Nitrogen forms affect root structure and water uptake in the hybrid poplar   总被引：1，自引：0，他引：1  

Susy Domenicano  Lluís Coll  Christian Messier  Frank Berninger 《New Forests》2011,42(3):347-362

The study analyses the effects of two different forms of nitrogen fertilisation (nitrate and ammonium) on root structure and water uptake of two hybrid poplar (Populus maximowiczii x P. balsamifera) clones in a field experiment. Water uptake was studied using sap flow gauges on individual proximal roots and coarse root structure was examined by excavating 18 whole-root systems. Finer roots were scanned and analyzed for architecture. Nitrogen forms did not affect coarse-root system development, but had a significant effect on fine-root development. Nitrate-treated trees presented higher fine:coarse root ratios and higher specific root lengths than control or ammonium treated trees. These allocation differences affected the water uptake capacity of the plants as reflected by the higher sapflow rate in the nitrate treatment. The diameter of proximal roots at the tree base predicted well the total root biomass and length. The diameter of smaller lateral roots also predicted the lateral root mass, length, surface area and the number of tips. The effect of nitrogen fertilisation on the fine root structure translated into an effect on the functioning of the fine roots forming a link between form (architecture) and function (water uptake).  相似文献   

Allometry, biomass, and chemical content of Novel African Tulip Tree (Spathodea campanulata) Forests in Puerto Rico     

Ariel E. Lugo  Oscar J. Abelleira  Alexander Collado  Christian A. Viera  Cynthia Santiago  Diego O. V��lez  Emilio Soto  Giovanni Amaro  Graciela Char��n  H��ctor Col��n Jr.  Jennifer Santana  Jos�� L. Morales  Katherine Rivera  Luis Ortiz  Luis Rivera  Mianel Maldonado  Natalia Rivera  Norelis J. V��zquez 《New Forests》2011,42(3):267-283

The African tulip tree, Spathodea campanulata, the most common tree in Puerto Rico, forms novel forest types with mixtures of native and other introduced tree species. Novel forests increase in area in response to human activity and there is no information about their biomass accumulation and nutrient cycling. We established allometric relationships and chemically analyzed plant parts of African tulip trees to determine the concentration and standing stock of chemical elements (C, N, P, K, Ca, Mg, S, Mn, Al, Fe, Na), and ash. Trees ranged in diameter at breast height from 8 to 85 cm and in height from 8.8 to 28 m. The concentrations of N, P, K, and Ca in leaves of the African tulip tree were similar to those of the native pioneer Cecropia schreberiana and higher than those of mature forest tree species in Puerto Rico. The over bark wood volume of African tulip trees in nine forest stands where it was dominant ranged from 163 to 849 m³/ha. Aboveground biomass ranged from 60 to 296 Mg/ha, and N and P stocks ranged from 190 to 988 and 32 to 137 kg/ha, respectively. Novel forests on abandoned agricultural lands can store more biomass and elements than native and plantation forest stands of similar age.  相似文献   

Associations between immune competence phenotype and feedlot health and productivity in Angus cattle     

Brad C Hine  Amy M Bell  Dominic D O Niemeyer  Christian J Duff  Nick M Butcher  Sonja Dominik  Laercio R Porto-Neto  Yutao Li  Antonio Reverter  Aaron B Ingham  Ian G Colditz 《Journal of animal science》2021,99(2)

Genetic strategies aimed at improving general immune competence (IC) have the potential to reduce the incidence and severity of disease in beef production systems, with resulting benefits of improved animal health and welfare and reduced reliance on antibiotics to prevent and treat disease. Implementation of such strategies first requires that methodologies be developed to phenotype animals for IC and demonstration that these phenotypes are associated with health outcomes. We have developed a methodology to identify IC phenotypes in beef steers during the yard weaning period, which is both practical to apply on-farm and does not restrict the future sale of tested animals. In the current study, a total of 838 Angus steers, previously IC phenotyped at weaning, were categorized as low (n = 98), average (n = 653), or high (n = 88) for the IC phenotype. Detailed health and productivity data were collected on all steers during feedlot finishing, and associations between IC phenotype, health outcomes, and productivity were investigated. A favorable association between IC phenotype and number of mortalities during feedlot finishing was observed with higher mortalities recorded in low IC steers (6.1%) as compared with average (1.2%, P < 0.001) or high (0%, P = 0.018) IC steers. Disease incidence was numerically highest in low IC steers (15.3 cases/100 animals) and similar in average IC steers (10.1 cases/100 animals) and high IC steers (10.2 cases/100 animals); however, differences between groups were not significant. No significant influence of IC phenotype on average daily gain was observed, suggesting that selection for improved IC is unlikely to incur a significant penalty to production. The potential economic benefits of selecting for IC in the feedlot production environment were calculated. Health-associated costs were calculated as the sum of lost production costs, lost capital investment costs, and disease treatment costs. Based on these calculations, health-associated costs were estimated at AUS$103/head in low IC steers, AUS$25/head in average IC steers, and AUS$4/head in high IC steers, respectively. These findings suggest that selection for IC has the potential to reduce mortalities during feedlot finishing and, as a consequence, improve the health and welfare of cattle in the feedlot production environment and reduce health-associated costs incurred by feedlot operators.  相似文献   

An anatomical study of the dorsal and ventral nasal conchal bullae and middle nasal conchae in normal Shetland ponies: Computed tomographic anatomical and morphometric findings     

Kerstin Gerlach  Ingrid Vervuert  Claudia Gittel  Lisa Köhler  Nane Schmidt  Karsten Winter  Dagmar Berner  Antonia Troillet  Ellen Schulz-Kornas 《Anatomia, histologia, embryologia》2021,50(3):431-438

Equine paranasal sinuses are susceptible to inflammation. Insufficient drainage through the nasal passages and meatus may lead to the accumulation of inspissated purulent discharge. Particularly in ponies, these anatomical structures are suspected to be relatively small. To date, there are no reports considering the morphology of nasal conchal bullae in small horse breeds such as Shetland ponies. The aim of the present study was to evaluate the size of the conchal bullae and the medial nasal conchae of Shetland ponies and their relation to the skull dimension using computed tomography. Reconstructed images of healthy adult heads of Shetland ponies were used. Linear skull measurements as well as two cranial indices of the head dimensions were taken. Length, width and height of the dorsal and ventral conchal bullae and the medial nasal conchae were measured in relation to the skull and compared with the data of skulls of large breed horses. The anatomical proportions of pony heads were characterized by a smaller cranial index and a greater nasal index than those of large breed horses. Shetland ponies showed a longer cranial length compared with the nasal length. Heads are consistently smaller, and the relationship of the bullae to the head length was also smaller than those measured in large breed horses. A negative correlation between the head and bullae size was found. In conclusion, this study suggests that Shetland ponies have distinguishing proportions of the head. These findings are relevant for clinical examination and surgical treatment of equine sinus disease in those breeds.  相似文献   

Clinical magnetic resonance image quality of the equine foot is significantly influenced by acquisition system     

Christian A. Byrne  John F. Marshall  Lance C. Voute 《Equine veterinary journal》2021,53(3):469-480

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Review of irrigation system performance with respect to initial objectives     

Herve L. Plusquellec  Kathryn McPhail  Christian Polti 《Irrigation and Drainage Systems》1990,4(4):313-327

This paper presents the results of assessment studies of the performance of gravity irrigation projects, in six countries in different climate and social environments, with respect to their original objectives in terms of water availability, water use efficiencies, equity of water distribution, cropping intensity and crop yields, and project economic rates of return.An important lesson is the need for more realistic assumptions in the adoption of design standards, especially irrigation efficiency which affect the cropping intensity, the overall productivity of the project and its economic viability. This comparative method of performance assessment applied to a variety of projects has also provided some useful insights into the relative value of the different approaches to design of gravity irrigation systems.The views expressed in this paper are those of the author and are not presented as official views of the World Bank.  相似文献   

Treatment of equine sarcoids using recombinant poxviruses expressing feline interleukin-2     

Johanna Loschelder-Ostrowski  Judith Christine Winter  Roswitha Merle  Robert Klopfleisch  Heidrun Gehlen 《Veterinary dermatology》2021,32(3):283-e77

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Effect of dietary sodium bicarbonate on leg structure in Duroc swine that differ genetically for leg weakness     

C W Ernst  M F Rothschild  L L Christian  R C Ewan 《Journal of animal science》1990,68(9):2583-2590

Two trials were conducted to evaluate the effect of dietary replacement of .30% sodium chloride (NaCl) with a sodium-equivalent amount of sodium bicarbonate (NaHCO3) on leg weakness in swine. Three lines of Duroc swine established by six generations of divergent selection for front leg structure were used. In the first trial, a total of 80 low-line (increased leg weakness), 75 high-line (decreased leg weakness), 80 control-line (intermediate leg weakness) and 80 high x low pigs were used. Pigs were assigned within litter to an experimental or control diet and tested from approximately 37 to 104 kg live weight. The experimental diet contained .43% NaHCO3, replacing .30% NaCl in the control diet. Pigs had ad libitum access to feed. In the second trial, 48 high- and 48 low-line pigs were fed the same diets from 29 to 104 kg. At the completion of each trial, pigs were scored for various leg traits. The model used for statistical analyses included the effects of replicate, genetic line, dietary treatment and the dietary treatment x genetic line interaction. Trials were analyzed separately. Results indicated that there was no significant improvement in clinical signs of leg weakness due to dietary supplementation with NaHCO3 for front leg structure and movement, rear leg movement or rear toe size. Rear hock angle was improved in Trial 1 (P less than .05) but was reduced in Trial 2 (P less than .10).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

CRASY: mass- or electron-correlated rotational alignment spectroscopy     

Schröter C  Kosma K  Schultz T 《Science (New York, N.Y.)》2011,333(6045):1011-1015

Rotational spectra have traditionally been measured without a concurrent means of differentiating the molecular constituents of the sample. Here, we present an all-optical multipulse experiment that allows the correlated measurement of rotational and mass or photoelectron spectra by combining Fourier transform rotational coherence spectroscopy with resonance-enhanced multiphoton ionization. We demonstrate the power of this method with the determination of ground-state rotational constants and fragmentation channels for 10 different isotopes in a natural carbon disulfide sample. Three of the reported rotational constants were previously inaccessible by conventional spectroscopic techniques.  相似文献   

A CAREER IN MEDICINE AND PRESENT-DAY REPARATION FOR IT     

Christian HA 《Science (New York, N.Y.)》1909,30(773):537-548

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