Irrigation’s effect and applied selection on the fiber quality of Ethyl MethaneSulfonate (EMS) treated upland cotton (Gossypium hirsutum L.)

[Background] Producing rainfed cotton (Gossypium hirsutum L.) with high fiber quality has been challenging in the Texas High Plains because of extended periods of insufficient rainfall during sensitive boll developmental stages. Genetic variation created by Ethyl MethaneSulfonate (EMS) mutagen has successfully improved fiber quality of cotton. However, little is known about the effect of water deficit environments on fiber quality. Three EMS treated populations were advanced from the first to the fourth generation (M1 to M4) as bulk harvested populations. In 2014, single-plant divergent selection was applied based on perceived morphological and agronomic differences seen during and at the end of the season.

[Results] Analyses from these selections in 2014–2016 showed significant (P < 0.05) improvement between and within populations for fiber traits (micronaire, length, strength, uniformity, and elongation) when compared with the original non-treated EMS source; some selections were found to have excellent fiber quality under diverse irrigation-regimes.

[Conclusions] Some of these selections are being considered for germplasm release and could be useful for improving the fiber quality of cotton under water limited conditions, thereby helping to ensure the long-term survival of the cotton industry on the Texas High Plains.

Irrigation’s effect and applied selection on the fiber quality of Ethyl MethaneSulfonate (EMS) treated upland cotton (Gossypium hirsutum L.)
WITT Travis W. , ULLOA Mauricio, PELLETIER Mathew G. , MENDU Venugopal and RITCHIE Glen L.
Journal of Cotton Research. 2018; 1:17.
https://jcottonres.biomedcentral.com/articles/10.1186/s42397-018-0016-8

IMPERIAL VALLEY COTTON FIELDS SURVEYED WITH PLANT MAPPING

Abstract                                                                         Back to Table of contents

We introduced the University of California Plant Mapping Program to growers in the Imperial Valley for the first time for the 1993 cotton season.  Because the equations used in the program were derived from data collected in the San Joaquin Valley for Acala varieties, many potential users questioned the validity of applying the program to Upland cotton fields growing in the low desert (i.e. Imperial Valley).  They wanted to know if the program could make accurate predictions for varieties other than Acalas in an environment other than the San Joaquin.  Could they trust their management decisions to a program developed from another region’s database?

In order to address these concerns and to help convince the growers of the value of plant mapping, we collected both in-season and final plant map data from thirty Imperial Valley cotton fields during the 1993 season. Height to node ratios vs. age (as number of nodes) for Imperial Valley plants followed the same pattern, but were slightly lower than, the curve for San Joaquin fields.  Some fields came closer to the line representing the San Joaquin database than others.  Nodes above white flower values from Imperial Valley fields followed the same relationship to days after first flower as the San Joaquin fields.  Growers actively making management decisions with the aid of the programs picked over 2242 kg lint/ha.  Those not guiding their decisions brought in less than 1121 kg lint/ha.  We determined two factors critical to good cotton production in the low desert:  timing of early season irrigation and early retention of first position fruits.  We conclude that the UC Plant Mapping Programs served as useful guides in an area quite different from the San Joaquin.

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METHAM IN COTTON

Abstract                                                                         Back to Table of contents

Metham is a soil fumigant which is used to kill germinating weed seeds and organisms in the  soil such as nematodes and fungi.  In cotton, nightshade and nutsedge are among the most difficult weeds to control.  Several trials were conducted in the southern San Joaquin Valley in 1991 through 1993 to evaluate different rates and methods of metham application to Acala cotton.  Metham treatments demonstrated good to excellent control of black nightshade and gave good suppression of purple nutsedge.  Good control of black or hairy nightshade was obtained with a single 20 cm-wide blade injecting metham into preirrigated beds at rates of 19 to 77 liters per treated hectare.  Nutsedge control was erratic.  The best nutsedge suppression was obtained by injecting metham with a 3-tiered fertilizer knife at rates between 138 and 184 liters per treated hectare.  This treatment held for 30 to 40 days after the application of metham; thereafter, nutsedge emerged through the treated band.

Conclusion

Metham test results have been variable.  Failures most often occur because incorrect application methods or the lack of sufficient soil moisture allow metham to volatilize and escape too fast.  Also some planting procedures and cultural practices move treated soil which diminishes the efficacy of metham treatments.  Applied and managed correctly, metham minimizes weed competition and prevents potential yield reduction.

Best results have been obtained when:

  1.  Metham is applied with a single spray blade for annuals and double spray blades or fertilizer knives for perennials.
  2. Rates of 38 to 77 liters per treated hectare are used for nightshade and > 115 liters for nutsedge.
  3. A firm, trash and clod free seedbed is prepared.
  4. The soil is preirrigated previous to application to insure that weed seeds have imbibed water.
  5. No tillage is performed between metham application and planting.
  6. Cotton is planted as soon as the required 14-21 day waiting period is met.
  7. Treated soil is not contaminated with untreated soil during planting.
  8. Soil Temperature is greater than 10 ˚C.

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EFFECT OF FOLIAR APPLIED NITROGEN AND POTASSIUM ON COTTON IN THE SAN JOAQUIN VALLEY OF CALIFORNIA

Abstract                                                                         Back to Table of contents

Improved cotton varieties and improved cultural practices have caused lint cotton yields to improve at a rate of 36 kg ha-1 year-1 over the past ten years. Earlier maturing varieties, 76 cm rows, better irrigation regimes, improved pest management, and the wide spread use of plant growth regulators, have all had a part in the yield increases. Since bolls are strong sinks for nitrogen and potassium, these nutrients are needed in even larger quantities during boll development. Foliar applications of nitrogen in conjunction with pix (mepiquat chloride) resulted in increased yields even when it was thought that soil levels were adequate.

Timing of foliar potassium in five tests in two years, showed that two to three weeks after first bloom was the best time for applications. Potassium applied prior to two weeks after first bloom or later in the season resulted in less yield response. There was no difference between the effects of potassium nitrate or potassium sulfate when used as a foliar potassium spray.

Conclusions

The results of these tests show that benefits can be obtained from foliar applications of nitrogen and potassium. New, more determinant cotton varieties which set the crop over a short period of time, require larger amounts of some nutrients during this critical stage of development. Determinant varieties coupled with cultural practices which push the crop toward earlier termination cause need for supplemental nitrogen and potassium to be even greater. Even though the soil nitrogen and potassium levels were adequate according to cotton fertility guidelines, foliar applications of these nutrients at two to three weeks after first bloom caused positive yields responses.

It should be emphasized that foliar applications are by no means a substitute for sound fertilizer practices, and, if used, should only be supplemental.

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NIGHTSHADE CONTROL WITH PYRITHIOBAC SODIUM (STAPLE) IN CALIFORNIA COTTON

Abstract                                                                         Back to Table of contents

The control of nightshade species with pyrithiobac Sodium at rates up to 210 liters/ha with and  without fluazifop, methanearsonate, and surfactants were examined from 1991-1993.  Phytotoxicity  to Acala cotton was also evaluated.

Control of nightshade levels 50 to 60 days after treatment ranged from 90 to 100%, with 100% control normally occurring at the 28.5 to 42.5 g ai/hg rate applied either singly or in a  sequential application.  When pyrithiobac sodium was tank mixed with either fluazifop or  monosodium methanearsonate control remained excellent.  Grass control was unaffected.

Cotton injury was evident four to five days after treatment.  Symptoms included mottled yellowing and  crinkling of leaves, but the cotton plant outgrew these symptoms within 30 to 40 days.  Symptoms  were greater and persist longer with higher rates.  Acala varietal screening indicated no adverse  effect to yield.

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FUTURE WEED CONTROL SYSTEMS FOR CONSERVATION TILLAGE COTTON IN THE SOUTHEASTERN USA

Abstract                                                                         Back to Table of contents

Bromoxynil used with transgenic cotton and pyrithiobac provided early season postemergence control of annual morningglory, Ipomoea spp., prickly sida, Sida spinosa, velvetleaf, Abutilon theophrasti, and common cocklebur, Xanthium strumarium without adversely affecting cotton.  Neither bromoxynil nor pyrithiobac controlled sicklepod, Cassia obtusifolia, postemergence.  Fluometuron alone or in combination with pyrithiobac provided preemergence sicklepod control.  Thiazopyr applied preemergence provided large crabgrass, Digitaria sanguinalis, control without significant crop injury.  High-residue cultivators allowed the use of banded preemergence herbicides in conservation tillage cotton, thus reducing herbicide usage.  Pyrithiobac soil-applied or early postemergence, bromoxynil applied postemergence with transgenic cotton, and the use of high-residue cultivators show potential for use in future weed control systems for conservation tillage cotton in the Southeastern USA, government regulations permitting.

Conclusions

Bromoxynil and pyrithiobac provided postemergence broadleaf weed control without cotton injury for conventional and conservation tillage cotton.  Neither product controlled sicklepod postemergence; therefore, a soil-residual herbicide having sicklepod activity will be required in cotton fields infested with this species.  Pyrithiobac has soil activity on sicklepod and may be used in combination with fluometuron for PRE treatments.  Thiazopyr showed potential for preemergence annual grass control in notill cotton on sandy loam soils without the cotton injury exhibited by metolachlor.  High-residue cultivators are available which allow the use of banded herbicide applications in conservation tillage cotton thus reducing chemical use in these systems.

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POTASSIUM NUTRITION OF COTTON IN THE USA, WITH PARTICULAR REFERENCE TO FOLIAR FERTILIZATION

Abstract                                                                         Back to Table of contents

Widespread late-season potassium (K) deficiency in the US Cotton Belt has focused attention on K nutrition of cotton (Gossypium hirsutum L.).  Potassium is required in large amounts by cotton for normal crop growth and fiber development, with a crop containing 112 to 246 kg K ha-1.  Plant uptake of K follows a pattern similar to dry weight accumulation except that K uptake peaks at 2.2 to 5.0 kg ha-1 day-1 a few weeks after the start of flowering.  Cotton is more sensitive to low K availability than most other major field crops, and often shows signs of K deficiency on soils not considered K deficient.  The K-deficiency syndrome appears to be a complex anomaly related to low soil K status, K fixation in the soil, a greater demand for K by modern cultivars, the inability of the root system to supply this, and possible relationships with diseases such as Verticillium wilt.  Preplant soil tests provide a means for estimating overall K fertilizer requirements, whereas petiole analysis has become a valuable diagnostic tool for assessing nutrient status and determining K requirements during the growing season.  There is still some uncertainty about K threshold levels and the validity of petiole diagnosis after peak boll development.  The sufficiency levels of K in petioles for cotton generally range from 4.0% at first flower to 0.25 at first open boll.  Luxury consumption of K can occur in cotton and could possibly perplex tissue diagnostic recommendations.  Foliar applications of K offer the opportunity of countering late-season K deficiencies quickly and efficiently with a resulting improvement in yield and quality.  Significant yield increases from foliar-applied K were obtained in approximately 40% of the field trials in the USA in the past five years, with an overall average increase of about 75 kg lint ha-1.  KNO3 was the preferred formulation with K2SO4 and K2S2O3 being similar in effectiveness, and KCl and K2CO3 having no beneficial effect on yield.  The use of adjuvants with foliar sprays increased the uptake of K but did not increase lint yield.  Additional research is needed to understand the physiology of K utilization in cotton and the specific causes of late-season K deficiency symptoms.

Conclusions

Potassium deficiency has occurred widely across the US Cotton Belt in recent years.  The occurrence of these outbreaks of K deficiency have been somewhat unpredictable and the explanations not clear.  The K-deficiency syndrome appears to be a complex anomaly related to low soil K status, K fixation in the soil, a greater demand for K by modern cultivars, less storage of K prior to flowering by modern cultivars, the inability of the root system to supply the needed K during boll development, and possible relationships with diseases such as Verticillium wilt.  Interest has focused on the possibility of foliar feeding with K to supplement traditional soil application methods.  Foliar applications of K offer the opportunity of correcting these deficiencies quickly and efficiently, especially late in the season when soil application of K may not be effective.  Research during the last five years has shown that foliar-applications of KNO3 can alleviate K deficiency and significantly increase yield and fiber quality. However, results from across the Cotton Belt have been variable and unpredictable, and additional research is needed to fully explain this phenomenon.  There is sufficient evidence that foliar application of KNO3 appears to be a useful production practice for supplementing preplant soil applications of potassium fertilizer especially when K deficiency symptoms occur and soil and petiole tests show a low K status.

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PLANT RESPONSES TO LATE SEASON WATER DEFICITS IN ACALA COTTON CULTIVARS

Abstract                                                                         Back to Table of contents

Continued development of irrigation strategies that minimize crop yield losses, while increasing water use efficiency are needed in many semi-arid and arid cotton producing areas world wide.  Controlled deficit irrigation (CDI) incorporates the knowledge of crop physiology and phenology to identify specific plant growth stages in which water deficits have a minimal impact on crop yield and quality.  Previous research in California and other irrigated agricultural regions have documented the severe yield impact when moderate early season water stress is allowed to accumulate in cotton (Gossypium hirsutum L.).  Conversely, similar late season water stress following plant cutout has had a minimal impact on crop yield and quality.  This paper is a report of recent studies that were undertaken in an effort to apply the concepts of CDI for cotton (Gossypium hirsutum L.) and suggest approaches to farm water managers which enable a greater understanding of deficit irrigation strategies.  Studies conducted in the San Joaquin Valley of California from 1991 to 1993 have consistently demonstrated that high yields can be obtained although late season water deficits in cotton were present.  The optimum timing of the final in-season irrigation for cotton was shown to be dependent on the cultivar.  The determinant plant types tended to have more significant yield reductions as water stress is increased following plant cutout, while the indeterminate types were found to be less sensitive to the timing of late season water stress.  The timing of late season water directly alters the stress accumulated in the crop thereby impacting late season boll retention, boll maturation and crop yield.

Conclusions

The monitoring of cotton plant performance characteristics following periods of induced late season water stress can assist in developing deficit irrigation management strategies.  To date, very little information is available regarding modern cotton cultivators and their tolerance to late season water stress.  By varying the degree and timing of water stress accumulation, we can begin to recognize both general trends for timing the final irrigation and select varieties that suit an individual field managers needs with respect to timing the final irrigation.    Moderate plant water stress induced late in the season, can reduce consumptive water use without severely impacting on crop yield or quality.  The decision of when to time the final irrigation for cotton, is dependent upon the variety and the degree of water deficits.  Delayed scheduling of late season water is preferred for more indeterminate plant types resulting from their improved tolerance to water deficits.  Shorter season, more determinant plant types, experienced significant yield reductions when moderate late season water stress was allowed to build.  The preferred irrigation strategies for determinant varieties would therefore favor the deliver of available water supplies prior to the development of moderate water stress levels (-21 bars).

The pressure chamber can be an effective tool in evaluating the intensity and duration of cotton water stress.  Generally, plants performed well with highest yields obtained when LWP readings were not allowed to exceed -23 bars.  Significant impacts on plant growth and fruit retention were observed when LWP readings were allowed to reach the wilting point of -30 bars.  At these high water stress levels, decreases in transpiration rate and photosynthesis are likely causes of delayed fruit set and hence the production of unharvestable late season bolls.  The production of these late season bolls, although not equivalent to the lost production of lower fruiting positions, does demonstrate a resiliency of cotton to partially recover from severe water stress levels.

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IMPROVEMENTS IN WATER USE EFFICIENCY IN IRRIGATED COTTON: CHOICES IN SYSTEMS AND MANAGEMENT

Abstract                                                                         Back to Table of contents

Major factors (crop, soil, topography, labor and management availability and skill, environmental concerns, regulatory controls, economic) influencing irrigation efficiency, water use efficiency and the choice of appropriate irrigation systems and management for cotton are reviewed and discussed.  One field experiment in the San Joaquin Valley of California which identifies the high yield potential, relatively low water use, and high water use efficiency possible under subsurface drip irrigation is described in detail.  Three different field experiments and grower experiences in evaluating different irrigation systems (furrow versus subsurface drip in all three, center pivots included in one grower evaluation)in terms of water requirements, water use efficiency and potential for minimizing deep percolation are reviewed in the context of options for improving water use efficiency in fully-irrigated cotton under conditions in the western United States.  Drip irrigation is discussed in detail but remains only one of the choices for changes in irrigation systems and management that are available to improve irrigation efficiency and water use efficiency while maintaining a favorable net economic return.

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THE PHYSIOLOGY OF COTTON WATER USE EFFICIENCY

Abstract                                                                         Back to Table of contents

Availability of water causes major variation in cotton yield. Water use efficiency confers meanings of water conservation (i.e., savings of water and/or costs of water application) and transpiration efficiency (i.e., increasing productivity per unit of water transpired).  Because of the commonality in the pathways shared between transpiration and CO2 assimilation, there is a strong link between crop growth and transpiration.  This paper briefly reviews the circumstances leading to water use efficiency of cotton through water conservation, but fully explores our knowledge and water use as it relates to the transpiration efficiency and productivity of the cotton plant.  Emphasis is placed on our understanding of carbon isotope discrimination as it relates to transpiration efficiency and productivity.

Conclusion

Relatively little progress has been made in increasing productivity of cotton or other major crops per unit of water or solar radiation, even though dryland and irrigated yields have increased.  These yield increases have arisen mainly from changes in carbohydrate partitioning favoring fruit production (Gifford et al., 1984), although recent work suggest that genetic advances in yield of Pima cotton varieties (G. barbadense L.) resulted, in part, from selection of plants with higher stomatal conductance and photosynthesis (Cornish et al., 1991).  Nevertheless, selection for photosynthesis and stomatal conductance, per se,  has not been used in improving yield of cotton and other field crops.  Measurements of photosynthesis and stomatal conductance with conventional gas exchange techniques are too variable, measuring plant performance over a brief period time. Integrated over the season small changes in leaf gas exchange can result in large differences in total carbon uptake or water use.  Errors associated with direct gas exchange measurements may be too large to detect small gains in gas exchange efficiency.  In contrast, ∆ appears to be more effective than conventional gas exchange measurements in detecting genotypic differences in transpiration efficiency and productivity for several important crops (Hall et al., 1992).

The crucial role of water in production of cotton will not change.  Industrial, municipal, environmental, and recreational demands for water will intensify. Cotton farmers must continually examine and adopt sound water conservation practices. At the same time scientists must continue to improve our understanding of  crop water use and productivity.  We believe carbon isotope discrimination provides us with a new tool to improve the transpiration efficiency and productivity of field crops. Whether carbon isotope discrimination can be use to improve water use efficiency of cotton remains to be answered.

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