Peer-review: Yes - Open Access: Yes|http://science.thomsonreuters.com/cgi-bin/jrnlst/jlresults.cgi?PC=MASTER&ISSN=0011-183X

Awned hard red winter wheat (HRWW, ,Triticutn aestivum L.) cultivars have prevailed in the Great Plains since the introduction of ?Turkey? wheat in the 1870s, but the role of awns in wheat productivity is unclear. Awns may serve a photosynthetic function during periods of drought stress, and may actually compensate for flag leaf photosynthesis reduced by drought stress. Our objectives were to determine the effect of genetic awn suppression on photosynthesis and instantaneons or season-long measurements of water-use efficiency (WUE), and to monitor associated changes in kernel characteristics. Plants of awned and awnletted near-isogenic lines of three contemporary HRWW cnitivars (TAM 107, Century, and Mustang) were grown controlled-environment chambers under well-watered and waterdeficit conditions. Photosynthetic rates of spikes and flag leaves were measured separately at two stages of kernel development. Whole-plant and grain WUE were measured based on actual water use. Under well-watered conditions, net photosynthetic rates of awnletted spikes were significantly lower than awned spikes for all cnitivars at 1~1 d after anthesis (DAA) and for two cultivars at 24 DAA. Under water-deficit conditions, rates were significantly lower for awnletted spikes of Mustang and TAM 107 at 14 DAA, while no differences were found at 24 DAA. No differences were found between isolines for flag leaf photosynthesis at either stage. Generally, differences in kernel characteristics were nonsignificant between awned and awnletted lines. Although some instantaneous photosynthetic measurements suggested higher WUE of awned spikes, this difference did not result in higher WIrE based on whole-plant biomass or grain weight for awned isolines.

English

Crop Science Society of America (CSSA)

Carelia Juarez

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