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Sunflower Plants (sunflower + plant)

Distribution by Scientific Domains

Life Sciences	50%
Chemistry	50%

Selected Abstracts

Carbon Metabolism Alterations in Sunflower Plants Infected with the Sunflower Chlorotic Mottle Virus

JOURNAL OF PHYTOPATHOLOGY, Issue 5 2003
M. C. Arias
Abstract Sunflower chlorotic mottle virus (SuCMoV) causes chlorotic mottling symptoms and important growth reductions and yield losses in sunflower (Helianthus annuus L., cv. Contiflor 7). This paper describes the effects of SuCMoV on some aspects of carbon metabolism of sunflower plants. After symptoms became evident, CO2 fixation rates decreased, nevertheless, soluble sugars and starch increased in infected leaves. High H2O2 accumulation, lipid peroxidation and chlorophyll degradation were, like the other changes, observed only after symptom expression. Increased soluble carbohydrate accumulation was not related to changes in , -amylase (EC 3.2.1.1) activity, nor in the activities of enzymes associated with sugar import and hydrolysis such as invertase (EC 3.2.1.26) and sucrose synthase (EC 2.4.1.13), suggesting it did not derive from starch hydrolysis nor increased sugar import. Rather, it may derive from recycling of cell components associated with the development of oxidative damage. The physiological alterations caused by this virus share many common features with the development of senescence. [source]

Examination of the distribution of nicosulfuron in sunflower plants by matrix-assisted laser desorption/ionisation mass spectrometry imaging

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 9 2009
David M. G. Anderson
Matrix-assisted laser desorption/ionisation mass spectrometry imaging (MALDI-MSI) has been used to image the distribution of the pesticide nicosulfuron (2-[[(4,6-dimethoxypyrimidin-2-yl)aminocarbonyl]aminosulfonyl]- N,N -dimethyl-3-pyridinecarboxamide) in plant tissue using direct tissue imaging following root and foliar uptake. Sunflower plants inoculated with nicosulfuron were horizontally sectioned at varying distances along the stem in order to asses the extent of translocation; uptake via the leaves following foliar application to the leaves and uptake via the roots from a hydroponics system were compared. An improved sample preparation methodology, encasing samples in ice, allowed sections from along the whole of the plant stem from the root bundle to the growing tip to be taken. Images of fragment ions and alkali metal adducts have been generated that show the distribution of the parent compound and a phase 1 metabolite in the plant. Positive and negative controls have been included in the images to confirm ion origin and prevent false-positive results which could originate from endogenous compounds present within the plant tissue. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Carbon Metabolism Alterations in Sunflower Plants Infected with the Sunflower Chlorotic Mottle Virus

Risk posed to honeybees (Apis mellifera L, Hymenoptera) by an imidacloprid seed dressing of sunflowers

PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 3 2001
Richard Schmuck
Abstract In a greenhouse metabolism study, sunflowers were seed-treated with radiolabelled imidacloprid in a 700,g,kg,1 WS formulation (Gaucho® WS 70) at 0.7,mg AI per seed, and the nature of the resulting residues in nectar and pollen was determined. Only the parent compound and no metabolites were detected in nectar and pollen of these seed-treated sunflower plants (limit of detection <0.001,mg,kg,1). In standard LD50 laboratory tests, imidacloprid showed high oral toxicity to honeybees (Apis mellifera), with LD50 values between 3.7 and 40.9,ng per bee, corresponding to a lethal food concentration between 0.14 and 1.57,mg,kg,1. The residue level of imidacloprid in nectar and pollen of seed-treated sunflower plants in the field was negligible. Under field-growing conditions no residues were detected (limit of detection: 0.0015,mg,kg,1) in either nectar or pollen. There were also no detectable residues in nectar and pollen of sunflowers planted as a succeeding crop in soils which previously had been cropped with imidacloprid seed-treated plants. Chronic feeding experiments with sunflower honey fortified with 0.002, 0.005, 0.010 and 0.020,mg,kg,1 imidacloprid were conducted to assess potential long-term adverse effects on honeybee colonies. Testing end-points in this 39-day feeding study were mortality, feeding activity, wax/comb production, breeding performance and colony vitality. Even at the highest test concentration, imidacloprid showed no adverse effects on the development of the exposed bee colonies. This no-adverse-effect concentration of 0.020,mg,kg,1 compares with a field residue level of less than 0.0015,mg,kg,1 (,=, limit of detection in the field residue studies) which clearly shows that a sunflower seed dressing with imidacloprid poses no risk to honeybees. This conclusion is confirmed by observations made in more than 10 field studies and several tunnel tests. © 2001 Society of Chemical Industry [source]

Effect of source,sink ratio on seed set and filling in sunflower (Helianthus annuus L.)

PLANT CELL & ENVIRONMENT, Issue 10 2003
M. ALKIO
ABSTRACT Poor seed development in sunflower may result from insufficient assimilate supply (source limitation). To test this hypothesis, the effects of changed source,sink ratio on seed set (measured as percentage of empty achenes) and seed filling (measured as dry mass per filled achene) in individual plants were investigated. Source,sink ratio, defined as leaf area per floret (LAF), was experimentally altered using invasive (floret removal, defoliation) and non-invasive (pulse of chilling, short days or shading during leaf or floret initiation) treatments. Shading at floret initiation proved the most effective non-invasive method. Generally, an increase, or decrease, in LAF improved, or impaired, both seed set and filling. Increasing LAF by 2.0 cm2[95% confidence interval (1.5, 2.5)] decreased the percentage of empty achenes by 36.9%-points (,41.9, ,30.9) and increased dry mass per filled achene by 20.1 mg (13.6, 26.7) in the capitulum centre. The effect of source,sink ratio on seed set was always strongest in the centre, whereas peripheral whorls were not affected. Achene mass was affected in all parts of the capitulum. It is concluded that source limitation is a major cause for empty achenes in sunflower plants grown under non-stress conditions. [source]