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Biomass and Growth Rate of a Spring Wheat Root System Grown in Free-Air CO2 Enrichment (FACE) and Ample Soil Moisture

G. Wechsung, F. Wechsung, G. W. Wall, F. J. Adamsen, B. A. Kimball, R. L. Garcia, P. J. Pinter Jr. and T. Kartschall
Journal of Biogeography
Vol. 22, No. 4/5, Terrestrial Ecosystem Interactions with Global Change, Volume 2 (Jul. - Sep., 1995), pp. 623-634
Published by: Wiley
DOI: 10.2307/2845963
Stable URL: http://www.jstor.org/stable/2845963
Page Count: 12
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Biomass and Growth Rate of a Spring Wheat Root System Grown in Free-Air CO2 Enrichment (FACE) and Ample Soil Moisture
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Abstract

The response of a wheat crop root system to full-season CO2-enrichment was investigated using a free-air CO2 enrichment (FACE) apparatus. A spring wheat (Triticum aestivum L. cv. Yecora Rojo) crop was growing at 0.25 m row spacing and 130 plants m-2 on a Trix clay loam (hyperthermic Typic Torrifluvent) under two atmospheric CO2 concentrations (FACE: $\sim550 \mumol mol^-1$; control: $\sim370 \mumol mol^-1$) and ample soil moisture (100% replacement of potential evapotraspiration). Irrigation was applied with a subsurface drip irrigation system. Root cores were collected at five growth stages (three-leaf, tillering, stem elongation, anthesis, dough development and final harvest, which corresponded with day of year (DOY) 16, 36, 63, 92, 113 and 159, respectively), using a soil core device (86 mm i. d.). Two cores were taken in-row and one in the inter-row space position to examine the horizontal and vertical distribution of roots to a 1-m depth. Root biomas was summed over the entire root profile across all positions to obtain a total. Total root mass was higher in FACE compared to control for all growth stages (i.e. 34% at three-leaf, 21% at tillering, 23% at stem elongation, 28% at dough development and 19% at harvest). Root growth rate was significantly higher in FACE compared to control for both in row and inter-row position. Rott senescence rate were similar between FACE and control grown plants, but the absolute diferrence in root mas during the senescence phase was greater in FACE compared to control grown plants. Roots from FACE grown plants explored a greater proportion of the soil profile earlier in the season than root from control grown plants. However, there was no evidence that plants grown in FACE had a deeper root system than plants grown in control.

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