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Water Deficit Alters Canopy Structure but not Photosynthesis during the Regrowth of Alfalfa


Pembleton, KG and Rawnsley, RP and Donaghy, DJ and Volenec, JJ, Water Deficit Alters Canopy Structure but not Photosynthesis during the Regrowth of Alfalfa, Crop Science, 49, (2) pp. 722-731. ISSN 0011-183X (2009) [Refereed Article]

DOI: doi:10.2135/cropsci2008.08.0456


Growth of alfalfa (Medicago sativa L.) following the correction of a water deficit will depend in part on the characteristics of the canopy grown during the water deficit. The current study was undertaken to determine the extent to which canopy structure and photosynthetic capacity are affected in alfalfa plants regrowing following defoliation while exposed to a water deficit. The effects of five levels of water application (100, 75, 50, 25, and 0% of the replacement water requirement) during the regrowth of two alfalfa cultivars with contrasting levels of fall dormancy was investigated in a controlled environment. Mass per shoot and shoots per plant were both significantly (P < 0.05) reduced by water applications 75% or less of the replacement water requirement. Dry matter accumulation was reduced in proportion to the level of the water deficit the plants were exposed to. The rate of CO2 assimilation and maximum efficiency of photosystem II were unaffected (P > 0.05) by water deficits except for the unwatered plants on which leaf senescence occurred. The only inhibition in the plants' capacity for photosynthesis from a water deficit was reduced leaf area. Shoot density and reduced overall canopy photosynthesis were the only canopy characteristics that were altered by water deficit in a way that could continue to inhibit plant growth following the correction of the water deficit. © Crop Science Society of America. All rights reserved.

Item Details

Item Type:Refereed Article
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Crop and pasture production
Research Field:Crop and pasture biochemistry and physiology
Objective Division:Animal Production and Animal Primary Products
Objective Group:Pasture, browse and fodder crops
Objective Field:Pasture, browse and fodder crops not elsewhere classified
UTAS Author:Pembleton, KG (Dr Keith Pembleton)
UTAS Author:Rawnsley, RP (Dr Richard Rawnsley)
UTAS Author:Donaghy, DJ (Associate Professor Danny Donaghy)
ID Code:52508
Year Published:2009
Web of Science® Times Cited:7
Deposited By:Agricultural Science
Deposited On:2008-07-28
Last Modified:2012-03-05

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