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Physiological Mechanism of Nitrogen Mediating Cotton (<i>Gossypium hirsutum</i>L.) Seedlings Growth under Water-Stress Conditions

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American Journal of Plant Sciences 2012年第6期3卷 721-730页

作者： Zhigou Zhou derrick M. oosterhuis Department of Crop Soil and Environmental Sciences University of Arkansas Fayetteville USA. Key Laboratory of Crop Physiology & Ecology in Southern China of Ministry of Agriculture Nanjing Agricultural University Nanjing China

The objective of this investigation was to study the effects of nitrogen on tolerance to water-stress in cotton (Gossypium hirsutum L.) seedlings. Growth chamber studies with pots of washed sand were carried out in Fayetteville, USA, and Nanjing, Chinawith three water conditions (well-watered, drought-stressed, and waterlogging), and three nitrogen rates, low nitrogen (16 mM, approximately 224 mg N·l–1 water), medium nitrogen (24 mM, approximately 448 mg N·l–1 water) and high nitrogen (32 mM, approximately 672 mg N·l–1 water), respectively. The results showed that water-stress treatments reduced plant biomass, C/N ratio, root vigor and leaf photosynthesis (Pn). The plant response to water-stress resistance was affected by nitrogen, and was correlated with the activities of antioxidant enzymes. The changes of anti-oxidant enzymes was the highest in the low nitrogen rate in the drought-stressed and waterlogged cotton seedlings. Malondialdehyde (MDA) content increased significantly in the water-stress treatments, and was the lowest in the low nitrogen rate. There was a significant reduction of N accumulation under water stress. Low-nitrogen treatmentincreased C accumulation, while high-nitrogen treatment decreased N accumulation. Root vigor was decreased by water stress, and was highest in the low-nitrogen rate. After terminating the water stress, N application promoted root vigor, especially in waterlogged seedlings. The trends of Pn weresimilarto that of root vigor. These results suggested that low N application may contribute to cotton drought tolerance by enhancing the activity of antioxidant enzymes and conse-quently decreasing lipid peroxidation, and enhancing root vigor. However, higher N should be applied to waterlog- ging-stressed cotton seedlings after terminating waterlogging.

关键词： Cotton Seedling Nitrogen Water Deficit Drought Stress Waterlogging Antioxidant Enzyme Activity Photosynthesis Root Vigor

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Effect of 1-MCP on Gas Exchange and Carbohydrate Concentrations of the Cotton Flower and Subtending Leaf under Water-Deficit Stress

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American Journal of Plant Sciences 2013年第1期4卷 142-152页

作者： Dimitra A. Loka derrick M. oosterhuis Department of Crop Soil and Environmental Sciences University of Arkansas Fayetteville USA

Ethylene is an endogenous plant hormone that increases under adverse environmental conditions, resulting in leaf and fruit abscission and ultimately yield reduction. In cotton, however, the effects of water-deficit stress on ethylene production have been uncertain. In this study it was hypothesized that application of an ethylene inhibitor 1-Methylcyclo- propene (1-MCP) would prevent ethylene production and result in alleviation of water-deficit stress consequences on the physiology and metabolism of the cotton flower and subtending leaf. To test this hypothesis, growth chamber experiments were conducted in 2009-2010 with treatments consisting of (C) untreated well-watered control, (C + 1MCP) well-watered plus 1-MCP, (WS) untreated water-stressed control, and (WS + 1MCP) water-stressed plus 1-MCP. The plants were subjected to two consecutive drying cycles during flowering, approximately 8 weeks after planting, and 1-MCP was foliar applied at a rate of 10g. ai/ha at the beginning of each drying cycle. The results showed that 1-MCP application had no significant effect on gas exchange functions and did not prevent reductions from water stress in leaf photosynthesis, respiration and stomatal conductance. However, application of 1-MCP resulted in a decrease in sucrose content of water-stressed pistils compared to the control indicating that 1-MCP has the potential to interfere in carbohydrate metabolism of reproductive units.

关键词： Cotton 1-Methylcyclopropene Ethylene Water-Deficit Stress Carbohydrates Gas Exchange

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Endogenous Levels of Polyamines under Water-Deficit Stress during Cotton’s Reproductive Development

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American Journal of Plant Sciences 2015年第2期6卷 344-354页

作者： Dimitra A. Loka derrick M. oosterhuis Cristiane Pilon Altheimer Laboratory Department of Crop Soil and Environmental Sciences University of Arkansas Fayetteville AR USA

Polyamines, putrescine (PUT), spermidine (SPD) and spermine (SPM) are implicated in plants’ responses under conditions of abiotic stress. Previous research in other crops has indicated that polyamines and changes in their concentrations are associated with drought tolerance under conditions of water-deficit stress;however, no information exists on cotton (Gossypium hirsutum L.). Growth chamber experiments were conducted with two cotton cultivars differing in drought tolerance, ST5288B2F (drought-sensitive) and Siokra L23 (drought-tolerant) in order to investigate the distribution of free polyamines, the effect of water-deficit stress on the polyamine metabolism of cotton reproductive units and their subtending leaves as well as the possible relationship between polyamines and drought tolerance in cotton. Our results showed that cotton ovaries contained significantly higher levels of total free polyamines compared to their subtending leaves under both control and water stress conditions. Water-deficit stress significantly increased PUT concentrations in ST5288B2F, while SPM levels significantly decreased in Siokra L23. The results indicated that water-deficit stress significantly affected cotton polyamine metabolism in reproductive structures and their subtending leaves;however, no clear relationship between drought-tolerance and changes in polyamine accumulation was established. Further research is needed to elucidate the mechanism according to which water-deficit stress affects polyamine metabolism.

关键词： Cotton Gas Exchange Polyamine Levels Reproductive Units Water-Deficit Stress

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Changes in the Ovarian Polyamine Content and Seed Set Efficiency of Cotton by the Plant Growth Regulator BM86

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American Journal of Plant Sciences 2012年第9期3卷 1328-1335页

作者： Androniki C. Bibi derrick M. oosterhuis Evangelos D. Gonias Department of Crop Soil and Environmental Sciences University of Arkansas Fayetteville USA

Naturally occurring polyamines in plants have been implicated in floral initiation, and fruit development. The plant growth regulator BM86 was formulated to stimulate seed production and fruit growth by enhancing polyamine synthe-sis. The objectives of this study were to determine the effect of BM86 on free polyamine content in cotton (Gos-sypium hirsutum L.) ovaries and on seed set efficiency, and also to investigate genotypic differences in ovarian polyamine content. BM86 was applied at the first flower stage and two weeks later at 2.34 mL/ha. This study showed that application of BM86 had a significant positive effect on ovarian polyamine content of cotton. Putrescine and sper-midine one week after the 1st BM86 application and putrescine two week after the 1st BM86 application, were significantly increased compared to the untreated control. Higher seed set efficiency with the BM86 application was observed when the total number of seeds was used for the calculation. However, when the number of harvestable seeds was used to calculate seed set efficiency BM86 had no significant effect. In addition, application of BM86 did not significantly alter seedcotton yield of the crop. Only small differences in ovarian polyamine content were detected among the genotypes tested, possibly due to the narrow genetic pool of the commercial cotton genotypes used. Application of BM86 can significantly increase cotton seed number by enhancing polyamines biosynthesis, but further research is needed to determine how to capitalize on the increased potential number of harvestable seeds.

关键词： Putrescine Spermidine Spermine BM86 Gossypium hirusutm L. Ovaries

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Speed and surface steepness affect internal tibial loading during running

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Journal of Sport and Health Science 2024年第1期13卷 118-124页

作者： Hannah Rice Markus Kurz Patrick Mai Leon Robertz Kevin Bill Timothy R.derrick Steffen Willwacher Department of Physical Performance Norwegian School of Sport SciencesOslo 0806Norway Sports Tech Research Centre Mid Sweden UniversityÖstersund SE-83125Sweden Department of Mechanical and Process Engineering Offenburg University of Applied SciencesOffenburg 77652Germany Institute of Biomechanics and Orthopaedics German Sport University CologneCologne 50933Germany Department of Kinesiology Iowa State UniversityAmesIA 50011USA

Background:Internal tibial loading is influenced by modifiable factors with implications for the risk of stress *** encounter varied surface steepness(gradients)when running outdoors and may adapt their speed according to the *** study aimed to quantify tibial bending moments and stress at the anterior and posterior peripheries when running at different speeds on surfaces of different ***:Twenty recreational runners ran on a treadmill at 3 different speeds(2.5 m/s,3.0 m/s,and 3.5 m/s)and gradients(level:0%;uphill:+5%,+10%,and+15%;downhill:-5%,-10%,and-15%).Force and marker data were collected synchronously *** moments were estimated at the distal third centroid of the tibia about the medial-lateral axis by ensuring static equilibrium at each 1%of *** was derived from bending moments at the anterior and posterior peripheries by modeling the tibia as a hollow ***-way repeated-measures analysis of variance were conducted using both functional and discrete statistical ***:There were significant main effects for running speed and gradient on peak bending moments and peak anterior and posterior *** running speeds resulted in greater tibial *** uphill at+10%and+15%resulted in greater tibial loading than level *** downhill at-10%and-15%resulted in reduced tibial loading compared to level *** was no difference between+5%or-5%and level ***:Running at faster speeds and uphill on gradients≥+10%increased internal tibial loading,whereas slower running and downhill running on gradients≥-10%reduced internal *** running speed according to the gradient could be a protective mechanism,providing runners with a strategy to minimize the risk of tibial stress injuries.

关键词： Bending moments Gradient Musculoskeletal modeling Overuse injury Tibial stress Training factors

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棉株氮营养状况评估方法的比较研究

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植物营养与肥料学报 2005年第5期11卷 665-669页

作者：王巧兰吴礼树赵竹青赵林萍 derrick oosterhuis 华中农业大学资源与环境学院中国农业科学院土壤肥料研究所北京100081 University of Arkansas

在田间和温室条件下分别用传统的硝化测氮法与叶绿素仪(SPAD meter)和Cardy NO3-nitrate meter两种便携式氮素测定仪对棉花花铃期氮素营养状况进行了评估和跟踪。结果表明,传统的硝化测氮法测得的叶片全N和叶柄NO3--N含量和叶绿素仪(SPA... 详细信息

在田间和温室条件下分别用传统的硝化测氮法与叶绿素仪(SPAD meter)和Cardy NO3-nitrate meter两种便携式氮素测定仪对棉花花铃期氮素营养状况进行了评估和跟踪。结果表明,传统的硝化测氮法测得的叶片全N和叶柄NO3--N含量和叶绿素仪(SPAD meter)及Cardy NO3-nitrate meter的读数都反应出大田生长的棉株叶片和叶柄的含氮量因施氮水平、棉桃载荷和后期施用叶面氮肥而不同。在较高施氮水平下,单株棉桃数较少(即低载荷)以及叶面施用氮肥的棉株叶片和叶柄的含氮量明显高于其它处理,且叶绿素仪(SPAD meter)和Cardy NO3-nitrate meter的读数与叶片的全N百分数和叶柄NO3--N含量存在显著的正相关,其相关系数在大田条件下平均为0.70;温室条件下平均为0.90。

关键词：棉株氮营养评估 SPAD仪 Cardy仪

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Radiation Use Efficiency of Cotton in Contrasting Environments

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American Journal of Plant Sciences 2012年第5期3卷 649-654页

作者： Evangelos D. Gonias derrick M. oosterhuis Androniki C. Bibi Bruce A. Roberts Department of Crop Soil and Environmental Sciences University of Arkansas Fayetteville USA Plant Science Department California State University Fresno USA

Crop growth and yield varies among locations due to differences in environmental parameters, such as temperature, relative humidity, solar radiation and vapor pressure deficit. Previous research has shown that increasing vapor pressure deficit has a negative effect on radiation use efficiency of many crops. In this study, the radiation use efficiency of cot-ton (Gossypium hirsutum L.) grown in two contrasting production environments, Arkansas and California, was evaluated for two years, in 2006 and 2007. Temperature, relative humidity, vapor pressure deficit and photosyntheti-cally active radiation were recorded at both locations. Although the crop in California accumulated more dry matter during the period of the study, the radiation use efficiency was found to be lower compared to Arkansas. Radiation use efficiency for the Arkansas and California locations was estimated at 2.060 and 1.518 g?MJ–1 of intercepted photosynthetically active radiation, respectively. The higher productivity observed in California can be attributed to larger amounts of incident and intercepted radiation in this location. Radiation use efficiency of cotton was estimated to decrease with increasing vapor pressure deficit by a slope of –0.47 g?MJ–1?kPa–1.

关键词： Dry Matter Environment Gossypium hirsutum L. Light Interception Radiation Use Efficiency Vapor Pressure Deficit

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Instruments of Change

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ChinAfrica 2024年第4期16卷 40-41页

作者： derrick SILIMINA Zambia

Lucy Wahome stumbles and struggles to maintain her balance and walk as a nurse rushes to lend her support,soon after she got admitted at the ***,30,initially sought medical treatment at her home clinic in Kiambu County,Kenya,which seemed well organised;but she later realised that constant power outages at the facility seriously compromised the quality of care at the clinic.

关键词： admitted nurse maintain

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Potential Association between Soil and Leaf Chemical Properties, and Soybean Seed Composition

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Agricultural Sciences 2014年第6期5卷 560-570页

作者： Luciano M. Jaureguy Pengyin Chen Kristofor Brye derrick oosterhuis Andy Mauromoustakos John R. Clark Agricultural Statistics Laboratory University of Arkansas Fayetteville USA Department of Crop Soil and Environmental Sciences University of Arkansas Fayetteville USA

Maximizing the expression of seed quality traits by understanding how they are affected by environmental variables may help develop high quality nutritious soybeans. Eight specialty soybean breeding lines were grown at two Arkansas locations differing by soil texture, with three replications in 2011. Before the reproductive period, soil and leaf samples were collected from each plot. Soil samples were analyzed for particle size distribution, electrical conductivity, pH, and a set of extractable nutrients from the top 12.5 cm, while leaf samples were analyzed for the same set of nutrients as the soil samples. At maturity, seed samples were analyzed for the same set of nutrients as were leaf and soil samples, plus protein, oil, fatty acids, and sugars. All leaf elements were within the adequate levels for soybean production at both locations. Overall, seed composition of breeding lines did not differ among locations and no significant changes in breeding line ranking among locations were observed. Attempting to modify seed composition by nutrient fertilization may not be profitable, as no direct relationships were observed between leaf or soil chemical properties, and seed composition. These findings may provide a starting point for future studies on fertilization and management practices that improve soybean seed quality.

关键词： Soybean Seed Composition Soil Properties

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A Boon for Sustainability China-Africa space cooperation to boost comprehensive development

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ChinAfrica 2024年第5期16卷 20-21页

作者： derrick SILIMINA 不详

Talking about space and Africa,Zambia stands out because of an incredible *** early as 1964,a Zambian teacher named Edward Nkoloso famously vowed to help his country to beat America to become the first country to put a man on the moon,and then go to *** his passion to launch a rocket that would send 12 astronauts,a space girl and cats to the moon,Nkoloso’s dream never came to *** his Zambian Space Academy,Nkoloso’s team of Zambian astronauts,whom he called“Afronauts,”underwent strenuous training,but it all came to nought because the United Nations wouldn’t give him the$700 million he needed to fund the space programme.

关键词： spite dream boost

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