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81.
H. M. Kidane-Mariam H. A. Mendoza R. O. Wissar 《American Journal of Potato Research》1985,62(12):643-652
Four different sets of true potato seed (TPS) families, representing a total of 262 hybrids derived from intermating tetraploid clones were evaluated in three different locations in Peru. Significant differences were observed among families in tuber yield, uniformity and transplant survival rate in the field. Several families produced an average tuber yield of more than 1.0 kg per plant, with a tuber uniformity of some families approaching that of standard varieties. Hybrid TPS families gave higher tuber yields and more uniform tubers than families from open-pollination. On the basis of an observed family-environment interaction for tuber yield, it is suggested that locally adapted cultivars or advanced selections should be used as parents to generate TPS progenies for specific areas. 相似文献
82.
The relative effectiveness of phosphorus (P) applications on growth and the effect of added P on the extent of infection of roots of narrowleaf birsfoot trefoil (Lotus tenuis) and of broadleaf birdsfoot trefoil (Lotus corniculatus) by an indigenous VAM fungi (Glomus sp.) was studied on a P‐deficient soil (Typic Natraquoll). In terms of rate of increase of shoot growth per unit of added P, broadleaf was more efficient than narrowleaf birsdfoot trefoil but they did not differ in the relative effectiveness of P for growth. For the two Lotus species, when increasing the level of added P there was an initial increase in the percentage of root length infected, and then with further additions, there was a consistent decrease of the infection. For narrowleaf, the maximum percentage of root length infected was when plants reached 11% of their maximum shoot growth. Whereas for broafleaf, the maximum percentage of root infected was when plants reached the 66% of their maximum shoot growth. Despite differences in both, the shape of the response curve of shoot growth to P and the extent of infection between Lotus species, they did not differ in their ability to utilize the P that had reacted with the soil for a period of time. 相似文献
83.
Luz Elizabeth Ruiz Suárez Violette Geissen Aarón Jarquín Sánchez Ricardo A. Castro Chan Ricardo Bello‐Mendoza 《植物养料与土壤学杂志》2013,176(1):40-46
Mancozeb is a fungicide frequently used in tropical countries. It rapidly decomposes into ethylenethiourea (ETU), a more stable and toxic metabolite than mancozeb that is, therefore, regarded as a pollutant of concern. The objective was to study ETU formation and decay kinetics in soil and water under tropical conditions in order to assess its potential for accumulation. Batch experiments, spiked with either mancozeb or ETU, were carried out under natural (= active) as well as tyndallized conditions. In active soils, dissipation of ETU occurred significantly faster (half‐life 1.5 h) than in tyndallized soils (half‐life time 28 h). In water under natural and sterile conditions, decay was slower than in soils with an ETU half‐life time of 115 and 99 h, respectively. Microbial activity was seen to play an important role in ETU dissipation in soil. However, in water nonbiological processes seem to be more important in the breakdown of the molecule, with hydrolysis being the most probable decay mechanism. Decay of both mancozeb and ETU was found to occur more rapidly than previously reported. The high humidity and temperatures under the simulated humid tropical conditions, and higher microbial activity, lead to more rapid decay of these molecules than under other conditions. Nevertheless, a concentration of 1.29 mg ETU L–1 was still observed 8 d after adding mancozeb (20.83 mg L–1) to water under humid tropical conditions. These results suggest that, in comparable regions in the humid tropics, it is unlikely that ETU would accumulate in soil but it represents a potential risk for accumulation in water bodies. 相似文献
84.
Bertin Yao Kouadio Jeffrey O. Dawson Guillermo A. Mendoza 《Journal of Sustainable Forestry》2013,32(6):397-416
ABSTRACTWe provide evidence that a factor contributing to the specific patterns of deforestation in Côte d’Ivoire is the set of spatial units of management used to structure wood extraction. Timber harvests were organized through a system of harvest perimeters, called “chantier,” for nearly a century. Chantiers were initiated as managerial instruments. However, their use as spatial tool for profit maximization led to positional anarchy. The lack of support for sustainable harvests from the legislation, the restoration system, and the tree-based policy governing the use of their content made the chantier the basis of a one-way resources extraction. Managerial scales facilitated clearing of forests. None served to regenerate forests. Using historical and official documents, satellite and cartographic data, we attempted to demonstrate how managerial scales aiming to organize logging have contributed to deforestation. We discuss the phases of fragmentation in the rainforest, the managerial scales, and the environmental context in which they were applied. We summarize the legislation that governed the managerial scales and how these scales organized space but the tree species-based policies and activities resulted in the forest’s dilapidation. The final section addresses the use of these scales in the creation of data for policy making. 相似文献
85.
Jimenez M Guzman AP Azuara E Garcia O Mendoza MR Beristain CI 《Plant foods for human nutrition (Dordrecht, Netherlands)》2012,67(1):57-63
Porophyllum tagetoides is an annual warm-weather herb that has an intense typical smell. Its leaves are commonly used in soup preparation and traditional
medicine for treatment of inflammatory diseases. Its volatile compounds and antioxidant properties were evaluated in crude,
aqueous and ethanol leaf extract and an oil emulsion using different antioxidant assays in vitro, such as: DPPH radical scavenging activity, redox potential, polyphenol content, reducing power and optical density. A high
antioxidative activity was found when comparing leaves with stems. The crude extract from leaves showed a very high reducing
power (2.88 ± 0.20 O.D.) and DPPH radical-scavenging activity (54.63 ± 4.80%), in concordance with a major concentration of
vitamin C (23.97 ± 0.36 mg/100 g). Instead, the highest polyphenol content (264.54 ± 2.17 mg GAE/g of sample) and redox potential
(561.23 ± 0.15 mV) were found by the ethanol and aqueous extract, respectively. Aldehydes and terpenes such as nonanal, decanal,
trans-pineno, β-myrcene and D-limonene were the major volatiles found. This study suggests that Porophyllum tagetoides extracts could be used as antioxidants. 相似文献
86.
Yuxin Miao David J. Mulla Gyles W. Randall Jeffrey A. Vetsch Roxana Vintila 《Precision Agriculture》2009,10(1):45-62
The chlorophyll meter (CM) has been commonly used for in-season nitrogen (N) management of corn (Zea mays L.). Nevertheless, it has limited potential for site-specific N management in large fields due to difficulties in using it
to generate N status maps. The objective of this study was to determine how well CM readings can be estimated using aerial
hyper-spectral and simulated multi-spectral remote sensing images at different corn growth stages. Two field experiments were
conducted in Minnesota, USA during 2005 involving different N application rates and timings on a corn-soybean [Glycine max (L.) Merr.] rotation field and a corn-corn rotation field. Four flights were made during the growing season using the AISA
Eagle Hyper-spectral Imager and CM readings were collected at four or five different growth stages. The results indicated
that single multi-spectral and hyper-spectral band or vegetation index could explain 64–86% and 73–88% of the variability
in CM readings, respectively, except at growth stage V9 in the corn-soybean rotation field where no band or vegetation index
could explain more than 37% of the variability in CM readings. Multiple regression analysis demonstrated that the combination
of 2–4 broad-bands or 3–8 narrow-bands could explain 41–92% or 61–94% of the variability in CM readings across the two fields
and different corn growth stages investigated. It was concluded that the combination of CM readings with high spatial resolution
hyper-spectral or multi-spectral remote sensing images can overcome the limitations of using them individually, thus offering
a practical solution to N deficiency detection and possibly in-season site-specific N management in large continuous corn
fields or at later stages in corn-soybean rotation fields. 相似文献
87.
88.
Lopez I Estepa JC Mendoza FJ Mayer-Valor R Aguilera-Tejero E 《American journal of veterinary research》2006,67(3):463-466
OBJECTIVE: To establish reference values for protein-bound, ionized, and weak-acid complexed fractions of calcium and magnesium in equine serum and determine stability of ionized calcium (iCa) and ionized magnesium (iMg) in serum samples kept under various storage conditions. ANIMALS: 28 clinically normal horses. PROCEDURE: Total calcium (tCa) and magnesium (tMg) in equine serum were fractionated by use of a micropartition system that allows separation of protein-bound calcium (pCa) and magnesium (pMg) and ultrafiltrable calcium (microCa) and magnesium (microMg) fractions. Serum concentrations of iCa and iMg were measured in the ultrafiltrate by use of selective electrodes. Serum concentration of complexed calcium (cCa) or magnesium (cMg) was calculated by subtracting iCa or iMg from microCa or microMg, respectively. RESULTS: Mean +/-SE serum tCa concentration was 3.26 +/- 0.06 mmol/L. Calcium fractions were as follows: pCa, 1.55 +/- 0.03 mmol/L (47.4 +/- 0.9%); iCa, 1.58 +/- 0.03 mmol/L (48.5 +/- 0.7%); and cCa, 0.13 +/- 0.02 mmol/L (4.1 +/- 0.9%). Serum tMg concentration was 0.99 +/- 0.04 mmol/L. Magnesium fractions were as follows: pMg, 0.33 +/- 0.04 mmol/L (33.3 +/- 4.2%); iMg, 0.57 +/- 0.02 mmol/L (57.6 +/- 1.7%); and cMg, 0.09 +/- 0.02 mmol/L (9.1 +/- 1.9%). Refrigeration (4 degrees C) did not affect iCa values, whereas iMg declined by 8% after 120 hours. Neither iCa nor iMg was affected by freezing (-20 degrees C). CONCLUSIONS AND CLINICAL RELEVANCE: In equine serum, iMg is less stable than iCa; thus, when serum samples are not going to be analyzed promptly, freezing may be preferable to refrigeration for storage. 相似文献
89.
Lopez I Estepa JC Mendoza FJ Rodriguez M Aguilera-Tejero E 《American journal of veterinary research》2006,67(8):1333-1336
OBJECTIVE: To provide reference values for serum biochemical variables that are used for evaluation of mineral metabolism in donkeys and compare values with those in horses. ANIMALS: 18 donkeys and 18 horses. PROCEDURES: Total calcium (tCa), total magnesium (tMg), and inorganic phosphorus (P) concentrations were measured in serum samples via spectrophotometry. Ionized calcium (iCa) and magnesium (iMg) concentrations were quantified with selective electrodes. By use of a micropartition system, tCa and tMg were fractionated to separate protein-bound (pCa, pMg) and ultrafiltrable fractions. Complexed calcium (cCa) and magnesium (cMg) concentrations were calculated by substracting ionized fractions from ultrafiltrable fractions. Parathyroid hormone (PTH) and calcitriol (CTR) concentrations were measured via radioimmunoassay. RESULTS: Serum tCa concentration in donkeys (3.37 +/- 0.21 mmol/L) was composed of pCa (1.59 +/- 0.21 mmol/L [47.0 +/- 4.2%]), iCa (1.69 +/- 0.04 mmol/L [50.4 +/- 3.0%]), and cCa (0.09 +/- 0.08 mmol/L [2.6 +/- 2.9%]). Serum tMg concentration (1.00 +/- 0.08 mmol/L) was fractioned in pMg (0.23 +/- 0.08 mmol/L [23.4 +/- 8.1%]), iMg (0.59 +/- 0.04 mmol/L [58.8 +/- 5.1%]), and cMg (0.18 +/- 0.08 mmol/L [17.8 +/- 7.2%]). Serum concentrations of P (1.14 +/- 0.30 mmol/L), PTH (20.4 +/- 21.2 pg/mL), and CTR (13.4 +/- 5.9 pg/mL) were determined. CONCLUSIONS AND CLINICAL RELEVANCE: Serum variables of mineral metabolism in donkeys were within reference ranges for horses. However, when compared with horses, donkeys had higher iCa, cMg, and CTR and lower pMg and PTH concentrations. 相似文献
90.
Philipp Hass Falk K. Wittel Miller Mendoza Hans J. Herrmann Peter Niemz 《Wood Science and Technology》2012,46(1-3):243-256
A study with synchrotron radiation X-ray tomographic microscopy (SRXTM) of PUR, PVAc, and UF adhesive bond lines in beech wood, bonded under various growth ring angles, is presented. The bond line morphologies and the adhesive penetration into the wood structure were evaluated after determining the hardening characteristics of the adhesives. Distinct bond line imperfections were found for the different adhesive systems. To describe the adhesive distribution inside the bond line, the saturation of the pore space instead of the commonly used maximum penetration depth seems to be adequate. 相似文献