Water use and root system development of competing cotton (Gossypium hirsutum L.) and common cocklebur (Xanthium strumarium L.) /
Water use of competing common cocklebur and cotton were measured under irrigated and non-irrigated field conditions with a stem heat balance method. Common cocklebur reduced cotton transpiration by depleting soil water under irrigated conditions. Cotton transpiration was reduced under non- irrigat...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1994.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=741965181&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Water use of competing common cocklebur and cotton were measured under irrigated and non-irrigated field conditions with a stem heat balance method. Common cocklebur reduced cotton transpiration by depleting soil water under irrigated conditions. Cotton transpiration was reduced under non- irrigated conditions; leaf area indicated that common cocklebur was not depleting soil water available to the cotton. Although common cocklebur has been found to be sensitive to water stress, common cocklebur transpiration was not reduced however, cotton transpiration normalized by total under non-irrigated conditions which suggested that a larger root system allowed common cocklebur to obtain soil water from allowed common cocklebur to obtain soil water from greater depths than cotton. while transpiration rates of cotton in proximity of common cocklebur were not reduced under non- irrigated conditions when normalized by total leaf area, shoot sizes were generally smaller indicating early season competition. Early season root competition between common cocklebur and cotton was studied in greenhouse conditions with minirhizotrons. was studied in greenhouse conditions with minirhizotrons. Plants were grown in large columns into which minirhizotron tubes had been installed to allow weekly observations of roots with a microvideo camera. In addition, time- domain reflectometry (TDR) probes were installed to monitor the depletion of soil water. Roots were collected from the columns seven weeks after planting for determination of soil root length density (RLD). Common cocklebur quickly developed a deep root system at the expense of expanding RLD at shallow depths, then began to increase RLD at all depths. Cotton increased RLD at shallow depths before expanding the root system to occupy greater depths. The mixture of common cocklebur and cotton produced much greater root growth than the sum of the monocultured cotton and common cocklebur as a whole and relative to shoot size. A negligible change in cotton shoot size and a dramatic change in common cocklebur shoot size in the mixture suggested a shift in the allocation of resources from shoot growth to root growth by the common cocklebur. The depletion of water monitored by the TDR system supported the sequence of root growth predicted by the minirhizotrons. |
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| Item Description: | Vita. "Major Subject: Agronomy". |
| Physical Description: | xiv, 164 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references. |