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EFFECT OF CARBON DIOXIDE ENRICHMENT ON DEVELOPMENT OF THE FIRST SIX MAINSTEM LEAVES IN SOYBEAN
Author(s) -
Leadley Paul W.,
Reynolds James F.
Publication year - 1989
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1989.tb15137.x
Subject(s) - leaflet (botany) , biology , horticulture , zoology , carbon dioxide , botany , ecology
Many conclusions concerning plant responses to CO 2 enrichment have been based on assumptions of increased leaf size derived from observations of average leaf area measured at some time well into the growth period. The objectives of this study were to study the effect of elevated CO 2 on 1) the timing of mainstem leaflet appearance, 2) the rate and duration of leaflet expansion, and 3) the final area of individual leaflets of soybeans ( Glycine max [L.] Merr. cv. Bragg) grown from seed at 348, 502, and 645 μ l 1 –1 CO 2 concentrations. Central leaflet areas from mainstem trifoliolates 1–6 were measured every two days from time of appearance to full expansion. Leaflets tended to appear earlier in elevated CO 2 treatments; leaflets 2 through 6 appeared an average of 0.4 days earlier in the 502 μ l 1 –1 treatment and 1.2 days earlier in the 645 μ l 1 –1 treatment than in the 349 μ l 1 –1 treatment. Relative rates of expansion were different among leaflets in their response to elevated CO 2 ; expansion rates of leaflets 1 and 4 were significantly higher at the highest CO 2 concentration. However, final area of leaflets was not affected by CO 2 , or (in leaflet 5 only) was slightly smaller at the highest CO 2 treatment. Apparently, higher expansion rates of leaflets 1 and 4 at high CO 2 were offset by a tendency for decreased duration of expansion. It appears that there are morphological constraints on final leaflet area in soybean seedlings which limit the effects of elevated CO 2 on the early development of mainstem leaf area.