十分清楚。本文从植物对硝酸根和钙的生理反应方面进行了探讨。植物对硝酸根的吸收与还原可引起根表和根细胞质pH上升,诱导植物缺铁,高量硝酸根对根系细胞质膜硝酸还原酶的诱导可引起亚硝酸根在根表形成,抑制根系尤其是根毛的生长和养分的吸收;细胞质膜硝酸还原酶有可能促进氧化锰在根表还原而利于锰在植物中的累积。高量可溶性钙既抑制其他阳离子的吸收,又通过对液泡膜阳离子/H+交换体的诱导,促进钙、锰、锌等离子在液泡中累积,加剧养分缺乏的程度。高硝态氮引起的高细胞质pH和可溶性有机氮含量等等,既可导致缺素症又可致抗病性下降,可能是病害容易发生的生理学原因。控温不好的温室如塑料大棚,昼夜温差大,易加剧细胞质pH的波动,促进离子或溶质在液泡中的累积,易加剧营养失衡,可能是温室生理障碍易发生的环境因素。     

内毒素对体外培养仓鼠肾细胞膜酶PLA2和ATPase活性影响及阳离子A拮抗效应研究

为研究内毒素(Endotoxin,ET)对体外培养的仓鼠肾细胞膜活性影响及阳离子A(Cation A,CA)对其的保护效应。随机将体外培养的仓鼠肾细胞(BHK-21)分为:对照组(Ⅰ组)、ET处理组(Ⅱ组)和ET+CA组(Ⅲ组),采用微量滴定法和定磷法,第3、6、12、24小时测定细胞膜上磷脂酶A2(PLA2)和ATP酶(ATPase)的活性。结果表明,II组中PLA2活性在整个实验过程中均显著高于I组(P<0.01或P<0.05),Na+-K+-ATPase、Ca2+-Mg2+-ATPase活性呈现先增高后降低的趋势(3、6、12 h增高,24 h以后降低)。III组与II组相比,PLA2的活性显著降低(P<0.05),Na+-K+-ATPase、Ca2+-Mg2+-ATPase活性在整个实验过程中均显著增高(P<0.01或P<0.05)。细胞膜上的PLA2活性增高,ATPase的活性先增高后降低,提示细胞膜受到损伤;CA能明显改善内毒素所致的体外细胞膜损伤。     

PAM-atta复合保水剂对土壤物理性质的影响

在研制开发出耐盐型丙烯酰胺/凹凸棒黏土复合保水剂(PAM-atta)的基础上,研究了该复合保水剂对土壤物理性质的影响。结果表明:PAM-atta复合保水剂可显著提高土壤含水量、>0.25mm团聚体含量、孔隙度以及阳离子交换量,降低土壤体积质量(容重)。同时PAM-atta复合保水剂粒径越小,对土壤体积质量、团聚体等的作用效果也越明显。与CK相比,施用120目的保水剂可提高土壤中>0.25mm团聚体含量达13.3%~16.2%。     

Development of ensemble pedotransfer functions for cation exchange capacity of soils of Qingdao in China

Soil cation exchange capacity (CEC), which is considered to be an indicator of buffering capacity, is an important soil attribute that influences soil fertility but is costly, time‐consuming and labour‐intensive to measure. Pedotransfer functions (PTFs) have routinely been used to predict soil CEC from easily measured soil properties, such as soil pH, texture and organic matter content. However, uncertainty in which one to select can be substantial as different PTFs do not necessarily produce the same result. In this study, a total of 100 soil samples were collected from surface horizons (0–20 cm) in different regions of Qingdao City, China. Three ensemble PTFs (ePTFs), including simple ensemble mean (SEM), individually bias‐removed ensemble mean (IBREM) and collective bias‐removed ensemble mean (CBREM), were developed to reduce the uncertainty in CEC prediction based on 12 published regression‐based PTFs. In addition, a local PTF (LPTF) for CEC was also developed using multiple stepwise regression and basic soil properties. The performances of the three ePTFs were compared with those of the published PTFs and LPTF. Results show that the differences between the performances of the published PTFs were substantial. When the systematic bias of each published PTF was removed separately, the prediction capability of the PTFs was increased. The performance of LPTF was significantly better than that of SEM, but slightly worse than IBREM. It is noted that CBREM had higher accuracy than all of the other methods. Overall, CBREM is a promising approach for estimating soil CEC in the study area.     

用悬液Wien效应研究阳离子与土壤粘粒间的能量关系

从能量关系研究土壤带电粘粒与电解质离子间的相互作用一直是土壤化学家希望解决的课题。本文介绍阳离子与带电粘粒间的平均结合自由能和平均吸附自由能的计算公式,并用悬液Wien效应法研究K 、NH4 、Ca2 和Cd2 与黄棕壤、棕壤和黑土粘粒间的能量关系。研究结果表明:K 和NH4 的平均结合自由能范围为6.3~7.1kJmol-1,K 的结合能稍大于NH4 的;Ca2 和Cd2 的结合能范围为7.2~9.4kJmol-1。同一阳离子与不同土壤的结合能顺序如下:黄棕壤<棕壤<黑土。它们在同一高场强(如150kVcm-1)下的平均吸附能ΔGad值:K 和NH4 在黄棕壤和棕壤粘粒上的很接近,分别为0.9和0.8kJmol-1,而在黑土粘粒上,NH4 的较K 的大0.1kJmol-1;Ca2 在黄棕壤和黑土上的吸附能较Cd2 的分别大0.3和0.6kJmol-1;二价阳离子的平均吸附自由能约为一价阳离子的2~2.5倍。     

Amelioration of subsoil acidity in an Oxisol of the humid tropics

Summary This work investigated the effectsof amendments of fertilizer N and lime on subsoil acidity and maize rooting depth in an acid soil of the central Amazon basin. A split-plot designed field experiment was conducted on a clayey Oxisol (Typic Acrudox) during a 16-month period. Main plots received 0 or 4 Mt ha^-1 of lime. Subplots were four crop sequences: (1) Maize-green manure (Canavalia ensiformes); (2) maize-green manure (Mucuna aterrima); (3) maize-bare fallow, with the maize receiving 300 kg ha^-1 of urea-N; and (4) bare fallow, with an application of 300 kg ha^-1 of urea-N at the same time as sequence 3. Plots were periodically sampled to 1.2 m. The experimental site received 4265 mm of precipitation during 16 months; approximately 60%–90% of this rain percolated through the profile. Substantial amounts of Ca were leached from the 0–30 cm horizon during the experimental period, but only limited amounts accumulated in the subsoil. Base saturation below 45 cm was less than 50% at the end of the experiment regardless of lime treatment. Roots of maize were concentrated in the 0–30 cm layers in limed plots and the 0–20 cm layers in unlimed plots. In all treatments less than 5% of the roots was found below 50 cm. An acidity balance indicated that considerable acidity was leached below the plow layer and out of the profile.     

Inverse models to analyze the spatiotemporal variations of chemical weathering fluxes in a granito-gneissic watershed: Mule Hole, South India

Water-rock reactions are driven by the influx of water, which are out of equilibrium with the mineral assemblage in the rock. Here a mass balance approach is adopted to quantify these reactions. Based on field experiments carried out in a granito-gneissic small experimental watershed (SEW), Mule Hole SEW (~ 4.5 km²), quartz, oligoclase, sericite, epidote and chlorite are identified as the basic primary minerals while kaolinite, goethite and smectite are identified as the secondary minerals. Observed groundwater chemistry is used to determine the weathering rates, in terms of ‘Mass Transfer Coefficients’ (MTCs), of both primary and secondary minerals.Weathering rates for primary and secondary minerals are quantified in two steps. In the first step, top red soil is analyzed considering precipitation chemistry as initial phase and water chemistry of seepage flow as final phase. In the second step, minerals present in the saprolite layer are analyzed considering groundwater chemistry as the output phase. Weathering rates thus obtained are converted into weathering fluxes (Q_weathering) using the recharge quantity.Spatial variability in the mineralogy observed among the thirteen wells of Mule Hole SEW is observed to be reflected in the MTC results and thus in the weathering fluxes. Weathering rates of the minerals in this silicate system varied from few 10 μmol/L (in case of biotite) to 1000 s of micromoles per liter (calcite). Similarly, fluxes of biotite are observed to be least (7 ± 5 mol/ha/yr) while those of calcite are highest (1265 ± 791 mol/ha/yr). Further, the fluxes determined annually for all the minerals are observed to be within the bandwidth of the standard deviation of these fluxes. Variations in these annual fluxes are indicating the variations in the precipitation. Hence, the standard deviation indicated the temporal variations in the fluxes, which might be due to the variations in the annual rainfall. Thus, the methodology adopted defines an inverse way of determining weathering fluxes, which mainly contribute to the groundwater concentration.     

Effect of residual sodium carbonate in irrigation water on the soil sodication and yield of palmarosa (Cymbopogon martinni) and lemongrass (Cymbopogon flexuosus)

The effects of residual sodium carbonate (RSC) in irrigation water on soil sodication and yield and cation composition of palmarosa (Cymbopogon martinii Roxb. Wats) and lemongrass (Cymbopogon flexuosus Steud Wats) were studied in the open bottom reinforced concrete cemented (RCC) cylindrical barrels embedded in the field and filled with sandy loam soils. The results indicated that the increasing RSC in irrigation water significantly increased the pH, electrolyte conductivity (ECe) and SARe of the soil and, hence, considerably decreased the herb and oil yield of both the palmarosa and lemongrass. The reduction in total herb yield was 14.5, 18.3, 28.8 and 32.0% in palmarosa and 38.6, 46.0, 57.7 and 62.6% in the lemongrass over control at 4.0, 8.0, 12.0 and 16.0 meq/l of RSC, respectively. The total oil yield of palmarosa increased by 22.6% with the increase in RSC from 2.0 (control) to 4.0 meq/l and further increase in RSC decreased the oil yield by 13.0, 22.4 and 22.9% over control at 8,12 and 16 meq/l of RSC, respectively. The total oil yield of lemongrass was decreased by 27.0, 39.4, 47.7 and 50.8% over control at 4, 8, 12 and 16 meq/l, respectively. The concentration of Na increased significantly and K and Ca decreased with increase in RSC of irrigation water in vegetative tissues of both species. The lemongrass accumulates significantly greater amount of Na in shoot tissues as compared to palmarosa and it failed to survive at high RSC after 21 months of transplanting. The results suggests that palmarosa is more tolerant to irrigation water sodicity than the lemongrass.     

Acid‐base titration of barley roots

H saturated barley roots were titrated in the presence of 3 different concentrations of KC1. From the observation of the curves obtained, four regions corresponding to ionogenic groups of different pK values are apparent. A CEC of 20 to 30 miliequivalents/100 g dry weight was calculated for barley roots. A pzc value of about 4.5 was found graphically for the root surface.