Structure and species composition of novel forests dominated by an introduced species in northcentral Puerto Rico     

Oscar J. Abelleira Martínez  Mariela A. Rodríguez  Ivonne Rosario  Nataly Soto  Armando López  Ariel E. Lugo 《New Forests》2010,39(1):1-18

The African tulip tree, Spathodea campanulata Beauv., is an introduced species forming novel forest types in Puerto Rico. These forests develop naturally after deforestation, agricultural use and land abandonment, and there are many questions as to their ecological characteristics. We sampled structure and species composition of large, small, and juvenile trees (≥10, ≥2.5 to <10, and <2.5 cm diameter at breast height, respectively) in nine secondary forests dominated by S. campanulata on alluvial, karst, and volcanic substrates in northcentral Puerto Rico. No differences were found in S. campanulata forest structure between substrates. Of a total of 79 species found, 17 were introduced. Forests on karst and alluvium had the highest and lowest global species richness, respectively. Species richness increased from large to small to juvenile trees in most sites, but more so on karst. The percentage of introduced species was inversely related to species richness of tree size classes on all substrate types. The dominance of S. campanulata in the large tree size class was highest and lowest in alluvial and volcanic sites, respectively, and decreased from large to small to juvenile trees on all substrate types. Species richness of S. campanulata forests is lower than that of native forests on equivalent substrates. Although land use history affects composition, the juvenile tree species established in S. campanulata forests seems to correspond to the geological substrate were sites are found. This study shows S. campanulata restores forest structure and native tree species on abandoned agriculture and grazing lands in Puerto Rico. Management of these novel forests should consider them as resources were natural processes have the potential of making them more diverse.  相似文献   

Interaction of Collimonas strain IS343 with Rhizoctonia solani at low carbon availability in vitro and in soil     

Ilya V. Senechkin  Leonard S. van Overbeek  Hong Ling Er  Oscar de Vos  Ariena H. C. van Bruggen 《European journal of plant pathology / European Foundation for Plant Pathology》2013,136(4):789-802

Collimonas sp. IS343, isolated from an organically-farmed arable soil and characterized as a broad-range oligotrophic bacterium, was shown to degrade chitin and to suppress R. solani mycelium growth under in vitro conditions at high and low carbon availabilities. In contrast to C. fungivorans Ter331, strain IS343 did not respond with an increase in growth rate to higher carbon levels in liquid medium, it reached higher cell numbers in carbon-poor media and it showed better survival in bulk soil. Therefore, it was concluded that strain IS343 cells are better adapted to circumstances of low carbon availability as present in bulk soils than strain Ter331 cells. Further, strain IS343 cells were more suppressive towards R. solani than strain Ter331 cells in vitro. When introduced into soil, strain IS343 cells delayed disease development caused by R. solani AG2-2IIIB in sugar beet plants. These results suggest that strain IS343 cells are able to tentatively suppress R. solani AG2-2IIIB mycelium growth in soil. Potential mechanisms behind the observed suppressive effects can be competition for available nutrients between strain IS343 cells and R. solani mycelium in soil or the production of chitinase as shown for this and other Collimonas species.  相似文献   

The Potato Association of America 75th Annual Meeting Spokane,Washington, U.S.A.     

David Curwen  Pete Weingartner  Ronald Knight  Therese M. Work  Hugh J. Murphy  Steven B. Johnson  Richard Zink  Leigh Morrow  A. R. Mosley  Rod Davidson  Thoms Owings  Don Halseth  John Bamberg  John C. Wallace  Stephen Love  Don Halseth  Elmer E. Ewing  LaMont Anderson  Neil Gudmestad  Oscar Malamud  Jane Seabrook  Robert E. Thornton  Ronald Voss  A. J. Mosley 《American Journal of Potato Research》1991,68(12):861-902

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Physico‐chemical characterization of humic‐metal‐phosphate complexes and their potential application to the manufacture of new types of phosphate‐based fertilizers          下载免费PDF全文

Oscar Urrutia  Javier Erro  Inaki Guardado  Sara San Francisco  Marcos Mandado  Roberto Baigorri  Jean Claude Yvin  José Ma Garcia‐Mina 《植物养料与土壤学杂志》2014,177(2):128-136

The aim of this review is to describe the main physicochemical characteristics of diverse types of humic‐metal‐phosphate acid complexes. The effects of these complexes on phosphorus (P) fixation in soils with different pH values and physicochemical features and on plant phosphorus uptake are also discussed. Humic‐metal‐phosphate complexes have apparent stability constants in the same range as those of metal‐humic complexes, in solutions with diverse pH and ionic‐strength values. Likewise, the molecular‐size distribution of humic‐metal‐phosphate complexes as a function of pH is similar to that of potassium or sodium humates and metal‐humic complexes. Humic‐metal‐phosphate complexes are able to decrease phosphate fixation in soils and increase plant growth and phosphate uptake. Phosphorus fertilizers containing humic‐metal‐phosphate complexes proved to be efficient to improve plant growth and P uptake with respect to conventional fertilizers such as single superphosphate. The values of parameters related to plant phosphorus‐utilization efficiency (PUt E) suggest that the regulation of root acquisition of phosphate from these complexes could involve the interregulation of a system for the optimization of metabolic P utilization in the shoot and another system involving stress responses of roots under phosphorus deficiency.  相似文献   

Genetic diversity in seven populations of Nicaraguan teosinte (<Emphasis Type="Italic">Zea nicaraguensis</Emphasis> Iltis et Benz) as estimated by microsatellite variation     

Carlos Henry Loáisiga  Agnese Kolodinska Brantestam  Oscar Diaz  Björn Salomon  Arnulf Merker 《Genetic Resources and Crop Evolution》2011,58(7):1021-1028

Teosintes are the closest relatives to modern maize, Zea mays L. ssp. mays. They are wild grasses with a native distribution area from Mexico to Nicaragua and represent an important genetic resource. However, the genetic diversity of Nicaraguan teosinte (Zea nicaraguensis Iltis et Benz) has not yet been determined. This teosinte species has decreased in the last 25 years and now must be regarded as an endangered species. An analysis of the genetic diversity of Zea nicaraguensis was carried out in a total of 240 individuals from seven populations. Eleven Simple Sequences Repeat (SSR) primer pairs were used. A total of 42 alleles were found, the range of alleles per locus was 2–5 (mean 3.8) and the numbers of genotypes varied between primers. The primer Bnlg 1538 showed the highest value, with 45 genotypes through all populations. The genetic diversity observed (Ho) between all populations varied from 0.51 to 0.63, with an average of 0.563. One of the populations had as many as 40 alleles. Analysis of molecular variance (AMOVA) revealed that most of the variation was within population, at a significantly high level (P < 0.001). Rare alleles were detected in all populations, but unique alleles were only found in four populations. These results are highly relevant when developing conservation strategies and show that preserving populations in their natural habits is highly important.  相似文献   

Morphophysiology of forage peanut submitted to different intensities of defoliation on grazing with sheep     

Costa  Olmar Antônio Denardin  Ferreira  Otoniel Geter Lauz  Henrique  Douglas Sampaio  Vaz  Ricardo Zambarda  Fluck  Ana Carolina  Paris  Wagner  Kröning  Alexsandro Bahr  Griffith  Luis Alberto Alonzo  Matos  Oscar Ivan Tuz 《Tropical animal health and production》2020,52(2):547-554

Tropical Animal Health and Production - The aim was to monitor the growth, the dry mass accumulation curve, and the structural photosynthetic components of forage peanut pasture, in different...  相似文献   

Survey of potato spindle tuber viroid in seed potato growing areas of the United States     

Mike Sun  Susan Siemsen  William Campbell  Pablo Guzman  Robert Davidson  Jonathan L. Whitworth  Terry Bourgoin  Jeff Axford  Willem Schrage  Gary Leever  Alan Westra  Steve Marquardt  Hossien El-Nashaar  Jeff McMorran  Oscar Gutbrod  Tom Wessels  Robert Coltman 《American Journal of Potato Research》2004,81(3):227-231

Fourteen United States (U.S.) seed potato certification agencies surveyed all U.S. seed potato growing areas for presence of the potato spindle tuber viroid (PSTVd). The survey included general surveillance, which involved searching for the occurrence of PSTVd in state seed potato certification records from 1990 through 2000, and a field survey, which involved testing selected crops for PSTVd infection by nucleic acid dot blot hybridization during 1999 through 2001. No PSTVd incident was documented in any of the state certification records, nor was PSTVd detected in the field surveys. All U.S. seed-growing areas were determined to be free of PSTVd. It is concluded that PSTVd has been eradicated and freedom from potato spindle tuber viroid has been successfully maintained in all of the seed potato growing areas in the United States.  相似文献   

Minutes of section’ meetings     

Gary A. Secor  David Holm  Oscar Gutbrod  Dermot Lynch  Joseph B. Sieczka  Merle L. Weaver 《American Journal of Potato Research》1983,60(11):906-910

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Efficacy of a woodchip-sediment integrated system in nitrate elimination from wastewater with low C/N condition     

Shihao  Gong  Cuicui  Tian  Pei  Hong  Donde  Oscar Omondi  Qijia  Cai  Xingqiang  Wu  Chunbo  Wang  Bangding  Xiao 《Journal of Soils and Sediments》2021,21(10):3392-3404

Journal of Soils and Sediments - Currently, effective methods to eliminate nitrate in wastewater with a low C/N ratio are urgently needed. Considering that sediment is the main nitrogen removal...  相似文献   

Improving Potato Production in Kenya, Uganda and Ethiopia: A System Diagnosis   总被引：1，自引：1，他引：0  

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