Urgency Index Ratios: a Simple Tool for Forest Management     

GRAY  S. J.; PRICE  COLIN 《Forestry》1990,63(2):161-175

Traditional forest economics deals with regularly-ordered activities.For many reasons, however, choices must often be made amongconflicting operational priorities. In these circumstances,maximizing net discounted revenue per hectare does not maximizeglobal profit. Priorities for action should be chosen in orderof urgency index ratio, defined as the cost of delaying an operationdivided by the units of limited resource needed to undertakethe operation. Forest managers tend to use informal and sometimesconflicting rules to assign priorities among uses of limitedresources. These priorities often differ from those indicatedby urgency index ratio. Urgency index ratio can be determinedby simple calculations based on readily-available data. Theconcept can be extended to include multiple constraints.  相似文献   

Mid-storage and pre-sowing seed treatments for lettuce and carrot     

Dolly Pan  R.N. Basu 《Scientia Horticulturae》1985,25(1):11-19

Mid-storage hydration-dehydration treatments with medium-vigour lettuce seed very effectively reduced physiological deterioration in storage and ultimately showed better field emergence and final yield. Soaking-drying treatment of high-vigour lettuce seed was not effective. Pre-sowing treatment of medium-vigour lettuce seed, though less effective than mid-storage treatment, gave better field performance, but high-vigour seed did not benefit from the treatment. For carrot, both mid-storage and pre-sowing seed treatments proved beneficial, with the former showing better performance than the latter. Unlike lettuce, well-preserved carrot seed responded positively to the pre-sowing treatment.  相似文献   

The extent of genetic diversity among Vanilla species: Comparative results for RAPD and ISSR     

Praveen C. Verma  Debasis Chakrabarty  Satya Narayan Jena  Devesh K. Mishra  Pradhyumna K. Singh  Samir V. Sawant  Rakesh Tuli 《Industrial Crops and Products》2009,29(2-3):581-589

Vanilla is a large genus of about 110 species in the orchid family (Orchidaceae), including the species Vanilla planifolia from which commercial vanilla flavoring is derived. Since most species of vanilla are considered rare and endangered there is an urgent need to conserve them through genetic analysis and propagation/conservation studies on this crop.The present study investigated the genetic diversity among nine leafy- and leaf-less Vanilla species employing 30 decamer RAPD primers and 10 ISSR primers. The species under study were diverse and displayed a range of variability (0–66% and 0–81% for RAPD and ISSR, respectively). A total of 154 RAPD polymorphic markers (83.24%, h = 0.378) and 93 ISSR polymorphic markers (86.11%, h = 0.363) were used to generate a genetic similarity matrix followed by the cluster analysis. Specific groupings were revealed by each cluster analysis with slight variation between two different markers. Among the nine species studied, V. planifolia, Vanilla aphylla and Vanilla tahitensis revealed very low level of variation within their collections, thus indicating a narrow genetic base. The large genetic distance of Vanilla andamanica from other species suggests its different origin. A close genetic affinity was observed between the pairs V. planifolia, V. tahitensis and Vanilla albida, V. aphylla. These are the first comparative results for RAPD and ISSR reporting inter-relationship among nine cultivated, wild and hybrid Vanilla species.  相似文献   

A ROLLER BOTTLE TISSUE CULTURE SYSTEM     

Shaw DT  Kingsland LC  Brues AM 《Science (New York, N.Y.)》1940,91(2354):148-149

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Neuerungen der Schädlingsbekämpfung     

H. 《Journal of pest science》1940,16(6):69-71

Ohne Zusammenfassung  相似文献   

Vitamins in Canine Metabolism     

H. E. Robinson  L. D. Frederick 《Canadian journal of veterinary research》1941,5(10):288-291

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Is the ocean surface depressed?     

S WH 《Science (New York, N.Y.)》1886,7(177):570-571

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THREE CASES OF MALE INFERTILITY     

W. L. Hindmarsh  B.V.Sc  M.R.C.V.S.  D.V.H. 《Australian veterinary journal》1941,17(1):21-23

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Science at Cornell     

W A 《Science (New York, N.Y.)》1886,7(170):416-417

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Ein starkes Auftreten des Ampferblattk?fers     

Fr. 《Journal of pest science》1942,18(11):131

Ohne Zusammenfassung  相似文献