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This study evaluates the percentage and rate of germination of rice (Oryza sativa L.) seeds, when exposed to magnetic treatment in laboratory conditions. The seeds were exposed to 150 and 250 mT magnetic fields both chronically and for 20 min after seeding. Nonexposed seeds were used as control. Chronic exposure to a 150-mT magnetic field increased ( p Ͻ 0.05) both the rate and percentage of germination relative to nonexposed seeds (18% at 48 h). Significant differences were also obtained for seeds exposed to a 250-mT magnetic field for 20 min (12% at 48 h). Additionally, seeds were moistened with water magnetically treated by static and dynamic methods. Dynamic and static treatment of water improved the germination of seeds related to the control, but significant differences ( p Ͻ 0.05) were only obtained for the dynamic method (16% at 48 h).

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A b s t r a c t. The effect of magnetic field on the growth and yield of crop plants is presented based on 80 references on the studies of many authors. The introduction gives an outline of the history of the effect of magnetic field on biological organisms including plants since the second half of the 19th century. Then the role of static and alternating magnetic fields is discussed in relation to seed germination, root and stem growth, yield, protein and chlorophyll content, rhizosphere community.

Summary• Most research analyzing nonstructural carbohydrate (NSC) concentrations on resprouter species in fire-controlled ecosystems has concentrated on how NSC concentrations recover immediately after fire. However, we know little of the effect of long periods without fire on NSC concentrations.• In order to assess the effect of different periods of time-since-fire on resprouter species, we studied carbohydrate concentrations (total [NSC], soluble sugars [SS] and nonsoluble sugars [NSS]) in five resprouting species with contrasting trends of abundance across a chronosequence of time-since-fire (0.5 -40 yr) in Florida.• Carbohydrate concentrations were highest in species with specialized reserve organs.[SS] was mainly explained by factors related to plant size, whereas timesince-fire was the main factor explaining [NSS]. Changes in [NSS] and [NSC] were correlated with the time-since-fire abundance patterns.• Variation in [NSS] carbohydrates can be related to the structural development of vegetation, with only those species capable of accessing full light able to accumulate carbohydrates, whereas subordinate plants show reductions in the [NSS] carbohydrate fractions. In areas with long intervals between fires, this carbohydrate reduction could affect subsequent postfire resprouting vigour, although this remains to be confirmed.

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Abstract-In this letter, we propose a novel method for unsupervised change detection (CD) in multitemporal Erreur Relative Globale Adimensionnelle de Synthese (ERGAS) satellite images by using the relative dimensionless global error in synthesis index locally. In order to obtain the change image, the index is calculated around a pixel neighborhood (3 × 3 window) processing simultaneously all the spectral bands available. With the objective of finding the binary change masks, six thresholding methods are selected. A comparison between the proposed method and the change vector analysis method is reported. The accuracy CD showed in the experimental results demonstrates the effectiveness of the proposed method.Index Terms-Local relative dimensionless global error in synthesis (ERGAS), multitemporal optical satellite images, thresholding, unsupervised change detection (CD).

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