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Published online 1 September 1999
Published in Agron J 91:851-858 (1999)
© 1999 American Society of Agronomy
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Agronomy Journal 91:851-858 (1999)
© 1999 American Society of Agronomy

AGROCLIMATOLOGY

Temperature Regime and Carbon Dioxide Enrichment Alter Cotton Boll Development and Fiber Properties

K.Raja Reddya, Gayle H. Davidonisb, Ann S. Johnsonb and Bryan T. Vinyardb

a Dep. of Plant and Soil Sciences, Box 9555, Mississippi State Univ., Mississippi State, MS 39762 USA
b USDA-ARS Southern Regional Res. Ctr., 1100 Robert E. Lee Blvd., P.O. Box 19687, New Orleans, LA 70179 USA

krreddy{at}ra.msstate.edu


   ABSTRACT
TOP
 NOTES
 ABSTRACT
INTRODUCTION
 Materials and methods
 Results and discussion
 Summary and conclusions
 REFERENCES
 
Temperature and atmospheric carbon dioxide concentration [CO2] affect cotton (Gossypium hirsutum L.) growth and development, but the interaction of these two factors on boll and fiber properties has not been studied. An experiment was conducted in naturally lit plant growth chambers to determine the influence of temperature and atmospheric [CO2] on cotton (cv. DPL-51) boll and fiber growth parameters. Five temperature regimes were evaluated: the 1995 temperature at Mississippi State, MS; the 1995 temperature minus 2°C; and the 1995 temperature plus 2, 5, and 7°C. Daily and seasonal variation and amplitudes were maintained. Atmospheric [CO2] treatments were 360 (ambient) and 720 µL L-1. Boll number, boll growth, and fiber properties were measured. Boll size and maturation periods decreased as temperature increased. Boll growth increased with temperature to 25°C and then declined at the highest temperature. Boll maturation period, size, and growth rates were not affected by atmospheric [CO2]. The most temperature-sensitive aspect of cotton development is boll retention. Almost no bolls were retained to maturity at 1995 plus 5 or 7°C, but squares and bolls were continuously produced even at those high temperatures. Therefore, the upper limit for cotton boll survival is 32°C, or 5°C warmer than the 1995 U.S. Mid-South ambient temperatures. The 720 µL L-1 atmospheric [CO2] had about 40% more squares and bolls across temperatures than the 360 µL L-1 [CO2]. Fibers were longer when bolls grew at less than optimal temperatures (25°C) for boll growth. As temperature increased, fiber length distributions were more uniform. Fiber fineness and maturity increased linearly with the increase in temperature up to 26°C, but decreased at 32°C. Short-fiber content declined linearly from 17 to 26°C, but was higher at higher temperature. As for boll growth and developmental parameters, elevated atmospheric [CO2] did not affect any of the fiber parameters. Changes in temperature, however, had a dramatic effect on boll set and fiber properties. The relationships between temperature and boll growth and developmental rate functions and fiber properties provide the necessary functional parameters to build fiber models under optimum water and nutrient conditions.

Abbreviations: AFIS, Advanced Fiber Information System • A(n), cross-sectional area • D(n), fiber diameter • FFF, fine fiber fraction • L(n), fiber length by number • HVI, high volume instrument [testing] • L(w), length by weight • SFC, short-fiber content • SFC(w), short-fiber content by weight • UQL, upper quartile length • {theta}, fiber circularity


   INTRODUCTION
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
Materials and methods
 Results and discussion
 Summary and conclusions
 REFERENCES
 
COTTON GROWTH AND DEVELOPMENT are very sensitive to temperature at all stages of development. Temperatures are often less than optimum for growth both at the beginning and at the end of the growing season, and above-optimum temperatures are known to occur during flowering. Many researchers have investigated various facets of growth and development of cotton (Reddy et al., 1997, and references cited therein).

A comprehensive database on the effects of temperature, water, and nutrient conditions on several aspects of cotton growth and development has been established. Studies by Baker et al. (1983), Hearn (1994), Hodges et al. (1998), Mutsaers (1984), Reddy et al. (1997) and Wall et al. (1994) have provided essential information to integrate many growth and developmental processes into comprehensive predictive simulation models for cotton growth and yield. Some of these models are being used to optimize production practices (McKinion et al., 1989). These models, however, are deficient in simulating any of the fiber properties grown on intact plants because of the lack of data on the effects of temperature on their fiber properties (Bradow et al., 1997; Reddy et al., 1997).

A comparison of two cotton cultivars grown in night temperatures ranging from 5 to 25°C showed that micronaire values increased when grown at higher temperatures. Fiber length was maximum when plants were maintained between 15 and 21°C (Gipson and Joham, 1968). In a study on cotton plants grown under a range of temperature regimes, micronaire values increased up to 33/28°C day/night, and then were lower when grown at higher temperatures (Hesketh and Low, 1968). Haigler et al. (1991) investigated the response of fibers developing in vitro under cycling temperature regimes. They found cotton fiber elongation and dry weight accumulation to be very temperature-dependent. Xie et al. (1993) found that in vitro cultured fiber was most sensitive to temperature at the initiation and early elongation stage. Little work on fiber quality production in vivo has been done in well-defined conditions. Detailed temperature effects on fiber parameters are needed, however, for a comprehensive understanding of weather on fiber quality and to develop a fiber model.

Increased atmospheric [CO2] and associated climatic changes are a major concern to agriculturalists throughout the world. Crops are expected to be grown in an environment with twice the present ambient atmospheric [CO2], and temperatures will probably be 2 to 5°C warmer than present during the latter part of the next century (Rotty and Marland, 1986; Houghton et al., 1996). In addition, unexpected late spring and early frosts and periodic episodes of heat and drought stress are predicted to occur more frequently in the changed weather environment, and these could exacerbate climate change effects on many aspects of crop growth and development, reducing crop yield and affecting crop quality.

Our objective was to evaluate the interactive effects of temperature and atmospheric [CO2] on cotton boll growth and development and fiber physical properties under optimum water and nutrient conditions.


   Materials and methods
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
 Materials and methods
Results and discussion
 Summary and conclusions
 REFERENCES
 
The Soil–Plant–Atmosphere Research (SPAR) Units
A suite of 10 controlled-environment chambers known as soil–plant–atmosphere research units (SPAR units) were used for this study; these have been described previously (Reddy et al., 1992a, 1995). Briefly, each SPAR unit consisted of a steel soil bin (1 m tall by 2 m long by 0.5 m wide) and a Plexiglas clear acrylic chamber (2.5 m tall by 2.0 m long by 1.5 m wide) to accommodate aerial plant parts, a heating and cooling system, and an environmental monitoring and control system. The SPAR units were normally sealed to allow monitoring of gas exchange processes, but a door could be opened to allow a person to enter and take measurements as needed.

Temperature and CO2 Control
Temperature was controlled based on ambient outdoor temperatures for 1995 at Mississippi State, MS (33°28'12'' N, 88°46'54'' W). The outdoor temperatures were monitored during the whole experiment at 10-s intervals and averaged over 900-s periods. Conditioned air entered the chambers from the top and flowed past the plants at approximately 1.3 m s-1. This rate of air flow was sufficient to cause leaf flutter, reduce boundary layer resistance, and to maintain uniform temperature throughout the chambers. The air was returned to the temperature-conditioning unit just above the soil surface (Reddy et al., 1992a). One set of chambers mimicked outdoor ambient temperature with a 900-s delay. The other chambers were set to maintain the previous 900 s of 1995 ambient minus 2°C or ambient plus 2, 5, or 7°C. The temperatures were averaged over different intervals, depending on the timing of fruit growth. Seasonal and diurnal differences were maintained within ±0.1°C. The actual mean daily temperature to which each boll was exposed from flowering to maturity was averaged over the fiber developmental period. Variable-density shade cloths around the edges of plants were adjusted regularly to match plant heights simulating the presence of other plants and eliminating the need for border plants.

At each temperature, plants were grown at either 360 (ambient) or 720 µL L-1 of atmospheric [CO2]. The atmospheric [CO2] was monitored at 10-s intervals and averaged over 900-s periods with a dedicated CO2 analyzer for each SPAR unit. Carbon dioxide was injected automatically from a gas cylinder into the chambers as necessary to maintain the desired set points ±10 µL L-1 of CO2.

Plant Culture
Upland cotton (Gossypium hirsutum L. cv. DPL 51) was seeded 6 June 1995 in the SPAR units. Fifty percent of seedlings had emerged after 4 d in all temperature and atmospheric [CO2] treatments. Each chamber was maintained with three rows of five plants per row (15 plants m-2) until final harvest. Final harvest occurred in each SPAR unit when 50% of the bolls were opened.

A computer-controlled timing device applied a half-strength Hoagland's nutrient solution to each row of plants via a drip irrigation system (Hewitt, 1952). Nutrients and water were supplied three times per day in sufficient quantities to more than meet the plant requirements with the excess allowed to drain. Fine sand was used as the rooting medium.

Measurements
Flowers and open bolls were tagged in all units every day throughout the experiment. Abscised bolls were also collected and counted daily. Cotton flowers are creamy-white on the day of anthesis and become purple the day after the anthesis. This allows one to tag each flower with the date of the anthesis. The date of open bolls was identified as the date when cotton lint could first be seen through cracks between the carpels. The numbers of bolls produced and retained were counted at the end of the experiment. The open bolls were air-dried at room temperature. Each boll was scored for the number of small short-fiber motes, large long-fiber motes, and normal seeds. Fiber samples were taken from the middle seeds of each locule and constituted the fiber sample for the boll (Davidonis et al., 1996). Fiber analysis was done on a per-boll basis.

A production-model Zellweger–Uster Advanced Fiber Information System (AFIS) equipped with a nep module, length and diameter module, and a fineness and maturity module located at the Southern Regional Research Center, New Orleans, LA, was used to measure fiber quality parameters as described (Davidonis and Hinojosa, 1994; Bradow et al., 1996). During the analysis, fibers were combed, separated, and transported in a high-speed air stream perpendicular to an electron ribbon of light directed at an electron–optical sensor (Behery, 1993; Bragg and Shofner, 1993; Wartelle et al., 1995). The light blocked by an individual fiber is directly proportional to its mean optical diameter (Bragg and Shofner, 1993). The extinction mode signal provides data on fiber length by number, L(n), length by weight, L(w), and fiber diameter, D(n). As the fibers move with the air stream, part of the beam is scattered, reducing the amount of undeflected light and increasing the light at a specified scattering angle (40°). The scatter mode signal was analyzed to determine fiber cross-sectional area, A(n), and fiber circularity, {theta}. The short-fiber content, SFC (i.e., the percentage of fibers < 12.7 mm long), was generated from fiber length histograms. The immature fiber fraction, IFF, is the percentage of fibers with {theta} < 0.25. The fine fiber fraction, FFF, was obtained from the distribution of A(n) and represents the percentage of fibers with A(n) < 60 µm2. Cotton samples of known micronaire values were used to calibrate the micronafis value, so that micronafis values are comparable with micronaire. Mean AFIS sample size in this study was 6796 fibers per assay.

Statistical analysis was conducted by using procedures in the SAS General Linear Model (SAS Inst., 1990). Dependent variables were regressed as linear functions of the independent variable. The standard error of the mean was calculated and is presented whenever applicable.


   Results and discussion
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
 Materials and methods
 Results and discussion
Summary and conclusions
 REFERENCES
 
Temperature Conditions
The average daily temperature conditions for the five temperature treatments are presented in Fig. 1 . The data in Table 1 show the number of times the average temperature exceeded optimum (28°C) and high (32°C) temperatures for cotton growth (Reddy et al., 1997) during critical stages of crop development for various treatments. Days to first square took 26 d for plants grown at 1995 ambient temperature conditions. The time required to produce first square increased by 27% for plants grown at the 1995 ambient temperature minus 2°C, compared with plants grown at ambient temperatures. The average temperatures from emergence to first square were 21.9°C for 1995 ambient temperature minus 2°C, 23°C for the 1995 ambient temperature, 24.7°C for 1995 ambient plus 2°C, 27.6°C for 1995 ambient plus 5°C, and 29.4°C for 1995 ambient plus 7°C. The time required, on the other hand, was decreased by 2 d for the 1995 ambient plus 2°C, by 5 d for the 1995 ambient plus 5°C, and by 7 d for the 1995 ambient plus 7°C. It took 65 d to produce first open flowers at 1995 ambient minus 2°C, and the time required was reduced by 21% for the 1995 ambient temperature, by 26% for the 1995 ambient plus 2°C, by 35% for the 1995 ambient plus 5°C, and by 40% for the 1995 ambient plus 7°C. The average temperatures from emergence to first flowers were 23.5°C for 1995 ambient temperature minus 2°C, 25.1°C for 1995 ambient, 26.9°C for 1995 ambient plus 2°C, 29.3°C for 1995 ambient plus 5°C, and 31.1°C for 1995 ambient plus 7°C. First open boll appeared at 101 d for the 1995 ambient temperatures. By lowering the temperature 2°C from the 1995 ambient, the number of days required was increased 43 d. On the other hand, by increasing the temperature by 2 and 5°C from the 1995 ambient, the number of days to first open boll decreased by 7 and 24, respectively. Essentially, no bolls were retained to maturity at the 1995 ambient temperature plus 7°C. The average temperatures during the whole experiment period were 20.5°C for 1995 ambient temperature minus 2°C, 23.1°C for 1995 ambient, 26.0°C for 1995 ambient plus 2°C, 30.3°C for 1995 ambient plus 5°C, and 32.3°C for 1995 ambient plus 7°C. These responses to temperature for the various developmental events are consistent with previously reported results (Reddy et al., 1997) for other cultivars. Doubling atmospheric [CO2] did not affect the developmental processes. The data indicate that any increase in seasonal temperatures by more than 2°C above the 1995 weather at Mississippi State, MS, may be injurious to boll set (Reddy et al., 1997).



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  		Fig. 1 Daily average temperature regimes for the five treatment conditions represented by five lines in the curves. From the bottom up: the first thin solid line represents 2°C below the 1995 ambient temperature; the next bold line represents the 1995 ambient temperature; the following thin, bold, and thin lines represent 2, 5, and 7°C warmer than the 1995 ambient temperature treatments. An overall bold line not closely following the curve pattern indicates the 42-yr long-term average daily temperature for Stoneville, MS (a site representing the U.S. Mid-South during that time frame; Reddy et al., 1997). Plants were harvested as they reached 50% open bolls; the higher temperature treatments were therefore harvested earlier than the cooler treatments

 

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  		Table 1 Number of days above optimum (28°C) and high (32°C) temperatures during critical stages of crop development for treatments relative to 1995 ambient temperature

 
Bolls and Squares
The number of total fruiting structures produced by plants growing at various temperature regimes and atmospheric [CO2] are shown in Fig. 2a . Large numbers of squares were produced at all temperatures. More bolls and squares were produced at the two highest temperatures than at the lower temperatures because few bolls were retained at the two highest temperatures (Fig. 2b). Without the carbon sinks (growing bolls) diverting C from the growing points, the plants continued to produce new nodes (data not shown) and fruiting structures. This effect was greater in the high-CO2 environments.



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  		Fig. 2 Bolls and squares produced and retained by cotton plants grown from emergence to maturity at various temperature deviations from 1995 ambient temperature at Mississippi State, MS. Square and boll counts were made when the plants had 50% of the bolls opened for any given treatment. Error bars indicate 1 SE

 
Plants growing at ambient temperatures and ambient minus 2°C in 360 µL L-1 of atmospheric [CO2] produced about equal number of bolls. Those grown at lower temperatures took longer to mature. Plants grown in the three lowest temperature regimes eventually stopped producing new fruiting structures because of boll load. Plants in high atmospheric [CO2] produced more squares and bolls, because additional vegetative growth was associated with greater photosynthesis. The relative seasonal average net C assimilation rate at 720 µL L-1 [CO2] was about 140, 179, 190, 150, and 137% of that at 360 µL L-1 [CO2] for plants grown at 1995 ambient temperature minus 2°C, at 1995 ambient temperature, and at ambient plus 2°C, 5°C, and 7°C, respectively (K.R. Reddy, unpublished data, 1995).

The number of bolls retained was very strongly controlled by temperature regimes in which the plants were grown (Fig. 2b). The number of times the average daily temperature exceeded the optimum for cotton boll retention (28°C) were 0 d for the 1995 ambient minus 2°C, 16 d for the 1995 ambient, 47 d for the 1995 plus 2°C, 74 d for the 1995 plus 5°C, and 88 d for the 1995 plus 7°C treatments. It has been demonstrated that young bolls abscise when exposed to average daily temperatures above 28°C, and the longer the exposure to above optimum temperatures the higher the abscission frequency (Reddy et al., 1992a, 1992b). The plants grown at high temperature produced large numbers of squares, and many of those squares matured to produce flowers. In the two highest temperature regimes, most bolls abscised 3 to 5 d after the anthesis. The apparent injury to fruiting structures was not identified, but we suspect that both pollen sterility and ovule injury due to high temperatures was the cause of the young boll abscission.

Similarly, soybean [Glycine max (L.) Merr.] grown at smoothly varying sinusoidal day/night temperatures of 28/18, 32/22, 36/26, 40/30, 44/34, and 48/38°C showed maximum vegetative biomass accumulation at 44/34°C, but essentially no seeds were produced (Pan, 1996). Also, soybean seeds were badly shriveled at the 40/30°C and seed yields were less than 50% of plants grown at optimum temperatures. Similar results were obtained in a similar controlled-environment chamber study for tropical lowland rice (Oryza sativa L.) (Baker et al., 1990) and in several varieties grown at ambient and elevated atmospheric [CO2] and at several temperature conditions (Ziska et al., 1996). As in cotton, the rice and soybean flowers appeared to be the most sensitive plant structures to high temperature. Increasing atmospheric [CO2] did not ameliorate the heat-sensitive condition at the high temperatures in either rice and soybean (Baker et al., 1990; Pan, 1996; Ziska et al., 1996) or cotton.

Boll Maturation Period, Boll Size, and Boll Filling Rate
Boll maturation period, the time required from anthesis to mature open boll, was very temperature-dependent and declined dramatically with increased temperature (Fig. 3) . The rate of boll filling increased with temperature up to 25°C and then declined at the highest temperature (Fig. 4) . Mature boll weight, a product of the rate of boll filling and boll maturation periods, was inversely related to temperature (Fig. 4). Boll size was maximum at the lower temperatures (17 to 18°C) and declined when grown at any higher temperatures. Atmospheric [CO2] did not affect boll maturation period and boll size. This suggests that C is not normally a factor limiting boll size or boll growth rates. Available reduced C, however, does limit the number of fruiting structures produced and retained (Fig. 2).



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  		Fig. 3 Influence of temperature and atmospheric [CO2] on boll maturation period. Circles represent means at ambient CO2 (360 µL L-1) and squares represent means at elevated CO2 (720 µL L-1). The temperatures were averages from flowering to open bolls. Error bars indicate ±1 SE (where larger than symbol size)

 


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  		Fig. 4 Influence of temperature and atmospheric [CO2] on boll growth rate (solid symbols) and mature open boll weight (open symbols). Circles represent means at ambient CO2 (360 µL L-1) and squares represent means at elevated CO2 (720 µL L-1). The temperatures were averages from flowering to open bolls. Error bars indicate ±1 SE

 
Fiber Properties
As temperature increased, the short-fiber mote percentage increased in both ambient and elevated CO2 levels (Table 2) . Bolls from plants grown in the 1995 ambient temperature (seasonal average, 23°C) and in the 1995 ambient temperatures plus 2°C (seasonal average, 26°C) under elevated [CO2] produced significantly more small short-fiber motes than bolls from plants grown in the ambient CO2 conditions. Pearson (1949) concluded that small motes were formed on days when the maximum air temperature was near 38°C. Since high temperatures may alter pollen and ovule development, eventually leading to inefficient fertilization, some small short-fiber motes are derived from unfertilized ovules. It appears that some other small short-fiber motes are fertilized ovules that abort shortly after. High temperatures cause the boll growth and eventually seed growth and development processes to occur more rapidly, with a higher percentage failing. In the high-CO2 environments, more ovules are produced because of greater number of bolls produced and retained per plant and the potential for ovule or seed abortion is greater. Boll temperatures were assumed to be the same as air temperatures, although actual measurements were not made. Essentially, all bolls were shaded in the canopy environment except for an occasional sunflex. Previous comparisons of air and canopy temperatures in these chambers have not found differences except in water-stress-imposed conditions, confirming observations in the field (Haigler et al., 1991). Long-fiber mote percentages fluctuated without an apparent pattern, and therefore it was not clear what environmental condition caused such motes to be produced.


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  		Table 2 Mote frequency, atmospheric [CO2], temperature treatments, and average temperature during the whole experimental period

 
Length, short-fiber content, and micronaire measured by high volume instrument (HVI) testing are traditionally used to measure fiber quality (Behery, 1993). A conventional method of assessing fiber length by weight, L(w), involves sorting fibers into length groups and then weighing them. The length–weight distribution is used in calculating mean length by weight and other fiber properties, such as UQL and SFC. Correlations of HVI upper-half mean length with AFIS length by weight, L(w), were high for field-grown cotton fiber (Calhoun et al., 1997). Correlations of HVI micronaire with AFIS A(n) were high and with AFIS micronafis were only slightly lower (Calhoun et al., 1997).

Mean fiber length L(w) showed a quadratic trend with temperature and decreased as temperature increased (Fig. 5a) in both CO2 levels. Short-fiber content (% fibers <12.7 mm) is important, both from the aspect of being a waste component and of being a fiber processing component (Behery, 1993). The highest short-fiber content was associated with plants grown at the lowest and the highest temperatures, while fibers from plants grown in the 1995 ambient temperatures (seasonal average, 26°C) had the lowest short-fiber content (Fig. 5b). An increase in short-fiber content may indicate that either the rate of fiber elongation and/or the duration of fiber elongation was decreased. Plants grown in the elevated [CO2] treatment and in the 1995 ambient temperatures minus 2°C (seasonal average, 20°C) produced fiber with a lower short-fiber content by weight, SFC(w), than plants grown in the ambient CO2 conditions (Fig. 5b). The decrease in length associated with elevated temperatures was in agreement with a study that found shorter fibers in plants grown under high night temperatures (Gipson and Joham, 1968). In a study of 20 field-grown varieties, SFC depended on variety, moisture content, and ginning fractions (Anthony, 1992).



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  		Fig. 5 Influence of temperature on (a) fiber length by weight, L(w), and (b) short-fiber content by weight, SFC(w), as a function of temperature for plants grown in ambient (circles) and twice ambient (squares) atmospheric [CO2]. The temperatures were averages from flowering to open bolls. Error bars indicate ±1 SE

 
The length uniformity index is the ratio between the mean length and the upper-half mean length expressed as a percentage of the upper-half mean length. Fiber length uniformity can be assessed by comparing L(w), SFC(w), and upper quartile length by weight [UQL(w)] and by examining fiber length frequency distributions. Frequency distributions demonstrated that fiber uniformity increased when plants were grown at temperatures closer to optimum (Fig. 6) . The range was reduced and the distribution of fiber lengths was more normal for fiber from plants grown in the 1995 ambient temperatures (seasonal average, 26°C).



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  		Fig. 6 Representative histogram of fiber lengths L(w) from bolls at the first position from Node 11 for plants grown in ambient atmospheric [CO2]. Histograms of fiber lengths from bolls grown in 1995 ambient minus 2°C (seasonal average, 20°C) and in 1995 ambient temperatures plus 2°C (seasonal average, 26°C) were based on 10000 and 6343 fibers, respectively. The temperatures were averages from flowering to open bolls

 
Fiber maturity is expressed in AFIS values for {theta} (fiber circularity). Fiber fineness is expressed in terms of mean cross-sectional area, A(n) <60 µm2. Micronafis is AFIS-calculated micronaire and is closely correlated with micronaire values (Calhoun et al., 1997). The micronaire values reflect a composite of fiber maturity and fineness characteristics. The degree of circularity is a dimensionless value that corresponds to the degree of fiber cell wall thickening divided by the area of a circle of the same perimeter. As average growing temperature during the boll-filling period increased up to 26°C (1995 ambient temperatures), {theta}, A(n), and micronafis increased linearly (Fig. 7) . Plants grown in the higher temperatures except in the 1995 ambient temperature plus 5°C and ambient atmospheric [CO2] produced very few mature bolls with lower fiber A(n), {theta}, and micronafis. At the low temperatures, fiber from plants grown under elevated atmospheric [CO2] conditions had higher {theta}, A(n), and micronafis values than fiber from plants grown under ambient atmospheric [CO2]. Gipson and Joham (1968) found that micronaire values increased from 2.0 to 4.5 as night temperatures increased from 5 to 25°C.



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  		Fig. 7 Fiber properties when grown at different temperature: (a) degree of circularity, {theta}, (b) cross-sectional area, A(n), and (c) micronafis, which is similar to micronaire as a function of temperature for plants grown in ambient (circles) and twice ambient (squares) atmospheric [CO2]. The temperatures were averages from flowering to open bolls. Error bars indicate ±1 SE

 

   Summary and conclusions
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
 Materials and methods
 Results and discussion
 Summary and conclusions
REFERENCES
 
The sustainability of cotton production in the U.S. Mid-South for climatic changes expected to occur by the middle of next century was evaluated in sun-lit controlled-environment plant growth chambers. Cotton plants responded positively by increasing the number of fruiting organs and retaining more bolls in response to increased atmospheric [CO2] at a wide range of temperatures that are projected to occur. The boll maturation period and boll size were decreased with higher temperature, whereas boll size, a product of boll maturation period and boll growth rates, was greatest at 23 to 26°C. Elevated atmospheric [CO2] did not affect any of these boll growth parameters. More fruiting structures were produced and more bolls were retained in the high-CO2 environments when temperatures were optimum for boll growth because of increased boll producing structures and C availability. Boll retention was severely curtailed when temperatures exceeded 2°C above the U.S. Mid-South 1995 ambient temperatures. Elevated atmospheric [CO2] did not ameliorate the damage caused by high temperatures.

Similar to boll growth parameters, fiber parameters that are of interest to textile mills were not affected by elevated atmospheric [CO2]. Mote numbers increased in higher temperature, while fiber length was less for the higher temperature treatments. Fiber {theta}, micronafis and cross-sectional area values increased linearly with temperature up to 26°C, but had lower values at higher temperatures. Short-fiber content showed a trend opposite to that of fiber maturity and fineness parameters. The data provided should be useful in developing quantitative temperature response functions for boll growth and development and associated fiber properties under potential growing conditions. Such functions, if incorporated into process-level simulation models (Hodges et al., 1998), will enhance the usefulness of model applications. If we could model fiber quality properties with weather during the fiber growth period, producers and textile firms could predict their fiber quality and the entire marketing process could proceed with knowledge of the fiber quality. Varietal, nutrient, and water-deficit effects are also needed to simulate fiber parameters in production environments.SAS Institute 1990


   ACKNOWLEDGMENTS
 
We wish to thank Debra Wilson, Kathryn Pusateri, Gary Burrell, Kim Gourley, Wendell Ladner, and Sam Turner for their valuable technical support, and James McKinion for use of the SPAR facility. Part of the research was funded by the USDOE National Institute for Global Environment Change through the South Central Regional Center at Tulane University (DOE cooperative agreement no. DE-FCO3-90ER 61010).


   NOTES
TOP
 NOTES
ABSTRACT
 INTRODUCTION
 Materials and methods
 Results and discussion
 Summary and conclusions
 REFERENCES
 
Contribution from the Dep. of Plant and Soil Sciences, Mississippi State Univ., and the USDA-ARS Southern Regional Res. Ctr., New Orleans, LA. Mississippi Agric. and Forestry Exp. Stn. Paper no. J9391.

Received for publication August 20, 1998.
   REFERENCES
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
 Materials and methods
 Results and discussion
 Summary and conclusions
 REFERENCES
 




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C. A. Braden and C. W. Smith
Phenology Measurements and Fiber Associations of Near-Long Staple Upland Cotton
Crop Sci., November 1, 2004; 44(6): 2032 - 2037.
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K. R. Reddy, S. Koti, G. H. Davidonis, and V. R. Reddy
Interactive Effects of Carbon Dioxide and Nitrogen Nutrition on Cotton Growth, Development, Yield, and Fiber Quality
Agron. J., July 1, 2004; 96(4): 1148 - 1157.
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G. H. Davidonis, A. S. Johnson, J. A. Landivar, and C. J. Fernandez
Cotton Fiber Quality is Related to Boll Location and Planting Date
Agron. J., January 1, 2004; 96(1): 42 - 47.
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