Is Discrimination of 13C in Potato Leaflets and Tubers an Appropriate Trait to Describe Genotype Responses to Restrictive and Well‐Watered Conditions?          下载免费PDF全文

D. A. Ramírez  J. L. Rolando  W. Yactayo  P. Monneveux  R. Quiroz 《Journal of Agronomy and Crop Science》2015,201(6):410-418

Selection for drought tolerance entails prioritizing plant traits that integrate critical physiological processes occurring during crop growth. Discrimination against ¹³C (?) in leaflets (?_leaflet) and tubers (?_tuber) was compared under two water regimes in two potato‐improved varieties selected to maintain yield under drought conditions (Unica and Sarnav) and one drought susceptible European cultivar (Désirée). In the control treatment, soil water content was kept at field capacity over the whole growth cycle, while in the drought treatment water supply was restricted after tuber initiation (50 % of field capacity). Gas exchange and N content per unit leaf area (N_area) as well as ? were assessed at different stages. Sarnav showed the highest tuber yield in both water conditions, suggesting that yield in the water restriction treatment was largely driven by yield potential in this genotype. Higher stomatal conductance (g_s) and N_area and lower ?_leaflet in well‐watered Sarnav suggested higher photosynthetic capacity. Under water restriction, Sarnav maintained higher g_s indicating that carbon diffusion was a key factor for biomass accumulation under water restriction. Our results suggest the use of ? determined after tuber initiation as an indirect selection indicator for tuber yield under both well‐watered and restricted soil water availability conditions.  相似文献   

Ecosystem services from coffee agroforestry in Central America: estimation using the CAF2021 model     

van Oijen  Marcel  Haggar  Jeremy  Barrios  Mirna  Büchi  Lucie  Cerda  Rolando  Cerretelli  Stefania  López  Erick  de Melo Virginio Filho  Elias  Ospina  Alejandra 《Agroforestry Systems》2022,96(7):969-981

The goal of sustainable coffee production requires multiple functions from agroforestry systems. Many are difficult to quantify and data are lacking, hampering the choice of shade tree species and agronomic management. Process-based modelling may help quantify ecosystem services and disservices. We introduce and apply coffee agroforestry model CAF2021 (https://doi.org/10.5281/zenodo.5862195). The model allows for complex systems with up to three shade tree species. It simulates coffee yield, timber and fruit production by shade trees, soil loss in erosion, C-sequestration, N-fixation, -emission and -leaching. To calibrate the model, we used multivariate data from 32 different treatments applied in two long-term coffee agroforestry experiments in Costa Rica and Nicaragua. Without any further calibration, the model was then applied to agroforestry systems on 89 farms in Costa Rica and 79 in Guatemala where yields had been reported previously in farmer interviews. Despite wide variation in environmental and agronomic conditions, the model explained 36% of yield variation in Costa Rica but only 15% in Guatemala. Model analysis quantified trade-offs between yield and other ecosystem services as a function of fertilisation and shading.

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Marketing of meat sheep with intensive finishing in southern state of Mexico     

Jaime Mondragón-Ancelmo  Juvencio Hernández-Martínez  Samuel Rebollar-Rebollar  Abdelfattah Zeidan Mohamed Salem  Rolando Rojo-Rubio  Ignacio Arturo Domínguez-Vara  Anastacio García-Martínez 《Tropical animal health and production》2014,46(8):1427-1433

The objective of the present study was to quantify the marketing margins of cold sheep carcass and barbacoa meat in the southern state of Mexico. Data were obtained from the production chain links (production, industrialization, and marketing) where the marketing margins were calculated along with the benefit/cost (B/C) ratio. In the absolute marketing margin of the final consumer price per kilogram of carcass meat, the producer obtained US$2.7/kg (47 %) of the utilities, while the intermediaries obtained US$3.1/kg (53 %). Considering the final cooked product in barbacoa (typical dish), the margin was US$6.3/kg (29 %) for the producer and US$15.2/kg (71 %) for the intermediaries. The B/C ratio was 1.0, 1.1, 2, and 1.3 for the producer, stocker, butcher, and barbacoa seller, respectively. It is concluded that the best marketing channel for the producer was the producer-stocker-processor (butcher and barbacoa seller). The highest marketing margin was for the intermediaries followed by the producer. The order of importance of the B/C kilogram ratio of meat was for the butcher first, then barbacoa seller, and lastly stocker and producer.  相似文献   

Radar soundings of the subsurface of Mars   总被引：2，自引：0，他引：2  

Picardi G  Plaut JJ  Biccari D  Bombaci O  Calabrese D  Cartacci M  Cicchetti A  Clifford SM  Edenhofer P  Farrell WM  Federico C  Frigeri A  Gurnett DA  Hagfors T  Heggy E  Herique A  Huff RL  Ivanov AB  Johnson WT  Jordan RL  Kirchner DL  Kofman W  Leuschen CJ  Nielsen E  Orosei R  Pettinelli E  Phillips RJ  Plettemeier D  Safaeinili A  Seu R  Stofan ER  Vannaroni G  Watters TR  Zampolini E 《Science (New York, N.Y.)》2005,310(5756):1925-1928

The martian subsurface has been probed to kilometer depths by the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument aboard the Mars Express orbiter. Signals penetrate the polar layered deposits, probably imaging the base of the deposits. Data from the northern lowlands of Chryse Planitia have revealed a shallowly buried quasi-circular structure about 250 kilometers in diameter that is interpreted to be an impact basin. In addition, a planar reflector associated with the basin structure may indicate the presence of a low-loss deposit that is more than 1 kilometer thick.  相似文献   

Volatile compounds of Psidium salutare (H.B.K.) Berg. fruit     

Pino JA  Marbot R  Bello A 《Journal of agricultural and food chemistry》2002,50(18):5146-5148

Volatile compounds were isolated from Psidium salutare fruits by simultaneous steam distillation-solvent extraction according to the Likens-Nickerson procedure. Compounds were identified by capillary GC and GC-MS. One hundred and fifty compounds were identified in the aroma concentrate, from which limonene, myrcene, and alpha-pinene were found to be the major constituents in the fruit.  相似文献   

Effect of human disturbance on the structure and regeneration of forests in the Nevado de Toluca National Park, Mexico     

Angel Rolando Endara Agramont  Sergio Franco Maass  Gabino Nava Bernal  Juan Ignacio Valdez Hernández  Todd S. Fredericksen 《林业研究》2012,23(1):39-44

Sample plots were established in the principal forest types in the the Nevado de Toluca National Park, Mexico including those dominated by Pinus hartwegii, Abies religiosa, Quercus laurina and Alnus jorullensis. The vertical structure was defined by three strata in the coniferous forests and two strata in the broadleaved forests. Timber harvesting in Abies religiosa and Quercus laurina forests and fires generated by humans in Pinus hartwegii forests impeded the recruitment of saplings. Mature trees were also heavily impacted by logging in Pinus hartwegii forests. On the contrary, Alnus jorullensis forests were increasing due to the disturbance of Pinus and Quercus forests, as well abandoned crop lands within the park. A combination of logging, uncontrolled fire, and grazing appears to be compromising the recruitment of important tree species in this national park. These factors, together with human settlements, have also increased the proportion of early successional species. Changes in forest structure from human disturbance indicate a need to control these activities if conservation goals are not to be compromised.  相似文献   

Comparison of yield based drought tolerance indices in improved varieties, genetic stocks and landraces of potato (Solanum tuberosum L.)     

Rolando Cabello  Philippe Monneveux  Felipe De Mendiburu  Merideth Bonierbale 《Euphytica》2013,193(2):147-156

Drought strongly influences potato (Solanum tuberosum) production and quality. Potato being a drought susceptible crop, the development of varieties with enhanced tolerance to water stress could highly improve productivity in drought prone areas. The objective of this study was to evaluate the ability of several yield based indices to be used in large scale screening for drought tolerance. The experiment included improved varieties, genetic stocks and landraces potatoes grown under drought and irrigated conditions. A group of accessions with high yield under both conditions was identified. Mean productivity (MP), geometric mean productivity (GMP), tolerance (TOL), drought tolerance index (DTI), drought susceptible index (DSI) and yield stability index (YSI) were calculated from tuber yield under drought and irrigated conditions. The relationships between these indices and yield were analyzed. The Fleiss’ Kappa concordance test was used to analyze the correspondence between accessions previously identified as highly productive under both drought and irrigated conditions and accessions with optimal values for the different indices. MP, GMP and DTI allowed identifying genotypes combining high yield potential and high yield under drought within the three subsets of genotypes. Conversely, DSI, YSI and TOL showed low and variable concordance values across subsets, suggesting that their efficiency in screening genotypes highly depends on the nature of the tested genetic material.  相似文献   

Regeneration patterns of Eastern white pine (Pinus strobus L.) in hardwood-dominated forests in Virginia, USA     

Todd S. Fredericksen  Angel Rolando Endara Agramont 《New Forests》2013,44(1):51-61

Eastern white pine (Pinus strobus L.) is a moderately shade-tolerant species that co-occurs with hardwood tree species in many forests of the eastern United States, as well as in pure stands. The species is valued for its timber, as well as for wildlife and recreation. Regeneration of this species is somewhat unpredictable and often occurs in patches of similarly-aged cohorts. We described the regeneration patterns of this species and examined their relation to environmental variables within hardwood forests of southwestern Virginia, USA. An average of 5.3 white pine patches per ha were observed in this study. The majority of patches consisted of saplings (85%), with 9% of patches in pole size classes, and 6% in seedling size classes. The average density of patches was 43.5 stems with an average age of 20 years. The size of patches averaged 80.6 m². The total density of seedlings and the number of regeneration patches of all sizes of regeneration (seedlings, saplings, and poles) in plots was related to the surrounding density of large white pine trees (potential seed trees). The density of seedlings or patches was not significantly related to current vegetation cover or soil surface cover variables, but more than half of regeneration patches were located in or adjacent to old canopy gaps, most of which were old logging gaps. While seedling regeneration may occur within the understory of these forests near seed trees, advancement to the sapling and pole stage appears to be associated with canopy gap formation.  相似文献   

Plasma lactate and purine derivatives accumulation after exercise of increasing intensity in standardbred horses     

Bruno Stefano  Tabellini Franco  Rolando Oberosler 《Journal of Equine Veterinary Science》1999,19(7):463

The aim of the experiment was to study the relationship between plasma lactate and allantoin accumulation in horses undergoing five exercises differing in intensity and length. Twenty-five adult trotter horses were used (18 males, two castrated, and five females), housed in three training centers. The horses were assigned to five groups: slow trot, over 2000 m (Group 1); slow trot over 1600 m (Group 2); fast trot over 1600 m (Group 3); fast trot over 2000 m (Group 4); fast trot over 2400 m (Group 5). Plasma was obtained from blood sampled at rest, at the end of the bout of exercise and after 15 and 45 minutes from the end of the bout of exercise and analyzed for glucose, lactate, uric acid, free fatty acids (FFA) and allantoin concentrations. Accumulations of plasma lactate and allantoin (mmol/sec) were calculated as difference between end of exercise and rest and between 45 minutes sample and rest, respectively.Ranking the intensity of exercise using the lactate concentrations at the end of exercise, the level of exertion was highest for Group 3 horses and lowest for Group 5 horses (20.9 and 2.8 mmol/l, respectively). At the end of exercise, glucose concentrations were much higher for horses undertaking the more intensive exercise (Groups 3 and 4 compared to Group 2). FFA concentrations were highest at the end of exercise for Groups 2 and 3 and after 15 minutes for Groups 4 and 5. Plasma uric acid and allantoin concentrations peaked 15 and 45 minutes from the end of exercise, respectively, independently of exercise intensity. The relationship between accumulation of plasma allantoin (y, dependent variables) and lactate (x, independent variable) was non-linear: y=0.15−2.61^*x+68.3^*x² (r²=0.900; se=0.19). This suggests that allantoin accumulation could be used together with plasma lactate to calibrate the workload to muscle conditions to prevent muscle injury.  相似文献   

Effect of Separation and Grinding of Corn Dry-Milled Streams on Physical Properties of Single-Screw Low-Speed Extruded Products     

Fen F. Jamin  Rolando A. Flores 《Cereal Chemistry》1998,75(6):775-779

Three streams of corn dry-milled products (corn grits, corn cones, and corn flour) were sieved and separated according to average diameter, and some segregated fractions were ground to produce nine streams. Corn grits were separated to produce grits with diameters of 1.19 and 0.841 mm, and selected fractions were ground into grits with average diameters of 0.297 and 0.210 mm. Corn cones were separated into average diameters of 0.595, 0.420, and 0.297 mm. Corn flour was separated into fractions with average diameters of 0.297 and 0.210 mm. The original and the additional streams were extruded at constant speed (50 rpm) and at three different processing extruder barrel temperature profiles: low (LTP, 100-110-120°C), medium (MTP, 110-120-130°C), and high (HTP, 120-130-140°C). The least significant difference (P < 0.01) test showed that additional grinding of corn grits affects the expansion ratio of extrudates processed at LTP and HTP. Additional separation of corn flour affects (P < 0.01) the bulk density and water solubility index of extrudates at HTP. At HTP, corn cones with diameters of 0.595 mm had significantly (P < 0.01) higher torque, specific mechanical energy, and die pressure than did the original corn cone extrudates without separation.  相似文献