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排序方式: 共有77条查询结果,搜索用时 156 毫秒
1.
In this study we determined soil moisture storage, evapotranspiration (ET) and light interception in an agroforestry trial consisting of pine trees grown over (1) control (bare ground), (2) ryegrass/clovers (Lolium perene/Trifolium spp.), (3) lucerne (Medicago sativa), and (4) ryegrass only during the third growing season between 1992 and 1993. The results show that:
相似文献
1. | In the period when rainfall was frequent and exceeded the evaporative demand (Epot), ET and depletion of soil moisture were not affected by the ground cover treatments. During summer when rainfall was less frequent, but with moisture readily available in the soil profile, ET was associated with plant canopy, and was significantly higher for the pasture ground covers than for the control. Therefore, the more rapid growth by lucerne caused higher ET in this ground cover than in the ryegrass/clovers ground cover in which the pasture was slow growing. At the end of the study period, total ET was in the following order: lucerne (757 mm) > ryegrass/clovers (729 mm) > Control (618 mm). |
2. | ET was dominated by pasture transpiration (Ep) during most of the growing season, but by tree transpiration (Et) in winter when large parts of the pasture canopy was shaded. Ep was always at least 16% higher for lucerne than for ryegrass/clovers species as a result of a greater radiation intercepted by the former. |
3. | Fraction of incoming radiation intercepted by the tree crowns was in the following order: control > ryegrass > ryegrass/clovers > lucerne. At the end of the one-year period, fraction of intercepted radiation was 140% greater for control than for lucerne ground cover. |
4. | The control produced the largest tree crowns, which were almost twice the tree crowns in the lucerne ground cover which produced the smallest trees. Accordingly, the trees in the control intercepted more radiation and rainfall, with the former being lost to evaporation, than the trees in the pasture. |
5. | The fractions of radiation intercepted and ET accounted for by the trees and pastures were associated with the proportion of the plot area they occupied. |
2.
Ana T M Viveiros Thiciana B Amaral Laura H Orfão Ziara A Isaú Danilo Caneppele Marcelo C Leal 《Aquaculture Research》2011,42(6):858-865
The aim of this study was to test the effects of cryoprotectants [dimethyl sulphoxide (DMSO) and methylglycol], extenders (0.9% NaCl, 5% glucose, Beltsville Thawing Solution? and Merck III?), thawing temperatures (30 and 60 °C) and activating agents (0.29% NaCl and 1% NaHCO3) on the cryopreservation process of tiete tetra Brycon insignis sperm. Sperm was loaded in 0.5 mL straws, frozen in nitrogen vapour at ?170 °C and stored in liquid nitrogen. Post‐thaw sperm quality was evaluated in terms of subjective motility rate, quality motility score (0=no movement; 5=rapidly swimming spermatozoa), duration of motility and vitality (eosin–nigrosin staining). Post‐thaw sperm motility rate was greater in methylglycol (76–88%), compared with DMSO (23–59%). In general, the highest quality motility scores were observed when sperm was thawed at 30 °C and triggered in 1% NaHCO3 (3.5–4.3). Duration of motility was longer when triggered in 1% NaHCO3 (95–120 s) compared with 0.29% NaCl (69–107 s). Sperm vitality was not affected by any of the parameters tested and varied from 51% to 69% intact sperm. Brycon insignis sperm frozen in methylglycol combined with any of the extenders tested and using the methods described above yields motility above 57% and that should last long enough to fertilize oocytes. 相似文献
3.
Morteza Bagheri Isa Abdi Rad Nima Hosseini Jazani Rasoul Zarrin Ahad Ghazavi 《Iranian Biomedical Journal》2015,19(3):183-187
Background:
The variable numbers of tandem-repeat (VNTR) alleles at the phenylalanine hydroxylase (PAH) gene have been used in carrier detection and prenatal diagnosis in phenylketonuria families. This study was carried out to analyze VNTR alleles at the PAH gene in Iranian Azeri Turkish population.Methods:
In this study, 200 alleles from general population were studied by PCR.Results:
The frequencies of VNTR alleles were 45%, 46%, 2%, 3%, 1%, and 3% in studied group regarding 3, 8, 9, 11, 12, and 13 repeat copies, respectively. Statistically significant differences were not found between expected and observed frequencies of VNTR genotypes (P > 0.05).Conclusions:
VNTR alleles with three and eight repeats were frequent, and the VNTR alleles with 13 repeats showed 3% frequency in the tested group. This study is the first report on tested population genetic structure using VNTR alleles at the PAH gene. Key Words: Phenylalanine hydroxylase, Population genetics, Variable numbers of tandem-repeat 相似文献4.
Watson Matamwa Chris Guppy Isa Yunusa 《Communications in Soil Science and Plant Analysis》2018,49(4):433-443
As single superphosphate availability decreases due to closure of aging manufacturing plants increasing attention is being paid to alternative phosphorus (P) and sulfur (S) sources. This glasshouse study, conducted under non-leaching conditions was undertaken to evaluate the S supplying capacity of gypsum, S bentonite, elemental S (ES) and a range of P containing fertilizers and those where ES was added as a coating or incorporated. The magnitude of crop response in terms of shoot biomass to applied S fertilizer sources followed the order of sulfates > powdered ES > coated/incorporated ES > S/bentonite. These results indicate that fertilizers containing a mixture of sulfate and micronized ES (<75 µm), either incorporated within the granule or coated onto the fertilizer are agronomically effective. The results also suggest that local S coating of finished fertilizers is a feasible alternative to S incorporation undertaken at a central fertilizer plant. 相似文献
5.
Isa Esfandiarpour-Borujeni Seyed Javad Hosseinifard Hossein Shirani Maryam Zeinadini Ali Asghar Besalatpour 《Communications in Soil Science and Plant Analysis》2018,49(12):1474-1490
The main objective of this study was to evaluate the potential use of a hybrid Genetic Algorithm-Artificial Neural Network (GA–ANN) method for predicting pistachio yield and for identifying the determinant factors affecting pistachio yield in Rafsanjan region, Iran. A total of 142 pistachio orchards were selected randomly and soil samples were taken at three depths. Besides, water samples and leaves from branches without fruit were taken in each sampling point. Management information and pistachio yields were achieved by completing a questionnaire. Primarily, 58 variables affecting pistachio yield were measured, and then 26 out of them were selected by minimizing mean square error (MSE) using a feature selection (FS) method. The results showed that the accuracy of the method was acceptable. Furthermore, the sensitivity analysis showed that the main determinant features affecting the pistachio yield were the irrigation water amount, leaf phosphorus, soil soluble magnesium, electrical conductivity (EC), and leaf nitrogen. 相似文献
6.
Roghayeh Shahriaripour Ahmad Tajabadipour Isa Esfandiarpoor Vahid Mozafary 《Journal of plant nutrition》2019,42(11-12):1277-1282
Developing a fast and reliable soil testing method is critical for improving soil testing efficiency and ensuring reliable fertilizer recommendation. The objectives of this study were to evaluate sodium ethylene diamine tetra acetic acid (Na2-EDTA) as a replacement for ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA) to extract phosphorus (P) to determinate the relationships between extractable P and its uptake by crop in calcareous soils. Na2-EDTA and AB-DTPA was compared by the amounts of extracted P by analyzing soil samples collected from agricultural production areas. There were significant correlations between Na2-EDTA and AB-DTPA for soil test P based on soils collected from the agricultural field. Soil test P by both extractants was significantly correlated with plant P concentration. Na2-EDTA was identified as an alternate improved extraction method instead of AB-DTPA in calcareous soils based on this study. However, more work will be needed to identify the correlation of the two extractants and crop responses under a field condition. 相似文献
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9.
Pluviographic data at 15 min interval from 6 stations in Pulau Penang of Peninsular Malaysia were used to compute rainfall erosivity factor (R) for the revised universal soil loss equation (RUSLE). Three different modelling procedures were applied for the estimation of monthly rainfall erosivity (EI30) values. While storm rainfall (P) and duration (D) data were used in the first approach, the second approach used monthly rainfall for days with rainfall ≥ 10 mm (rain10) and monthly number of days with rainfall ≥ 10 (days10). The third approach however used the Fournier index as the independent variable. Based on the root mean squared error (RMSE) and the percentage error (PE) criteria, models developed using the Fournier index approach was adjudged the best with an average PE value of 0.92 and an average RMSE value of 164.6. Further, this approach was extended to the development of a regional model. Using data from additional sixteen stations and the Fournier index based regional model, EI30 values were computed for each month. ArcView GIS was used to generate monthly maps of EI30 values and also annual rainfall erosivity (R). The rainfall erosivity factor (R) in the region was estimated to vary from 9000 to 14,000 MJ mm ha− 1 h− 1 year− 1. 相似文献
10.