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United States Department of Agriculture

Agricultural Research Service

Title: Influence of ultranarrow row and conventional row cotton on the last effective boll population

Authors
item Viator, Ryan
item Gwathmey, C - UNIV OF TENNESSEE/JACKSON
item Cothren, J - TEXAS A&M UNIVERSITY
item Reed, Jack - MISSISSIPPI STATE UNIV
item Vories, Earl
item Nuti, Russell
item Edmisten, Keith - NORTH CAROLINA STATE UNIV
item Wells, Randy - NORTH CAROLINA STATE UNIV

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 1, 2008
Publication Date: June 20, 2008
Repository URL: http://hdl.handle.net/10113/48931
Citation: Viator, R.P., Gwathmey, C.O., Cothren, J.T., Reed, J.T., Vories, E.D., Nuti, R.C., Edmisten, K.L., Wells, R. 2008. Influence of ultranarrow row and conventional row cotton on the last effective boll population. Agronomy Journal. 100(5):1327-1331.

Interpretive Summary: Cotton crop management is often based on when the last uppermost boll that will produce cotton lint is fully mature; this boll on a land area basis is referred to as the last effective boll population. The objective of this research was to determine the last effective boll population for both ultra-narrow row cotton (UNRC), grown in rows spaced 25 cm or less, and conventional cotton (CONC) grown in rows spaced 96 to 102 cm. Experimental sites included locations in North Carolina, Tennessee, Mississippi, Arkansas, and Texas. On 60 flagged plants for each row spacing at each location, the horizontal position relative to the number of branches above this flower (NAWF) was recorded on a tag and attached to the boll. Tagged bolls were handpicked, sorted, counted, and seedcotton was weighed and recorded. Lint yield did not differ significantly between UNRC and CONC across site-years. The UNRC produced the majority of seedcotton on the upper portion of the plant, NAWF 3 to 5, while CONC produced the most seedcotton at NAWF 4 to 6. Moreover, cotton could be produced economically at NAWF 2 and 3 for UNRC and CONC, respectively. Previous data indicated that cotton could only be produced economically at NAWF greater than 4.

Technical Abstract: The last effective boll population is the basis for many cotton (Gossypium hirsutum L.) management decisions such as defoliation timing. The objective of this research was to determine the last effective boll population for both ultra-narrow row cotton (UNRC), grown in rows spaced 25 cm or less, and conventional cotton (CONC) grown in rows spaced 96 to 102 cm. Experimental sites included locations in North Carolina, Tennessee, Mississippi, Arkansas, and Texas. At each site, UNRC and CONC plots were planted in a RCB design. At first flower, 15 plants per plot were flagged for subsequent flower tagging. On flagged plants, all first position flowers were tagged every two days throughout the reproductive stage with date and nodes above white flower (NAWF) data. Tagged bolls were handpicked, sorted, counted, and seedcotton was weighed and recorded by NAWF for each plot. The last effective boll population was considered that NAWF position where cotton could be economically produced. Lint yield did not differ significantly between UNRC and CONC across site-years. The UNRC produced the majority of seedcotton on the upper portion of the plant, NAWF 3 to 5, while CONC produced the most seedcotton at NAWF 4 to 6. Boll numbers showed a similar pattern. Furthermore, canonical discrimination demonstrated that for both the CONC and UNRC, NAWF positions less than five are not statistically separated from NAWF positions greater than five as one would expect if upper position bolls were not effectively contributing to yield. These data demonstrate that physiological cutout occurred at NAWF'5 in both UNRC and CONC. Cotton could be produced economically at NAWF 2 and 3 for UNRC and CONC, respectively.

Last Modified: 7/31/2014
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