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Effects of elevated CO 2 on intra‐specific competition in Sinapis alba : an examination of the role of growth responses to red:far‐red ratio
Author(s) -
Cowan J. E.,
Reekie E. G.
Publication year - 2008
Publication title -
plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 1435-8603
DOI - 10.1111/j.1438-8677.2007.00026.x
Subject(s) - sinapis , biology , competition (biology) , photosynthesis , far red , zoology , canopy , biomass (ecology) , growth rate , shade avoidance , botany , relative growth rate , agronomy , ecology , red light , biochemistry , geometry , mathematics , arabidopsis , gene , mutant , brassica
Response of plants to elevated CO 2 differs markedly between individually‐ and competitively‐grown plants, both in terms of mean size and variation about the mean. Using Sinapis alba , we explored whether these contrasting effects are a consequence of the effect of competition on the red:far red (R:FR) light ratio. Plants were grown at both ambient and elevated (700 μl·l −1 ) CO 2 in competitive stands, and as individuals at either a low (0.7) or high (1.25) R:FR ratio at a constant photosynthetic photon fluence rate. Elevated CO 2 increased stand biomass by enhancing the growth of canopy dominants, but not the subordinates. As a consequence, elevated CO 2 increased the coefficient of variation in size within the stands. Elevated CO 2 did not enhance the growth of individually‐grown plants at the low R:FR ratio, but did at the high R:FR ratio. Both the poor response of subordinate plants to elevated CO 2 and the increased size inequalities of individuals within the stand can be explained in terms of the effect of the R:FR ratio on CO 2 responsiveness. The effect of the R:FR ratio on CO 2 response may be related to its effect on allocation patterns and nutrient uptake.