摘要:

The beneficial effect of sewage sludge in crop production has been demonstrated, but there is concern regarding its contribution to nitrate (NO3) leaching. The objectives of this study were to compare nitrogen (N) rates of sewage sludge and ammonium nitrate (NH4NO3) on soil profile (0–180 cm), inorganic N [ammonium nitrate (NH4‐N) and nitrate nitrogen (NO3‐N)] accumulation, yield, and N uptake in winter wheat(Triticum aestivumL.). One field experiment was established in 1993 that evaluated six N rates (0 to 540 kg·ha‐1·yr‐1) as dry anaerobically digested sewage sludge and ammonium nitrate. Lime application in 1993 (4.48 Mg ha‐1) with 540 kg N ha‐1·yr‐1was also evaluated. A laboratory incubation study was included to simulate N mineralization from sewage sludge applied at rates of 45, 180, and 540 kg N ha‐1·yr‐1. Treatments did not affect surface soil (0–30 cm) pH, organic carbon (C), and total N following the first (1994) and second (1995) harvest. Soil profile inorganic N accumulation increased when ≥270 kg N ha‐1was applied as ammonium nitrate. Less soil profile inorganic N accumulation was detected when lime was applied. In general, wheat yields and N uptake increased linearly with applied N as sewage sludge, while wheat yields and N uptake peaked at 270 kg N ha‐1when N was applied as ammonium nitrate. Lime did not affect yields or N uptake. Fertilizer N immobilization was expected to be high at this site where wheat was produced for the first time in over 10 years (previously in native bermudagrass). Estimated N use efficiency using sewage sludge in grain production was 20% (average of two harvests) compared to ammonium nitrate. Estimated plant N recovery was 17% for sewage sludge and 27% for ammonium nitrate.

ISSN:0190-4167    

DOI:10.1080/01904169709365244

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Whether the extent of dry weight inhibition by nitrogen (N) or phosphorus (P) deficiencies on different plant parts is the same and whether imposing moderate N and P deficiencies selectively suppress undesirable vegetative growth has not been studied in Pima cotton(Gossypium barbadenseL.). The purpose of this study was to determine the extent to which dry matter accumulation in leaves, stems, and reproductive structures is inhibited by N and P deficiencies in Pima cotton. The study was conducted in 1991 and 1992 in a Uvalde silty clay loam soil (fine‐silty, mixed, hyperthermic Aridic Calciustolls). The treatments included applied rates of 0, 67, 135, 202, and 269 kg N ha‐1in a factorial combination with 0, 15, 29, and 44 kg P ha‐1. Nitrogen deficiency (0 kg N ha‐1) significantly (P≤0.05) reduced leaf (LDW) and stem (SDW) dry weights in both years and reproductive dry weight (RDW) in 1992. Nitrogen deficiency suppressed dry weight accumulation in leaves to a greater extent than in stems. Relative to 269 kg N ha‐1, the 0 kg N ha‐1treatment resulted in a maximum LDW reduction of 62% at 144 DAP (days after planting) in 1991 and 36% at 121 DAP in 1992, compared with a corresponding SDW reduction of only 39% in 1991 and 25% in 1992. Dry weight accumulation in reproductive parts was the least affected by N deficiency. The decline in LDW associated with senescence and defoliation began earlier in treatments that received 0 or 67 kg N ha‐1than treatments that received ≥135 kg N ha‐1. Phosphorus affected LDW and SDW in 1991, but its differential effect on LDW, SDW, and RDW was much smaller than that of N. Imposing a moderate level of N deficiency, not P deficiency, may be an effective Pima cotton management strategy to selectively suppress undesirable vegetative growth and enhance maturity.

ISSN:0190-4167    

DOI:10.1080/01904169709365245

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The regulation of plasma membrane ATPase activity by salt stress was investigated in barley roots. The plasma membrane fractions were prepared from the roots treated with or without 200 mM sodium chloride (NaCl) for one day. After salt treatment, ATPase activity reduced by 20 to 30% as compared with that of control roots. No significant changes in the content of total phospholipid and sterol were detected in the plasma membrane fraction by salt stress. After extraction of most of the phospholipids in the plasma membrane vesicles with a solution containing 1% (W/V) octylglucoside and 1% (W/V) Triton X‐100, the ATPase activity in salt‐stressed roots was lower than that of control roots. After reconstitution of detergent‐extracted protein into liposome, the reduction of ATPase activity by salt stress did not recover. Based on immunoblott analysis, the relative amount of H+‐ATPase in plasma membrane fraction prepared, from NaCl‐stressed roots was smaller than that of control roots. These results indicate that the reduction of H+‐ATPase activity by salt stress was caused by the decrease in the amount of H+‐ATPase rather than the modification of ATPase.

ISSN:0190-4167    

DOI:10.1080/01904169709365246

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Increasing nitrogen (N) fertilizer prices give rise to the question of N benefits from legumes in cropping systems in the Southern Great Plains. This study quantified wheat (Triticum aestiviumL.) hay production and N uptake over seven years following six years of alfalfa(Medicago sativaL.), cicer milkvetch (Astragalus cicerL.), or grass (Old World bluestem,Bothriochloa ischaemumL.) production in western Oklahoma. Precipitation over the seven years averaged 550 mm·yr‐1. The major residual N effects were measured within the first five years. On a fine sandy loam soil, wheat hay yields averaged 3,070 kg·ha‐1·yr‐1over five years following alfalfa, 2,580 kg·ha‐1·yr‐1following milkvetch, and 950 kg·ha‐1·yr‐1following grass with N uptake attributed to the residual effect from legumes (calculated by the difference method) averaged 34 kg N ha‐1·yr‐1from alfalfa and 25 kg·ha‐1·yr‐1from milkvetch. On a deep loamy sand soil, wheat hay yields averaged 1,290 kg·ha‐1·yr‐1over five years following alfalfa and 710 kg·ha‐1·yr‐1following grass with N uptake attributed to the residual effect from alfalfa averaged 8 kg N ha‐1·yr‐1. Thus, the residual N effect attributed to legumes was substantial on the fine sandy loam soil and relatively small on the deep loamy sand soil.

ISSN:0190-4167    

DOI:10.1080/01904169709365247

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

An investigation was conducted to investigate the effect of strontium on peroxidase (POD) activity and chlorophyll (Chl) degradation in sugar beets(Beta vulgaris).Peroxidase activity was considerably increased by 10 mM strontium (Sr) addition to a Hoagland nutrient solution without additional application of calcium (Ca). When grown in a Hoagland nutrient solution containing both 5 mM Ca and 5 mM Sr, POD activity in all leaves and roots decreased, whereas Chl content per g fresh weight (f.w.) was increased slightly compared to POD activity and Chl contents in plants treated with calcium alone. Chla/bratios were also affected by Sr treatment. Both Sr and Ca contents were higher in older leaves than in younger leaves. Cation spectra obtained by a laser microprobe mass analyzer indicated that the intensity of sodium (Na) and potassium (K) peaks were greatly reduced by EDTA and EGTA treatments, but those of Ca, Sr, and magnesium (Mg) peaks were not.

ISSN:0190-4167    

DOI:10.1080/01904169709365248

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A simple model to compare and predict phosphorus (P) uptake behavior of plants may be useful to agronomists. A predictive equation based on Michaelis‐Menten kinetics was developed for this purpose. Kinetic parameters for use in the model were determined in an experiment using two cultivars of winter wheat grown for 21 days in 14 soil treatments, including seven P levels, each in fumigated and unfumigated soil. In another experiment, the same wheat cultivars were grown for 7, 14, or 21 days at one soil P level in both fumigated and unfiimigated soil. Using parameter values developed in the first experiment with multiple P levels and one time period, the model closely (R2=0.966, P<0.001) predicted P uptake in the second experiment with one P level over multiple time periods. The model could be a useful agronomic tool because of its simplicity and because no data need be collected from artificial growing conditions.

ISSN:0190-4167    

DOI:10.1080/01904169709365249

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The influence of low pH (4.0–4.5) of the medium on nodulation, nodule biomass, nodule nitrogenase activity, and ultrastructure at various concentrations of calcium (Ca) (0.127 mM and 0.508 mM) and nitrate (NO3) (0.390 mM and 1.560 mM) at different stages of development (2nd, 3rd, 6th, and 7th compound leaf) of the common bean plants was studied. The experiment was conducted using Hellriegel's nutrient solution under greenhouse conditions. Bean root nodule nitrogen (N2) fixation was influenced favorably at a decrease of Ca (0.127 mM) and NO3(0.390 mM) concentrations in the growth solution. In contrast, the biomass of the roots, stems, leaves, and pods decreased at low Ca and NO3levels while the most sensitive were the leaves and pods of the plants. The number of nodules, their fresh and dry weight, nitrogenase activity, and ultrastructure was affected to a greater extent at a low pH of the medium when Ca and NO3concentrations were low (0.127 mM and 0.390 mM, respectively). Under these conditions, the roots, stems, leaves, and pods were slightly affected. Nodule N2fixation was more sensitive to low pH at the 2nd and 3rd leaf stage of plant development. The root and pod biomass had the same tendency of change as the nodules. On the contrary, at low pH and decreased Ca and NO3levels (0.127 mM and 0.390 mM, respectively), the stem and leaf biomass increased significantly at the later stages of bean plant development (6th and 7th leaf). Our conclusion was that the stress effects of low pH of the medium had different affects at various Ca and NO3concentrations in the nutrient solution and stages of common bean plant development.

ISSN:0190-4167    

DOI:10.1080/01904169709365250

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The effect of preharvest calcium (Ca) foliar application on ethylene (C2H4) production, respiratory rate, soluble polyuronides, and fruit firmness of ‘Bebekou’ apricot fruits was determined. The study was carried out in two experimental years, 1991 and 1992. Calcium was applied 21, 17, and 13 days before harvest for 1991 at the concentration of 0.5% calcium chloride (CaCl2) each time and 16 and 12 days before harvest for 1992 at the concentrations of 0.8 and 0.7% CaCl2, respectively. Calcium treatment resulted in a 30–76% increase in the Ca content of fruit flesh. Treated fruits had significantly lower C2H4production rates than control during (i) four (1991) or five days (1992) at 21°C out of the 7‐day period examined immediately after harvest, and (ii) one (1991) or two days (1992) at 21°C out of the seven‐day period examined immediately after a 3rd‐ (1991) or 4th‐week (1992) storage period at 0°C. After harvest, Ca‐treated fruits displayed one day delay to reach the peak rate of C2H4production. Respiratory rate was significantly suppressed over a five‐day period at 21°C out of the seven‐day period examined immediately after harvesting. However, after four weeks of storage at 0°C, there was not any significant effect of Ca on the respiratory rate. The respiratory peak rate occurred earlier in the control fruits compared to that of the Ca‐treated fruits at harvest time. Calcium‐treated fruits were about 70% firmer than the untreated ones at harvest time. Furthermore, this difference persisted after four weeks of storage at 0°C. Foliar‐applied Ca produced a 29% decrease in the soluble polyuronide content of the fruits at harvest time, but not after four weeks of storage. Fruit firmness was positively correlated to the Ca content of fruits while the soluble polyuronide content of the fruit was negatively correlated to fruit Ca.

ISSN:0190-4167    

DOI:10.1080/01904169709365251

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Forensic laboratories can be called to examine illicitCannabissamples (marijuana) to identify their geographical origin. They can also be required to compare different seizures to establish whether they were drawn from the same original lot. The quantitative determination of selected organic components is one of the criteria currently used in such investigations. This study aimed at evaluating the inorganic element pattern of marijuana as a possible additional diagnostic tool. Four commercial cultivars ofCannabis sativa L.were grown in field experiments planned so that edaphic and climatic growth conditions varied slightly among the fields. The experimental design produced six populations. Population variability for the elements sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), copper (Cu), manganese (Mn), iron (Fe), zinc (Zn), and molybdenum (Mo) accumulation in leaves (L) and inflorescences (FL) of female plants was determined. For each element, the analytical data for the L and FL belonging to the same sample were pooled to simulate the chemical profile of marijuana preparations (L+FL). Within every population frequent important differences in elemental concentrations between corresponding L and FL fractions were detected, chiefly for the elements Ca, Mg, Cu, Mn, Fe, Zn, and Mo. This suggests that: i) the mean composition of marijuana produced in a single field depends on the relative amounts of plant parts harvesters pick, and ii) whenever a small drug sample is examined, the analytical outcome will be influenced by the weight ratio of the different plant parts which happen to make up the sample itself. Whatever the fraction considered (L, FL, and L+FL), a narrow scattering of data for all elements except Na was observed within each population, with RSD values generally well below 10%. When populations were compared for their elemental composition, many significant differences were found; for the mock drugs (L+FL fractions) they were most frequently determined by Ca followed by Mo, K=Fe, Zn, Mn, Cu=Na, and Mg in this order of decreasing frequency. Multi variate (discriminant) statistical analysis for product description was effective in separating the L, FL, and L+FL fractions of the six populations.

ISSN:0190-4167    

DOI:10.1080/01904169709365252

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Many dicotyledonous species respond to iron (Fe) deficiency by morphological and physiological changes at root level, which are usually defined as Strategy I. Particularly, these latter modifications include a higher acidification of the external medium and the induction of a high root Fe reductase activity. The aim of this work was to investigate the response of kiwi(Actinidia deliciosacv. Hayward) plants, which often exhibit Fe chlorosis in the field, to Fe deficiency.Actinidiakept for two weeks in nutrient solution without Fe showed visual deficiency symptoms (leaf chlorosis). Moreover, upon prolonged micronutrient shortage shoot, and to a lesser extent, root dry weight accumulation was greatly impaired. Roots of Fe‐deficientActinidiashowed an increased capacity of net proton extrusion and higher ferric ethylenediaminetetraacetate [Fe(III)EDTA] reductase activity as compared to plants grown in the presence of 10 μM Fe(III)EDTA. Localization of the increased acidification and reductase capacity by means of agar‐technique revealed that these activities are both present in the sub‐apical region of the roots. Re‐supply of Fe after two weeks partially reversed the tendency of the roots to acidify the nutrient solution and to reduce Fe(III)EDTA.

ISSN:0190-4167    

DOI:10.1080/01904169709365253

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor