Boll Maturation Research Articles

Effect after introducing Bacillus thuringiensis gene on nitrogen metabolism in cotton

Bacillus thuringiensis (Bt) transgenic cotton has shown changes of vegetative and reproductive growth characteristics. The objective of this study was to investigate the physiological change of nitrogen metabolism that related closely to the growth in Bt cotton cultivars. The study was undertaken on two Bt transgenic cotton cultivars and their parents, one conventional (Xingyang822) and recurrent parent (Sumian No. 9), the other a hybrid (Kumian No. 1) and female parent (Yumian No. 1), during the 2001 and 2002 growing seasons at the Yangzhou University Farm, Yangzhou, China. In the 2001 study, The results indicated that the Bt cotton cultivars were higher than their parents in leaf total nitrogen, free amino acid and soluble protein content, greater in NR and GPT activity, and lower in protease activity, during peak square and boll developing period. The biggest increase of total nitrogen was at peak boll period, which increased by 36.01 and 18.96% for Kumian No. 1 and Xingyang822, respectively. There were similar results for free amino acid and soluble protein content. The results showed further in 2002 study that NR activity increased dramatically at peak square and early boll open period, the biggest increase at early boll open period, with Kumian No. 1 and Xingyang822 being 87.5 and 61.4% higher than their parent, respectively, the biggest increase of GPT activity was at peak boll period, with Kumian No. 1 and Xingyang822 being 39.1 and 29.1% higher than their parent, respectively. However, protease activity of Bt cultivars reduced significantly before flowering and early boll open period, the biggest decrease was before flowering period, with Kumian No. 1 being more than 30%, Xingyang822 being 26.5% at peak square period. Moreover, the boll total nitrogen content reduced sharply. The results suggest that the Bt cotton cultivars have higher intensity of leaf nitrogen metabolism than their parent, especially during square and boll development period. It is disadvantage for square development and earlier boll maturity under high nitrogen condition. The cultural practice should aim at reducing leaf nitrogen metabolic strength and keep the balance of vegetative and reproductive growth.

Effects of methyl jasmonate on phytoalexin production and aflatoxin control in the developing cotton boll

Artificially wounded 22–27-day old developing cotton bolls were initially inoculated with, (1) a cell-free, hot water-soluble mycelial extract (CFME) of an atoxigenic strain of Aspergillus flavus or with, (2) chitosan lactate (CHL) or with, (3) CFME or CHL and then exposed to gaseous methyl jasmonate (MJ) or, (4) exposed to MJ alone. Five days after these treatments, the induction of the sesquiterpenoid naphthol phytoalexins, 2,7-dihydroxycadalene (DHC) and 2-hydroxy-7-methoxy cadalene (HMC), lacinilene C, lacinilene C7-methyl ether, and the coumarin phytoalexin-scopoletin was determined on the excised carpel discs surrounding the inoculated surfaces of the developing cotton bolls. The results indicated a two- or three-fold increase in the production of the phytoalexins when gaseous MJ was added in combination to the CFME or the CHL elicitors. In a separate experiment, 22–27-day old developing cotton bolls were pretreated for a five-day period as described above and then a spore suspension of a toxigenic strain of A. flavus was introduced into a second artificial wound which was produced adjacent to the first wound. On boll maturity, the cottonseeds located within the locules underlying the areas that were pretreated with both elicitors and MJ then later infected with toxigenic A. flavus exhibited a 75–95% aflatoxin B1 inhibition. These results suggest a host defense mechanism which may be triggered by both elicitors and MJ.

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

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.

Genetic analysis of earliness in upland cotton (Gossypium hirsutum L.). I. Morphological and phenological variables

Inheritance and interrelationships of morphological and phenological components of earliness were evaluated in a diallel analysis involving seven early-maturing parents and a standard cultivar. This study was initiated in 1993 by making all possible crosses, without reciprocals, among the eight parents. Field evaluation of the eight parental genotypes and the 28 F1 was made in 1994 in a randomized complete block design with four replications. Of 13 earliness components studied, all but days to first square, vertical flowering interval, boll maturation period, and production rate index showed significant additive genetic variance. Heritability estimates ranged from 0.02 for production rate index to 0.39 for days to first open boll. Correlation analysis showed generally that the lower the node to the first fruiting branch and the shorter the plant, the earlier was the onset of squaring, flowering, and boll opening.

Planting Date and Potassium Fertility Effects on Cotton Yield and Fiber Properties

Late planting causes cotton (Gossypium hirsutum L.) to flower later in the season so boll development occurs at lower temperatures. Potassium deficiency elicits some of the same responses in cotton that delayed planting does. Together, these stresses may affect the yield and fiber quality beyond the individual effects of late planting and K deficiency. Our objective was to determine the effect of K fertilization on normal- and late-planted cotton. In 1991, 1992, and 1993, three cotton genotypes (PD 5286, PD 5358, and PD 5472) were seeded in late April and late May on a Hornsville loamy sand (clayey, kaolinitic, thermic Aquic Hapludult) soil with and without annual applications of 100 Ib K 2 O/acre. Soil K in the upper 6-in. was 95 Iblacre at the initiation of the experiment. Soil K did not differ between the two K fertilizer treatments after the 1991 growing season. After the 1992 and 1993 seasons, K in the 0- to 6- and 6- to 12-in. soil layers was greater in the 100 Ib K 2 O/acre treatment than in the 0 Ib K 2 O/acre treatment, but no differences occurred at greater depths. Potassium fertilization did not affect flower production in either planting date in any year. Potassium deficiency reduced the lint yield and fiber length of PD 5286 and PD 5358 but not that of PD 5472. Besides yield and fiber length, fiber perimeter was the only parameter reduced by K deficiency. Late planting caused reduced yield in only I of the 3 yr, and for only two of the three genotypes. In general, cotton planted in late May had higher yarn strength, elongation, and fiber length, but lower micronaire and fiber maturity than cotton planted in late April. No interactions that included both K and planting date were significant for lint yield, yarn strength, or any of the fiber properties. This indicates that additional attention to K fertility is not needed in production systems where the boll maturation period is delayed.

Cotton Response to Seasonal Patterns of Flower Removal: II. Growth and Dry Matter Allocation

Development of a cotton (Gossypium hirsutum L.) crop is a full‐season process involving a complex balance between vegetative and reproductive allocation. Despite this fact, fruit removal studies have seldom examined the effects of flower removal during late anthesis. Flower removal treatments were imposed on two cotton cultivars to assess effects on vegetative and reproductive dry weights (DW) and boll maturation patterns. Flower removal treatments were imposed during early‐, mid‐, and late‐anthesis. Removal of 1st and 2nd and 1st through 3rd week flowers caused a decrease in the reproductive/vegetative ratio (RVR) at 105 d after planting (DAP) or 93 DAP 1991 and 1992, respectively. However, no difference in RVR was found between these treatments and the control (no removal) at either 133 or 131 DAP (1991 and 1992). Early removals (3rd week and earlier) increased number of bolls developing above Node 10 and decreased the number of bolls developing at first positions on sympodial branches. Flower removal during the 4th week and later decreased the RVR at 133 and 131 DAP (1991 and 1992) by at least 23% as compared with the controls. Late‐season removal treatments decreased the final number of total bolls and significantly reduced the number of bolls residing at main stem Nodes 11 and higher. Although fruit retention early in reproductive growth is often important for early maturity and maximal yield, this study found that subsequent development of distal and more apical flowers adequately replaced fruit lost durin early anthesis. In contrast, later developing bolls, often thought to be unimportant, were needed to achieve maximal yield.

Plant-Quality Effect on Life-History Parameters of the Twospotted Spider Mite (Acari: Tetranychidae) on Cotton

The suitability of cotton for the development and reproduction of the two-spotted spider mite, Tetranychus urticae Koch, was assessed. Mites were reared on young and old cotton leaves at several times of the season to determine if plant quality influenced the early-season decline in mite populations on cotton or their within-plant distribution. The developmental time, preoviposition period, reproductive period, and life span of mites was influenced only slightly by leaf age or stage of plant development. However, lifetime fecundity was lowest on cotyledons and on old leaves. Fecundity on young leaves was high for most of the season but declined when plants reached boll maturation. The low suitability of cotton cotyledons may slow the development of mite populations early in the season but only until true leaves develop. Nitrogen content of leaves declined as plants developed and was lowest in older leaves. In contrast, tannin content increased progressively with plant development and was higher in younger leaves than in older leaves. Mite developmental time was related negatively to nitrogen content, whereas fecundity was related positively. In preference tests, mites strongly preferred to feed and oviposit on younger leaf tissue compared with older leaf tissue. In the field, mites released near the tops of plants remained there, whereas those released onto leaves in the middle and bottom of plants moved upward, either along the mainstem or along branches, to younger leaves. Rearing studies indicate a fitness advantage will accrue to mites developing on younger leaves, possibly because of the higher nitrogen content than in older leaves. The within-plant distribution of mites is a result of both the ability of mites to assess leaf quality and a likely positive phototaxis, which directs the mites toward younger leaves.

Plant Nitrogen Status and Boll Load of Cotton

AbstractNitrogen management is important in determining cotton (Gossypium hirsutum L.) yield and fiber quality. Plant tissue tests are often used to estimate cotton N status and determine if further fertilization is needed during the growing season. This study was conducted to examine the relationship between plant tissue tests of petiole NO3 concentration and leaf N content and cotton performance as measured by vegetative growth (i.e., leaf area) and boll load. Nitrogen rates of 0, 18, 36, 72, and 144 mMN pot−1 were applied at 2‐wk intervals beginning 13 and 26 d after emergence in 1987 and 1988 through boll maturity to a greenhousegrown cultivar, Stoneville 213. The strong relationship between leaf N and leaf area and boll number (r2 = 0.80 and r2 = 0.89) 1 wk after first flower appearance suggests that the transition period between vegetative and boll development is a critical time to assess cotton's N status in relation to yield. Nitrogen deficits had little effect on boll weight, boll period duration, and number of main stem nodes. Although boll weight decreased with increasing N deficit, final boll weight of the high‐N plants were within 20% of the plants receiving low N supply. The relationship between leaf N and petiole NO3 content, was best described by Y = a + bXC; however, with this function only one‐half of the variation in leaf N was accounted for by variation in petiole NO3 content (r2 = 0.48). Leaf area and boll number were poorly correlated with petiole NO3 content. Leaf N content was a better predictor of cotton vegetative growth (as indicated by LAI) and boll number than petiole NO3 content, particularly when measurements are made 1 wk after first flower.

EFFECT OF DIFFERENT PICKINGS ON THE QUALITY OF UPLAND COTTONS

Overall, in all the varieties studied, higher mean fibre length values were recorded in second picking with desirable bundle tenacity and micronaire value over other pickings. The extent of variation in fibre properties differed between boll maturation periods. Pickings had significant effect on quality of fibre suggesting picking-wise marketing of the produce to get premium price in the market.

Response of Fast Fruiting Cotton Cultivars to Nitrogen on a Clayey Soil

The present cotton (Gossypium hirsutum L.) N recommendations for Arkansas were developed primarily on silt loam and sandy loam soils, but interest in cotton production on clayey soils has increased. The objective of this study was to determine the appropriate quantity of N for the new faster fruiting cotton cultivars grown on clayey soils. Experiments were conducted from 1988 to 1990 on a Sharkey silty clay (very fine, montmorillonitic, nonacid, thermic, Vertic Haplaquept) at Keiser, AR. The response of cotton cultivars 'Deltapine 20', 'Deltapine 5O', 'Stoneville 453', and 'Stoneville 506' were evaluated at five N rates (O, 50, 100, 150, and 200 lb/acre). Cultivars were found to respond similarly to increasing N fertilizer. These cultivars yielded differently each year but averaged the same across years []

Simulated larval feeding damage patterns ofHeliothis armigera(Hübner) andH. punctigera(Wallengren) (Lepidoptera: Noctuidae) on cotton in Australia

Abstract Damage by Heliothis armigera (Hübner) and H. punctigera (Wallengren) was simulated by incorporating into a fruit predation model, the effects of host (structure) preference, larval and fruit age‐specific consumption rates, fruit (age class) availability, and seasonal larvae age class availability. The two species showed similar patterns of damage. Differences emerged when fruit and instars were separated by age class. The first‐, fourth‐and fifth‐instar H. armigera larvae damaged more fruiting structures than respective stages of H. punctigera and conversely for other instars. Larvae of H. armigera damaged a greater number of older structures, while those of H. punctigera generally preferred and damaged more younger structures. Numbers of fruiting structures damaged, especially small and medium squares, decreased throughout the season and only increased with cotton regrowth at the end of the season. Damage to large squares occurred throughout the season. Flower damage fluctuated. For small, medium and large bolls, damage increased, and then decreased late in the season. For both species the proportion of bolls representing the larval diet increased with larval age and as the season progressed. The relative control threshold values of H. armigera were obtained by dividing the product of the number of fruiting structures damaged by this species and their mean scalar age, by the corresponding product for H. punctigera. The relative threshold for each species is hence the inverse of the other. The relative control threshold for H. armigera decreases with time, whereas the reverse trend was thus obtained for H. punctigera. These trends indicate the increasing (with time) need to control H. armigera populations more than that of H. punctigera to better protect the fruiting structures during peak squaring and early boll maturation periods. Such differences should be incorporated into an integrated pest management programme for the two species.

Seasonal History and Damage Caused by Neurocolpus nubilus (Hemiptera: Miridae) on Cotton in Northern Mississippi

Adult clouded plant bugs, Neurocolpus nubilus (Say), were caged for 2 d on individual cotton plants ( Gossypium hirsutum L.) during two stages of plant physiological development. Regression analyses of number of plant fruiting structures and yield on insect densities indicated that feeding by N. nubilus at the peak squaring period caused shedding of small pinhead squares and delayed crop maturation, although with no significant effects on total yield. The effects of N. nubilus feeding were less apparent at boll maturation. Observations of cotton fields with a history of N. nubilus infestations and analysis of data collected by the Mississippi Cooperative Extension Service in northern Mississippi indicated that N. nubilus overwinters in the egg stage, develops its population on several host plants, and moves to cotton during late season, when cotton is less susceptible to its damage.

EVALUATING DECISION CRITERIA FOR IRRIGATION SCHEDULING OF COTTON

ABSTRACT Irrigation scheduling methods using three threshold canopy temperatures (28 C, 30 C, and 32 C) were compared with soil water balance methods that replaced depleted soil moisture weekly (SWR) or at approximately two-week intervals (AUS) and a treatment that received only preplant irrigation (DRY). The largest quantity of water applied (rainfall plus irrigation) was to SWR (138 cm). The quantities for AUS (75 cm) and 28C (70 cm) treatments were similar, followed by 30C (46 cm) and 28 C (70 cm) treatments were similar, followed by 30C (46 cm), 32C (36 cm), and DRY (18 cm). Water used by these treatments was 133, 75, 78, 52, 46, and 29 cm, respectively. Volumetric soil profile moisture content of 0.28 in the SWR and AUS treatments at the end of the season showed little depletion while the 28 C, 30 C, and 32C treatments were lower at 0.24. Average canopy temperatures during the period DOY 187-274 when net radiation exceeded 200 w/m^ were 26.0, 26.8, 27.8, 24.1, 25.3, and 28.9 C, respectively, for 28 C, 30 C, 32 C, SWR, AUS, and the DRY treatments. Above 600 w/m^, the difference between canopy and air temperature increased in the 30 C, 32 C, and DRY treatments indicating water stress. Lint yield was positively related to water applied and water used, except for the SWR treatment. Rate of boll maturity was highest in the three threshold canopy temperature and DRY treatments. Cotton fiber length was decreased by water stress, micronaire value was reduced by low temperature, and fiber strength was reduced by either high water stress or low canopy temperature. Irrigation scheduled by threshold canopy temperature permits automated decision-making of both application time and amount.

Seasonal Leaf Area‐Leaf Weight Relationships in the Cotton Canopy

AbstractSpecific leaf area (SLA), the ratio of leaf area to leaf dry weight, is used in crop simulation models to estimate total leaf area or dry weight. This experiment was designed to study changes in SLA in various parts of a cotton (Gossypium hirsutum L.) canopy throughout the growing season. The main stem of the cotton plant was divided into five‐node segments. Leaf area and leaf dry weight were measured for each segment throughout the growing season. The mean seasonal SLAs for the segments from the bottom to the top of the canopy were 26.2, 25.6, 20.9, 19.4, and 18.1 m2 kg−1. Except for the uppermost segment, SLA increased from 43 to 90 d after emergence (DAE) and declined from 100 DAE. The decline coincided with boll maturation but also with canopy defoliation. It was possible to account for 93% of the variation in SLA for all segments by plotting SLA against light flux density within the cotton canopy. Variations in SLA with time, growth stage, and leaf maturity were small to insignificant when variation due to light flux density was removed. Sampling for SLA should include leaves throughout the crop canopy. Modelers who use SLA to estimate total leaf area or dry weight should determine the relationship between SLA and light flux density for their particular crop.

Response of Leaf Ontogeny and Photosynthetic Activity to Reproductive Growth in Cotton

This study was conducted to determine if reproductive growth in cotton (Gossypium hirsutum L.) affects concurrent leaf development. Apparent photosynthesis (AP), stomatal conductance (Cs), soluble protein (SP), ribulose bisphosphate carboxylase (RuBisCO), and chlorophyll (Chl) were monitored in four main-stem cotton leaves which emerged at approximately 2 week intervals. The leaf which emerged during vegetative growth (48 days after planting) had higher AP, SP, and RuBisCO levels than that present in any leaves which emerged during fruit development. The last leaf studied (89 days after planting) was still present after boll maturation was completed and exhibited a rejuvenation in AP, SP, RuBisCO, and Chl starting at 30 days after leaf emergence. At 96 days after planting, the P700 Chl a-protein complex (PSI) was virtually absent from the leaves that emerged at 48 and 62 days after planting. The light harvesting Chl a/b complex was still present in these leaves, indicating greater degradation of PSI. The data emphasize the influence of developing fruit on concurrently developing leaves, an effect which was alleviated after boll maturation was completed. The declining AP per unit leaf area and smaller leaf size at the top of the plant results in a reduced photosynthetic potential of successively later emerging leaves. This reduction in leaf AP is consistent with earlier reported seasonal canopy photosynthesis patterns.

Cotton lint yield accumulation rate and quality development

Abstract Crop production management during the period of boll setting and maturation of cotton (Gossypium hirsutum L.) is critical in determining lint yield and quality. A field investigation conducted at Lubbock, Texas, during 1977–1980 included three cultivars to study the effect of temperature on factors that influence the rate of cotton yield accumulation and the development of lint quality parameters. A linear regression of physiological days (heat units) explained 93% of the variation in prebloom period expressed in days. The number of physiological days needed to complete the prebloom period was negatively related to average daily temperature in a linear manner and included a significant cultivar effect. The length of the boll setting period was determined by temperature and plant moisture stress. In the absence of plant water stress, 20–25 physiological days were needed to complete boll setting. The length of time to fully mature bolls was related to air temperature in a negative exponential manner (r2 = 0.85) with little direct influence of plant water stress or effect of cultivars. Average boll weight of crop increments fluctuated, but the only trend across years was for the mean boll weight of the last two crop increments to be smaller than the average for the total crop. However, there was a direct correlation between the percentage of total bolls set and percentage of final yield. Fiber micronaire was correlated with temperature in a positive linear manner. In the absence of significant plant water stress, temperature explained 80–90% of the micronaire values of individual cultivars compared with 60% when moisture stress conditions were included. An average crop boll temperature of 27°C appears adequate to achieve maximum development of fiber micronaire. Fiber strength also displayed a linear increase as boll period temperature increased, with coefficients of determination ranging from 0.60 to 0.77 among cultivars. Plant water stress significantly reduced micronaire values but had little effect on fiber strength. Fiber length was not affected by the range of environmental conditions during the four-year period of the study.

Effect of Removal of Bracts and Bagging the Flowers on Boll and Seed set in CBS 156 Hybrid Cotton

With the parents of CBS 156 hybrid cotton viz.. Glandless Acala and SB 1085-8 stu- dies were conducted to find out the effect of removal of bracts and bagging the flowers on seed set. Removal of bracts significantly reduced the boll maturation period, number and weight of seeds per boll and 100-sued weight. However, there was no significant reduction in the percentage of boils set.

Bollworm Damage and Yield of Cotton Infested at Different Time Periods1

By confining females and males of Heliothis zea (Boddie) to cotton in field screen cages for 2 nights, egg lay and subsequent larval populations were produced during five time periods from early squaring to late boll maturation. The results imply that colton can compensate for high levels of bollworm damage up to late July when grown under irrigated condition. Larval densities for the later periods of infestation were suppressed by high larval mortality, apparently predation induced, to a level that damage was very limited and the importance of such damage was not determined.

Stormproof Boll in Upland Cotton III. Genotype‐Environment Interaction and Genetic Analysis1

Stormproofness (lock tenacity) of cotton (Gossypium hirsutum L.) was defined as the amount of force required to extract a locule of seedcotton from the bur of a mature boll. Six entries representing the range of variability in stormproofness of Upland cotton were grown in seven environments to study the relationship of the character to temperature and precipitation. In a separate experiment, a complete diallel set of crosses among the six entries was grown for 2 years to estimate general (GCA) and specific combining ability (SCA) associated with the inheritance of the stormproof trait.In general, stormproofness increased as temperature during the boll maturation period decreased or seasonal precipitation increased. Temperature appeared to influence stormproofness more than precipitation, although responses among the entries varied. ‘Acala 1517 BR‐2,’ TM‐1, Contextum, and ‘Macha’ were more responsive to temperature than to precipitation. Unique Stormproof was about equally influenced by both variables, and ‘Lankart Sel. 57’ was most responsive to precipitation. Results from the genetic study revealed that significant GCA and SCA effects were associated with the expression of stormproofness, but that the SCA effects were small and hybrids tended to be intermediate between their respective parents. The GCA effects interacted with years primarily as a result of relative changes in lock tenacity between the stormproof and nonstormproof cultivars. A relationship between lock tenacity and the percentage of storm loss (seedcotton that fell on the ground) showed that hybrids between non stormproof cultivars may suffer relatively high storm losses.

Role of Minimum and Maximum Environmental Temperature on Maturation Period of the Cotton Boll1

AbstractTemperature is critical in boll formation, and in temperate climates earliness is one of the main breeding objectives. The effect of night and day temperature on the boll maturation period of five genetically divergent cultivars of cotton (Gossypium hirsutum L.) was studied in a 3‐year field experiment at Sindos, Greece. Under a 24‐hour cycle (mean temperature 18 to 32 C) night temperature shortened the boll period up to five times more than day temperature. Under a range of 16 to 30 C, day temperature favored boll maturation four to six times greater than night temperature did. The favorable or adverse effect of mean day and night temperature depended on the maximum and minimum temperatures.