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How rainfall, relative humidity and temperature influence volatile emissions from apple trees in situ.

Phytochemistry (2005-06-14)
Armelle Vallat, Hainan Gu, Silvia Dorn
ABSTRACT

Headspace volatiles from apple-bearing twigs were collected in the field with a Radiello sampler during three different diurnal periods over the complete fruit growing season. Analyses by thermal desorption-GC-MS identified a total of 62 compounds in changing quantities, including the terpenoids alpha-pinene, camphene, beta-pinene, limonene, beta-caryophyllene and (E,E)-alpha-farnesene, the aldehydes (E)-2-hexenal, benzaldehyde and nonanal, and the alcohol (Z)-3-hexen-1-ol. The variations in emission of these plant odours were statistically related to temperature, humidity and rainfall in the field. Remarkably, rainfall had a significant positive influence on changes in volatile release during all three diurnal periods, and further factors of significance were temperature and relative humidity around noon, relative humidity in the late afternoon, and temperature and relative humidity during the night. Rainfall was associated consistently with an increase in the late afternoon in terpene and aldehyde volatiles with a known repellent effect on the codling moth, one of the key pests of apple fruit. During the summer of 2003, a season characterized by below-average rainfall, some postulated effects of drought on trees were tested by establishing correlations with rainfall. Emissions of the wood terpenes alpha-pinene, beta-pinene and limonene were negatively correlated with rainfall. Another monoterpene, camphene, was only detected in this summer but not in the previous years, and its emissions were negatively correlated with rainfall, further supporting the theory that drought can result in higher formation of secondary metabolites. Finally, the two green leaf volatiles (E)-2-hexenal and (Z)-3-hexen-1-ol were negatively correlated with rainfall, coinciding well with the expectation that water deficit stress increases activity of lipoxygenase. To our knowledge, this work represents the first empirical study concerning the influence of abiotic factors on volatile emissions from apple trees in situ.

MATERIALS
Product Number
Brand
Product Description

radiello Cartridge Adsorbents, for sampling BTEX and VOCs (thermal desorption), matrix SS net (3 x 8 μm, 4.8 mm diam.), Carbograph, pk of 20
radiello Triangular Support Plate, pk of 20
radiello Cartridge Adsorbents, for sampling Aldehydes, matrix SS net with 2,4-DNPH coated FLORISIL®, pk of 20
radiello Vertical Adapter, threaded for standard use, pk of 20
radiello Cartridge Adsorbents, for sampling BTEX and VOCs (CS2 Desorption), matrix SS net (100 mesh, 5.8 mm diam.), activated with activated charcoal (30-50 mesh), pk of 20
radiello Barcode Labels, pk of 198
radiello Anesthetic Gases and Vapor Sampler
radiello Cartridge Adsorbents, for sampling Anaesthetic Gases/Vapors, matrix SS net with mix of mol sieve and activated charcoal (30-50 mesh), pk of 20
radiello Cartridge Adsorbents, for sampling Ammonia (NH3), matrix microporous PE impregnated with phosphoric acid, pk of 20
radiello Outdoor Shelter, pk of 10
radiello Replacement Mounting Strips, for use with Radiello Outdoor Shelter, pk of 100
radiello Filtration Kit, pk of 20
radiello BTEX/VOC Starter Kit, CS2 Desorption
radiello BTEX/VOC Starter Kit, Thermal Desorption
Supelco
radiello Aldehyde Calibration Standard, 50 μg/mL each component in acetonitrile, pkg of 10 mL
Supelco
radiello BTEX Calibration Kit (CS2 Desorption)
Supelco
radiello VOC Calibration Kit (Workplace Environment)
radiello Diffusive Bodies, yellow, configured for reduced sampling rates, pk of 20
radiello Empty Storage Tubes, polypropylene (with stopper), volume 12 mL, pk of 100
Supelco
radiello BTEX Calibration Kit (Thermal Desorption)
radiello Clips, suspending Radiello triangular support plate, pk of 20
radiello On-Field Thermometer, Includes one standard Radiello vertical adapter (RAD122) for each thermometer, configured for standard use, pk of 3
radiello Diffusive Bodies, white, configured for general use, pk of 20
radiello On-Field Thermometer, Reader, pk of 1
Supelco
radiello Methylene Blue Calibration Standard for H2S (Hydrogen Sulfide), pkg of 100 mL
radiello Empty Storage Tubes, glass (with stopper), volume 2.8 mL, pk of 100
radiello 1,3-Butadiene Starter Kit, Thermal Desorption, pkg of 1 kit (2 RAD141 adsorbing cartridges and barcode labels, 1 RAD1202 yellow diffusive body, 1 RAD121 triangular support plate, 1 instruction sheet)
radiello Hydrogen Sulfide Starter Kit
radiello Diffusive Bodies, blue, configured for sampling light sensitive compounds, pk of 20
radiello Diffusive Bodies, permeative, configured for anaesthetic gases and vapors, pk of 20