共查询到20条相似文献，搜索用时 31 毫秒
1.
《土壤圈》1994,4(3):209-216
2.
ZHANGHONG ZHANGXIAO－NIAN 《土壤圈》1992,2(1):31-42
The contribution of iron and aluminum oxides to electrokinetic characteristics of variable charge soils was studied through determination of electrophoretic mobilities of the red soils treated with either removal of iron oxides or coating of aluminum oxides,and of those deferrated under natural conditions.After removal of the iron oxides,zeta potentials of the latosol and the red earth decreased obviously with a shift of IEP to a lower pH,from 6.4 to 5.3 and 4.1 to 2.4 for the former and the latter,respectively,and the electrokinetic change for the latosol was greater than for the red earth.Zeta potentials of the kaolinite sample increased markedly after coated with iron oxides.The striking effect of iron oxides on electrokinetix properties of the soils was also demonstrated by the electrokinetic differences between the samples from the red and white zones of a plinthitic horizon formed naturally,and between the samples from the gley and bottom horizons of a paddy soil derived from a red earth.The coatings of aluminum oxides on the latosol and the yellow earth made their zeta potentials rise pronouncedly and their IEFs move toward higher pHs,from 6.2 to 6.8 and 4.3 to 5.3 for the former and the latter,respectively.The samples with different particle sizes also exhibited some electrokinetic variation.The experiment showed that the effects of iron and aluminum oxides were closely related to the pH and type of the soils. 相似文献
3.
The irrigation and nitrogen (N) requirements of potatoes (cv. Delaware) were determined using sprinklers in a line‐source design on a Spearwood sand. Irrigation water was applied at 73 to 244% of the daily pan evaporation (Epan) and N at 0 to 800 kg N ha‐1 (total applied) as NH4NO3 in 10 applications post‐planting. There was a significant yield (total and marketable) response to irrigation, at all levels of applied N, and N at all levels of applied water (P<0.001). The interaction between irrigation and N was also significant (P<0.001). There was no significant yield response to irrigation from 149% Epan (i.e., W3 treatment) to 244% Epan (i.e., W6 treatment). Irrigation at 125 and 150% of Epan was required for 95 and 99% of maximum yield, respectively, as determined from fitted Mitscherlich relationships. Critical levels of N required for 95 (417 kg ha‐1) and 99% (703 kg ha‐1) of maximum yield were also determined from a Mitschlerlich relationship fitted to the average of the W3 to W6 treatments. The percent total N and nitrate‐N in petioles of youngest fully expanded leaves required for 95 and 99% of maximum yield was 1.78 and 2.11, respectively, at the 10 mm tuber stage, and 0.25 and 0.80% at the 10mm plus 14 day stage (from quadratic regressions). There was a significant (P≤0.001) increase in N uptake by tubers with level of applied N from 57 kg ha‐1 at 0 kg applied N ha‐1 to 190 kg ha‐1 at 800 kg applied N ha‐1 (from a Mitscherlich relationship fitted to the average of W3 to W6 treatments). After accounting for N uptake from soil reserves (57 kg N ha‐1), apparent recovery efficiency (RE) of fertilizer N by tubers [RE=(Up‐Uo/Np) where Up=uptake of N by the crop, Uo=uptake in absence of applied N and Np is the level of applied N, expressed as a fraction] declined from 0.28 at 100 kg applied N ha‐1 to 0.17 at 800 kg applied N ha‐1. There was a linear increase in ‘after cooking darkening’ (i.e., greying) of tubers with increasing level of applied N. Conversely, ‘sloughing’ (i.e., disintegration) of tubers decreased (inverse polynomial) with increasing level of applied N. Rate of irrigation had no effect on these cooking qualities. Reducing applied irrigation and N from levels required for 99% of maximum yield to levels required for 95% of maximum yield would not lead to a significant reduction in profit. This would increase apparent recovery efficiency of applied N by plants, maintain tuber quality, and reduce the impact of potato production on the water systems of the Swan coastal plain. 相似文献
4.
半悬挂犁工作幅宽大，作业效率高，非常适应大农业生产的要求，为了合理地进行半悬挂犁与拖拉机机组的配套设计和使用，减少耕作过程中的功率消耗，提高机组效率，就必须要对半悬挂犁进行受力和结构参数分析，传统的分析方法是利用图解法。本文从理论上分析了采用图解法进行半悬挂犁受力分析所存在的问题，建立了半悬挂犁受力的矩阵方程组，利用计算机辅助分析，预测了半悬挂犁机组各结构参数变化对机组受力工况的影响，从而为半悬挂犁机组的合理配置、强度计算和优化设计提供了理论依据。 相似文献
5.
6.
A experiment was carried to evaluate the effects of Al on growth,accumulations of free proline and amino acid in 2 wheat cultivars(Triticum aestivum L.),Yangmai No.5 and Jian 864,differing in Al Sensitivity.Plants grew initially in a nutrient solution without Al for 13 days before the addition of Al and finally in a nutrient solution containing 0.5mmol Al(L^-1)for 19 days,the results showed that there were marked deceases in dry weight,relative growth rate(RGR) and net assimilation rate (NAR)of Al-treated seedlings compared with control plants.The Al effects were more evident in Yangmai No.5 than Jian 864.Leaf area ratio(LAR) was little affected by Al.RGR was highly correlated with NAR rather than LAR.Aluminum increased the concentrations of free proline and total free amino acid in shoots of both the cultivars.The increases were greater in Yangmai No.5 than in Jian 864.The percentage of free proline in total amino acid in shoots was not affected by Al treatment.It was possible that accumulation of proline was merely a symptom of Al injury.The concentrations of total nitrogen in Al-treated plants did not significantly differ from those of control plants.Nitrate reductase activity(NRA),in leaves was severely decreased by Al,and a greater decrease was noted in Yangmai No.5 than in Jian 864,but NRA in roots of both the cultivars was not affected.The decreases in NRA might be and indirect(accumulation of amino acid) rather than a direct result of Al toxicity. 相似文献
7.
The potential of combining solid-phase microextraction (SPME) with gas chromatography and chemometric data analysis to differentiate between pure strawberry samples (Fragraria ananassa) and strawberry samples adulterated with 10, 40, and 70% (v/v) apple purée was investigated. The method involved the extraction of aroma volatiles from the headspace of the purée samples using a SPME fiber followed by GC analysis with flame ionization detection. The principal component analysis (PCA) data matrix consisted of the relative percent peak areas of 37 compounds deemed to be significant in the differentiation of the samples on the basis of adulteration. The PCA results clearly showed that differentiation of the adulterated and unadulterated samples was possible, particularly at the higher levels of adulteration. Partial least-squares regression (PLSR) using a dummy set of Y variables (set to 0 for unadulterated and 1 for adulterated samples) resulted in clear discrimination between unadulterated purées and those containing 40 and 70% (v/v) apple. PLSR using a second set of Y variables, consisting of the actual level of adulteration, enabled quantification of apple purée with a standard error of prediction of 11.6%, implying a minimum detectable level of 25% (v/v) apple. GC-MS analysis enabled identification of the compounds with the greatest influence on sample differentiation. These compounds were identified as hexanoic acid, 2-hexenal, and alpha-farnesene, all of which are key aroma compounds in apples. 相似文献
8.
Nature of Soil Acidity in Relation to Properties and Lime Requirement of Some Inceptisols 总被引：1，自引：0，他引：1
Some Inceptisols representing the Singla catchment area in Karimgaunge district of Assam, India, were studied for lime requirement as influenced by the nature of soil acidity. The electrostatically bonded (EB)-H+ and EB-Al3+ acidities constituted 33 and 67 percent of exchangeable acidity while EB-H+, EB-Al3+,exchangeable and pH-dependent acidities comprised 6, 14, 20 and 80 percent of total potential acidity. The pH-dependent acidity made a major contribution towards the total potential acidity (67%～84%). Grand mean of lime requirement determined by the laboratory incubation method and estimated by the methods of New Woodruff, Woodruff and Peech as expressed in MgCaCO3 ha-1 was in the order: Woodruff (15.6) ＞ New Woodruff (14.9) ＞ Peech (5.1) ＞ incubation (5.0). Correlations analysis among different forms of acidity and lime requirement methods with selected soil properties showed that pH in three media, namely water, 1 mol L-1 KCl and 0.01 mol L-1 CaCl2, had a significant negative correlation with different forms of acidity and lime requirement methods. Exchangeable Fe and Al showed significant positive correlations with EB-Al3+ acidity, exchangeable acidity, pH-dependent acidity and total potential acidity, and also lime requirement methods. Extractable Al showed positive correlations with different forms of acidity except EB-H+ and EB-Al3+ acidities. The lime requirement by different methods depended upon the extractable aluminium.Significant positive correlations existed between lime requirements and different forms of acidity of the soils except EB-H+ acidity and incubation method. The nature of soil acidity was mostly pH-dependent. Statistically, the Woodruff method did slightly better than the New Woodruff, incubation and Peech methods at estimating lime requirement and hence the Woodruff procedure may be recommended for routine soil testing because of its speed and simplicity. 相似文献
9.
10.
B.L. Jalali 《Soil biology & biochemistry》1976,8(2):127-129
The alterations brought about in the carbohydrate spectrum of root exudates of wheat in response to six foliar treatments, and their influence on the fungal population of the rhizosphere have been correlated. Pronounced suppression of ribose, maltose and raffinose exudation, which were liberated abundantly from root-rot infected roots, was recorded in response to foliar treatments with chloramphenicol and KCl. Chloramphenicol and to a lesser extent 2,4-D also reduced the rhizosphere population, including the test pathogen Helminthosporium saticiun. Previous and present investigations, therefore, indicate that the composition of root exudates could effectively be altered by foliar sprays, in an attempt to control the activity of Helminthosporium sativum, causing root-rot of wheat, in soil. 相似文献
11.
《Communications in Soil Science and Plant Analysis》2012,43(17-18):1931-1940
Abstract Recent research has indicated that land application of municipal sewage sludge to calcareous soils can be used to ameliorate iron (Fe) deficiency of grain sorghum [Sorghum bicolor (L.) Monech]. A greenhouse study was conducted to determine the response of grain sorghum grown on three different soils to application of sewage sludge. Sludge applied at rates of 0, 7.5, 15.0, and 25.0 g/kg soil did not completely ameliorate grain sorghum Fe deficiency. When FeEDDHA was soil applied, sewage sludge application significantly increased plant growth due to increases in soil phosphorus (P) availability. Application of sewage sludge at rates greater than 7.5 g/kg reduced dry matter production of grain sorghum in the FeEDDHA amended Orelia SC soil, the soil with the lowest total neutralizing potential. The decreases yield was possibly due to toxic levels of soil and plant copper (Cu) and zinc (Zn), and increased soil salinity. 相似文献
12.
《Communications in Soil Science and Plant Analysis》2012,43(7):571-581
Abstract Phosphorus sorption studies were conducted on volcanic ash influenced surface horizons of 29 northern Idaho soils. Results show that the amount of P sorbed was significantly correlated with citrate‐dithionite extractable aluminum (r = .64**), but not with Fe. Other significantly correlated soil properties were: percent base saturation (r = ‐.73**), percent clay (r = .42**), and exchangeable acidity (r = .39*). 相似文献
13.
《Communications in Soil Science and Plant Analysis》2012,43(17-18):2381-2399
Abstract This study was conducted to investigate the effects of four boron (B) doses (control, 0 kg B ha?1; B1, 1 kg B ha?1; B2, 3 kg B ha?1; and B3, 6 kg B ha?1) in soils deficient in available B (0.19 mg B kg?1) and lime (CaCO3) content (20.7%) on yield and some yield components of five chickpea (Cicer arietinum L.) genotypes, namely Akçin‐91, Population, Gökçe, ?zmir‐92, and Menemen‐92 in central Anatolian Turkey in the 2002 and 2003 growing seasons. Plant height, pods per plant, grain yield, protein content, protein yield, thousand seed weight, and leaf B concentration were measured. Grain yields in all genotypes (except for Gökçe) were significantly increased by 1 kg ha?1 B application. Application of 1 kg ha?1 B increased the yield by an average of 5%. Genotypes studied showed significant variations with respect to their responses to additional B. Akçin‐91 gave the highest grain yield (1704.8 kg ha?1) at 3 kg B ha?1, whereas Population, ?zmir‐92, and Menemen‐92 yielded best (1468.2 kg ha?1, 1483.0 kg ha?1, and 1484.7 kg ha?1, respectively) at 1 kg B ha?1. Interestingly, Gökçe reached to the highest level of grain yield (1827.1 kg ha?1) at the control. Gökçe was a B deficiency B tolerance genotype. The other genotypes appeared to have high sensitivity to B deficiency. This study showed that B deficiency could result in significant yield losses in chickpea under the experimental conditions tested. Thus, B contents of soils for the cultivation of chickpea should be analyzed in advance to avoid yield losses. 相似文献
14.
15.
Manlio S. Fernandes 《Journal of plant nutrition》2013,36(11):1151-1164
A study was made on the effects of light and temperature combinations, nitrogen (N) carriers, and N levels on the growth and free amino‐N pool size of rice plants. The experiment was conducted in a growth chamber in nutrient solution. Combinations of high light supply (40,000 lux), or high temperature (35°C), or both, resulted in accumulation of large amino‐N pools. There were negative relationships between free amino‐N pool sizes and the fresh weight of plants. These negative relationships could be best described by decay curves. On the other hand, in plants under the low light (17,280 lux) and low temperature (24°C) combination, the amino‐N to fresh weight relationship was positive, and fitted to a straight line. The amino‐N to free sugars relationship fitted decay curves, irrespective of light and temperature combinations. The ammonium‐N to amino‐N relationship under high light and/or high temperature combinations showed a quadratic response. Analysis of these curves suggests that deamination takes place as free NH4‐N increases in plants. The results show a strong effect of the free sugar pools on the N‐metabolism of plants under stress. We suggest the decay type curves are a characteristic of the amino‐N versus fresh weight relationships of plants under environmental stress. 相似文献
16.
Field and greenhouse studies were conducted in Prince Edward Island (P.E.I.) on soybean (Glycine max(L.) Merr.), red clover (Trifolium pratense L.),alfalfa (Medicago sativa L.), and rutabaga (Brassica napobrassica,Mill).Plant B concentrations were compared to soil B extracted by hot-water,0.05 M HC1,1.5 M CH3COOH and 0.01 M CaCl2.The r values for extractable soil B vs.plant B were:hot water (0.67),0.05 M HCl(0.82),1.5M CH3COOH(0.78) and hot 0.01 M CaCl2(0.61).Results of soil B from the 0.05 M HCl extracts were generally found to give the best correlation and linear regression among the four extractants tested for predicting the availability of B to the plants.Overall,the 0.05 M HCl proved to be superior to hot water extraction and is recommended for predicting the available B status of the acid soils of P.E.I.The probability of error with 0.05 M HCL is less since it is shaken for a fixed period of time as opposed to subjective error which could be caused in monitoring the boiling time using hot water. 相似文献
17.
《Communications in Soil Science and Plant Analysis》2012,43(5-6):597-605
Abstract In Morocco,response of dryland wheat (Triticum aestivuro) to ? has not been related to soil ? availability index. The objectives of the experiments reported were to determine the critical NaHCO3‐extractable ? level in soils of Settat Province in Morocco and to compare the effect o‐f banding with broadcasting of concentrated superphosphate (CSP) for wheat, crops. Eighteen ?‐P factorial experiments were conducted on three different soil types (Rendolls, Caloixerolls and Chromoxererts) with different ? availability indexes and lime levels in 1985–86 and 1986–87. The ? rates were 0, 9, and 18 in 1985–86 and an additional 36 kg P/ha rate in 1986–87. The rainfall levels were 300 mm with an excellent distribution and 220 mm with a poor distribution in the above years, respectively. In the latter year, a P placement study was conducted on a Rendoll with a NaHCO3‐P level of 4.5 mg/kg. For the placement study the rates were 0, 9, 18, 36, and 54 kg P/ha. The grain yield response to ? averaged 8% in the wet year and 40% in the drier year. The maximum yields obtained were close to 3 and 1 Mg/ha for the above years, respectively. A critical level of 5 mg/kg of NaHCO3‐P was obtained, separating responsive from nonresponsive soils for a relative yield of 90%. The ? placement study showed that yield response to broadcast ? reached a plateau at 9 kg P/ha, but the response to banded ? continued up to the highest rate. This shows that the banding effect of CSP is more than a simple ? nutrition effect 相似文献
18.
Pawel Wojcik 《Journal of plant nutrition》2013,36(11):1897-1906
The objective of this experiment was to examine the vegetative and generative responses of highbush blueberry to boron fertilization. The study was carried out in 2002–2003 in Central Poland on mature ‘Bluecrop’ blueberries (Vaccinium corymbosum L.) planted at a spacing of 3 × 1 m on a sandy loam soil with pH value of 3.9 and low hot water soluble boron status. Blueberries were soil- or foliar-supplied with boron. Foliar boron sprays were done four times per season: at the beginning of blooming, at petal fall, and three and six weeks after the ending of flowering. In each spray treatment, boron was applied at a rate of 0.2 kg ha?1. Soil boron was applied at the stage of bud break at a rate of 2 kg ha?1. Plants untreated with boron served as control. The results showed that boron fertilization increased boron levels in flower and leaf tissues. This treatment, regardless of boron application mode, did not affect plant vigor, the number of flowers per cane, fruit set, nor yield. Also mean fruit weight and berry firmness were not influenced by boron fertilization. Fruit of boron-supplied blueberries had higher soluble solids concentrations than those of the control plants. It is concluded that boron requirements of highbush blueberry are relatively low compared to most fruit crops and that critical leaf boron concentrations of ‘Bluecrop’ blueberry are below 15 mg kg?1 DW. 相似文献
19.
Differential response of groundnut genotypes to iron‐deficiency stress was studied in soils containing high calcium carbonate. Genotypes differed significantly for some traits that appeared to be important in determining adaptation to low iron. The genotypes TCGS 273, TCGS 2, TCGS 37, and Kadiri 3 had higher total chlorophyll, total dry matter, and active iron (Fe2+) contents under iron‐deficiency stress conditions. Total chlorophyll followed by active iron were found to be sensitive parameters to Fe deficiency. Based on the visual deficiency symptoms (chlorosis score), the genotypes were classified into three groups. Efficient (no genotype was found efficient), moderately efficient (TCGS 273, TCGS 2, TCGS 3, and Kadiri 3), and inefficient (TCGS 1, TCGS 7, TCGS 11, TCGS 26, TCGS 28, TCGS 29, TCGS 30, TCGS 1518, TPT 1, TPT 2, ICGS 11, ICGS 44, Girnar, JL 24, ICGS(E) 21, and TMV 2). 相似文献
20.
《Communications in Soil Science and Plant Analysis》2012,43(9):931-941
Abstract Comparisons are made of three methods of Al analysis in micro‐samples (≤ 100 mg) of plant material. Direct current plasma emission spectrometry (DCP), graphite furnace atomic absorption spectrometry (GFAAS), and pyrocatechol violet (PCV) all gave comparable results for the plant materials analyzed. The importance of adequate sample dissolution of digested samples prior to analysis by PCV was strikingly apparent. Our results indicate that to insure complete formation of reactive Al species to complex with the dye that a combination of 12 N HCl and a 1 hr heat treatment at 70°C in a steam bath is necessary. Residue decomposition of materials with HF acid resulted in more apparent Al only by DCP analysis. Contribution of the residue to the total Al content varied between 7 and 14%. 相似文献