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  • Electronic Resource  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Weed research 43 (2003), S. 0 
    ISSN: 1365-3180
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The influence of rain and drought before, and air temperature during, weed control with hot water was studied in laboratory experiments on the test weed Sinapis alba (white mustard). The plants were grown in a greenhouse and treated outdoors. There was no difference in weed control effect when S. alba plants at the four-leaf stage were treated at the air temperatures 7°C and 18∘C. The effective energy dose for a 90% fresh weight reduction was 465 kJ m−2 for both air temperatures. Weed control of S. alba at the four- to six-leaf stage in rainfall above the rainwater run-off level increased the required effective energy dose by 20% (i.e. 120 kJ m−2) compared with dry plants. A short period of drought just before treatment on S. alba at the two- to four-leaf stage increased the plant fresh weight reduction, which was 22% at low energy dose (190 kJ m−2) and 44% at high energy dose (360 kJ m−2). Hot water weed control should thus be carried out when the plants are drought stressed and avoided when the plants are wet. The air temperature seems to be of little importance in the range 7–18∘C.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0983
    Keywords: Key words Lichen-forming fungi ; SSU rDNA ; Group-I intron ; Insertion ; 5′-splice site
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An exceptional group-I intron-like insertion at position 940 of the nuclear small subunit rDNA is found in lichen mycobionts of the families Parmeliaceae and Lecanoraceae. This shared insertion site is exceptional as it follows a G. Although several features of the self-splicing Tetrahymena intron are missing, the conserved structure of the presumed core region indicates that the new intron-like insertion, which is missing in mature transcripts, is not part of a silenced ribosomal repeat. It is unlikely that the new insertion is horizontally transferred from the adjacent position 943. A phylogenetic analysis indicates congruence with lichen phylogeny and suggests that the insertion has been vertically inherited.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Plant systematics and evolution 183 (1992), S. 113-160 
    ISSN: 1615-6110
    Keywords: Ascomycotina ; Lecanorales ; Parmeliaceae ; cetrarioid genera ; Cladistics ; asci ; conidiomata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract TheAcharian genusCetraria has not been scrutinised in the same way as the genusParmelia in terms of circumscription of segregate genera. A few generic names have been introduced, but mainly in checklists without any real indication of what these names stand for. After a detailed investigation of characters in the apothecia, conidiomata, anatomical structures, as well as morphology and secondary chemistry, it is clear that several, more or less distinctive, phylogenetic lines exist among taxa which earlier were accommodated inCetraria. Some of these distinctive phylogenetic lines are distinguished by ascus characters: (1) clavate asci with a small axial body, an apical ring structure in the tholus and ellipsoid ascospores; (2) uniseriate asci with a large axial body and globose ascospores; and (3) taxa with broadly clavate asci with a large axial body and ellipsoid ascospores. Sixty-three character states were studied and results from the character analyses were evaluated by cladistic analysis against 43 examined terminal taxa. Seven further taxa were included in one analysis. Results from the cladistic analyses give rather strong support for a new systematic treatment of at least certain groups in the cetrarioid lichens. A formal systematic arrangement is not made here but will be presented elsewhere. The characters investigated are illustrated in 78 half tone pictures and one line drawing. Five cladograms are presented.
    Type of Medium: Electronic Resource
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