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Title: Interaction of air temperature and nitrogen supply on root growth and nitrogen uptake by corn

Author
item Chun, Jong
item YANG, YANG - University Of Maryland
item Timlin, Dennis
item Fleisher, David
item Reddy, Vangimalla

Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: 3/12/2009
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Nutrient uptake rates by plants are governed by both plant processes and soil properties. Simulation models of nitrogen uptake should account for both demand and availability of nitrogen. The goal of this study was to quantify root growth and nitrogen uptake by corn plants (maize) as affected by air temperature and nitrogen supply. Corn plants were planted in outdoor plant growth chambers in which temperature, humidity, and atmospheric carbon dioxide concentrations were precisely controlled. Four different nitrogen levels (2, 6, 8, and 12 mM) combined with two different temperature regimes (25/19 and 31/25 degrees in Celsius, at 05:00/21:00 Eastern Standard Time) were applied to the corn plants using 4 chambers. Polyvinyl Chloride (PVC, 152.4 mm in diameter and 762 mm in length) tubes filled with sand (710 mm in length) were used for this study. Soil water contents were monitored by a Time Domain Reflectometry (TDR) system. Two 30 cm TDR probes were installed at the top and the bottom of the sand columns, respectively. Over the growing season, six destructive harvests were carried out. The sand columns and roots were sampled at every 127 mm (5 inches) of depth to measure the depth distribution of the nitrogen. Corn plants were separately collected, dried, and analyzed for the Carbon to Nitrogen (C:N) ratio and leaf, stem, ear, and root dry weights. The C:N ratio of the root ranged from 15 to 72, was higher under low temperature, and tended to inversely vary to nitrogen levels. The Root to Shoot ratio (R:S ratio) in corn ranged from 0.1 to 4.3, and was higher under low temperature. However, the ratio was not significant for different nitrogen levels. We expect that this study can be used to improve the root growth model for MAIZSIM, and consequently provide more effective water and nitrogen application strategies.