Effect of an upper temperature threshold on heat unit calculations, defoliation timing, lint yield, and fiber quality in cotton /

Bibliographic Details
Main Author: Fromme, Daniel D.
Other Authors: Cothren, Joe Tom (Thesis advisor)
Format: Thesis eBook
Language:English
Published: [College Station, Tex.] : [Texas A&M University], [2010]
Subjects:
Online Access:Link to OAK Trust copy

MARC

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035 |a (OCoLC)ocn609884022 
035 |a (OCoLC)609884022 
035 |a (TxCM)http://hdl.handle.net/1969.1/ETD-TAMU-1410 
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099 |a 2007  |a Dissertation  |a 1969.1/ETD-TAMU-1410 
100 1 |a Fromme, Daniel D. 
245 1 0 |a Effect of an upper temperature threshold on heat unit calculations, defoliation timing, lint yield, and fiber quality in cotton /  |c by Daniel D. Fromme. 
264 1 |a [College Station, Tex.] :  |b [Texas A&M University],  |c [2010] 
300 |a 1 online resource. 
336 |a text  |b txt  |2 rdacontent 
337 |a computer  |b c  |2 rdamedia 
338 |a online resource  |b cr  |2 rdacarrier 
500 |a "Major Subject: Agronomy" 
500 |a Title from author supplied metadata (automated record created 2010-03-12 12:08:51). 
502 |b Doctor of Philosophy  |c Texas A&M University  |d 2007  |o http://hdl.handle.net/1969.1/ETD-TAMU-1410 
504 |a Includes bibliographical references. 
516 |a Text (Dissertation) 
520 3 |a Crop managers need to determine the most profitable time to defoliate cotton (Gossypium hirsutum L.) in a high rainfall environment such as the coastal region of Texas. In cotton production, delaying defoliation exposes open bolls to a higher probability of rainfall, and thus, reduces lint yield and fiber quality. Premature defoliation, however, has detrimental affects on lint yield and fiber quality. A more recent method to determine defoliation is based on heat-unit (HU or DD15) accumulation after physiological cutout or five nodes above white flower (NAWF=5). Results have been inconsistent across a wide range of field environments when utilizing HU accumulation past cutout; therefore, adoption of this method has been limited. Many regions of the Cotton Belt have maximum day time temperatures during the growing season that are above optimum for maximum growth. Field studies were conducted for three consecutive growing seasons in the Brazos River Valley and Upper Gulf Coast regions of Texas. The purpose of this research was to identify an upper temperature threshold (UTT) for calculating degree days for defoliation timing. The experimental design consisted of a split-plot design with four replications. The main plots consisted of three upper temperature thresholds (32C, 35C, and no upper limit) and the subplots were five HU timings (361, 417, 472, 528, and 583) accumulated from date of cutout. Utilizing an UTT to calculate daily HU failed to explain differences in the optimum time to defoliate based on accumulated HU from cutout for the upper thresholds investigated. Accumulated HU had a significant impact, however, on defoliation timing. Comparison of the two locations showed that maximum lint yield was obtained at 472 HU and 52% open boll at Wharton County versus a maximum of 528 HU and 62% open boll for the Burleson County location. Employing the NACB=4 method to time defoliation at both locations would have resulted in premature application of harvest aids and reduced lint yields. No differences were observed in adjusted gross income values at Wharton County among the 417, 472, 528, and 583 HU treatments. For Burleson County, adjusted gross income peaked in value at 528 HU. 
500 |a Electronic resource. 
650 4 |a Major agronomy. 
653 |a cotton 
653 |a heat unit calculations 
653 |a lint yield 
653 |a defoliation timing 
653 |a heat units 
653 |a upper temperature threshold 
653 |a fiber quality 
700 1 |a Cothren, Joe Tom,  |e thesis advisor. 
856 4 0 |u http://hdl.handle.net/1969.1/ETD-TAMU-1410  |z Link to OAK Trust copy  |t 0 
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952 f f |a Texas A&M University  |b College Station  |c Electronic Resources  |d Available Online  |t 0  |e 2007 Dissertation 1969.1/ETD-TAMU-1410  |h Other scheme 
998 f f |a 2007 Dissertation 1969.1/ETD-TAMU-1410  |t 0  |l Available Online