Nitrogen and zinc effects on cotton yield and quality: Insights from a 6‐year field study

Excessive weathering may diminish cotton (Gossypium hirsutum L.) lint yield and fiber quality to the extent that economic losses occur for the producer. Our objective was to determine the effects of systematic delayed harvest on cotton lint yield, fiber quality, and profitability. Experiments were conducted from 1998 to 2000 at the Coastal Plain Experiment Station, Tifton, GA, on a Tifton loamy sand (fine‐loamy, kaolinitic, thermic Plinthic Kandiudults). The treatments consisted of a standard harvest‐aid combination applied at weekly intervals over a 13‐wk period beginning at first open boll. Harvest aids were applied to each plot according to its week after first open boll designation and machine harvested 2 wk thereafter. After ginning, fiber quality was determined on lint samples from each plot. High volume instrument (HVI) fiber length uniformity was greatest in 1999 and 2000 when harvest aids were applied between 58 and 88% open boll, while the advanced fiber information system (AFIS) fiber length by number coefficient of variation and short fiber content by number were lowest when harvest aids were applied from 40.1 to 46.8% open boll. The HVI upper half mean fiber length and the AFIS mean fiber length by number were greatest when harvest aids were applied between 39.1 and 56.7% open boll. In 1999 and 2000 lint yield and adjusted gross income were greatest when harvest aids were applied from 76.5 to 89.0% open boll. Results from this study indicate optimum fiber quality is established earlier during boll opening than lint yield and profitability.

Yield-enhancing compounds are among the many inputs used in cotton (Gossypium hirsutum L.) production systems across the United States Cotton Belt. Some of these products, however, have not been adequately tested in field settings and their impact on cotton yield and quality is unknown. Messenger, marketed by the Eden Bioscience Corporation (Bothell, WA), is a new product containing a protein that may stimulate the hypersensitive response of higher plants, resulting in increased yields. The objective of our investigation was to determine if Messenger applications would result in enhanced cotton crop maturity, lint yield or fiber quality. Messenger studies were conducted in Colquitt, Grady, and Tift Counties in South Georgia and at the University of Georgia Coastal Plain Experiment Station (UGA-CPES) in Tifton in 2000. Plot size at each location ranged from 1.2 ha (Grady County) to 0.01 ha (UGA-CPES). Messenger was applied as a foliar treatment at several stages of crop development at each location with either a John Deere (Moline, IL) high clearance sprayer or a CO2 backpack sprayer. Mid- and late-season plant maps at each location revealed no significant differences in crop maturity among the treatments. Lint yields in Colquitt, Grady, and Tift Counties and the UGA-CPES averaged 1159, 941, 1292, and 1654 kg ha− 1, respectively with no significant treatment differences within a location. Likewise, Messenger did not significantly affect fiber properties at any location. *Mention of a trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by the University of Georgia, the U.S. Department of Agriculture, or other cooperating agencies and does not imply its approval to the exclusion of other products or vendors that may also be suitable. Messenger, Eden, and Eden Bioscience are registered trademarks of the Eden Bioscience Corporation.

Potassium (K) deficiency reduces cotton (Gossypium hirsutum L.) growth, development, lint yield, and fiber quality. The study's objective was to compare the effects of K fertilizer rate on cotton plant height (CPH), yield, and fiber quality in three cotton cultivars. Three cotton cultivars studied were NG 5711 B3XF (C1), PHY 480 W3FE (C2), and FM 1953GLTP (C3). Granular K fertilizer was surface broadcast and incorporated 1 week before planting at 34, 50, and 67 kg ha−1. The CPH and canopy width were measured from 30 to 105 days after planting. The cotton CPH increased by 13%, 17%, and 12% in 2020 and by 6%, 4%, and 8% in 2021 with 34, 50, and 67 kg ha−1 K fertilizer rates compared to control. The K application increased cotton canopy width by 39% in 2021 compared to 2020. The K application at 50 kg ha−1 yielded significantly more cotton yield than the control in 2020. The cotton lint yield increased by 25%, 34%, and 9% in 2020 and by 4%, 17%, and 11% in 2021 with 34, 50, and 67 kg ha−1 K fertilizer application rates than control. The cotton fiber staple length and color grade increased significantly with the 50 kg ha−1 K application rate than the control in 2020. Cultivars significantly impacted Col‐Rd and Col‐b in 2020 and 2021. This study shows that fertilizer‐K application improves not only yield, but also staple length and color grade in rainfed cotton crops.

Nitrogen fertilizer sources and tillage effects on cotton growth, yield, and fiber quality in a coastal plain soil

Field experiments were conducted in 2014 and 2015 at the "Inner Mongolia cotton comprehensive test station" (39°27' N, 105°39' E) in Alxa Left Banner of Alxa League in Inner Mongolia. By using cotton cultivar CCRI-50 as material and the "6 cotton rows with 3 dripping pipes under a plastic film mulching" plantation pattern, different sowing dates (20-Apr, 30-Apr and 10-May) were set to study the effect of sowing dates on cotton yield, fiber quality and nutrient uptake and utilization. The results showed that as the sowing date delayed, the development of cotton plant was delayed, the yield forming stage shortened, and the mean daily temperature of boll deve-lopment reduced, but the harvesting density increased. Sowing date influenced the biomass accumulation, fiber yield and fiber quality, it also influenced the absorption and distribution of N, P and K. Among the three sowing dates, the biomass distribution proportion to reproductive organ, nutrition (N, P and K) accumulation, lint production efficiency of nutrient and yield were higher in the cotton plant that was sowing at 30-Apr, the seed cotton and lint yield were the highest which could reach up to 6505.9 kg·hm-2 and 2660.9 kg·hm-2, respectively, and the fiber quality was better than that of 10-Mar. For the plant which was sowed at 20-Apr, harvesting density, biomass and nutrient accumulation were the lowest, although economic coefficients of biomass and nutrient were the highest, and the seed cotton and lint yield were respectively 10.9%-14.0% and 11.1%-14.2% lower than that of 30-Apr. When sowing at 10-May, cotton could avoid the low temperature during seed germination, but mean daily temperature during boll development were the lowest, although biomass and nutrient accumulation were the highest. The economic index, lint production efficiency of nutrient were the lowest, which leading to the poorest fiber quality, lowest seed cotton and lowest lint yield which were respectively 32.5%-34.7% and 35.9%-36.2% lower than that of 30-Apr. These results suggested that the optimum sowing date for cotton planting was about 30-Apr in Inner Mongolia west desert area.

There have been conflicting results reported about the effect on cotton (Gossypium spp.) lint yield of altering planting and irrigation termination (IT) timing. The objectives of this study were to identify a planting window (PW), on a heat unit (HU) basis, and IT timing, as a function of crop growth stage, for optimum yield potential of Upland (G. hirsutum L.) and American Pima (G. babadense L.) cotton. Two PWs of Upland 'Deltapine 90' (DPL 90), Pima 'S-6', and IT treatments were included in field experiments for 11 site-years. Planting windows were defined as PW1 and PW2 for plantings prior to and following 600 HU accumulated after 1 January, respectively. Two IT treatments were imposed for each planting. Irrigation termination in the desert Southwest generally results in cessation of growth (crop termination). The first IT treatment (IT1), was imposed to ensure full development of bolls set up to cutout, and the second (IT2) was after two additional irrigations. From covariate analysis, there was no evidence of interaction between PW and IT, indicating that these treatments responded the same across the different environments for both cotton species. There were, however, differences in lint yields among treatments. For DPL 90, PW1 IT2 yielded 83 and 97 Ib/acre more than PW1 IT1 and PW2 IT2; and for Pima S-6, PW1 IT2 was 118 and 204 Ib/acre more than PW1 IT1 and PW2 IT2, respectively. Early planting is necessary for optimum yield potential of full-season cotton varieties; with the greatest yield coming from early planting and termination after the development of a second fruiting cycle (PW1 IT2). However, if a reduction in input costs and the avoidance of late-season insect pests are important considerations then cotton should be planted early (300 to 600 HU after 1 Jan) and terminated at the end of the first fruiting cycle (approximately 600 HU past cutout) to maintain the lint yield potential of full-season maturity types of Upland and Pima cotton.

Cotton (Gossypium hirsutum L.) growers are motivated to reduce seeding rates due to increased technology fees associated with improved transgenic cotton cultivars. Advances in planting machinery have improved precision of seed metering and seed placement in recent years. A two-year study was conducted to evaluate the effect of seeding rate, planter downforce, and cultivar on crop emergence and lint yield in cotton planted as singulated and hill-drop (two seed hill-1) configuration. Study treatments consisted of two seeding rates (71,660 and 107,490 seed ha-1), two to three planter downforces (0, 445 and 890 N in 2017; 0 and 890 N in 2018) and two cotton cultivars (representing a large-seeded and small-seeded cultivar, 9,259 - 10,582 and 11,244 - 14,330 seed kg-1, respectively) arranged in a strip-split plot design in both seeding configurations. Crop emergence and lint yield in the middle two rows (four-row plots) were measured to evaluate treatment effects among seeding configurations. Results showed that seeding rate and cultivar did not affect (p>0.05) crop emergence and lint yield in both singulated and hill-drop cotton. Crop emergence varied between the two years due to differences in field tillage conditions. Planter downforce affected crop emergence in singulated cotton but not in hill-drop cotton during both years. Field tillage conditions also influenced downforce effect on crop emergence. Selection of an optimal planter downforce had more significant effect (p<0.05) on singulated cotton than hill-dropped cotton. Results showed that large-seeded cultivars can be utilized to attain a high crop emergence early in the season which can help in minimizing production risks associated with poor stand establishment. High seed and technology fees incurred by growers can be effectively reduced by planting lower seeding rates - given an adequate stand establishment is attained using appropriate planter setup including downforce and cultivar selection.

Cotton acreage in the Coastal Plain of the Southeast has increased in recent years. The soils in this region are sandy and typically have a low retention capacity for sulfate S. A 3-yr (1993-1995) field test was conducted in south Alabama on a Lucy loamy sand (loamy, kaolinitic, thermic Arenic Kandiudults) to evaluate the response of cotton (Gossypium hirsutum L.) to the source, rate, and timing of S fertilizer applications. Sulfur was broadcast preplant as either ammonium sulfate, elemental S, potassium sulfate, potassium thiosulfate, or K-Mg-sulfate at rates of 0, 10, 20 and 40 lb S/acre. Additionally, ammonium sulfate was applied at first square to evaluate timing effects. Lint yields were increased each year and they peaked at a rate of approximately 20 lb S/acre on this Lucy Is soil. Averaged across sources, 20 lb S/acre increased lint yields by an average of 21% as compared with the no S check treatment. Lint yields were not affected by time of S application in 1993 or 1995, but a preplant application of S increased yield compared with S applied at first square in 1994. The response to time of S application was attributed to heavy rainfall that was received soon after the first square application of S. Sources of S did not affect lint yield in 1993 or 1995, but ammonium sulfate and K-Mg-sulfate produced slightly higher yields than those of other sources in 1994, an extremely wet growing season. Lint quality, as measured by high volume instrumentation (HVI), was not affected by any S treatment in 1993 or 1994. In 1995, fiber length increased with S rate, but the differences among sources were inconsistent. Results of this test suggest that cotton produced on sandy Coastal Plain soils that are low in S may require annual applications of 20 lb S/acre to ensure high yields. The S should be applied preplant, although delaying application to first square should not limit yields. For lint production, differences among commercial S fertilizer sources should be minimal.

Soil properties, nutrient uptake and crop growth in an irrigated Vertisol after nine years of minimum tillage

Photosynthetic photon flux density (PPFD) has variable effects on cotton (Gossypium hirsutum) plant growth, development and lint yield, but little is known about the responses of yield, yield components and fibre quality to low PPFD at different developmental stages. Field studies were conducted in 1993–95 to determine the effects of an 8-d period of shade (63% reduction in PPFD) imposed at different developmental stages (pinhead square (PHS), first flower (FF), peak flower (PF) and boll development (BD)) on cotton growth, lint yield, yield components and fibre quality. Shade for 8 d at the early square stage did not affect cotton growth and yield. Shade during FF, PF and BD increased fruit abscission, and decreased specific leaf weight, dry matter accumulation, lint yield, fibre micronaire, and fibre strength compared with the unshaded control. The detrimental effect of shade on yield increased with later growth stages. Shade at the FF, PF and BD stages decreased lint yield by 18, 34 and 52% in 1993, and by 18, 21 and 29% in 1994 respectively compared with the unshaded control. Shade caused the greatest decrease in the dry weight (DW) of fruits (squares + flowers + bolls) and the smallest decrease in leaf DW among leaves, stems and fruits. Of the three yield components (boll number, boll weight and lint percentage), boll number was the most sensitive to shade. Shade during squaring and early flowering had little effect on average boll weight, and did not affect lint percentage. Decreased yield of cotton shaded during FF and PF appeared to be related to decreased boll retention. Shade during BD decreased both boll retention and average boll weight. Under shade conditions, fibre micronaire and fibre strength were decreased, while other fibre properties were unaffected. These results help explain the yield response of field-grown cotton to low PPFD stress.

Many cotton growers sow rotation crops after irrigated cotton (Gossypium hirsutum L.), assuming that they will improve soil quality and maintain profitability of cotton. Wheat (Triticum aestivum L.) is the most common rotation crop, although more recently, legumes such as faba bean (Vicia Faba L.) and chickpea (Cicer arietinum L.) have come into favour. This paper reports data on soil quality (organic C, nitrate-N, soil structure), yield (cotton lint and rotation crop grain yield, fibre quality), economic returns (gross margins/ha, gross margins/ML irrigation water), and management constraints from an experiment conducted from 1993 to 1998 near Wee Waa, north-western New South Wales, Australia. The soil is a medium-fine, self-mulching, grey Vertosol. The cropping sequences used were cotton followed by N-fertilised wheat (urea at 140 kg N/ha in 1993; 120 kg N/ha thereafter), unfertilised wheat, and unfertilised grain legumes (chickpea in 1993; faba bean thereafter), which were either harvested or the grain incorporated during land preparation. Soil organic C in the 0—0.6 m depth was not affected by the rotation crop, although variations occurred between times of sampling. Regression analysis indicated that there had been no net gain or loss of organic C between June 1993 and October 1998. Sowing leguminous rotation crops increased nitrate-N values. A net increase in root-zone nitrate-N reserves occurred with time (from June 1993 to October 1998) with all rotation crops. Soil compaction (measured as specific volume of oven-dried soil) was lower with wheat by October 1998. A net decrease in soil compaction occurred in the surface 0.15 m with all rotation crops between 1993 and 1998, whereas it increased in the 0.15–0.60 m depth. Cotton lint yield and quality, and gross margins/ha and gross margins/ML, were always higher where wheat was sown, with highest gross margins occurring when N fertiliser was applied. Applying N fertiliser to wheat did not significantly increase cotton lint yield and fibre quality, but increased gross margins of the cotton–wheat sequence due to higher wheat yield and protein percentage. Lint yield and fibre quality were decreased by sowing leguminous rotation crops. Management constraints such as lack of effective herbicides, insect damage, harvesting damage, and availability of suitable marketing options were greater with legumes than with wheat. Overall, wheat was a better rotation crop than grain legumes for irrigated cotton.

Potassium (K) deficiency is a common yield‐limiting factor in cotton ( Gossypium hirsutum L.) production, requiring effective management to minimize yield losses and maintain fiber quality. We evaluated how K availability influences cotton lint yield and fiber quality. Ten fertilizer‐K rate (0–187 kg K ha −1 ) trials were conducted on silt loam soils with soil‐test K (STK) ranging from very low to above optimum during the 2023 and 2024 growing seasons. Cotton was planted in raised beds and furrow‐irrigated, and lint yield, turnout, and fiber quality (i.e., fiber length, micronaire, uniformity, strength, and elongation) were measured at maturity. Cotton lint yield was positively affected by fertilizer‐K rates ( p ≤ 0.10) at STK ≤ 114 mg K kg −1 . Yields were maximized at responsive sites with applications of 56 kg K ha −1 in long‐term trials and 37, 75, or 112 kg K ha −1 in single‐site‐year trials, showing yield increases of 20%, 53%, 47%, and 70% compared to the no‐K control, respectively. Lint turnout and fiber quality were affected by K availability. Overall, at yield‐maximizing fertilizer‐K rates, lint turnout was 2.4% greater across cultivars in relation to the control. Similarly, fiber elongation increased by 0.35%. At sites with Very Low STK, as little as 37 kg K ha −1 increased lint uniformity and strength up to 0.67% and 1.84 g tex −1 . Micronaire increased on average by 0.50, with greatest values occurring with 112 kg K ha −1 application. These findings suggest adequate K management is key to maximizing both cotton yield potential and fiber quality.

When comparing soil potassium (K) levels common in West Texas to the current Mehlich III-K critical levels for cotton (Gossypium hirsutum L.), fertilizer K applications are seldom recommended. However, when soil K is applied, positive responses in cotton yield have been reported. Studies were conducted in Lamesa and New Deal, TX to: 1) determine K effects on leaf K concentrations; 2) evaluate whether K application increases crop growth, yield, and fiber quality in sufficient K soils; and 3) evaluate whether K application under water deficit conditions also increases growth, yield, and fiber quality. In Lamesa, muriate of potash (KCl) was applied using two methods, knife-injected (0-0-15) and broadcast (0-0-60); and at New Deal, KCl was applied using knife injection. Potassium application rates included 0, 45, 90, 135, and 180 kg ha-1 with both high (90% ET) and low (30% ET) irrigation levels. At Lamesa in 2016 at 90% ET irrigation, lint yield was greater when 90 kg K ha-1 was broadcast (2,153 kg ha-1 lint) compared to the 180 kg K ha-1 treatment, and all K treatments with 30% ET irrigation. There were no lint yield differences in 2017 at Lamesa. At New Deal, lint yield was similar amongst all K application rates in both years. Although K application increased yield with the 90% ET irrigation level with broadcast application, no differences were observed in water-deficit cotton suggesting further research is needed to better understand the dynamics of K on lint yield in semiarid cotton production systems.

Cotton (Gossypium hirsutum L.) lint yields have not changed appreciably during the last decade. Because more and higher infestations of reniform nematodes (Rotylenchulus reniformis) have been identified in mid‐southern USA fields, this nematode might be a mitigating factor in the cotton yield stagnation. The objectives were to determine how varying rates of K fertilization interacted with different cotton genotypes to influence dry matter partitioning, lint yield, fiber quality, and reniform nematode populations. Nine cotton genotypes were grown in the field under two levels of K fertilization (0 and 112 kg K ha−1) and two levels of aldicarb [2‐methyl‐2‐(methylthio)propionaldehyde 0‐methylcarbamoyloxime] application (0 and 1.68 kg a.i. ha−1) from 1999 through 2001. Reniform nematode numbers and aboveground dry matter partitioning were determined at various times in the growing season. Lint yield, yield components, and fiber quality were determined at the end of the season. Cotton grown with K fertilization hosted a 12% larger post‐harvest population of reniform nematode than the unfertilized control plants. Plants grown without K fertilization averaged a 10% greater specific leaf weight than the K fertilized plants. Of the 9 genotypes grown, only PayMaster 1218BR increased lint yield (10%) in response to K fertilization. An interaction between aldicarb application and K fertilization for lint yield during the 2000 growing season indicated that both reniform nematode parasitism and insufficient K fertilization may impose limitations to lint yield production. Large reinform nematode populations may be suppressing the yield response to K fertilization. Production practices that encourage robust plant growth may enhance proliferation of existing reniform nematode populations.

Mulch Application and Plant Spacing Influence on Growth Traits, Pests, Insects and Weeds in Cotton (Gossypium hirsutum L.) Varieties