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Super‐Optimal CO 2 Reduces Seed Yield But Not Vegetative Growth in Wheat
Author(s) -
Grotenhuis Timothy P.,
Bugbee Bruce
Publication year - 1997
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1997.0011183x003700040031x
Subject(s) - yield (engineering) , anthesis , cultivar , zoology , horticulture , biology , carbon dioxide , greenhouse , vegetative reproduction , poaceae , botany , agronomy , ecology , materials science , metallurgy
Although terrestrial atmospheric CO 2 levels will not reach 1000 μmol mol −1 (0.1%) for decades, CO 2 levels in growth chambers and greenhouses routinely exceed that concentration. CO 2 levels in life support systems in space can exceed 10 000 μmol mol −1 (1%). Numerous studies have examined CO2 effects up to 1000 μmol mol −1 , but biochemical measurementisn dicate that the beneficial effects of CO 2 can continue beyond this concentration. We studied the effects of near‐optimal (≈1200 μmol mol −1 ) and super‐optimal CO 2 levels (2400 μmol mol −1 ) on yield of two cultivars of hydroponically grown wheat ( Triticum aestivum L.) in 12 trials in growth chambers. Increasing CO 2 from sub‐optimal to near‐optimal (350‐1200 μmol mol −1 ) increased vegetative growth by 25% and seed yield by 15% in both cultivars. Yield increases were primarily the result of an increased number of heads per square meter. Further elevation of CO 2 to 2500 μmol mol −1 reduced seed yield by 22% ( P < 0.001) in cv. Veery‐10 and by 15% ( P < 0.001) in cv. USU‐ApogeeS. uper‐optimal CO 2 did not decrease the number of heads per square meter, but reduced seeds per head by 10% and mass per seed by 11%. The toxic effect of CO 2 was similar over a range of light levels fromh alf to full sunlight. Subsequenttr ials revealed that super‐optimal CO 2 during the interval between 2 wk before and after anthesis mimickedth e effect of constant super‐optimal O 2 . Furthermore, near‐optimal CO 2 during the same interval mimicked the effect of constant near‐optimal CO 2 . Nutrient concentration of leaves and heads was not affected by CO 2 . These results uggest that super‐optimal CO 2 inhibits some process that occurs near the time of seed set resulting in decreased seed set, seed mass, and yield.