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51.
Peter R. Gildemacher Wachira Kaguongo Oscar Ortiz Agajie Tesfaye Gebremedhin Woldegiorgis William W. Wagoire Rogers Kakuhenzire Peter M. Kinyae Moses Nyongesa Paul C. Struik Cees Leeuwis 《Potato Research》2009,52(2):173-205
Increased productivity of potatoes can improve the livelihood of smallholder potato farmers in Kenya, Uganda and Ethiopia
and is required to meet the growing demand. This paper investigates the opportunities for potato system improvement that could
result in improved productivity. Through a diagnosis of the potato systems in the three countries on the basis of surveys
and stakeholder workshops, seed potato quality management, bacterial wilt control, late blight control and soil fertility
management were identified as key technical intervention topics. For effective problem solving in these areas, the functioning
of the potato innovation system requires improvement to better deliver the functions of potato marketing as well as knowledge
development and information exchange. With use of a ‘system failure framework’ the shortcomings of the potato innovation system
are identified and discussed and options for improvement are suggested. 相似文献
52.
Levels and distribution of allozyme and RAPD variation in populations of Elymus fibrosus (Schrenk) Tzvel. (Poaceae) 总被引:5,自引:0,他引:5
Oscar Díaz Gen-Lou Sun Björn Salomon Roland von Bothmer 《Genetic Resources and Crop Evolution》2000,47(1):11-24
To study the magnitude and nature of genetic variation in E. fibrosus, the levels and distribution of allozyme and RAPD variations were investigated in populations collected from Finland and Russia. The results obtained from the allozyme and RAPD studies were compared to each other in 10 of the populations. The allozyme analysis showed that 6 of 12 presumed loci (50%) were polymorphic within the species, while the mean number of polymorphic loci within populations was 4.8%. The mean number of allele per locus for the species was 1.5 and 1.05 across the populations. Genetic diversity at the species level was low (H
es = 0.025), and the mean population genetic diversity was even lower (H
ep = 0.007). Both these values were much lower than the average for other Elymus and self-fertilising species. The largest proportion of the total allozyme diversity was found among, rather than within the populations (G
ST = 0.70). The allozyme genetic distances between the populations did not reflect geographic distances. Cluster and principal coordinates analyses revealed the same allozyme relationship patterns among the populations. A comparison of allozyme and RAPD variation in 10 of the populations showed differences in the amount of genetic variation. The RAPD analysis revealed higher levels of variation (A
p = 1.19, P
p = 20.3 and H
ep = 0.09) than the allozyme one) A
p = 1.06, P
p = 5.8 and H
ep = 0.008). For both markers, the largest proportion of the total gene diversity was found among the populations studied (G
st = 0.63 for RAPDs and G
st = 0.65 for allozyme). In contrast to the allozyme analysis, the RAPD based genetic distances did reflect geographic distances. The cluster and principal coordinates analyses showed different grouping of populations for each data set. There was a positive, but not significant, correlation (r = 0.41) between the genetic distance matrices resulting from these markers. Regional comparison revealed that the Finnish populations had a higher diversity than the Russian ones. Generally, this study indicates that E. fibrosus contains low genetic variation in its populations. The results are discussed in the context of conservation of the species. 相似文献
53.
Reducing copper use in the environment: the use of larixol and larixyl acetate to treat downy mildew caused by Plasmopara viticola in viticulture
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54.
Francisco Gomez‐Coronado Ana S. Almeida Oscar Santamaria Ismail Cakmak Maria J. Poblaciones 《Journal of Agronomy and Crop Science》2019,205(3):341-352
About 3 billion people may suffer from micronutrient deficiency such as Ca, Fe, Mg or Zn, caused not only by a mineral deficiency in staple food but also by a high content of phytates which bind those minerals and inhibit their absorption. With the aim of evaluating the potential of new cultivars of bread‐making wheat to accumulate those minerals and low phytates, nine advanced breeding lines from an ongoing Portuguese breeding program were studied during 2 years in a field experiment. A wide genetic variability was found between the studied genotypes in all the parameters studied, especially grain yield (ranging on average between 2,027 and 3,209 kg/ha) and grain Mg and Zn concentrations (ranging on average between 1,070 and 1,336 mg/kg, and 23.4 and 30.7 mg/kg, respectively). In global terms, the cultivars with best performance, and therefore, the most potentially suitable to be used in a breeding program, were the Cultivars 3 and 4. However, such a potential varied depending on the analysed trait, and it was clearly influenced by the climatic conditions. The consumption of 100 g of Cultivar‐4 produced under the most favourable conditions might provide a 5.2% of Ca, 26.4% of Fe, 38.9% of Mg and 31.9% of Zn of the recommended daily intakes, with a very good bioavailability for Fe and Ca, but low for Mg and Zn. 相似文献
55.
R. Raposo V. Gomez T. Urrutia P. Melgarejo 《European journal of plant pathology / European Foundation for Plant Pathology》2001,107(2):229-236
The relative importance of sclerotia and mycelia of Botrytis cinerea Pers ex Fr. as structures of survival in southeastern Spanish greenhouses was investigated. Sclerotia were not found in the SE region, neither on plant debris nor on living plant material, suggesting it may serve only a minor role in epidemic development. B. cinerea survived mostly as mycelium. The percentage of artificially inoculated tomato stem pieces from which mycelium was recovered, was used to quantify its survival rate. Outside the greenhouses, mycelium survived in 33% and 5% of the tomato stem pieces 110 days after inoculation in 1995 and 1997, respectively. After the same number of days inside the greenhouses, no mycelium was recovered from stem pieces in 1995, and in 1997 only 7% of the stem pieces contained mycelium. Survival of mycelium outside and inside the greenhouses was significantly (P < 0.05) different after 47, 83, and 110 days of exposure to field conditions in 1995, but they were not different in 1997. Under controlled conditions, mycelium of B. cinerea lost viability at 100% relative humidity at temperatures ranging from 5 to 40°C, suggesting that air temperature and relative humidity accounted for loss of viability of mycelium. 相似文献
56.
Thiago Martins Guilherme Pugliesi Mariana Sponchiado Angela M.Gonella-Diaza Oscar A.Ojeda-Rojas Frederich D.Rodriguez Roney S.Ramos Andrea C.Basso Mario Binelli 《畜牧与生物技术杂志(英文版)》2019,(1)
Background: A major,unresolved issue is how the uterine microenvironment determines pregnancy success in cattle.Before implantation,conceptus development depends on the uterine secretome(i.e.,histotroph).Despite its pivotal role,little is known about the dynamics of histotroph synthesis and changes in composition throughout the early diestrus and the relevance to pregnancy establishment.We hypothesize that disturbances on histotroph composition affect the establishment of pregnancy.Aim was to disturb histotroph composition at early diestrus and verify the effects on:(Exp.1) timing to restore its composition; and(Exp.2) pregnancy rate after multiple-embryo transfer.Estrous cycle of multiparous Nelore cows were synchronized and estrus was considered d 0(D0) of the experiments.Disturbance was through flushing each uterine horn with 30 m L of DMPBS and collecting the resulting uterine luminal flushing(ULF) on D1; D4; D7; D1 + D4 + D7.Control group remained not-collected.In Exp.1,ULF was collected on D7.5 from all animals and used for quantification of total protein concentration and abundance of albumin.In Exp.2,three in vitro-produced embryos were transferred to the uterine horn ipsilateral to the ovary containing the CL on D7.5 and pregnancy was checked on D25 by ultrasound.Results: In Exp.1,ULF collection on D4 or D7 increased(1.5-to 2.2-folds) the total protein concentration and albumin abundance.ULF collection on D1 did not alter(P 0.10) these endpoints.In Exp.2,ULF collected on D4 or D7 decreased pregnancy rates to approximately half of that measured in the remaining groups.Conclusions: Subtle perturbations imposed to the native intrauterine milieu,such as those caused by a single,low-volume collection of ULF,profoundly disturbs intrauterine composition and pregnancy success.At least 4 d were necessary for the uterus to recover its composition and the functional capacity to carry post-implantation gestation. 相似文献
57.
Rodolfo Rogelio Posadas-Domínguez Oscar Enrique Del Razo-Rodríguez Isaac Almaraz-Buendía Armando Pelaez-Acero Verónica Espinosa-Muñoz Samuel Rebollar-Rebollar Jesús Armando Salinas-Martínez 《Tropical animal health and production》2018,50(5):947-956
This article combines a Policy Analysis Matrix with a sensitivity and poverty line analysis with the objective of evaluating the economic contribution of comparative advantages to the private profitability and competitiveness of small-scale dairy systems. For 1 year, socioeconomic data were collected from 82 farms selected from four strata via statistical sampling. Two scenarios were established to determine the quantitative contribution of comparative advantages: (1) a simulated scenario, which accounted for the cost of purchasing the total food and the opportunity cost of the family labour force (FLF), and (2) an actual production scenario, which accounted for the cost of producing food and eliminating the payment of the FLF and included other income. The E3 and E4 producers were the most profitable and competitive in the simulated scenario and actual production scenario. Of the four scales evaluated, the E2 and E1 producers were the most efficient in taking advantage of the economic contribution provided by the comparative advantages in their own production of food and employment of the FLF, in addition to accounting for other income, a condition that increased their profitability by 171 and 144% and competitiveness by 346 and 273%, respectively. The poverty results indicated that only E3 and E4 producers were non-vulnerable in the simulated scenario and actual production scenario. The purchase of food was the comparative advantage with the greatest sensitivity to cost increases in the two scenarios analysed, which exacerbated the effect on the E1 and E2 producers. 相似文献
58.
Expected consequences of including methane footprint into the breeding goals in beef cattle. A Spanish Blonde d'Aquitaine population as a case of study
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Javier López‐Paredes Rafael Alenda Oscar González‐Recio 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2018,135(5):366-377
This study evaluates two potential scenarios for including methane (CH4) emissions in the breeding objectives of beef cattle, using the Spanish population of Blonde d′Aquitaine as a case of study. First, CH4 emissions were included as a cost using a shadow carbon price of 1.22€/CH4 kg (0.044€/CO2 kg) (carbon tax scenario). In the other scenario, a CH4 quota was applied, optimizing emissions per unit of product. The current production system was used as benchmark scenario (Scenario 1). The economic value of CH4 was calculated under all scenarios using a bioeconomic model that translated the production system into a mathematical function. Then, CH4 emissions were included with proper relative weight in the selection index under each scenario. The economic value of CH4 production from cows was ?0.54€/year and ?0.16€/year in a carbon tax and in a CH4 quota scenario, respectively. Economic values for CH4 production from fattening calves were ?1.22€/year and ?0.34€/year in a carbon tax and a quota scenario, respectively. The relative weights of total CH4 traits in the indices were 4.9% and 1.8% in a carbon tax and quota scenario. The carbon tax scenario led to smaller cows (?7.59 kg of mature weight) and a decrease in carcass weight gain of calves (?4.78 g/day) involving a reduction in emissions in comparison with Scenario 1 (?0.76 CH4 kg/slaughtered calf/year). However, it also led to a lower expected gain in profit per unit of product (?7.86 €/slaughtered calf/year). A carbon quota scenario would select slightly smaller cows (?0.48 kg) with similar responses in maternal abilities (age at first calving, calving interval, maternal weaning weight, and calving ease) and growth, and lower emissions (?0.22 CH4 kg/slaughtered calf/year) regarding the benchmark scenario. Profit per cow would increase by +1.52€/slaughtered calf/year although this scenario implies a reduction in the number of cows per herd. In a carbon tax scenario, higher reduction in emissions implied a reduction of profitability per animal. 相似文献
59.
Martínez-Alvarez O Guimas L Delannoy C Fouchereau-Peron M 《Journal of agricultural and food chemistry》2007,55(14):5469-5475
Fish protein hydrolysates (FPH) may have potential as bioactive components in functional foods as nutraceuticals. This study focused on the identification of calcitonin gene-related peptide (CGRP) molecules in FPH. CGRP is a neuropeptide belonging to the calcitonin/CGRP family and is known as potent arterial and venous vasodilator in humans. Hydrolysates of industrial origin were prepared from siki (Centroscymnus coelolepsis) heads and were analyzed for the presence of CGRP-like molecules using specific radioimmunoassays and radioreceptorassays. The biological activity of the CGRP-related molecules was assessed by their ability to stimulate the adenylate cyclase activity in rat liver membranes. They were finally purified using gel exclusion chromatography and high-performance liquid chromatography (HPLC). These molecules presented a molecular weight around 1500-2500 Da and were obtained with a purification factor of 79. The incorporation of FPH with CGRP-like molecules in functional foods could lead to the development of new useful products for health and nutrition markets. 相似文献
60.
OBJECTIVE: To determine the relative validity and reproducibility of two alcohol intake frequency questionnaires (AFQ-A; AFQ-B), designed to classify subjects according to their alcohol intake level, in Bucaramanga, Colombia. METHOD: One hundred and nine randomly selected subjects, aged between 20 and 60 years, completed three 30-day semi-quantitative alcohol intake records (30-DR). The AFQs were applied three months after the last 30-DR. AFQ-A contained 53 items; AFQ-B contained five items, with the alcoholic drinks for AFQ-B selected by Max_r. The correlation and agreement between alcohol intake assessed with the AFQs and the 30-DR were obtained using Pearson's correlation coefficient (r), Lin's concordance correlation coefficient (rhoC), Spearman's rank correlation coefficient (rS), Bland and Altman's limits of agreement (LOA) and Cohen's weighted kappa statistic (Kw). RESULTS: The reproducibility of the 30-DR was poor; rS ranged from 0.33 to 0.41. The reproducibility of the AFQs was higher, with rS between 0.50 and 0.73. The agreement (Kw) of the 30-DR and the AFQs was 0.40. The lower and upper LOA were between -56.4% and -11.0%. The AFQs and 30-DR were well correlated. Assessment of relative validity between the two methods yielded r values for alcohol between 0.52 and 0.60, which reduced to 0.20-0.29 after energy adjustment. CONCLUSIONS: These AFQs may be useful to rank subjects according to their alcohol intake. The AFQ-B is easy and quick to apply, and is also highly cost-effective. 相似文献