Boll Distribution Research Articles

Nitrogen Reduction and Organic Fertiliser Application Benefits Growth, Yield, and Economic Return of Cotton

The application of excessive nitrogen fertiliser has been found to have a detrimental impact on the growth and development of cotton in Xinjiang, China. This has resulted in a reduction in cotton yield and economic benefit. The aim of this study was to investigate the potential for reducing the input of inorganic N fertiliser while maintaining the quality and yield formation of cotton. The objective of this study was to examine the growth, photosynthesis, and yield of cotton crops subjected to varying fertiliser treatments. The experiment was conducted in 2021–2022 with eight treatments in the experiment: no fertiliser (CK); conventional application of inorganic nitrogen fertiliser (T0); T1–T3, with 8%, 16%, and 24% reduction in inorganic nitrogen fertiliser application, respectively; and T4–T6, with organic fertilisers replacing the reduced inorganic nitrogen fertiliser application of T1–T3, respectively. In comparison to T0, T5 demonstrated the most notable agronomical performance and yield components across both years. This is attributable to the spatial distribution of cotton bolls, which was more conducive to the net photosynthetic rate and yield formation. This, in turn, led to an augmented photosynthetic capacity, enhanced biomass accumulation, and an elevated harvesting index. The results of the economic benefit analysis demonstrated that in comparison to the control treatment (T0), the net profit of all treatments except T3 increased. In conclusion, the economic benefit reached its maximum in the range of a 9.90–14.10% reduction in nitrogen and a 16.60–17.60% substitution of organic fertiliser.

Fourier Transform Infrared (FT-IR) Spectroscopy and Simple Algorithm Analysis for Rapid and Non-Destructive Assessment of Cotton Fiber Maturity and Crystallinity for Plant Mapping.

Information on boll distribution within a cotton plant is critical to evaluate the adaptation and response of cotton plants to environmental and biotic stress in cotton production. Cotton researchers have applied available conventional fiber measurements, such as the high volume instrument (HVI) and advanced fiber information system (AFIS), to map the location and the timing of boll development and distribution within plants and further to determine within-plant variability of cotton fiber properties. Both HVI and AFIS require numerous cotton bolls combined for the measurement. As an alternative approach, attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy was proposed to measure fiber maturity (MIR) and crystallinity (CIIR) of a sample as little as 0.5 mg lint. Extending fiber maturity and crystallinity measurement into a single boll for node-by-node mapping, FT-IR method might be advantageous due to less sampling amount compared with HVI and AFIS methods. Results showed that FT-IR technique enabled the evaluation of fiber MIR and CIIR at a boll level, which resulted in average MIR and CIIR values highly correlated with HVI micronaire (MIC) and AFIS maturity ratio (M). Hence, FT-IR technique possesses a good potential for a rapid and non-destructive node-by-node mapping of cotton boll maturity and crystallinity distribution.

Boll distribution of cotton effected by varying potassium rates within different irrigation levels

AbstractCotton (Gossypium hirsutum L.) requires potassium (K) in large amounts for crop growth and development and is more sensitive to low K availability in soils than other agronomic crops. Low K concentrations within the plant may decrease the rate of photosynthesis, which will impact plant growth and development. Cotton yield potential has increased due to genetic improvements, which may have increased the quantity and rate at which cotton takes up K. This research aimed to determine the effect of K fertilizer rates within irrigation level on boll distribution and yield contribution from specific node zones. This study was conducted at New Deal, TX in 2016 and 2017. Muriate of potash (KCl) was applied using knife injection at rates of 0, 45, 90, 135, and 180 kg K h−1 with 80% and 30% evapotranspiration (ET) irrigation levels. Differences were not noted for estimated box mapping yield between K rates in 2016 (p = 0.3996). When 180 kg K ha−1 was applied, total bolls and estimated box mapping yield within 30% ET increased in the early and middle node zones and total nodes over all other K application rates in 2017. It was observed with box mapping that the early and middle node zones were able to utilize applied K more effectively due to the increase in bolls and yield compared to the late and vegetative node zones. Our results suggest that K is an important nutrient in cotton production due to the impacts it has on the early and middle node zones.

Boll distribution in the cotton canopy is affected by nitrogen management and cover crops in a sandy soil under water scarcity

Context or problemA favorable cotton boll distribution within the plant canopy can promote early fruit retention and increase crop yield and fiber quality, particularly in rainfed crops in sandy soils that are subject to periodic water deficits. However, the effects of different cover crop rotation systems combined with different nitrogen (N) rates and sources on boll distribution and cotton earliness are unknown. Objective or research questionThe objective of this study was to evaluate the boll distribution and earliness of cotton as a function of the cover crop rotation system and N sources and rates, in a sandy soil of a tropical region of Brazil prone to drought. MethodsA field study was carried out for two growing seasons (2018–2020) in southeastern Brazil in an area with sandy soil. The treatments consisted of the following crop rotation systems, which were implemented in 2016: Fallow; single grass; grass + grass; grass + legume; and MIX (grass+legume+grass). In addition, N rates of 70, 100, and 130 kg ha−1 (applied as topdressing) and two N sources (urea; and controlled-release urea, CRU) were evaluated. ResultsLow water availability in the 2018/2019 crop season resulted in early plants that reached 95% boll yield below fruiting node 12 when 70 kg ha−1 N (urea) was applied. Satisfactory rainfall in the 2019/2020 crop season resulted in 95% boll yield below fruiting node 14 when 130 kg ha−1 N was applied for all N sources and rotation systems. Applying CRU increased the boll distribution in the top third of the plant. Applying 130 kg ha−1 N increased the boll distribution in the middle and top thirds of the plant, particularly in the treatments with legume cover crops and CRU. In the crop season with higher rainfall and yield potential, the rotation systems without legumes that received 70 kg ha−1 N (urea) had a lower boll distribution in the top third of the plant. ConclusionsCotton boll distribution is affected by cover crop rotation systems, N rates and sources and water availabity throughout the season. The best strategy for improving early boll setting is to apply lower rates of N as CRU in a rotation system with a mixture of grasses and legumes as cover crops. Additionally, there is still a challenge to increase the cotton earliness in years with high water availability. Implications or significanceCover crops and increased efficiency fertilizers are important to improve boll setting throughout the entire cotton canopy. Because these technologies improve the availability of nitrogen and water in the soil, especially in dry years. Improving cotton earliness is still a challenge in low-altitude regions, since plant cycle is naturally short in these environments, due to the greater accumulation of degrees days. Even so, the use of lower N rates associated with cover crops and controlled-release urea may have a small increase in cotton earliness, but mainly help in early fruit retention.

EFFECT OF SOWING TIME IN COTTON (GOSSYPIUM HIRSUTUM L.) ON BOLL DISTRIBUTION, CELLULOSE RATIO AND FIBER QUALITY

The growth, flowering, square, and boll formation of the cotton plant are significantly affected by sowing time and fruiting distributions. This study was carried out in order to determine the effect of sowing time, varieties and boll distribution on fiber yield and fiber quality of cotton, under the GAP region ecological conditions of Türkiye during 2017 and 2018 cotton growing seasons. In this study, Candia and Lima cotton varieties were used as plant material. Cotton seeds were sown on 5 May (normal sowing) and 10 June (late sowing) using a pneumatic seeder in both years. In the study, the number of bolls (per plant-1), yield per plant (g plant-1), boll weight (g), ginning outturn (%), holocellulose, cellulose, scan viscosity, and polymerization degree were studied. According to the research, the number of bolls, boll weight, and fiber yield were higher in normal planting than in late planting. The low positional sympodial branch (1-5 fruit branches) boll position was better in the number of bolls, and the middle positional sympodial branch (6-10 fruit branches) was better in boll weight compared to other positions. The fiber yield obtained in a low positional sympodial branch (1-5 fruit branches) and middle positional sympodial branch (6-10 fruit branches) positions was higher than the upper positional sympodial branch position (11 and higher fruit branches). The effects of sowing times and cultivars on cellulose and holocellulose rations were statistically insignificant. The cellulose ratio (94.40) obtained in the upper positional sympodial branch position (11 and higher fruit branches) in the first year was higher than the other sympodial positions, while the effect of the boll position was statistically insignificant in the second year of the experiment. In conclusion, the planting time had a significant effect on boll positions and fiber quality of cotton. Late sowing had negative impact on boll maturation, cellulose synthesis, yield and fiber quality. Hence, the delay in cotton planting caused a decrease in yield; so, cotton should be sown as early as possible in the region. Keywords: Cotton, sowing date, boll position, boll weight, fiber quality

Optimizing plant type structure to adjust the temporal and spatial distribution of water consumption and promote the growth and yield formation of cotton

Global warming leads to further shortage of agricultural water resources. Understanding the water consuming characteristics of different cotton cultivars is crucial for efficient utilization of water resources and yield increasing. However, there is little evidence about the effects of cotton cultivars with different plant-type structures on yield formation and temporal and spatial distribution of water consumption. A two-year experiment was conducted at the Cotton Research Institute of the Chinese Academy of Agricultural Sciences in 2020 and 2021 to evaluate the water consumption of six cotton cultivars with different plant-type structures cotton using spatial grid method and water balance method combined with 5TE sensor. The leaf area index (LAI), biomass, yield and spatial distribution of bolls were also measured and analyzed. The results showed that the loose-type cultivars consumed more soil water than the compact-type cultivars, which was due to the higher water consumption in the 40–120 cm soil layer. The cumulative water consumption and water consumption of each soil layer (0–40 cm 40–80 cm and 80–120 cm) of different cotton cultivars had significant quadratic function relationship with LAI, and had significant linear positive correlation with biomass accumulation (aboveground biomass and underground biomass), with R2 greater than 0.8. When consuming the same amount of water, loose-type cultivars produced more biomass and larger green leaf area than compact-type cultivars. However, the yield-increasing and water-saving effects of the two plant-type structure cotton cultivars were similar, while SCRC 28 and Ji 228 have higher yield and water use efficiency (WUE), which were suitable to be popularized and planted in the cotton area of the Yellow River basin. Cotton yield was significantly negatively correlated with boll setting rate in upper canopy and water consumption in 0–40 cm soil layer, and the R respectively were − 0.82 and − 0.69; it was positively correlated with boll setting rate in lower canopy and water consumption in 80–120 cm soil layer, and the R respectively were 0.75 and 0.64. Therefore, increasing the WUE of 0–40 cm soil layer and water consumption in 80–120 cm soil layer was beneficial to high yield of cotton. By optimizing the structure of different plant types, the temporal and spatial distribution of water consumption of cotton can be adjusted, and the yield of cotton can be effectively improved. The results can provide a basis for cotton cultivar selection and precision irrigation management.

Cover cropping history affects cotton boll distribution, lint yields, and fiber quality

AbstractThere has been limited introduction of new cover crop species into cotton (Gossypium hirsutum L.) production within the last 30 years. Mounting evidence shows that traditional cover cropping species may be detrimental to cotton production, either by depleting soil fertility with crop removal, immobilizing minerals from high carbon residue, or excessive quantity of residue remaining at planting. The objective of this study was to determine the effects of growing a novel cover crop species, carinata (Brassica carinata A. Braun), as a winter annual cover crop for cotton rotation in the southeastern Coastal Plain. Over a 2‐year period, carinata, winter wheat (Triticum aestivum L.), and fallow covers were maintained over winter months, then rotated into cotton. Each year, seedcotton and lint yields were collected, along with subsamples for ginning and subsequent fiber quality analyses. Additionally, end‐of‐season plant mapping was conducted on plants from 1 m of row per plot to determine cover crop effects on boll formation, retention, and distribution, as well as canopy architecture. Results indicated that seedcotton and lint yield of cotton following carinata was greater than cotton following winter wheat, and lint yields of cotton following wheat were lower than cotton after fallow. Fiber quality was largely unaffected by preceding cover crop. End‐of‐season plant mapping indicated that cotton grown after carinata had more position 2 bolls, which correlated to greater lint yields. These results indicate that carinata can potentially serve as a new, more effective cover crop than winter wheat for cotton rotations in Coastal Plain soils.

Chemical Topping with Mepiquat Chloride at Flowering Does Not Compromise the Maturity or Yield of Cotton

The balance between vegetative and reproductive growth is the central objective in the cotton production system, which is associated with cotton maturity and yield. In China, manual topping (MT) has been performed many years prior to or during the flowering period to inhibit vegetative growth and enhance reproductive growth. MT is gradually being replaced by chemical topping (CT) with mepiquat chloride (MC, 180 g ha−1, 98% soluble powder) due to labor shortages and increasing labor cost. To determine whether CT influences cotton maturity and yield relative to MT, we carried out field experiments at four locations in the Yellow River Valley of China during 2018–2020. The results showed that CT did not alter the boll age, and although it produced taller and slender spatial boll distribution under several environments, it had little effect on the accumulation of boll fraction (the number of bolls in a given period divided by total boll number) over time at the end of blooming across locations. As a result, there were no significant differences between MT and CT in boll opening percentage in the late season. CT did not influence yield or yield components, except under severe drought. Therefore, CT with MC (180 g/ha, 98% soluble powder) during the flowering period will not compromise the maturity or yield of cotton in the Yellow River Valley of China. Similar outcomes would be achieved in other areas with similar ecological conditions and social conditions that require an alternative to extensive manual labor.

Modifying the planting density to change water utilization in various soil layers and regulate plant growth and yield formation of cotton

Planting density management can regulate cotton (Gossypium hirsutum L.) biomass accumulation and seed cotton yield formation, which are associated with water consumption. However, it is unclear whether modifying the planting density affects the water use in different soil layers and thus regulates the plant growth and yield formation of cotton. In a two-year field experiment in 2020–2021, cotton was grown at various plant densities (1.5, 3.3, 5.1, 6.9, 8.7, and 10.5 plants m−2), and the spatial profile of water consumption, plant height, the leaf area index (LAI), biomass accumulation, and seed cotton yield were evaluated. The results showed that increase in planting density leads to more water consumption in the middle and lower soil layers (40–80 and 80–120 cm), and improved water use efficiency (WUE) in each soil layer (0–40, 40–80, 80–120 and 0–120 cm). The difference in plant height was attributed to cumulative total water consumption (0–120 cm), and the variation in LAI was due to planting density and cumulative total water consumption. More aboveground biomass at higher planting density was mainly attributed to more water consumption of the middle and lower soil layers (40–80 and 80–120 cm). Additionally, excessively high planting density may lead to the premature senescence of root systems, as the correlation between the water consumption at 40–100 cm and belowground biomass was weaker under high planting density. Moreover, the WUE at 0–40 cm was proportional to the boll distribution on the lower part (1st-6th fruiting branches) of the plant and boll number per unit area, was inversely proportional to boll weight and harvest index (HI), and had parabolic relationship with seed cotton yield (y = −426.83 +244.50–3.48x2). Taken together, our data focused on the effects of water use in various soil layers induced by planting density on cotton growth and yield formation; moreover, these findings fill knowledge gaps within cotton science and provide a feasible direction for determining reasonable water management practices on the North Plain China.

Nitrogen fertilization can mitigate cotton yield loss by temporary shading at early flowering

Cotton (Gossypium hirsutum L.) yield is decreased under low radiation, but there are few reports on possible interactions of N fertilizer application and light limitation on cotton production. The objective of this work was to evaluate growth, yield components, and boll distribution in cotton as affected by N rates under light restriction. Three experiments were conducted for two years in Central (Primavera do Leste and Chapadão do Sul) and Southeastern (Itapeva) Brazil. Cotton plants were shaded at early flowering to a 42 % reduction in global radiation for 16–25 days. Four N rates were used in Primavera do Leste and Itapeva; and three N rates and two genotypes, an early- (FM 906GLT) and a late-maturing (FM 983GLT) cultivar, were used in Chapadão do Sul. Shading decreased lint yield by 10 % in Primavera do Leste and by 12 % in Chapadão due to 24 % and 32 % reduction in boll number at the lower third of the plant, respectively. In Itapeva, the number of bolls at the lower fruiting branches was decreased 19% by shading, but a 10% lint yield reduction was observed only with 35 kg ha−1 of N. As to the main effects, lint yield and number of bolls increased with N rates up to 155, 142 and 105 kg ha−1, depending on the site. Lint yield of shaded plants was more responsive to higher N rates, which also increased plant height, number of bolls and the main stem node number of the last fruiting branch. Cotton cultivars had similar lint yields despite differences in boll distribution. At lower fruiting branches, the early-maturing cultivar showed an average boll number 59 % higher, but the late one produced 81 % and 63 % more bolls on the upper branches at 105 and 185 kg ha−1 of N, respectively. We concluded that N-deficiency inhibited the recovery of cotton from losses caused by shading, whereas a high-N availability minimizes damages after shading during blooming.

Irrigation management impacts on cotton reproductive development and boll distribution

AbstractCotton (Gossypium hirsutum L.) reproductive development is affected by irrigation management and reduced soil moisture, leading to yield impacts. This study was conducted to determine how irrigation timing and reduced soil moisture affects the distribution of cotton reproductive structures throughout the canopy. Reduced soil moisture was achieved through varied irrigation amounts based on recommendations from an agroecosystem model. Plants from each irrigation treatment were destructively sampled bi‐weekly and squares, green bolls, and abscissions were counted on mainstem fruiting branches. Plant height, leaf area, and dry weights of squares, flowers, and green bolls were measured. Reduced irrigation from first square to peak bloom reduced the number of green bolls in the lower middle quarter of mainstem nodes, where most bolls are located. Reproductive development and growth were most sensitive to reduced soil moisture treatments and irrigation rates from squaring to peak bloom, whereas the period from peak bloom to 90% open boll was unaffected by irrigation rates.

Early Relay Intercropping of Short-Season Cotton Increases Lint Yield and Earliness by Improving the Yield Components and Boll Distribution under Wheat-Cotton Double Cropping

Wheat-cotton double cropping has improved crop productivity and economic benefits per unit land area in many countries, including China. However, relay intercropping of full-season cotton and wheat, the most commonly adopted mode, is labor-intensive and unconducive to mechanization. The direct sowing of short-season cotton after wheat (CAW) has been successful, but cotton yields and economic benefits are greatly reduced. Whether the relay intercropping of short-season cotton before the wheat harvest increases cotton yields remains unclear, as does the earliness and fiber quality relative to those for CAW. Therefore, we directly planted short-season cotton after wheat harvest on 15 June (CAW) as the control and interplanted short-season cotton in wheat on 15 May (S1), 25 May (S2) and 5 June (S3), which were 30, 20 and 10 days prior to wheat harvest, respectively, from 2016 to 2018. The crop growth, yield, yield components, boll distribution, and earliness of the cotton were evaluated. The yields and earliness of short-season cotton under relay intercropping were 26.7–30.6% and 20.4–42.9% higher than those under CAW, respectively. Compared with CAW, relay intercropping treatments increased the boll density, boll weight and lint percentage by 5.6–13.1%, 12.5–24.5% and 5.8–12.7%, respectively. The dry matter accumulation and harvest index under the relay intercropping treatments were also greater than those under CAW, which might be attributed to the greater partitioning of dry matter to the seed cotton than to the boll shells. Among the relay intercropping treatments (S1, S2 and S3), the lint yield did not differ, but S1 and S2 were considerably better than S3 based on earliness and fiber quality. The analysis of the within-plant spatial boll distribution showed that more bolls were formed on the lower to middle fruiting branches and at the first fruiting sites for S1 and S2 than for S3 and CAW. Therefore, the increased earliness and fiber quality induced through early relay intercropping (S1 and S2) could be attributed to an improved spatial boll distribution compared to late relay intercropping (S3) or CAW. Conclusively, compared to late relay intercropping and CAW, early relay intercropping considerably increased the lint yield, fiber quality, and earliness by improving the yield components, boll distribution, and dry matter accumulation and partitioning. The relay intercropping of short-season cotton 20 to 30 days before wheat harvest represents a promising alternative to CAW in wheat-cotton double-cropping systems in the Yellow River Basin of China and other regions with similar conditions.

Inhibition of apical dominance affects boll spatial distribution, yield and fiber quality of field-grown cotton

Apical dominance inhibition is important in cotton (Gossypium hirsutum L.) production due to its indeterminate growth habit. Apical dominance can be inhibited physically by the manual removal of apical buds or chemically by the application of plant growth regulators. However, knowledge of the yield and boll distribution of cotton under different methods of apical dominance inhibition remains limited. Thus, an experiment was conducted to evaluate the effects of different methods of apical dominance inhibition (physical inhibition, chemical inhibition and no inhibition) on the plant growth, within-plant boll distribution, crop maturity, yield and fiber quality of cotton from 2016 to 2018. Compared with no inhibition, chemical inhibition and especially physical inhibition reduced plant height, whereas only physical inhibition promoted the ratio of fruiting sites to fruiting branches, which indicated that chemical inhibition resulted in a more compact plant type than physical inhibition. Earlier crop maturity was observed with both physical and chemical inhibition methods than without inhibition, and this finding was attributed to a higher number of inner bolls at lower and middle nodes. The lint yield response to the different inhibition methods varied among years and between varieties. The lint yield of XIN4 was significantly enhanced by physical inhibition and chemical inhibition in 2 of the 3 years, by an average of 11.5 % and 8.7 %, respectively. An effect of inhibition method on the lint yield of CRI60 was observed only in 2016, in which physical inhibition significantly improved the lint yield by 14.0 % compared with that obtained without inhibition. Chemical inhibition achieved a similar lint yield to physical inhibition in all three years. Fiber quality was slightly reduced under chemical inhibition compared to physical inhibition, but the values were within the acceptable range regarding grade standards. Overall, although apical dominance inhibition did not consistently improve lint yield, it remains a desirable management tool for achieving a favorable cotton architecture for mechanical harvest. Additionally, chemical inhibition appears to be a promising alternative to physical inhibition in cotton production due to its simplicity as a management tool.

Foliar melatonin stimulates cotton boll distribution characteristics by modifying leaf sugar metabolism and antioxidant activities during drought conditions.

Drought is a severe abiotic stress affecting the plant's antioxidant system and interrupting compatible solute translocation processes, which leads to low productivity. Melatonin acts as a common growth regulator enhancing the plants defense system and regulates sugar metabolism in challenging environments. Melatonin treatments enable plants to be tolerant to abiotic stresses via enhancing their recovery potential, but its impact using various concentrations has not yet been studied in leaf physiological aspects when applied to cotton foliage during their peak flowering and boll loading stage. The overall objective of this research was to facilitate cotton boll distribution characteristics by modifying cotton leaf sugar metabolism and antioxidant activity by applying foliar melatonin (0, 25, 50, and 100 μmol l-1 ) under drought levels with a relative soil water content of 75%, 60%, and 45% ± 5 (FC1, FC2, and FC3, respectively). Higher rates of melatonin application (100 μmol l-1 ) enhanced boll distribution characteristics and controlled the boll shedding rate during drought conditions. An increase in melatonin rates proved to be more helpful in stimulating cotton sympodial leaf physiological attributes, including leaf gas exchange parameters, sugar metabolism, proline content, and antioxidants defense system as compared with less or no melatonin application during all FC conditions and showed the most significant effect at a higher melatonin concentration (M100) at 7-21 DAF. The total proline content and antioxidant activity were enhanced in the M100 treatment during all FC levels, which caused a reduction in the total malondialdehyde (MDA) contents and hydrogen peroxide (H2 O2 ) concentrations in cotton leaves. Moreover, sugar metabolism responsible genes GhSusA and SPS2 showed an upsurge in expression levels and enhanced sucrose degradation in M100 treatments during all FC levels. Furthermore, cotton boll attributes showed also a positive relation with leaf physiological and gas exchange attributes. The results suggested that foliar melatonin application during the flowering initiation stage improved the overall performance and is helpful for cotton crops productivity against drought stress.

High plant density increases seed Bt endotoxin content in Bt transgenic cotton

Plant density is the cultivation practice usually employed to manipulate boll distribution, boll setting and yield in cotton production. In order to determine the effect of plant density on the insecticidal protein content of Bacillus thuringiensis (Bt) cotton plants, a study was conducted in Yangzhou University of China in 2015 and 2016. Five plant densities (PD1-PD5, representing 15000, 30000, 45000, 60000, and 75000 plants ha−1) were imposed on two Bt cotton cultivars, Sikang 1 (the conventional cultivar, SK-1) and Sikang 3 (the hybrid cultivar, SK-3). The boll number per plant, boll weight and boll volume all decreased as plant density increased. As plant density increased from 15000 to 75000 plants ha-1, seed Bt protein content increased, with increases of 66.5% in SK-1 and 53.4% in SK-3 at 40 days after flowering (DAF) in 2015, and 36.8% in SK-1 and 38.6% in SK-3 in 2016. Nitrogen (N) metabolism was investigated to uncover the potential mechanism. The analysis of N metabolism showed enhanced soluble protein content, glutamic-pyruvic transaminase (GPT) and glutamate oxaloacetate transaminase (GOT) activities, but reduced free amino acid content, and protease and peptidase activities with increasing plant density. At 20 DAF, the seed Bt toxin amount was positively correlated with soluble protein level, with correlation coefficients of 0.825** in SK-1 and 0.926** in SK-3 in 2015, and 0.955** in SK-1 and 0.965** in SK-3 in 2016. In contrast, the seed Bt protein level was negatively correlated with free amino acid content, with correlation coefficients of –0.983** in SK-1 and –0.974** in SK-3 in 2015, and –0.996** in SK-1 and –0.986** in SK-3 in 2016. To further confirm the relationship of Bt protein content and N metabolism, the Bt protein content was found to be positively correlated with the activities of GPT and GOT, but negatively correlated with the activities of protease and peptidase. In conclusion, our present study indicated that high plant density elevated the amount of seed Bt protein, and this increase was associated with decreased boll number per plant, boll weight and boll volume. In addition, altered N metabolism also contributed to the increased Bt protein content under high plant density.

Cotton boll distribution: A review

AbstractBoll distribution provides an important assessment of the response and adaptation of upland cotton (Gossypium hirsutum L.) to its environment and is strongly linked to yield and fiber quality and consequently to economic value. Several studies have measured boll distribution through end‐of‐season field or box mapping to study the spatiotemporal characteristics of bolls at both the plant and field levels, to quantify the effects of stress on cotton maturity and fiber quality, and to estimate yield as a function of the relative partitioning of resources to competing sinks. This paper discusses the environmental factors affecting boll production and distribution, reviews methods of measuring and analyzing boll distribution, and discusses the comparative advantages and drawbacks of these methods. With the advent of advanced imaging technologies, this paper also discusses the potential transition from traditional methods to machine‐based boll distribution measurements, the challenges associated with these technologies, and how continuous improvements in the baseline technologies being used in the different methods will translate to improved measurement capacities. Overall, major strides can still be made in the area of boll distribution measurement by combining the positive elements in the different studies described in this review to circumvent each of their respective limitations.

History of USDA-ARS Cotton Host Plant Resistance and Breeding Research at Mississippi State, MS

Cotton host plant resistance research was initiated with the establishment of the Boll Weevil Research Laboratory in 1960. Laboratory objectives were to conduct research and develop technology that ultimately could be used to eradicate the boll weevil. Early research concentrated on developing techniques and screening germplasm for resistance. A full-scale boll weevil eradication trial began in southern Virginia and eastern North Carolina in 1978 and after initial success the USDA Animal and Plant Health Inspection Service established an eradication program. This led the host plant resistance program to broaden its research into other pests of cotton. During the 1980s, research continued to focus on tarnished plant bug, tobacco budworm, expanding the genetic diversity of cotton, basic genetic and cotton breeding studies. With the development of field infestation techniques for the tobacco budworm, in the 1990s the research team conducted the first field test of Bacillus thuringiensis (Bt) transgenic cotton for resistance. During this time, root-knot nematode research expanded. Cotton fruiting efficiency and distribution of harvestable bolls and the concept of plant mapping were developed. During the 2000s, research expanded with the use of chromosome substitution lines for the introgression of new alleles into Upland cotton. Nematode research remained active during this time. To date, the research program has developed and released more than 800 germplasm lines and four random-mating populations. Scientists in the program have trained more than 60 graduate students and countless others have been mentored. The full impact of the research team will only be revealed with time.

The Influences of Different Irrigation Water on Spatial Distribution of Cotton Bolls and Yields

Takeing the jujube orchard intercropping cotton as experimental material In southern Xinjiang to study the influences of different irrigation water on spatial distribution of cotton bolls and yields. Setting the moderate water stress W1 (250 m3/667m2), mild water stress W2(300 m3/667m2), the appropriate moisture W3(350 m3/667m2), the sufficient water supply W4(400 m3/667m2), in total four different irrigation water processing. The results show that : (1) The cotton boll’ shedding rate in different water processing in order W4 > W1 > W3 > W2,the shedding rate of upper and lower is much higher than the middle fruit spur.(2)the effective boll of cotton are mainly in the middle part. (3)The total boll weight of cotton middle fruit spur greater than the total boll weight of fruit spur in the upper and lower. And the lower part’ weight is slightly higher than the upper.(4) The boll weight of upper fruit spur have bigger fluctuations than the lower,each part of the cotton boll weight as W2 > W3 > W4 > W1. (5) Four water treatment have a little effect on lint percent, seed cotton and ginned cotton showed the same trend as W2 > W3 > W4 > W1. Comprehensive consideration in many aspects, the drop irrigation amount 300-350m3/667m2 could as the reference standard of this locality jujube orchard intercropping.

Cotton boll distribution and yield estimation using three‐dimensional point cloud data

AbstractNode‐by‐node boll mapping has been used to determine the effects of several environmental and management strategies, including irrigation rate and cultivar, on cotton (Gossypium hirsutum L.) boll distribution. The advent of consumer 3D digital imaging may make rapid node‐by‐node mapping of greater acreage possible in the future. Effects of irrigation rate and cultivar on boll distribution were determined from line plots of node‐specific boll distribution and boll accumulation estimate data and from vertical box and whisker plots of boll fraction using data collected by a 3D sensor system to rapidly detect open bolls before harvest over three seasons. Differences were observed between the dryland (2018 only), low irrigation, and high irrigation rates in terms of boll fraction and boll accumulation for each cultivar. The low irrigation tended to produce bolls more toward the bottom of the plant, while the high irrigation produced bolls towards the top of the plant. Yield correlation between sensor obtained and manually counted measurements was strong, with r2 values as high as 0.87. Results obtained indicated that differences among irrigation rate and cultivar were identifiable using the sensor system during the 3 yr research study. Similar systems may allow rapid, broad‐scale identification of boll distribution and yield in breeding and physiology research in the future, leading to improved identification of elite cultivars and improved management practices in cotton.

Colonization and Spatial Distribution of Boll Weevil in Commercial Cotton Fields.

The departure and arrival of boll weevil in cotton fields have fostered major control decisions against this pest over time. Field colonization and distribution of boll weevil were evaluated using cotton fields from 93.7 to 154ha each, located in Serra da Petrovina and Campo Verde, both in the Cerrado biome of Mato Grosso State, Brazil, as a function of cotton field bordering vegetation and crop phenology. The monitoring of adult weevils was carried out using traps containing sex and aggregation pheromone. The traps were set up considering the four coordinates of the field, bordering vegetation, and distances from the field margin. Six traps were set in each direction with three representing the field margin (0m, 60m, and 120m from the borderline) and the other three set up equidistant from the center of the field (> 200m). Traps were evaluated weekly beginning 10days after plant emergence (DAE) throughout the cotton phenology until harvesting. Boll weevils were caught in the first evaluation 10 DAE, irrespective of the vegetation bordering the cotton field and distance of trap from field margin. The average weevils per trap was relatively low throughout the crop development but increased significantly through the maturation and harvesting periods. Furthermore, the bordering vegetation was not the only determinant factor for boll weevil colonization and distribution throughout the cotton field. Based on these data, boll weevil exhibited early colonization, already occurring beyond the border of the field.