Auzeville-Tolosane, France
Auzeville-Tolosane, France
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Seassau C.,French National Institute for Agricultural Research | Dechamp-Guillaume G.,ENSAT | Mestries E.,British Petroleum | Debaeke P.,French National Institute for Agricultural Research
Field Crops Research | Year: 2010

Premature ripening (PR) is one of the most important diseases of sunflower in France since the 90s. Previous results indicated that girdling canker of the stem base, caused by Phoma macdonaldii was its primary cause but elucidation of critical environmental factors involved is crucial for better control of the disease. A field study was conducted in three contrasting cropping seasons (2006-2008) and investigated the effect of N fertilization (0, 75 and 150 kg N ha-1) and water regime (rainfed, irrigated) on two cultivars with artificial inoculation (AI) and natural infection (NI). Disease assessment was recorded weekly to calculate the area under disease progress curve (AUDPC) and the final percentage of PR plants. Data showed that high levels of N fertilization led to significantly (P < 0.05) more PR than non-fertilization. Water deficit conditions were significantly (P < 0.05) involved in disease severity, and AUDPC and PR were increased when dry conditions were associated with high N supply. This was true for two cultivars which differed in their susceptibility to the disease but cv. Heliasol RM was significantly (P < 0.05) more affected than cv. Melody, partially resistant to PR. Despite contrasting weather patterns, these results demonstrated a clear role of crop management and environmental conditions on the incidence and severity of stem base attacks responsible for the PR syndrome. These findings suggest that sunflower crop husbandry should be adapted to minimize premature ripening induced by P. macdonaldii. © 2009 Elsevier B.V. All rights reserved.

Seassau C.,French National Institute for Agricultural Research | Debaeke P.,French National Institute for Agricultural Research | Mestries E.,British Petroleum | Dechamp-Guillaume G.,ENSAT
Plant Disease | Year: 2010

Three inoculation methods were evaluated for effectiveness to cause sunflower premature ripening (PR). Evaluations were conducted on a sunflower (Helianthus annuus) cultivar susceptible to PR in replicated, multilocation experiments under greenhouse conditions. Plants were inoculated with Phoma macdonaldii, either with mycelium, conidia, or infected residues at the stem base or with buried residues. Disease severity (DS) was measured by percent girdling necrosis at the stem base and percent final PR; the infection spread was assessed using the area under the disease progress curve (AUDPC). Inoculation with mycelia or 1 × 106 spores/ml caused significantly more DS and PR than lower spore concentrations or infected residues (P < 0.05). Amending soil with residues induced root necrosis but no PR. P. macdonaldii was mainly isolated at the stem base and above but rarely on root systems. Microscopic evaluations showed that hyphae colonized mainly the cortex and vascular stem tissues. The overall results demonstrated a clear role of aerial infection in PR compared with soilborne inoculum, and that inoculation at the stem base with a spore suspension could be used for screening genotypes for resistance to PR. © 2010 The American Phytopathological Society.

Ye S.,CAS Wuhan Institute of Hydrobiology | Moreau J.,ENSAT | Zeng W.,CAS Wuhan Institute of Hydrobiology | Zeng W.,Shaoxing University | And 3 more authors.
Journal of Applied Ichthyology | Year: 2014

This study examined the growth and mortality of two widespread small fish species, Toxabramis swinhonis (Cyprinidae) and Hyporhamphus intermedius (Hemiramphidae), from a shallow lake (Niushan Lake, China) along the Yangtze River, by analyzing monthly length frequency data (July 2005 to June 2006) with the FAO-ICLARM stock assessment tool (FiSAT). Estimated von Bertalanffy growth equation parameters were: L∞ (asymptotic length) = 145 mm TL, and K (growth coefficient) = 0.66 year-1 for T. swinhonis; L∞ = 189 mm TL, and K = 0.68 year-1 for H. intermedius. The instantaneous rates of natural mortality (M) calculated for T. swinhonis and H. intermedius were 1.35 and 1.28 year-1, respectively. The length-converted catch curve method gave the total annual instantaneous mortality rate (Z) of 2.92 year-1 for T. swinhonis and 1.53 year-1 for H. intermedius. Recruitment patterns of both species were continuous, displaying a single major peak event per year. Despite not being of direct fishing interest, T. swinhonis, with high abundance and productivity as indicated by a high Z-value, can be an important species in fisheries management as an excellent food source for aquatic organisms, especially for larger fishes of economic value. These results represent the first information on population characteristics of T. swinhonis and H. intermedius, and constitute a comparison base for future growth studies in other lake environments. © 2014 Blackwell Verlag GmbH.

El Aroussi M.,LETI | El Hassouni M.,Mohammed V University | Ghouzali S.,ENSAT | Rziza M.,Mohammed V University | Aboutajdine D.,Mohammed V University
Signal Processing | Year: 2010

In this paper, an efficient local appearance feature extraction method based on Steerable Pyramid (S-P) wavelet transform is proposed for face recognition. Local information is extracted by computing the statistics of each sub-block obtained by dividing S-P sub-bands. The obtained local features of each sub-band are combined at the feature and decision level to enhance face recognition performance. The purpose of this paper is to explore the usefulness of S-P as feature extraction method for face recognition. The proposed approach is compared with some related feature extraction methods such as principal component analysis (PCA), as well as linear discriminant analysis LDA and boosted LDA. Different multi-resolution transforms, wavelet (DWT), gabor, curvelet and contourlet, are also compared against the block-based S-P method. Experimental results on ORL, Yale, Essex and FERET face databases convince us that the proposed method provides a better representation of the class information, and obtains much higher recognition accuracies in real-world situations including changes in pose, expression and illumination. © 2010 Elsevier B.V. All rights reserved.

Nguyen H.T.M.,Nha Trang University | Sylla K.S.B.,French Research Institute for Exploitation of the Sea | Randriamahatody Z.,French Research Institute for Exploitation of the Sea | Donnay-Moreno C.,French Research Institute for Exploitation of the Sea | And 3 more authors.
Food Technology and Biotechnology | Year: 2011

Long-term proteolysis of tuna by-products (head, viscera and tail) by the wide spectrum protease Protamex has been investigated and compared. After hydrolysis, two fractions (soluble aqueous phase and insoluble sludge) were collected. Chemical compositions of each fraction and molecular mass distributions of soluble peptides were determined. Degrees of hydrolysis obtained after 12 h of hydrolysis of head, viscera and tail were 32.3, 16.8 and 22.2 %, respectively. Nitrogen recovery in the soluble fractions was 73.6 % for the head, 82.7 % for the viscera and 85.8 % for the tail. Lipid distribution indicated that the majority of lipids remained in the sludge. Such proteolysis appears useful for the production of very different fractions: one rich in peptides of medium to small molecular mass and poor in lipids, and another one containing the insoluble proteins and the majority of lipids.

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