Sour orange fine root distribution after seventeen years of atmospheric CO₂ enrichment

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• 作者：S.A. Prior^a ; ^{steve.prior@ars.usda.gov} ; G.B. Runion^a ; H.A. Torbert^a ; S.B. Idso^b ; B.A. Kimball^c
• 关键词：Citrus aurantium ; Elevated CO2 ; Root dry weight density ; Root length density
• 刊名：Agricultural and Forest Meteorology
• 出版年：2012
• 期刊代码：2_01681923
• 类别：abs
• 出版时间：15 September, 2012
• 卷：162-163
• 期：Complete
• 页码：85-90
• 文件大小：502 K

摘要

Long-term (more than 15 years) effects of elevated CO₂ on belowground responses of trees have received limited attention in the literature. We report on a study in which sour orange trees (Citrus aurantium L.) grown in an Avondale loam in Phoenix, AZ, were exposed to ambient and elevated (ambient + 300 渭mol mol^鈭?) levels of atmospheric CO₂ for 17 years. At study termination, soil cores were collected to determine how long-term CO₂ enrichment affected horizontal (0.5, 1.0, 1.5, and 2.0 m from each tree) and vertical (0-105 cm in 15 cm increments) standing crop fine root dry weight and length. Overall, elevated CO₂ increased both root length (35.6%) and root dry weight (39.1%) densities. There was no effect of CO₂ concentration on horizontal root distribution patterns. However, significant CO₂ by depth interactions were noted for both root length and root dry weight densities with differences occurring only in the top two depths. Elevated CO₂ increased fine root length density by 64.5 and 57.2%at the 0-15 and 15-30 cm depths. Respective increases for root dry weight were 80.3 and 82.8%. These large responses occurred under water and nutrient supplies typical of orchard conditions and suggest that long-term citrus productivity can be enhanced under future levels of atmospheric CO₂.