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Exploring the limits of crop productivity. I. Photosynthetic efficiency of wheat in high irradiance environmentsThe long-term vegetative and reproductive growth rates of a wheat crop (Triticum aestivum L.) were determined in three separate studies (24, 45, and 79 days) in response to a wide range of photosynthetic photon fluxes (PPF, 400-2080 micromoles per square meter per second; 22-150 moles per square meter per day; 16-20 hour photoperiod) in a near-optimum, controlled-environment. The CO2 concentration was elevated to 1200 micromoles per mole, and water and nutrients were supplied by liquid hydroponic culture. An unusually high plant density (2000 plants per square meter) was used to obtain high yields. Crop growth rate and grain yield reached 138 and 60 grams per square meter per day, respectively; both continued to increase up to the highest integrated daily PPF level, which was three times greater than a typical daily flux in the field. The conversion efficiency of photosynthesis (energy in biomass/energy in photosynthetic photons) was over 10% at low PPF but decreased to 7% as PPF increased. Harvest index increased from 41 to 44% as PPF increased. Yield components for primary, secondary, and tertiary culms were analyzed separately. Tillering produced up to 7000 heads per square meter at the highest PPF level. Primary and secondary culms were 10% more efficient (higher harvest index) than tertiary culms; hence cultural, environmental, or genetic changes that increase the percentage of primary and secondary culms might increase harvest index and thus grain yield. Wheat is physiologically and genetically capable of much higher productivity and photosynthetic efficiency than has been recorded in a field environment.
Document ID
20040112090
Acquisition Source
Ames Research Center
Document Type
Reprint (Version printed in journal)
Authors
Bugbee, B. G.
(Utah State University Logan 84322-4820, United States)
Salisbury, F. B.
Date Acquired
August 21, 2013
Publication Date
January 1, 1988
Publication Information
Publication: Plant physiology
Volume: 88
ISSN: 0032-0889
Subject Category
Man/System Technology And Life Support
Funding Number(s)
CONTRACT_GRANT: NCC2-139
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Number 61-10
Non-NASA Center
NASA Discipline Life Support Systems
NASA Program CELSS

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