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Cotton (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. Core Ideas: Potassium impacts cotton boll distribution and yield contribution from specific node zones within irrigation levels.The early and middle node zones for yield were the greatest with the 180 kg K ha−1 rate within 30% evapotranspiration.The early and middle node zones benefited from added potassium through increased boll formation and yield. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Cotton (Gossypium hirsutum L.) and potassium (K) dynamics are not well understood particularly in soils with high K levels. Potassium is important for cotton reproductive development as it influences the number, size, and weight of bolls and can improve fiber quality by mitigating moisture stress. In the case that soil cannot replenish solution K from exchangeable reserves to meet the plant demands, deficiencies may occur leading to decreased yield (lint and seed) and fiber quality, reduced drought and disease tolerance, and premature boll opening. Studies were conducted in 2016 and 2017 in Lubbock (Olton clay loam and Acuff loam) and Lamesa (Amarillo fine sandy loam), TX, to determine the effects of K application rates and timing on lint yield and fiber quality of modern cotton cultivars (DP 1518 B2XF, DP 1522 B2XF, DP 1321 B2XF, and DP 1612 B2XF). Pre‐plant soil tests were >250 mg K kg–1 at both locations and years at the 0‐to‐15‐cm soil depths. Potassium treatments were applied at 0 (control), 90, and 180 kg K ha–1 as pre‐plant, side‐dress, or split applications. Harvest results determined that pre‐plant and side‐dress K applications produced significantly greater lint yield only for DP 1518 B2XF at both locations, while effects on fiber quality varied by location. The response of DP 1518 B2XF to K fertilizer was due to greater K use efficiency and possibly K demand of this cultivar compared to the others. This research provides evidence for continued investigation of cultivar by environment‐based K management. Core Ideas: Lint yield of DP 1518 B2XF responded to soil K fertilizer treatment in Lamesa and Lubbock.Pre‐plant and side‐dress K applications produced greater lint yield at these locations.DP 1518 B2XF was determined to have greater K use efficiency than the other cultivars tested.Yield response to K differed depending on location, which had different textures and K levels. [ABSTRACT FROM AUTHOR]

Harvest aids provide cotton farmers with the ability to harvest in an efficient and timely manner. Harvest aids also assistant in preserving overall fiber quality by reducing fiber degradation and discoloration from exposure to weather and by the reduction of foreign matter. Many harvest-aid active ingredients do not translocate within the plant, thus adequate spray coverage is recommended to improve efficacy of these products. The widespread and rapid adoption of auxin-tolerant cotton varieties has increased the use of larger droplet size nozzles that are required for use with auxin herbicides. Subsequently, the use of larger droplet size nozzles for harvest-aid applications will likely increase. The objective of this study was to determine the impact of droplet size and carrier volume on defoliation, desiccation, boll opening, terminal and basal regrowth, and cotton leaf grade. Varying water volumes of 47, 93, 140, and 187 L ha-1, and nozzles that produced fine, medium, and ultra-coarse droplets were evaluated at 14 site years across the Cotton Belt in 2016 and 2017. Numeric trends indicate higher carrier volumes are more successful at defoliating and opening bolls than lower carrier volumes. Water volumes of 47 L ha-1 should be avoided when making cotton harvest-aid applications, as all defoliation, open boll, and regrowth values were consistently reduced at the lowest carrier volume. Treatments of various nozzle types had less impact on harvest-aid efficacy than carrier volume. Site interactions with harvest aids had a greater effect than nozzle type or water volume. [ABSTRACT FROM AUTHOR]

Upland cotton (Gossypium hirsutum L.) is an important socioeconomic crop throughout most of the southern U.S. In Texas, cotton is the lead cash crop and its productivity is often limited by abiotic stress events such as drought and elevated ambient temperatures. The objective of this study was to assess the effects of 1-methylcyclopropene (1-MCP) applications triggered by canopy temperature and forecasted ambient temperatures on field-grown cotton plants. Yield and crop morphological responses to 1-MCP applications were investigated in field studies conducted during the summers of 2012 to 2014 at the Texas A&M University Field Laboratory in Burleson County, TX. Positive effects of 1-MCP were found for fruit retention in 2013 and 2014 for both irrigated and dryland studies; however, a negative impact was found in the 2012 irrigated study. By harvest, 1-MCP applications had no effect on final cotton yield or fiber quality parameters. Applications of 1-MCP affected some morphological characteristics of cotton plants; however, it did not improve crop yield. [ABSTRACT FROM AUTHOR]

Cotton (Gossypium hirsutum L.) is the lead cash crop in Texas, and its productivity is often challenged by stressful environmental conditions such as high temperatures and sub-optimal water supply. The objective of this investigation was to assess the impact of 1-methylcyclopropene (1-MCP) applications triggered by canopy temperature and forecasted ambient temperatures on field-grown cotton plants. Physiological responses to 1-MCP applications were investigated in field studies conducted during the summers of 2012-2014 at the Texas A&M University Field Laboratory in Burleson County, TX. During all three growing seasons, more than 65% of the days reached temperatures above 28 °C, which indicated great potential for high temperature stress. Daily plant canopy temperature, net photosynthesis, transpiration, and photosystem II quantum yield were affected by 1-MCP treatment when plants were irrigated, but not under dryland conditions. Positive effects of 1-MCP were found for fruit retention in 2013 and 2014, for both irrigated and dryland studies, although a negative impact was found in the 2012 irrigated study. Applications of 1-MCP affected physiological characteristics; however, it did not affect crop yield. [ABSTRACT FROM AUTHOR]

Cotton (Gossypium hirsutum L.) leaf grade values significantly increase with remnants of leaf and bract materials in cotton lint and can result in economic discounts to the producers. We are hypothesizing that cotton harvest aid regimes, and level of defoliation and desiccation are contributing factors in higher cotton leaf grades. The interaction of morphological characteristics of cotton cultivars and the various harvest aid regimes were evaluated to identify key factors contributing to the increased leaf grade values. Multiple trials were conducted during 2010, 2011, and 2012 in Burleson, Colorado, and Matagorda counties in South and southeastern Texas. Cotton cultivars were selected with a range of leaf hairiness and were sprayed with five harvest aid treatments to obtain a range of defoliation and desiccation levels. Leaf and bract pubescence, and leaf and bract area were collected, as well as defoliation and desiccation levels, to analyze the resulting impact on cotton leaf grade values. Seed cotton samples were ginned in a microgin and lint quality was measured with high volume instrument (HIV) analysis. Results from trichome density quantification indicated substantial variation in cultivars and discrepancies from company based rating systems. Defoliation level rating ranged from 0 to 84% at 14 d after treatment application, while desiccation levels were low despite the use of herbicidal products. Defoliation or desiccation did not impact leaf grade. Leaf grades generally increased with higher leaf trichome densities, although not always significantly. Among morphological characteristics of cotton, leaf hairiness is more important for cultivar selection to reduce leaf grade. [ABSTRACT FROM AUTHOR]

In addition to numerous health and industrial uses, flax (Linum usitatissimumL.) has been evaluated throughout the United States as a potential biodiesel crop. One approach for improving flax yields was to identify the physiological characteristics contributing the most to flax yield. Two locations in southern Texas were selected to evaluate the association between tiller number, number of pods per tiller, number of seeds per pod, seed weight, and overall yields. Tiller number was the most significant positive contributing trait (P < 0.05) to seed yield of flax at both locations. However, the effect of tiller number was almost equally negated by that of pods per tiller (compensatory) at both locations. Seed per pod and seed weight were not significant (P > 0.05) components of seed yield in flax in this study. Selection for higher tiller number would increase grain yield of flax in southern Texas and should be the focus of plant breeders to further enhance seed yield for this area. [ABSTRACT FROM PUBLISHER]

A standardized experiment was conducted during 2009 and 2010 at 20 location-years across U.S. cotton (Gossypium hirsutum L.)- producing states to compare the N use requirement of contemporary cotton cultivars based on their planting seed size. Treatments consisted of three cotton varieties with planting seed of different numbers of seed per kg and N rates of 0, 45, 90, and 134 kg ha-1. Soil at each trial location was sampled and tested for nitrate presence. High levels of soil nitrate (>91 N-NO3 - kg ha-1) were found in Arizona and western Texas, and soil nitrate in the range of 45 to 73 kg N-NO3 - ha-1 was found at locations in the central United States. Cotton lint yield responded to applied N at 11 of 20 locations. Considering only sites that responded to applied N, highest lint yields were achieved with 112 to 224 kg ha-1of applied plus pre-plant residual soil NO3-translating to an optimal N requirement of 23 kg ha-1 per 218 kg bale of lint produced. Among the varieties tested those with medium-sized seed produced higher yields in response to N than did larger and smaller seeded varieties. Varieties with larger seed had longer and stronger fibers, higher fiber length uniformity than small seeded varieties and decreased micronaire. Seed protein and oil increased and decreased slightly in response to increasing amounts of soil nitrate plus applied N, respectively. [ABSTRACT FROM AUTHOR]

Studies of fungi in upland cotton (Gossypium hirsutum) cultivated in the United States have largely focused on monitoring and controlling plant pathogens. Given increasing interest in asymptomatic fungal endophytes as potential biological control agents, surveys are needed to better characterize their diversity, distribution patterns and possible applications in integrated pest management. We sampled multiple varieties of cotton in Texas, USA and tested for temporal and spatial variation in fungal endophyte diversity and community composition, as well as for differences associated with organic and conventional farming practices. Fungal isolates were identified by morphological and DNA identification methods. We found members of the genera Alternaria, Colletotrichum and Phomopsis, previously isolated as endophytes from other plant species. Other recovered species such as Drechslerella dactyloides (formerly Arthrobotrys dactyloides) and Exserohilum rostratum have not, to our knowledge, been previously reported as endophytes in cotton. We also isolated many latent pathogens, but some species such as Alternaria tennuissima, Epicoccum nigrum, Acremonium alternatum, Cladosporium cladosporioides, Chaetomium globosum and Paecilomyces sp., are known to be antagonists against plant pathogens, insects and nematode pests. We found no differences in endophyte species richness or diversity among different cotton varieties, but did detect differences over time and in different plant tissues. No consistent patterns of community similarity associated with variety, region, farming practice, time of the season or tissue type were observed regardless of the ecological community similarity measurements used. Results indicated that local fungal endophyte communities may be affected by both time of the year and plant tissue, but the specific community composition varies across sites. In addition to providing insights into fungal endophyte community structure, our survey provides candidates for further evaluation as potential management tools against a variety of pests and diseases when present as endophytes in cotton and other plants. [ABSTRACT FROM AUTHOR]

Studies of fungi in upland cotton (Gossypium hirsutum) cultivated in the United States have largely focused on monitoring and controlling plant pathogens. Given increasing interest in asymptomatic fungal endophytes as potential biological control agents, surveys are needed to better characterize their diversity, distribution patterns and possible applications in integrated pest management. We sampled multiple varieties of cotton in Texas, USA and tested for temporal and spatial variation in fungal endophyte diversity and community composition, as well as for differences associated with organic and conventional farming practices. Fungal isolates were identified by morphological and DNA identification methods. We found members of the genera Alternaria, Colletotrichum and Phomopsis, previously isolated as endophytes from other plant species. Other recovered species such as Drechslerella dactyloides (formerly Arthrobotrys dactyloides) and Exserohilum rostratum have not, to our knowledge, been previously reported as endophytes in cotton. We also isolated many latent pathogens, but some species such as Alternaria tennuissima, Epicoccum nigrum, Acremonium alternatum, Cladosporium cladosporioides, Chaetomium globosum and Paecilomyces sp., are known to be antagonists against plant pathogens, insects and nematode pests. We found no differences in endophyte species richness or diversity among different cotton varieties, but did detect differences over time and in different plant tissues. No consistent patterns of community similarity associated with variety, region, farming practice, time of the season or tissue type were observed regardless of the ecological community similarity measurements used. Results indicated that local fungal endophyte communities may be affected by both time of the year and plant tissue, but the specific community composition varies across sites. In addition to providing insights into fungal endophyte community structure, our survey provides candidates for further evaluation as potential management tools against a variety of pests and diseases when present as endophytes in cotton and other plants. [ABSTRACT FROM AUTHOR]

• DSSAT CROPGRO-Cotton model was evaluated using in-season crop growth and crop yield data. • Average percent error of <15% was achieved for all target categories during evaluation. • Four irrigation strategies were evaluated using the evaluated model. • TTT-7.5 h 12 mm simulated irrigation strategy had the highest water use efficiency. • ET-95% simulated irrigation strategy had the lowest water use efficiency. The Texas High Plains (THP) region, a vital part of U.S. grain and fiber production, is experiencing the effects of conflicting interests in the diminishing Ogallala Aquifer, making necessary the adoption of more efficient irrigation strategies. Decision Support System for Agrotechnology Transfer (DSSAT) is a process-based model that uses meteorological, soil, and crop management data to predict crop growth, development, and yield. A well-evaluated DSSAT model is useful for simulation of efficient crop and irrigation management strategies. This study details the evaluation of CROPGRO-Cotton module in the DSSAT model based on measured in-season biomass and canopy height, and crop yield data from a field study as well as the use of the evaluated model for determining the best irrigation strategy for cotton (Gossypium hirsutum L. var. hirsutum) in terms of crop yield and irrigation water use efficiency. Irrigation simulation experiments were conducted over a testing range for four separate irrigation scheduling strategies —Time Temperature Threshold (TTT)-5.5 h, TTT-7.5 h, Daily Irrigation (DI), and percent ET replacement —to determine the most efficient irrigation strategy that results in maximum yield with minimum irrigation water input. The DSSAT CROPGRO-Cotton model demonstrated potential to simulate the effects of various irrigation strategies on cotton yield and water use efficiency. The 12 mm, 7.5 h TTT strategy was found to be the best strategy to achieve a maximized yield with the greatest irrigation water use efficiency, with a modelled yield of 5887 kg ha−1 using 195 mm of irrigation throughout the season. [ABSTRACT FROM AUTHOR]

Studies of fungi in upland cotton (Gossypium hirsutum) cultivated in the United States have largely focused on monitoring and controlling plant pathogens. Given increasing interest in asymptomatic fungal endophytes as potential biological control agents, surveys are needed to better characterize their diversity, distribution patterns and possible applications in integrated pest management. We sampled multiple varieties of cotton in Texas, USA and tested for temporal and spatial variation in fungal endophyte diversity and community composition, as well as for differences associated with organic and conventional farming practices. Fungal isolates were identified by morphological and DNA identification methods. We found members of the genera Alternaria, Colletotrichum and Phomopsis, previously isolated as endophytes from other plant species. Other recovered species such as Drechslerella dactyloides (formerly Arthrobotrys dactyloides) and Exserohilum rostratum have not, to our knowledge, been previously reported as endophytes in cotton. We also isolated many latent pathogens, but some species such as Alternaria tennuissima, Epicoccum nigrum, Acremonium alternatum, Cladosporium cladosporioides, Chaetomium globosum and Paecilomyces sp., are known to be antagonists against plant pathogens, insects and nematode pests. We found no differences in endophyte species richness or diversity among different cotton varieties, but did detect differences over time and in different plant tissues. No consistent patterns of community similarity associated with variety, region, farming practice, time of the season or tissue type were observed regardless of the ecological community similarity measurements used. Results indicated that local fungal endophyte communities may be affected by both time of the year and plant tissue, but the specific community composition varies across sites. In addition to providing insights into fungal endophyte community structure, our survey provides candidates for further evaluation as potential management tools against a variety of pests and diseases when present as endophytes in cotton and other plants.