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This article in CS

  1. Vol. 32 No. 3, p. 797-801
     
    Received: May 16, 1991
    Published: May, 1992


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doi:10.2135/cropsci1992.0011183X003200030044x

Response of Soybean Growth to Root and Canopy Competition

  1. James N. Marvel,
  2. Craig A. Beyrouty  and
  3. Edward E. Gbur
  1. Agricultural Statistics Lab., Univ. of Arkansas, Fayetteville, AR 72701

Abstract

Abstract

Interplant competition in soybean [Glycine max (L.) Merr.] influences plant growth. Because of the difficulty of evaluating root competition, studies to date have concentrated on competition within the canopy. We used a below-ground porous membrane to isolate and evaluate the effects of root and canopy competition on soybean growth. Field studies were conducted in 1985 and 1986 on a Captina silt loam (fine-silty, siliceous, mesic Typic Fragiudult) with four competition treatments imposed on ‘Forrest‘ soybean: (i) no competition, (ii) root competition only, (iii) canopy competition only, and (iv) root and canopy (combined) competition. At growth stage R4, leaf area was reduced 29% by root competition and 48% by canopy competition. Root competition reduced net assimilation rate by 48% in 1985 and 10% in 1986, while canopy competition resulted in a 28% reduction both years. Combined competition reduced total plant dry weight an average of 78%, with intermediate dry weights for root or canopy competition. At R4 and R8, shoot dry weight was reduced 31 and 43% with root competition, and 57 and 62% with canopy competition, respectively. Canopy competition reduced root dry weight at R4 by 43% in 1985 and 70% in 1986. Root competition reduced root dry weights in both years by 24 and 42% at R4 and R8, respectively. Canopy and combined competition resulted in taller plants with smaller stem circumferences while root competition did not alter shoot structure. Results suggest that canopy competition may have a greater influence on plant development than root competition.

Published with permission of the Director of the Arkansas Agricultural Experiment Station.

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Copyright © 1992. Crop Science Society of America, Inc.Copyright © 1992 by the Crop Science Society of America, Inc.