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United States Department of Agriculture

Agricultural Research Service

Title: Centenary Review: Phytomers, Phyllochrons, Phenology and Temperate Cereal Development

Author
item McMaster, Gregory

Submitted to: Journal of Agricultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 23, 2004
Publication Date: February 1, 2005
Citation: Mcmaster, G.S. 2005. Centenary review: phytomers, phyllochrons, phenology and temperate cereal development. Journal of Agricultural Science. Cambridge. 43:1-14. 2005

Interpretive Summary: Extensive research has been conducted on temperate cereal development since the inception of the Journal of Agricultural Science in 1905. This invited review presents an overview showing how wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) plants develop in an orderly and predictable pattern. It begins with the concept of building canopies by the formation, growth, and senescence of basic building blocks called phytomers (the unit comprised of the leaf, axillary bud, node, and internode). Existing morphological naming schemes for uniquely identifying each plant part are then extended to uniquely name each phytomer unit. The role of the phyllochron (or rate of leaf appearance) in synchronizing cereal development and phytomer formation is discussed, as is how phenology can be used to predict when the individual phytomer components form, grow, and senesce. The complete developmental sequence of the winter wheat shoot apex correlated with growth stages is extended to spring barley. This overview concludes with consideration of abiotic factors controlling cereal development, and special attention is given to some key questions regarding the critical role of temperature. The paper finishes with some wary forward glances to the exciting possibilities for new understanding of mechanisms controlling the phyllochron and phenology being derived from genome mapping and molecular biology.

Technical Abstract: Extensive research has been conducted on temperate cereal development since the inception of the Journal of Agricultural Science in 1905. This review presents an overview of the orderly and predictable development of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). It begins with the concept of building canopies by the formation, growth, and senescence of phytomers (the unit comprised of the leaf, axillary bud, node, and internode). Morphological naming schemes for uniquely identifying each plant part are then extended to uniquely name each phytomer unit. The role of the phyllochron (rate of leaf appearance) in synchronizing cereal development and phytomer formation is discussed, as is how phenology can be used to predict when the individual components form, grow, and senesce. The complete developmental sequence of the winter wheat shoot apex correlated with growth stages is extended to spring barley. This overview concludes with consideration of abiotic factors controlling cereal development, and special attention is given to some key questions regarding the critical role of temperature. The paper finishes with some wary glances forward to the exciting possibilities for new understanding of mechanisms controlling the phyllochron and phenology being derived from functional genomics and molecular biology.

Last Modified: 7/31/2014
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