<i>Avena fatua</i>development and seed shatter as related to thermal time

Shirtliffe, Steven J.; Entz, Martin H.; Acker, Rene C. Van

doi:10.1614/0043-1745(2000)048[0555:afdass]2.0.co;2

Cited by 53 publications

(78 citation statements)

References 17 publications

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“…4). Under fi eld conditions, a 75-GDD interval equates to wheat plants having roughly one additional or one fewer leaves than the crop given a spring wheat phyllochron interval of approximately 80 to 100 GDD (Bauer et al, 1984;Shirtliff e et al, 2000). Volunteer spring wheat emerging within this window must be controlled in wheat crops to minimize fl owering synchrony and reduce the probability of fl owering overlap with the crop.…”

Section: Discussionmentioning

confidence: 99%

Flowering Phenology and Synchrony between Volunteer and Cropped Spring Wheat: Implications for Pollen‐Mediated Gene Flow

et al. 2009

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Genetically engineered (GE) wheat (Triticum aestivum L.) volunteers could present a problem in cultivated wheat because they may facilitate movement of a GE trait to other volunteers or non‐GE wheat crops. However, volunteers can emerge periodically throughout the growing season and, thus, flowering overlap with the crop may be largely asynchronous, presenting a significant barrier to gene flow. Field experiments were initiated to determine the influence of volunteer wheat emerging at various densities and emergence times relative to the crop on flowering phenology and synchrony between cropped and volunteer spring wheat populations. Using a novel analytical method that treats individual flowering curves as a series of probability density functions, we characterized flowering phenology and quantified flowering synchrony between cropped and volunteer spring wheat. The results indicated that volunteer wheat initiated and ceased flowering earlier when emergence occurred before crop emergence. Thermal time requirements for completion of 5, 50, and 75% flowering decreased as volunteer emergence was progressively delayed. Flowering was further accelerated when emergence coincided with the crop and, consequently, flowering synchrony between volunteer and crop plants was significantly higher. Levels of flowering synchrony peaked at 86% and were highly dependent on volunteer emergence time relative to the crop. Our results suggest that pollen‐mediated gene flow (PMGF) in spring wheat will be dependent on emergence timing of volunteers and, thus, if hybridization between cultivated wheat and volunteers or neighboring wheat crops is going to transpire, it will most likely occur when volunteer emergence occurs within a hybridization window of 75 growing degree‐days on either side of crop emergence. Coupled with seed‐mediated gene flow, the additional admixture caused by PMGF could be problematic for coexistence between GE and non‐GE wheat.

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Section: Discussionmentioning

confidence: 99%

Flowering Phenology and Synchrony between Volunteer and Cropped Spring Wheat: Implications for Pollen‐Mediated Gene Flow

et al. 2009

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“…There is evidence that a high level of seed retention occurs for many weeds, but seed retention can also be influenced by the growing environment (Shirtliffe et al 2000, Taghizadeh et al 2012. For example, in wheat (Triticum aestivum L.) production fields in western Australia, rigid ryegrass (Lolium rigidum Gaudin L.), wild radish (Raphanus raphanistrum L.), brome grass (Bromus spp.…”

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confidence: 99%

Effects of relative emergence time and water deficit on the timing of fruit dispersal in Raphanus raphanistrum L.

2012

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Seed dispersal is both a spatial and a temporal phenomenon, although most studies focus on spatial aspects. Seed initiation on the maternal plant may occur over a considerable period, especially in indeterminately flowering species, and thus seeds may be exposed to a wide range of environmental conditions during their development. The result is variation in the timing of seed development, the anatomy of structures related to the dispersal process, and the behaviour and fate of seeds post-dispersal. A key resource during the growth and development of summer-maturing species in most areas, and one that is thus likely to modify these processes, is water. Two experiments were therefore undertaken to describe (i) the development of Raphanus raphanistrum fruits and the timing of fruit dispersal, and (ii) the effects of water availability on the timing of fruit dispersal. Fewer seeds were produced and subsequently dispersed by later emerging plants. The duration of fruit dispersal became shorter when the plants emerged progressively later than the crop, and the time of maximum dispersal was later. For cohorts of fruits initiated at the same time, those that developed under mild and severe water deficit reached their final length sooner, and were dispersed sooner, than those receiving a plentiful supply of water. Thus, the phenology of the maternal plant and the nature of its environment can modify the timing of propagule maturity and consequently dispersal. Such information may provide an opportunity for managers to reduce weed seed return to their field or, conversely, to regulate the amount of contaminated grain or reduce dispersal to other locations.

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“…Combine harvesters can spread the seeds of some weed species over large areas (McCanney and Cavers 1988;Shirtliffe 1999). For a seed-limited weed species such as wild oat (Boyd and Van Acker 2004) it is possible to use chaff collection in conjunction with a delay in harvest timing to limit the wild oat population and wild oat patch spread (Shirtliffe et al 2000). Such a reduction in population and patch spread could facilitate the use of reduced herbicide rates and site-specific weed management in order to reduce herbicide use.…”

Section: Prevention Of New Weed Problemsmentioning

confidence: 99%

Strategies and tactics for herbicide use reduction in field crops in Canada: A review

Nazarko¹,

Acker²,

Entz³

2005

Can. J. Plant Sci.

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There are many economic and health reasons for reducing pesticide use in Canada. Herbicide use on field crops is by far the most common pesticide use in Canada. This paper is a review of four topics related to herbicide use reduction on field crops in Canada: (1) broad strategies and (2) specific tactics for herbicide use reduction; (3) factors affecting adoption; and 4) research approaches for improving the implementation of herbicide use reduction. Numerous tactics exist to use herbicides more efficiently and herbicides can sometimes be replaced by non-chemical weed control methods. Many of these tactics and methods have been investigated and demonstrated for use on field crops in Canada. However, herbicide use reduction is fundamentally dependent upon preventative strategies designed to create robust cropping systems that maintain low weed densities. Diverse crop rotation forms the basis of preventative strategies as it inherently varies cropping system conditions to avoid weed adaptation. There is evidence that residual weed densities resulting from herbicide use reduction are manageable within competitive cropping systems. A great deal of research has been done on herbicide use reduction on field crops in Canada, and most projects report definite possibilities for herbicide use reduction in field crop production in Canada. Synthesizing and extending this information and customizing it for use on individual farms remain challenges. Collaboration between researchers and farmers can help to build successful strategies for herbicide use reduction which reflect the context of modern farming, the will of farmers and the culture of technology adoption among farmers. Key words: Pesticide use reduction, low-input agriculture, integrated pest management, integrated weed management

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Avena fatuadevelopment and seed shatter as related to thermal time

Cited by 53 publications

References 17 publications

Flowering Phenology and Synchrony between Volunteer and Cropped Spring Wheat: Implications for Pollen‐Mediated Gene Flow

Flowering Phenology and Synchrony between Volunteer and Cropped Spring Wheat: Implications for Pollen‐Mediated Gene Flow

Effects of relative emergence time and water deficit on the timing of fruit dispersal in Raphanus raphanistrum L.

Strategies and tactics for herbicide use reduction in field crops in Canada: A review

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