Indicators of cotton nitrogen status and response to foliar applied urea and triazone nitrogen /
Upland cotton (Gossypium hirsiitum) requires adequate
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| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1997.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739888041&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Upland cotton (Gossypium hirsiitum) requires adequate nitrogen for optimum yields. One method of supplementing soil applied nitrogen is through foliar application. Foliar applications of urea nitrogen have been tried for many years across the Cotton Belt, but response has been highly variable. No published information is available regarding nitrogen status indicators for irrigated cotton grown in the Rio Grande Valley of Texas. This study investigated various indicators of cotton N status and response to foliar applied N. Foliar N fertilizers investigated were urea and triazone. Studies were conducted for three years at Weslaco Texas. Treatments were applied in a factorial arrangement with soil N applied at four rates and multiple foliar treatments of either none, triazone, or urea. In all years, foliar applied urea tended to increase seedcotton yield when soil applied N was limiting. In the absence of soil applied N, the increase due to urea was significant in two of the three years (28.7 and 15.7 percent increase). Foliar applied triazone N was ineffective at increasing seedcotton yield. The concentration of nitrate-N in the petiole (PNN) of the most recently matured leaf was found to be a good indicator of plant N status. Irrigated cotton in this area should have PNN equal or greater than 15.0, 9.0, 4.5, and 2.0 g kg-' at first bloom, and 10, 20, and 30 days thereafter, respectively. Cotton with PNN below these levels would likely respond to foliar applied urea during the bloom period. Leaf total N indicated that 35 g kg-' N represented a deficient level at any time during the bloom period, and that optimum levels may be closer to 40 g kg-' N. Nodes above white flower, height to node ratio, and portable chlorophyll meter readings were not suitable indicators for determining cotton N status. |
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| Item Description: | Vita. "Major Subject: Agronomy". |
| Physical Description: | xi, 106 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 98-102. |