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weed seed dispersal mechanisms

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Block Reference: #9de23fa0-f9d6-11eb-bbd3-f51e9ec54c4a
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Date and time: Tue, 10 Aug 2021 12:29:33 GMT

Specialized seed structures affect whether, and how, animals spread seed:
-burrs: cocklebur, sandbur seed
-appendages: beggarticks seed

Poverty of seed fall in the immediate neighborhood of the parent characteristic of of plants in isolation; e.g. mullein, musk thistle is pasture

Human dispersal
-new continent, region invasions
-local dispersal: machinery, crop seed contamination

The Role of Animals in Dispersal

-ones with hard gizzards that destroy seeds;
-soft gizzards that pass on viable seed

"Tumble Weeds: movement of parent plant (with seeds) on ground after dispersal, -blow with wind;
-seeds dispersed in rolling action;
-examples: kochia on mother plant, forms rolling ball;
-velvetleaf capsules

Specialized mechanisms of some weed species to bury themselves: wild oat hygroscopic awns that twist themselves into the soil (self-seeding)

Seed ejaculation
-example: mistletoe seed propelled by parent plant
-sticky seed surface to adhere to tree host, bird foot vector

This paper reviews the current knowledge on weed seed movement in an agricultural environment. Seed movement is analyzed both from an agronomic and ecological perspective, focusing predominantly on horizontal seed movement. Abiotic (anemochory and hydrochory), as well as biotic (autochory, myrmecochory, epizoochory, and endozoochory) weed seed dispersal typologies are examined, highlighting the mechanisms involved, the specializations displayed by weed species that have evolved by exploiting a particular dispersal mechanism, and their adaptive interaction with the surrounding ecosystem. Emphasis is also placed on the crucial role of human activity (anthropochory), which can affect natural (biotic and abiotic) weed seed dispersal at several stages, partly via the worldwide commercial seed trade but, above all, by crop management operations, thereby potentially facilitating the entry and spread of alien weed species. This phenomenon, together with the invasive expansion of existing weeds that more successfully coevolve and adapt to the new environment, might exert an adverse effect on biodiversity. In-depth knowledge of weed seed dispersal, survival, and germination mechanisms is therefore essential for effective and eco-compatible management of the weed phytocoenoses present in the agroecosystem in order to promote a rational trade-off between agricultural productivity and environmental protection.