Aerobic methane emissions from stinkweed (Thlaspi arvense) capsules

Abstract

Abbreviations: AWOVA, analysis of variance; dw, dry weight; LSD, least significant difference; PPFD, photosynthetically active photon flux density.Aerobic methane (CH 4 ) emission from plant vegetative parts has been confirmed by many studies. However, the origin of aerobic CH 4 from plants and its emission from reproductive parts have not been well documented. We determined the effects of developmental stages (early, mid, late) and incubation conditions (darkness, dim light, bright light) on CH 4 emissions from stinkweed (Thlaspi arvense) capsules. We found that CH 4 emissions from capsules varied with developmental stage and incubation light. Methane emission was highest for the late harvested capsules and for those incubated under lower (dim) light condition. Our results also showed a significant negative correlation between CH 4 emission and capsule moisture content. We conclude that CH 4 emissions vary with capsule age and diurnal light environment.Methane is the second most important greenhouse gas, producing an enhanced 'greenhouse effect' and contributing to global warming. It is approximately 25 times more potent than CO 2 in trapping heat.10 Atmospheric concentrations of CH 4 have more than doubled since pre-industrial times.1 Its natural and anthropogenic sources have contributed to increased air temperature in recent years.2,17 Keppler et al. 11 have shown that, besides anaerobic sources, plants can also emit CH 4 under aerobic conditions and this new source may have implications to global methane budget. There has been discussion on the methods of estimation, 6,8,9 emission rates, 7,13,21 and origin of aerobic CH 4 from plants. 4,5,12,14 In these studies, CH 4 emissions were measured mostly from plant vegetative parts, 5 but rarely from reproductive parts.3 It has been shown that stressed plants emit more methane than non-stressed ones, 5,18-21 and emission rates vary with plant species. The objective of this study was to measure CH 4 emissions from the stinkweed capsules at 3 developmental stages that were incubated under 3 light conditions. We hypothesized that aerobic CH 4 emissions increase with capsule maturity, which can be influenced by light conditions and capsule moisture content.We used stinkweed (Thlaspi arvense) to measure CH 4 emissions from its capsules. Stinkweed was selected because of its prolific nature of seed production, its potential for aggressively competing with crops under future climate conditions, its distinct and spread out seed pods along the stem, and its wide distribution in Canada. In September 2007, mature seeds of stinkweed were collected from a population located near the fence at the corner of Shaganappi Trail NW and 40 Avenue NW in Calgary, Canada. Plants were grown from seeds in 1 L pots, containing a mixture of peat moss, Perlite, Vermiculite and Terragreen (2:1:1:0.5, by volume) and a few pellets of slow-releasing fertilizer (N-P-K, 14-14-14) in a controlled-environment walk-in growth chamber (model GRW36, Econair Technologies, Inc.., Winnipeg, MB, Canada) und...

Light quality and quantity regulate aerobic methane emissions from plants

“…There is growing evidence that plants release aerobic methane (CH 4 ) emissions, and that these emissions are greatly influenced by a number of environmental factors (Vigano et al , Bruhn et al , Wang et al , Wang et al 2011a, 2011b, Qaderi and Reid , Qaderi and Reid , Qaderi and Reid , Liu et al ). Here, we present evidence for the first time that CH 4 emissions are also regulated by variable light quantity and quality, and these effects act in a time‐dependent fashion as plants are able to acclimate to their surroundings.…”

“…Methane emissions were determined by using a protocol similar to the method that is commonly used to determine the production of endogenous ethylene (Liu et al , Emery et al , Qaderi and Reid , , ). From each growth condition, three replicates of leaves, approximately 0.2 g FW, were detached and immediately incubated for 2 h within 3‐ml plastic syringes flushed with CH 4 ‐free air.…”

“…In 2006, the proposition that plants may act as a source of aerobic CH 4 emissions, and that these emissions could increase with both light and temperature (Keppler et al ), generated significant controversy within the scientific community. It was originally met with skepticism (Dueck et al , Beerling et al , Wang et al ); but while the mechanism remains unknown, evidence has been mounting in support of this finding, with compounds such as biopolymers as potential precursors (Cao et al , Keppler et al , McLeod et al , Vigano et al , , Wang et al 2008, 2011a, 2011b, Brüggermann et al , Bruhn et al , , Messenger et al , Qaderi and Reid , , , Althoff et al , Wishkerman et al , Watanabe et al , Zhang et al , Fraser et al , Liu et al ). These studies suggest that the global CH 4 budget may be more complicated than originally anticipated.…”

“…According to a recent mathematical model (Carmichael et al ), it is now estimated that aerobic CH 4 production may account for 1.2–9% of the global CH 4 budget, regardless of its lack of inclusion in the IPCC reports (Carmichael et al ); however, these results remain under debate today. While ultraviolet light (Nisbet et al , Wang et al , Bruhn et al ) and direct sunlight have been shown to induce CH 4 emissions in some species (Keppler et al ), incubation in bright light was shown to increase emissions only from younger stinkweed capsules ( Thlaspi arvense ), whereas incubation in dim light increased emissions from older ones (Qaderi and Reid ). Another study found only minimal CH 4 release from Grey poplar ( Populus × canescens (Aiton) Sm.)…”

“…We examined the effects of light quality and light intensity on plant growth, physiology and CH 4 emissions from sunflower ( Helianthus annuus ), a shade‐intolerant plant and chrysanthemum ( Chrysanthemum coronarium ), a shade‐tolerant plant. We hypothesized that CH 4 emissions would decrease as plants age (Qaderi and Reid ), and since low light levels in controlled‐environments are lower than that observed in nature, we hypothesized that lower light may act as a stress factor and increase emissions. Higher light may result in lower emissions because it is closer to light levels in nature.…”