Planting Date Effects on Soil Temperature, Crop Growth, and
Yield of Upland Cotton, 1999
J.C. Silvertooth and E.R. Norton
Abstract
A field study was conducted in 1999 at the University of Arizona
Marana Agricultural Center (1,974 ft. elevation) to evaluate the effects
of three planting dates on yield and crop development for eight Upland
varieties. Soil temperature effects associated with date of planting and
method of planting (dry or wet planting) were also evaluated in
relation to soil temperature at the depth of seed placement. Planting
dates ranged from 28 April to 20 May and 821-1157 heat units
accumulated since Jan 1 (HU/Jan 1, 86/55o F thresholds). Lint yields
generally declined with later dates of planting for all varieties. Soil
temperatures associated with the dry planting method, which requires a
water-up irrigation, experienced much wider diurnal variations, had
slightly lower mean temperatures, and were more strongly coupled to
ambient air conditions. Thus, dry planting methods impose more
potential risk in terms of seedling stress. Overall, crop growth and
development patterns or yield results were not significantly different
between the planting methods. Either method can provide satisfactory
results if managed appropriately.
Introduction
There are numerous factors that contribute to the realization of a successful cotton crop in
Arizona. Two major management decisions, variety selection and planting date management can have a
profound effect on the development and final outcome of the crop. Selection of a specific variety will have
a large impact on the way in which planting date should be managed. Similarly, the time frame in which a
crop can be planted due to weather and/or other circumstances should have a large impact on the selection
of a suitable variety.
Previous research in Arizona has shown that delayed plantings often result in higher vegetative
growth tendencies at the expense of yield. Optimum planting date windows have been developed for
different variety maturity groups (Figure 1) based upon heat units accumulated from January 1 (Silvertooth
et al., 1989; Silvertooth et al., 1990; Silvertooth et al., 1991; Silvertooth et al., 1992; Silvertooth et al.,
1993; Silvertooth et al., 1994; Unruh et al., 1995; Norton et al., 1997; Silvertooth et al., 1997; Silvertooth et
al., 1998; Norton and Silvertooth, 1999). Planting date management not only has a large effect on crop
growth, development, and yield but it also impacts insect pest management (Brown et al. 1992, 1993, 1994,
1995, 1996, 1997, and 1998). Reduced season management, of which early planting plays a major role, has
become increasingly important in recent years. The ability to plant and establish a crop early, carry it
through the primary fruiting cycle in a timely and efficient manner, followed by early termination; has
become increasingly important with increased late-season insect pressures in Arizona. This approach to
earliness management has also been important in terms of avoiding inclement weather conditions
commonly associated with the summer monsoon season, which creates higher humidities (higher dew point
temperatures) and higher night temperatures, resulting in accelerated rates of fruit loss and abortion (Brown
and Zeiher, 1997).
Another method used for insect pest management is delayed planting. Delayed plantings have
been utilized by many producers in some parts of Arizona to aid in the management of pink bollworm
(PBW, Pectinophora gossypiella (Saunders)) populations. Delayed plantings are intended to encourage
suicidal emergence of over-wintering PBW populations, theoretically lowering early season infestation
levels. However, with the increasing use of transgenic cotton varieties that provide resistance to PBW
pressures this method of pest management is becoming less common.
This is part of the 2000 Arizona Cotton Report, The University of Arizona College of Agriculture,
index at http://ag.arizona.edu/pubs/crops/az1170/
Both wet and dry planting methods are commonly used in the cotton producing regions of the
desert Southwest. In a dry plant situation, seeds are commonly placed at a very shallow depth in the soil,
with a very thin layer of soil covering the tops of the seeds. Thus, seeds planted into dry soil and
subsequently “watered-up” are directly exposed to the soil surface and atmospheric conditions. Seeds that
are planted into moisture (wet planting) are commonly placed in a seed line one to two inches below the
soil surface, depending on soil conditions and depth to adequate soil moisture. In desert cotton production,
it is common to cover seeds planted into moisture with a “cap” or layer of soil approximately six to eight
inches deep to serve as a dry mulch or insulating layer above the seedline. Many questions commonly arise
regarding the pros and cons associated with these two planting techniques, particularly in terms of
temperature effects on the seeds.
The primary objective of this study was to further evaluate planting date windows and use the
information for the validation and revision of current UA Extension agronomy recommendations. This
evaluation involves an investigation of the effects of planting date management on the growth,
development, and yield of cotton. Another objective of this project was to compare the differences in soil
temperatures at the depth of seeding due in relation to planting method (dry vs. wet planting).
Materials and Methods
The experiment was conducted at the University of Arizona Marana Agricultural Center in
Marana, Arizona on a Pima clay loam soil (1,974 ft. elevation). The experimental design employed in this
experiment was a split-split plot arrangement of treatments within a randomized complete block design.
Mainplots were method of planting treatments. The two planting methods were evaluated in terms of crop
growth, development, and yield. One planting method treatment was initiated by planting the seed into a
dry bed and then irrigating in order to obtain seed germination. The other method involved a pre-irrigation
two weeks prior to planting. The beds were then mulched and the seed was planted into a moist seedbed.
Subplots consisted of three planting dates (Table 1) while the sub-subplots consisted of eight different
varieties (Table 1). All plots were replicated four times. Sub-subplots consisted of four, 40” rows in width
and 30’ in length with 10’ alleys.
Planting dates were selected so as obtain three representative dates along the recommended
planting date range. Varieties selected for this study (Table 1) ranged in maturity from a early-season,
determinate variety (Deltapine DP20) to more indeterminate varieties (DP 5415 and DP33B). The varieties
selected for this study also provide a direct comparison between a transgenic Bt variety and its recurrent
parent. All inputs such as fertilizer, water, and pest control were managed on an as-needed basis. Each of
the three planting dates were managed in such a manner as to complete the first cycle fruit set. Irrigation
termination dates were also selected based upon completion of the primary fruiting cycle.
Climatic conditions and heat unit accumulations were monitored using an Arizona Meteorological
Network (AZMET) site located at the station. Soil temperature sensors and data loggers were placed in the
line of seed placement immediately following planting, but just prior to the application of the water-up
irrigation in the case of the dry planting plots.
Lint yields were obtained for each treatment by harvesting the center two rows of each plot with a
two row mechanical picker. Results were analyzed statistically in accordance to procedures outlined by
Steel and Torrie (1980) and the SAS Institute (SAS, 1988).
Results
The differences in soil temperature at the depth of seeding for both the dry and wet planting
techniques are shown in Figures 2-5. The dates of planting and accumulated heat units (HU) from 1
January for each date are also shown. Figure 2 is for a 1 April planting date that was ultimately abandoned
due to poor stands and very poor seedling vigor following a strong cold front (with rain and snow) that hit
the area on 2 – 4 April 1999. In that case, soils were saturated for both planting techniques due to rainfall
and one can easily see the extent of cold temperature stress that the seeds were exposed to.
Figures 2-5 describe the temperature regimes associated with both the wet and dry planting
techniques for three subsequent planting dates. It was found that either technique can be used to produce
favorable stands and yields. However, seeds planted shallow with a dry plant method are subject to wide
fluctuations in temperature, following very closely the diurnal shifts in air temperature. These temperature
ranges can commonly involve changes of 40o F in one day, which can result in a greater potential for
seedling stress in a dry plant situation if air temperatures drop significantly. In the first few days following
a water-up irrigation, while soils are still wet, the average soil temperature in the dry plant situation is
usually slightly lower than in a wet planting.
Thus, there is more risk associated with a dry planting operation and watering-up in terms of cold
temperature stress on the seeds in the event of cold weather. It is also important to note that seedlings are
often considered to be most sensitive to cold stress during the first few days of germination. Accordingly,
this information reinforces the common recommendations to carefully consider the five-day weather
forecast prior to planting in relation to expected weather conditions and HU accumulations.
Results from the analysis of variance for lint yield are shown in Table 1 with all main effects and
interaction terms for the experiment. The degree of variation within the experiment was relatively small for
this type of study with a coefficient of variation (CV%) of about 7.0% for the first two dates of planting and
approximately 11.43% for the third.
Main effects associated with planting date and variety were
significant (P < 0.05). There were no significant interaction terms. Thus, lint yields are presented among
varieties by planting date in Table 3 with mean separations and appropriate statistical parameters. In
general, higher lint yields were realized for all varieties at the earlier date of planting (28 April). Lint yield
trends among planting dates for each variety are also shown graphically in Figure 6. DP 20B performed
very well at all planting dates. More indeterminate varieties, such as DP 33B, had tendencies to provide
higher lint yields at earlier dates of planting and decline with later dates of planting.
Lint yield results among dates of planting for each variety are shown in Table 4. The varieties DP
50 and DP 50B demonstrated the greatest degree of stability among the three dates of planting. It is
interesting to note that the more determinate varieties (e.g. DP 20, DP 20B, SG 125, and SG 125BR)
realized a greater decline in yield with delayed or later planting in this study.
Percent lint turn-out and lint quality parameters are listed for each variety by planting date in
Table 5. Samples were collected and composited among variety by planting date combinations for turn-out
and HVI analyses. Therefore, mean values are provided in Table 5.
References
Brown P. W., B. Russel, J. C. Silvertooth, L. Moore., S. Stedman, G. Thacker, L. Hood, S. Husman, D.
Howell, and R. Cluff. 1992. The Arizona cotton advisory program. p. 233-240. Cotton, Univ. of
Arizona Rep. P-91.
Brown P. W., B. Russel, J. C. Silvertooth, L. Moore., S. Stedman, G. Thacker, L. Hood, S. Husman, D.
Howell, and R. Cluff. 1993. The Arizona cotton advisory program. p. 11-16. Cotton, Univ. of
Arizona Rep. P-94.
Brown P. W., B. Russel, J. C. Silvertooth, P. Ellsworth., S. Stedman, G. Thacker, L. Hood, S. Husman, D.
Howell, and R. Cluff. 1994. The Arizona cotton advisory program. p. 11-17. Cotton, Univ. of
Arizona Rep. P-96.
Brown P. W., B. Russel, J. C. Silvertooth, P. Ellsworth., S. Stedman, G. Thacker, S. Husman, D. Howell,
R. Cluff, S. Winans, and R. Grumbles. 1995. The Arizona cotton advisory program. p. 13-19.
Cotton, Univ. of Arizona Rep. P-99.
Brown P., B. Russel, J. Silvertooth, P. Ellsworth., S. Stedman, G. Thacker, S. Husman, D. Howell, R.
Cluff, S. Winans, R. Grumbles, T. Knowles, D. Dunn, and M. Schneider. 1996. The Arizona
cotton advisory program. p. 26-33. Cotton, Univ. of Arizona Rep. P-103.
Brown P., B. Russel, J. Silvertooth, P. Ellsworth., S. Stedman, G. Thacker, S. Husman, D. Howell, T.
Knowles, L. Clark, D. Dunn, and M. Schneider. 1997. The Arizona cotton advisory program. p.
23-30. Cotton, Univ. of Arizona Rep. P-108.
Brown P., B. Russel, J. Silvertooth, P. Ellsworth., S. Husman, T. Knowles, L. Clark, D. Dunn, and M.
Schneider. 1998. The Arizona cotton advisory program. p. 5-12. Cotton, Univ. of Arizona Rep.
P-112.
Brown P. W., and C.A. Zeiher. 1997. Cotton heat stress. Pp. 91-104. Cotton, Univ. of Arizona Rep. P108.
Norton, E.R., J.C. Silvertooth, and P.W. Brown. 1997. Evaluation of date of planting effects on crop
growth and yield for Upland and Pima cotton, Marana, 1995. p. 41-48. Cotton, Univ. of Arizona
Rep. P-108.
Norton, E.R., J.C. Silvertooth. 1999. Evaluation of date of planting effects on crop growth and yield for
Upland cotton, Marana, 1998. p. 29-37. Cotton, Univ. of Arizona Rep. Series P-116.
SAS Institute. 1988. SAS/STAT:Procedures. Release 6.03 ed. SAS Inst., Cary, NC.
Silvertooth J. C., J. E. Malcuit, D. R. Howell and P. Else. 1989. Effect of date of planting on the lint yield
of several cotton varieties planted at four locations in Arizona, 1988. p. 69-72. Cotton, Univ. of
Arizona Rep. P-77.
Silvertooth J. C., T. F. Watson, J. E. Malcuit, and P. W. Brown. 1992. Evaluation of date of planting and
irrigation termination in the yield of Upland and Pima cotton. p. 252-273. Cotton, Univ. of
Arizona Rep. P-91.
Silvertooth J. C., T. F. Watson, J. E. Malcuit, and P. W. Brown. 1993. Evaluation of date of planting and
irrigation termination in the yield of Upland and Pima cotton. p. 27-39. Cotton, Univ. of Arizona
Rep. P-94.
Silvertooth J. C., T. F. Watson, L. I. Terry, and J. E. Malcuit. 1990. Evaluation of date of planting and
irrigation termination in the yield of Upland and Pima cotton. p. 6-12. Cotton, Univ. of Arizona
Rep. P-81.
Silvertooth J. C., T. F. Watson, L. I. Terry, and J. E. Malcuit. 1991. Evaluation of date of planting and
irrigation termination in the yield of Upland and Pima cotton. p. 1-14. Cotton, Univ. of Arizona
Rep. P-87.
Silvertooth J.C., P.W. Brown, E.R. Norton, and B.L. Unruh. 1994. Evaluation of date of planting on the
yield of several Upland varieties at Marana, 1993. p. 26-32. Cotton, Univ. of Arizona Rep. P-96.
Silvertooth J.C., P.W. Brown, E.R. Norton, and B.L. Unruh. 1997. Evaluation of planting date effects on
crop growth and yield for Upland and Pima cotton, 1996. p. 49-61. Cotton, Univ. of Arizona
Rep. P-108.
Silvertooth, J.C., E.R. Norton, and P.W. Brown. 1998. Evaluation of planting date effects on crop growth
and yield for Upland and Pima cotton, 1997. Cotton, Univ. of Arizona Report Series P-112 p2033.
Steel, R.G.D., and J.H. Torrie. 1980. Principles and procedures of statistics. McGraw-Hill, New York.
Unruh, B.L., J.C. Silvertooth, P.W. Brown, and E.R. Norton. 1995. Effect of planting date on yield of
Upland and Pima cotton varieties at Marana. p. 20-24. Cotton, Univ. of Arizona Rep. P96.
Short-Season
Medium-Season
Full-Season
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
Heat Units Accumulated After January 1
Figure 1. General recommended planting date windows for different maturity type varieties grown in
Arizona.
Table 1. Planting dates and varieties, planting date by variety study, Marana, AZ, 1999.
Varieties
Maturity Type
Deltapine DP33B
Mid-Full Season
Deltapine DP5415
Mid-Full Season
Deltapine DP50B
Mid Season
Deltapine DP50
Mid Season
Deltapine DP20B
Early Season
Deltapine DP20
Early Season
Sure Grow 125BR
Early Season
Sure Grow 125
Early Season
Planting Dates*
Planting Date 1
28 April (821 HU/Jan. 1)
Planting Date 2
10 May (970 HU/Jan. 1)
Planting Date 3
20 May (1157 HU/Jan. 1)
*Actual planting date for pre-irrigated plots and water-up date for dry planted plots.
Table 2. Experimental effects and statistical significance from the analysis of variance, planting date by
variety study, Marana, 1999.
Source of Variation (Effect)
OSL (Pr >F)
Planting Method (wet or dry)
NS (0.1691)
Planting Date
0.0013
Variety
0.0001
Planting Method * Planting Date
NS (0.4558)
Planting Method * Variety
NS (0.2582)
Planting Date * Variety
NS (0.2582)
Planting Method * Planting Date * Variety
NS (0.6325)
Significance declared at the = 0.05 level.
Table 3. Lint yield results for all varieties by planting date, Marana, AZ, 1999.
Planting Date 1 (28 April)
Lint Yield (lbs. lint/acre)
Deltapine DP20B
1946 a*
Deltapine DP33B
1813 b
Sure Grow 125BR
1754 bc
Deltapine DP50
1677 cd
Deltapine DP20
1663 cd
Sure Grow 125
1639 cd
Deltapine DP5415
1616
d
Deltapine DP50B
1572
d
LSD*
121.4
OSL**
0.0001
C.V. (%)
7.07
Planting Date 2 (10 May)
Deltapine DP20B
Sure Grow 125BR
Sure Grow 125
Deltapine DP33B
Deltapine DP50B
Deltapine DP20
Deltapine DP50
Deltapine DP5415
LSD*
OSL**
C.V. (%)
1764 a*
1725 ab
1706 ab
1671 abc
1623 bc
1612 bc
1575 c
1454
d
116
0.0001
7.01
Planting Date 3 (20 May)
Sure Grow 125BR
1518 a*
Deltapine DP20B
1505 a
Deltapine DP50
1489 a
Deltapine DP50B
1442 a
Deltapine DP33B
1420 a
Sure Grow 125
1410 a
Deltapine DP20
1381 a
Deltapine DP5415
1157 b
LSD*
163
OSL**
0.0014
C.V. (%)§
11.43
*Least Significant Difference – means followed by the same letter within a planting date are not
significantly different according to a Fishers mean separation test.
**Observed Significance Level
§Coefficient of Variation
Table 4. Lint yield results by variety for each planting date, Marana, AZ, 1999.
Planting
Deltapine
Deltapine
Deltapine
Deltapine
Deltapine
Deltapine
Sure Grow
Sure Grow
Date
DP20B
DP20
DP33B
DP5415
DP50B
DP50
SG125BR
SG125
1
1664 a*
1946 a
1813 a
1616 a
1572 a
1677 a
1754 a
1639 a
2
1612 a
1764 b
1671 a
1454 a
1623 a
1575 a
1725 a
1706 a
3
1381 b
1505 c
1420 b
1157 b
1442 a
1489 a
1518 b
1410 b
LSD*
160
169
149
170
NS
NS
164
228
OSL**
0.0045
0.0003
0.0002
0.0002
0.0842
0.0868
0.0162
0.0355
C.V. (%)§
9.62
9.06
8.52
11.28
9.88
9.84
9.21
13.39
*Least Significant Difference – means followed by the same letter within a column are not significantly different according to a Fishers means separation test.
**Observed Significance Level
§Coefficient of Variation
Table 5. Percent turn-out and lint quality parameters for each variety by planting date combination, Marana, AZ, 1999.
Planting Date 1 (28 April)
Turn-out
Staple
Micronaire
Strength
Deltapine DP20
33.3
35
41
25.0
Deltapine DP20B
36.0
34
44
25.0
Deltapine DP33B
33.8
37
43
29.5
Deltapine DP50
33.3
36
44
25.5
Deltapine DP50B
30.8
36
44
26.9
Deltapine DP5415
34.6
36
42
27.9
Sure Grow 125
34.7
36
45
24.6
Sure Grow 125BR
34.1
35
48
25.4
Planting Date 2 (10 May)
Deltapine DP20
32.8
35
41
24.6
Deltapine DP20B
35.5
37
40
25.3
Deltapine DP33B
34.0
37
45
26.1
Deltapine DP50
30.6
37
43
28.3
Deltapine DP50B
30.8
37
41
25.1
Deltapine DP5415
33.9
35
44
27.0
Sure Grow 125
35.8
35
47
22.8
Sure Grow 125BR
35.1
36
45
24.7
Planting Date 3 (20 May)
Deltapine DP20
31.4
35
40
25.1
Deltapine DP20B
33.3
37
41
26.4
Deltapine DP33B
32.8
37
41
27.6
Deltapine DP50
31.9
36
42
26.3
Deltapine DP50B
30.8
37
44
27.2
Deltapine DP5415
34.0
36
37
27.6
Sure Grow 125
33.3
37
42
26.2
Sure Grow 125BR
32.8
36
44
26.3
Length
109
107
116
111
113
112
112
109
Uniformity
82
80
82
82
81
81
81
83
109
114
115
116
115
110
108
112
81
82
82
82
81
81
80
82
110
114
115
113
116
113
114
113
81
81
81
80
81
82
82
82
120
Soil Temperature
o
F
PD = 1 April HU=564
Dry Plant
100
Wet Plant
80
60
40
20
0
0
1
2
3
4
5
6
7
8
9
Date (1 April - 9 April)
Figure 2. Soil temperature results for both planting methods on planting date 1 April, 1999.
110
Dry
Wet
100
Soil Temperature
o
F
PD = 28 April HU=821
90
80
70
60
50
40
26-Apr 28-Apr 30-Apr 2-May 4-May 6-May 8-May 10-May 12-May
Figure 3. Soil temperature results for both planting methods on planting date 28 April, 1999.
120
Dry
Wet
110
Soil Temperature
o
F
PD = 10 May HU=970
100
90
80
70
60
50
8-May
10-May 12-May 14-May 16-May 18-May 20-May 22-May
Figure 4. Soil temperature results for both planting methods on planting date 10 May, 1999.
130
110
Soil Temperature
o
F
120
Dry
Wet
PD = 20 May HU=1157
100
90
80
70
60
50
40
18-May 20-May 22-May 24-May 26-May 28-May 30-May 1-Jun
3-Jun
Figure 5. Soil temperature results for both planting methods on planting date 20 May, 1999.
Lint Yield (lbs. lint/acre)
2000
1800
1600
1400
1200
1000
0
1
2
3
4
Planting Date
DP20
DP20B
DP33B
DP50
DP50B
DP5415
SG125
SG125BR
Figure 6. Lint yield response to planting date for each variety, Marana, 1999.