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Weed–Corn Competition Parameters in Late-Winter Sowing in Northern Italy
- Stefan Otto, Roberta Masin, Giorgio Casari, Giuseppe Zanin
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- Journal:
- Weed Science / Volume 57 / Issue 2 / April 2009
- Published online by Cambridge University Press:
- 20 January 2017, pp. 194-201
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- Article
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In recent years, interest has increased in late-winter sowing of corn in northern Italy because of many agronomic advantages. However, cold and rainy weather slows initial crop growth, which can favor weed infestation. There is, therefore, a need for appropriate timing of weed control tactics based on an understanding of the competitive relationship and dynamics between crop and weeds. Five experiments were conducted over 4 yr, with a series of treatments increasing either duration of interference or length of weed-free period. Yield data were fitted with sigmoidal equations to find the critical point (CP) and critical period of weed control (CPWC). Although the CP is determined only by the competition between weed and crop, the CPWC is also market dependent. To quantify the effect of weed flora on the CP, a multiple regression model was tested, taking into account weed density, inflection point, and slope parameter of the Gompertz model of the cumulated infestation. The results confirmed that the late-winter sowing date increases the importance of late winter– and early spring–emerging weeds. In general, the precompetitive period was longer in the late winter–sown corn than in traditional midspring-sown corn. The delayed start of the CPWC makes control more difficult with a preemergence herbicide, which raises questions on the utility of this agronomic technique. Multiple regression analysis showed that the position of CP can be estimated with the density, earliness, and competitiveness of the infestation. Furthermore, the slope/inflection point ratio of the Gompertz model appears to be independent of sowing date. Results suggest that the weed–crop competition mechanism can be represented with simply the weed flora dynamic parameters and that a combination of crop–weed competition studies and emergence prediction models can predict the position of CP and give useful information about the CPWC and weed management.
26 - Syndromes with epilepsy and paroxysmal dyskinesia
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- By Renzo Guerrini, Neurosciences Unit, Institute of Child Health, The Wolfson Centre, London, UK, Lucio Parmeggiani, Institute of Child Neurology and Psychiatry, University of Pisa, Italy, Giorgio Casari, Department of Human Molecular Genetics IRCCS San Raffaele Hospital, Milan, Italy
- Edited by Renzo Guerrini, University of London, Jean Aicardi, Hôpital Robert-Debré, Paris, Frederick Andermann, Montreal Neurological Institute & Hospital, Mark Hallett, National Institutes of Health, Baltimore
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- Book:
- Epilepsy and Movement Disorders
- Published online:
- 03 May 2010
- Print publication:
- 13 December 2001, pp 407-420
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Summary
Introduction
Epilepsy and paroxysmal dyskinesia (PD) may sometimes be difficult to differentiate clinically. Although for this reason in the past it has been hypothesized that episodes of PD could represent a form of epilepsy (Lishman et al., 1962; Whitty et al., 1964; Burger et al., 1972), the current understanding is that the two disorders are distinct (Fahn, 1994).
However, there are several recent reports of families in which some individuals presented either or both paroxysmal disorders, with different age-related expression. Co-occurrence makes it likely that a common, genetically determined, pathophysiological abnormality is variably expressed in the cerebral cortex and in basal ganglia.
A rather homogeneous syndrome of autosomal dominant infantile convulsions and paroxysmal (dystonic) choreoathetosis (ICCA) was described in 20 families from France, China, Japan, and the United States (Szepetowski et al., 1997; Lee et al., 1998; Guerrini et al., 1999; Swoboda et al., 2000; Tomita et al., 1999). Linkage analysis allowed the mapping of the disease gene to partially overlapping loci in the pericentromeric region of chromosome 16.
Additional autosomal dominant pedigrees are on record, from Australia and Italy, in which epilepsy was variably associated with paroxysmal kinesigenic or exercise-induced dystonia (Perniola et al., 1998; Singh et al., 1999).
A pedigree in which three members in the same generation were affected by rolandic epilepsy, paroxysmal exercise-induced dystonia (PED) and writer's cramp was reported from Italy (Guerrini et al., 1999).
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