March 2010
Comparison of StanceTM and Mepiquat Chloride Plant
Growth Regulators on DPL 164B2RF Cotton in the Palo
Verde Valley, 2006
Michael D. Rethwisch, Joe Van Dyke, Michael Williams, Anna Grimm and Manuel Luna
Abstract
An experiment to determine response of DPL 164B2RF cotton to the p lant g rowth
regulators Stance TM and Mepiqu at Chloride 4.2 was initiated in early July 2006
when crop was at four boll stage of development. Increasing amounts of mepiquat
chloride active ingredient resulted in increasing levels of leaf chlorophyll content
as measured w ith a M inolta SPAD 502 meter only on July 17. Stance TM treatm ents
resulted in significantly lower leaf chlorophyll levels on July 24, although on
Aug ust 2 sign ificantly higher levels of leaf chlorophyll was noted in cotton treated
with 2 oz./acre rate of Stance or Mepiquat Chloride 4.2 than untreated cotton.
Plant height and node measurement data on August 2 indicated that DPL164BR
cotton heights increased a nd nodes p er plant decreased as level of mepiquat
chloride active ingred ient per acre increased. No statistical difference s were
noted for retention percentages or numbers of fruiting struc tures p er plant.
Trea tments did effect certain cotton lint pa rameters, such as red ucing micron aire
by 0.1, as well as reducing lint fiber uniformity. Stance TM treatm ents resulted in
significa ntly stronger lint fibers than untreated or Mepiquat Chloride 4.2 treated
cotton. Stance TM treatments also resulted in visible differences of boll ca rpels
remaining on stalks after picking, which was reflected in higher lint and seed
turnout percentages than untreated or Mepiquat Chloride 4.2 treated cotton. All
treatm ents resulted in increased cotton lint yields and values, with highest lint
yields (1,832 lbs) and value per acre ($1,032) noted from the 2 oz./acre rate of
Stance TM, valued at $65.38/acre more than untreated cotton. Different results may
occur if treatments are initiated earlier in crop deve lopm ent.
Introduction
A shift in cotton varieties grown in the Palo Verde Valley was noted in 2006 as a new variety (DPL 164 B2RF) was
widely planted. This variety has a more robust growth habit than DPL 449 BR , the stand ard variety of recent yea rs in
the Palo Verd e Valley. As varieties were changing, locally derived information about crop growth management was
need ed to determine if management modifications were necessary.
Mo st cotton growers are very familiar with products that contain mepiquat chlo ride (P ix ®, Pix ® Ultra, Mepiquat
Chloride 4.2) from their firsthand usage of these products for controlling growth of DPL 449B R cotton. StanceTM is a
fairly new plant growth regulator from Bayer CropScience for usage on cotton. It is a combination plant growth regulator
product, consisting of 2.1% cyclanalide (1-(2,4-dichlorophenylaminocarbonyl)-cyclopropane carboxylic acid) in addition
to 8.4% mep iquat chloride (0.1 84 and 0.736 lbs./gallon active ingred ients resp ectively). StanceTM had not pre viously
been tested in the Palo Verde Valley nor known to be tested on any upland cotton variety in the low desert cotton
prod uction area o f the United States.
Arizona Cotton Report (P-159) March 2010
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This experiment was initiated to obtain data on the effects of Stance TM on various cotton growth para meters, to
compare StanceTM with a plant growth regulator containing the active ingredient mepiquat chloride, and to document the
response of DP L 164 B2 RF co tton grown in the P alo Ve rde V alley to plant growth regulato rs.
Methods and Materials
Applications were made the morning of July 1, 200 6, to D PL 164 B2 RF cotton was lo cated in a field west of Ripley,
CA. Cotton was at the four boll stage of developm ent on this date. Treatments were applied with a Melroe SpraCoupe
calibrated to deliver 20 gallons/acre. Each treatment was replicated four times using a randomized complete block
design. Plots were 1,153 feet long by eight rows (40 inch) wide (0.706 acres).
Treatments included two rates of Stance TM (2 and 3 oz/acre) and 12 oz./acre of Mepiquat Chloride 4.2% (marketed
by Farm$aver.com L LC). Resulting amo unts of m epiquat chloride active ingredien t for each of these three treatme nts
was 0.011 5, 0.0 172 5, and 0.03 28 lb s./acre re spectively.
Cotton went into “cutout” within 10 days of application, thereby negating an expected sequential application. The
experiment was initially designed to evaluate a single vs. two sequential applications of StanceTM, but the lack of second
application resulted in eight replications for each rate of Stance TM.
Cotton was subjected to average high temperatures during the experiment, with high temperatures of only 110 oF
recorded on July 22 and 23, altho ugh co tton may still have b een in “cutout” physiology stage on these dates.
Chlorophyll data were collected from plants on a weekly basis for three weeks beginning July 17 utilizing a M inolta
502 SPAD meter. Data were collected from the fifth terminal leaf of 1 5-25 plants o f each p lot.
Plant mapping was conducted August 2, and consisted of removing five plants per plot, counting and recording
numbers of nodes, plant height, first fruiting node, and presence/absence of fruiting structures at the first three positions
for each fruiting b ranch. Percent retention and fruiting structures/plant were then calcu lated.
Plots were harvested Dec. 15-18, 2006, with a four row John Deere 996 5 cotton picker. All eight rows o f each
individual plot were harvested, using a twice pick method (one pass in each direction) to elimin ate any first picking
percentage differences potentially associated with treatme nts. Seed cotton weights were ob tained using a Cru st Buster
boll buggy equip ped with scales. All 32 rows of each treatment (= individual treatment such as Mepiquat Chloride 4.2,
untreated check, etc.) were placed together in a module and kept separate from other c otton treatme nts to ob tain quality
and turnout data after ginning (Mod ern Gin, Blythe, CA) for each treatment. Cotton from Stance TM treatme nts was also
handled in this manner (one vs. two scheduled applications), resulting in two modules for each Stance TM rate.
Two grab ba g samples of seed cotton were collected from each module, with two adjacent replicates combined per
bag. Seed cotton from grab bag samp les was ginned at the U niversity of Arizona Maricopa Agricultural Center, and
precise turnout percentages for seed and lint were calculated. The turnout and other information were then utilized to
calculated lint yields per acre as well as ac reage values o f cotton, using turnout data from each corre sponding replicate
area for calculations. Lint values were calculated using actual commercial payments received for cotton for each bale.
Data and treatment means were statistically analyzed using Fisher's least significant difference (Statgraphics for
W indows, Manugistics, Inc.).
Results
Chlo rophyll levels
Chlorophyll levels as measured by a Minolta 502 SPAD meter were significantly effected by treatments, although
such effects were not noted until 23 days after app lication (Table 1). No statistical differe nces were no ted at 1 6 days
Arizona Cotton Report (P-159) March 2010
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after application (July 17 ), although all treated co tton had slightly high er chlo rophyll levels than untreated cotton.
Chlorophyll levels on that sample date were thought related to mepiquat chloride levels, as mean chlorophyll level
increased as amo unt of mepiquat chlo ride in treatment increa sed.
Significant differences in chlorophyll level means s were noted on bo th July 24 and August 2. Co tton treated with
StanceTM had significantly red uced chloro pyhll leve ls on July 24 when compared with untreated or Mepiquat Chloride
4.2 treated cotton. This was thought due to the carboxylic acid portion of Stance TM resulting in increased co tton gro wth
and therefore a shorter time perio d spe nt in ‘cut out’. Chloro phyll levels were highest in untreated cotton on this samp le
date.
Significant differences in leaf chlorophyll levels were also noted on August 2, although chlorophyll levels were lowest
in untreated co tton on this date. Cotton treated with 12 oz./acre of Mepiquat Chloride 4.2 as well as 2 oz./acre of
StanceTM had significantly higher chlorophyll content than the untreated check. Cotton treated with 3 oz./acre of
StanceTM was intermed iate between these levels, but was mo re similar to treated than untreated co tton.
Plant heights and nodes
Data collected on August 2 indicated some unexpected trends associated with treatments based on previous
experiences with DPL 449 BR cotton. Mepiquat chlorid e app lications usually results in shorter plants o f this variety, with
higher rates of this chem istry associated with increasing sup pression of cotton height. Height of DPL 164B2RF cotton
as measured on August 2 was noted to increase as amount of mepiquat chloride active ingredient applied/acre increased
however, with means of treated cotton taller than untreated cotton (Table 2). Numbers of nodes per plant also decreased
as level of mep iquat chloride increased.
While heigh t to nod e ratios were not statistically different, increasing height:no de ratios appeared correlated with
increasing amounts per acre of mepiquat chloride active ingredient (Table 2). Although the exact reaso n for these
observations is unknown, it may be that DPL164B2RF cotton was held in check slightly by a single application (w ith
increased supp ression associated with higher rates of m epiquat chlo ride active ingredien t/acre), with resultant regrowth
therefore occurring at a higher rate. Data for leaf chlorophyll content obtained on July 17 noted higher levels of
chloroph yll as level o f mepiquat chloride active ingredient increased, expected with usage of this compound and
consistent with other local data previously derived from D PL 449 BR cotton (Rethwisch et al., 2006).
No trends or statistical differences were noted for first fruiting node or for total fruiting nodes (Table 2), although total
number of fruiting nodes was highest in untreated cotton (21.35/plant). Lowest number of fruiting nodes was noted for
cotton treated with 3 oz./acre Stance TM (Ta ble 2).
Retention percentages
No differences existed for retention percentages when measured on August 2, although some trends were noted.
StanceTM treatments resulted in cotton having a numeric reduction in retention at first position, but a slight num eric
increase at the third position when compared with Mepiquat Chloride 4.2 treated or untreated cotton (Table 3).
Untreated cotton had the highest retention percentages at positions 1, 2 an d com bined first and seco nd fruiting positions.
Untreated and Mepiquat Chloride 4.2 treated cotton had very similar retention pe rcentage for comb ined p ositions 1-3
(both slightly above 45%), and were higher than that noted for either Stance TM treatme nt.
Fruiting structures per p lant
No statistical differences existed for numbers of fruiting structures (bolls, developing bolls, flowers) per plant for
fruiting po sitions 1-3 due to treatments in this experiment (Table 4). Nume rically more such structures were noted at
positions 2 and 3 for treated cotton than for untreated cotton., although combined fruiting structures for positions 2 +
3 were not statistically different. Cotton was not mapp ed beyond the third fruiting p osition.
Lint quality
No differences were noted due to treatments for cotton grade (grad e 31) or stap le (35 ). Differences, so me statistically
significant, were noted for other cotton quality param eters ho wever (Table 5 ). A slight numerical increase was noted
for spotting in the two treatments that contained the highest amounts of mepiquat chloride (StanceTM at 3 oz./acre and
Mepiquat Chloride 4.2). All treatments resulted in a lower micronaire (4.4) than that of untreated cotton (4.5). Cotton
Arizona Cotton Report (P-159) March 2010
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fiber co loration was m ost similar in cotton treated with the 2 oz./acre rate of StanceTM and the Mepiquat Chloride 4.2,
with the latter treatment resulting in significant differences for both C red and C +b than that recorded for untreated
cotton (Table 5). Stance TM treatments resulted in a higher leaf content and cotton fiber strength than Mepiquat Chloride
4.2 treated o r untreated co tton, but also resulted in significantly low er uniformity of cotton fibers.
Effect of quality upon lint value
Although cotton varied in quality parameters due to treatments, no differences existed for lint price per pound when
cotton received payment from a commercial gin on per pound lint value. All cotton lint in this experiment received
commercial payment of $0.5635/lb. irregardless of treatment, thereby meaning that cotton yields would be the major
difference in lint value/acre. Potential increases in lint economic values due to noted increased fiber strength associated
with StanceTM treatme nts were negate d by lo wer fibe r uniform ity of these treatments (Table 5 ).
Seed Cotton
As the northern half of the northern replicate experienced a precipitous reduction in seed cotton yields (200-300 lbs
less lint/acre), this replicate was removed from calculations pertaining to yields and economic values p er acre. Th is left
three replicates for untreated and Mepiquat Chloride 4.2 treated cotton, and six replicates for each StanceTM rate. No
statistical differences existed for pounds of seed cotton per acre (Table 6). Highest amounts of seed cotton per acre were
noted from cotton treated with Mepiquat Chloride 4.2 (5,765 lbs./acre) and the 2 oz./acre rate of Stance TM (5,702
lbs./acre). Visible differences were no ted after picking in regards to boll carpel retention on stalks, with many more
carpels remaining noted on Stance TM treated cotton stalks than non-Stance TM treated cotton stalks . The exact reason for
the increased number of carpels remaining on Stance TM treated cotton is unknown, but may involve the carboxylic acid
(cyclanalide) com pon ent of this m aterial.
Turnout percentages
The observation of increased numbers of carpels in StanceTM treated cotton was reflected as numerically higher lint
turn-out percentages for Stance TM treated cotton by almost 1.5% more lint than untreated cotton (Table 6). All treated
cotton had higher percentages of seed (based on weight) of seed cotton than untreated cotton, with StanceTM treatme nts
resulting in a significantly higher p ercen tage (5 4.4+ % ) than untreated cotton (51 .7% ).
Lint yields and cotton values per acre
Significant differences in lint yields were noted between the extremes in this experiment (1,716 lbs./acre, untreated;
1,832 lbs/acre, 2 oz./acre of StanceTM). Lint yields for 3 oz./acre of Stance TM and 1 2 oz./acre o f Me piquat Chlo ride 4 .2
were almost identica l (Table 6). As price received for cotton lint was identical ($0.5635/lb.) for all treatments, cotton
value per acre was therefore a function of lint yields, ranging from a high of $1,032.56/acre (2 oz./acre of Stance TM) to
$967.19 /acre for untreated c otton. This difference in value of cotton treated with the 2 oz./acre rate of Stance TM was noted
to be $65 .38/acre more tha n untrea ted co tton. Net values were not calculated .
Literature Cited
Rethwisch, M.D., T . Cox, D.M . Ram os, M . Luna and J . W ellman. 2006. Effects of Goemar ® BM 86 and Mepiquat
Chloride on D PL 449 BR /DP L 49 4R Cotton. Pp. 17 9-19 4. In University of Arizona Co llege of Agricu lture and Life
Sciences 2006 Cotton Repo rt. Series P -145 , AZ1 409 . R. Tronstad and E.R. Norton, ed s. 311 pp.
Arizona Cotton Report (P-159) March 2010
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Table 1. Mean chlorophyll levels of DPL 164B2RF cotton following plant growth regulator
application on July 1, 2006, Ripley, CA.
Treatment
StanceTM
Rate/acre
July 17
Sample Date
July 24
Aug. 2
2 oz
43.85a
46.8 b
48.3a
3 oz
44.16a
45.5 b
46.25ab
Mepiquat Chloride 4.2 12 oz
45.58a
51.6a
48.05a
Untreated Check
42.75a
54.3a
42.58 b
Stance
TM
------
Me ans in colum ns follo wed by the sam e letter are no t statistically d ifferent a t the p< 0.05 level (Fisher's LSD test).
Table 2. Plant heights and fruiting node means of DPL 164B2RF cotton on August 2 following
plant growth regulator application on July 1, 2006, Ripley, CA.
Treatment and rate/acre
Height(“)
Ht:Node
Nodes ratio
Fruiting Nodes
First Total
StanceTM 2 oz
35.85a
22.8a
1.58a
2.7a
21.1a
StanceTM 3 oz
36.1 a
22.6a
1.61a
2.75a
20.8a
Mepiquat Chloride 4.2 12 oz
37.15a
22.5a
1.66a
2.35a
21.1a
Untreated Check
35.8a
23.4a
1.54a
3.0a
21.35a
Me ans in colum ns follo wed by the sam e letter are no t statistically d ifferent a t the p< 0.05 level (Fisher's LSD test).
Table 3. Retention percentages of DPL 164B2RF cotton on August 2 following plant growth
regulator application on July 1, 2006, Ripley, CA.
Treatment andRate/acre
StanceTM
2 oz
TM
Stance
3 oz
Mepiquat Chloride 12 oz
1st
37.9a
41.7a
43.0a
2nd
51.7a
51.0a
52.0a
Fruiting position
3rd
42.4a
42.1a
40.8a
Untreated Check
42.9a
53.3a
39.0a
1-2
44.7a
46.2a
47.4a
1-3
43.9a
44.9a
45.2a
48.1a
45.1a
Me ans in colum ns follo wed by the sam e letter are no t statistically d ifferent a t the p< 0.05 level (Fisher's LSD test).
Arizona Cotton Report (P-159) March 2010
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Table 4. Mean fruiting structures at positions 1-3 of DPL164B2RF cotton on August 2
following plant growth regulator application on July 1, 2006.
Treatment andRate/acre
StanceTM 2 oz
StanceTM 3 oz
Mepiquat Chloride 4.2 12 oz
Untreated Check
1st
8.1a
8.9a
9.3a
9.4a
2nd
9.0a
8.9a
9.1a
8.3a
Fruiting position
3rd
4.0a
4.1a
4.0a
3.3a
1-2
17.1a
17.8a
18.4a
17.7a
1-3
21.0a
21.9a
22.4a
21.0a
Me ans in colum ns follo wed by the sam e letter are no t statistically d ifferent a t the p< 0.05 level (Fisher's LSD test).
Table 5. Lint quality parameters of DPL 164 B2RF cotton harvested Dec. 15-19 following plant
growth regulator application on July 1, 2006, Ripley, CA.
Rate/
Treatment
Fiber Length
acre
Grade
TM
2 oz.
31a
1.0a
StanceTM
3 oz.
31a
Mepiquat Chloride 12 oz.
31a
Untreated Check -----
31a
Stance
Spo tting Leaf
Strength
Color
Mic
Staple
1/100"
(g/tex) C Red
2.17ab
4.4a
35a
110a
29.4a
81.56ab 6.87a
79.9c
1.15a 2.31 b
4.4a
35a
109b
29.1b
81.87a
79.6d
1.18a 2.0a
4.4a
35a
109b
28.4c
81.34 b 6.69a
80.1b
1.0a
4.5b
35a
109b
28.5d
81.91a
80.5a
2.09a
C+b
Unif
6.55ab
6.48b
Me ans in colum ns follo wed by the sam e letter are no t statistically d ifferent a t the p< 0.05 level (Fisher's LSD test).
Table 6. Yields, turnout percentages and economic values of DPL 164B2RF cotton following
application of StanceTM and mepiquat chloride on July 1, 2006, Ripley, CA.
Treatment and rate/acre
Lbs./acre
Seed Cotton
Turnout %
Lint
Seed
Per acre
Lbs. Lint
$ Value
vs. check
TM
2 oz.
5,702a
31.95a
54.4a
1,832a
StanceTM
3 oz.
5,578a
31.92a
54.5a
1,774ab
999.90ab
+32.71
Mepiquat Chloride 4.2 12 oz
5,765a
30.91a
53.5ab
1,775ab
1,000.46ab
+33.27
Untreated check
5,676a
30.37a
51.7 b
1,716 b
967.19 b
---------
Stance
1,032.56a
+65.38
Me ans in colum ns follo wed by the sam e letter are no t statistically d ifferent a t the p< 0.05 level (Fisher's LSD test).
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