Effect of Planting Density and Fertilizer Application on Fiber Yield of Ramie (Boehmeria nivea)

As the most important cultural practices for ramie （Boehmeria nivea） production, the single effects of plant density and nitrogen （N）, phosphorus （P）, potassium （K） fertilization on yield are well documented. To achieve the high yield and quality of ramie fiber, it is principal to quantify the fertilizer dosage for ramie sustainable production. A central composite design （CCD） was adopted with three replications, for a two-year field experiment （2008-2009） in the Yangtze River Valley of China. The aim was to evaluate both the individual and combined effects of plant density and N, P, and K fertilization on yield and fiber quality. The effects of the four factors on yield and quality of ramie cultivar Huazhu 4 were tested. Then mathematical models of the relationship among the four factors affecting ramie production and quality were established and analyzed to optimize the four factors, and used to establish optimum cultivation methods for the elite cultivar suitable to this area of the Yangtze River Valley. Supplements of N （X2）, P 0（3） and K 0（4）, and the density （X0 with N （X2） interaction significantly influenced strength in tests of mature ramie. The influence on fiber yield in the two year tests by the four factors ranked as follows： X3〉X4〉X~〉X2. We established the optimization technique attaining yield of 2 600 kg ha-~ in the tests as following： density of 28 350-31 650 plants ha-1, and supplements of N, P and K of 363-387, 98.58-105.48 and 280.20- 319.8 kg ha-1, respectively. It was concluded that nitrogen mostly improved plant growth and fiber yield while potassium had discernible effects on fiber quality.

Expression Profiling Identifies Candidate Genes for Fiber Yield and Quality

Gene expression profiling at early stages(0～2 DPA) of fiber development in Gossypium hirsutum identified a number of transcription factors which were down regulated in fiberless mutants relative to wild type controls and which could play a role in controlling early fiber development.Chief among these was GhMYB25,a Mixta-like MYB gene.Transgenic GhMYB25-silenced cotton

Improvements of Fiber Yield and Fiber Fineness by Expressing the iaaM Gene in Cotton Seed Coat

Cotton,the most important natural fiber crop in the world,is a mainstay in China's economy.However,for over two decades,cotton yields both in China and U.S.have been at a plateau.

Down-regulation of GhADF1 in cotton(Gossypium hirsutum)improves plant drought tolerance and increases fiber yield

Fiber productivity and quality of cotton are severely affected by abiotic stresses.In this study,we identified the role of GhADF1,an actin depolymerizing factor,in cotton response to drought stress.GhADF1 expression in cotton could be induced by PEG6000.GhADF1-RNAi transgenic cotton showed increased tolerance to drought stress during seed germination and seedling development as well as at the reproductive stage.In contrast,overexpression of GhADF1 led to a drought-sensitive phenotype in transgenic plants.GhADF1-RNAi plants produced an enlarged root system with longer primary roots,more lateral roots,increased root dry biomass,and increased cell size.In leaves of GhADF1-RNAi cotton,proline content and activities of reactive oxygen species-scavenging enzymes were increased following drought stress compared with those in wild type.GhADF1-RNAi lines showed higher water-use efficiency than the wild type,accompanied by reduced leaf stomatal density and conductance.GhADF1-RNAi cotton produced higher fiber yield in the field under both normal and drought conditions.Transcriptomic analyses identified 124 differentially expressed genes in leaves of GhADF1-RNAi lines compared with the wild type following drought treatment.Upregulated genes included those encoding transcription factors,protein kinases,heat shock proteins,and other proteins known to be involved in stress responses.We conclude that GhADF1 reduces the expression of abiotic stress-associated genes in cotton response to drought stress and may be a promising candidate gene for crop improvement by genetic manipulation.

Effects of planting dates and shading on carbohydrate content,yield,and fiber quality in cotton with respect to fruiting positions

Two cotton（Gossypium hirsutum L.） cultivars, Kemian 1（cool temperature-tolerant） and Sumian 15（cool temperaturesensitive） were used to study the effects of cool temperature on carbohydrates, yield, and fiber quality in cotton bolls located at different fruiting positions（FP）. Cool temperatures were created using late planting and low light. The experiment was conducted in 2010 and 2011 using two planting dates（OPD, the optimized planting date, 25 April; LPD, the late planting date, 10 June） and two shading levels of crop relative light rate（CRLR, 100 and 60%）. Compared with fruiting position 1（FP1）, cotton yield and yield components（fiber quality, leaf sucrose and starch content, and fiber cellulose） were all decreased on FP3 under all treatments. Compared with OPD-CRLR 100%, other treatments（OPD-CRLR 60%, LPD-CRLR 100%, and LPD-CRLR 60%） had significantly decreased lint yield at both FPs of both cultivars, but especially at FP3 and in Sumian 15; this decrease was mainly caused by a large decline in boll number. All fiber quality indices decreased under late planting and shading except fiber length at FP1 with OPD-CRLR 60%, and a greater reduction was observed at FP3 and in Sumian 15. Sucrose content of the subtending leaf and fiber increased under LPD compared to OPD, whereas it decreased under CRLR 60% compared to CRLR 100%, which led to decreased fiber cellulose content. Therefore, shading primarily decreased the ＂source＂ sucrose content in the subtending leaf whereas late planting diminished translocation of sucrose towards cotton fiber. Notably, as planting date was delayed and light was decreased, more carbohydrates were distributed to leaf and bolls at FP1 than those at FP3, resulting in higher yield and better fiber quality at FP1, and a higher proportion of bolls and carbohydrates allocated at FP3 of Kemian 1 compared to that of Sumian 15. In conclusion, cotton yield and fiber quality were reduced less at FP1 compared to those at FP3 under low temperature and low light conditions. Thus, reduced cotton yield and fiber quality loss can be minimized by selecting low temperature tolerant cultivars under both low temperature and light conditions.

An Application of the Modified Shear Lag Model to Study the Influence of Thermal Residual Stresses on the Stiffness and Yield Strength of Short Fiber Reinforced Metal Matrix Composites

The modified shear lag model proposed recently was applied to calculate thermal residual stresses and subsequent stress distributions under tensile and compressive loadings. The expressions for the elastic moduli and the yield strengths under tensile and compressive loadings were derived which take account of thermal residual stresses. The asymmetries in the elastic modulus and the yield strength were interpreted using the derived expressions and the obtained results of the stress calculations. The model predictions have exhibited good agreements with the experimental results and also with the other theoretical predictions

A New Modification to Shear Lag Model as Applied to Stiffness and Yield Strength of Short Fiber Reinforced Metal Matrix Composites

A new modification for the shear lag model is given and the expressions for the stiffness and yield Strength of short fiber metal matri×composite are derived. These expressions are then compared with our experimental data in a SiCw/Al-Li T6 composite and the published experimental data on different SiCw/Al T6 composites and also compared with the previous shear lag models and the other theoretical models.

Phenotypic plasticity and genetic variation of cotton yield and its related traits under water-limited conditions

Global warming is limiting availability of water resources in arid and semi-arid regions,and so understanding water use efficiency(WUE)is increasingly important for agricultural production in those areas.As China is the largest cotton producing area,the problem of balancing WUE and efficient cotton production is a major issue.In this study,we used a natural population of 517 Upland cotton accessions to conduct a water-controlled trial in south and north of Xinjiang over two years.A total of 18 traits including agronomic traits,fiber yield indices and fiber quality indices,were investigated for broad-sense heritability and coefficient of variation.Appropriate water limitation was found to promote the establishment of favorable agronomic traits in cotton,associated with an increased cotton yield of 8.46%in Xinjiang,at the expense of a certain degree of fiber quality,such as decreased fiber length and an over-higher micronaire value.We detected 33 QTL related to response to water limitation using a drought resistance coefficient(DRC),and 6 QTL were found using a comprehensive indicator of CIDT(comprehensive index of drought tolerance)at the genetic level by integrating resequencing data.Two novel QTL-hotspots including six differentially expressed genes(DEGs)were further identified related to the drought response of cotton.These findings not only suggested a new approach to irrigation of cotton fields in Xinjiang,but also provided abundant genetic evidence for genetic breeders to study drought improvement of crops.

Report on Screening Test of Dazhou Superior Ramie Germplasm Resources

[Objectives]To promote the development of the ramie industry in Dazhou City of Sichuan Province and provide a material basis for the breeding of new ramie varieties.[Methods]The Institute of Bast Fiber Crops of Dazhou Academy of Agricultural Sciences performed a screening test of excellent ramie germplasm resources from 2017 to 2019 to compare the growth,resistance,raw fiber yield and fiber fineness of the experimental materials.[Results]All the experimental materials showed strong growth potential,drought resistance and disease resistance.There were 8 kinds of resources with a fiber fineness greater than 2000 m/g,of which 3 kinds of resource materials had a fiber fineness greater than 2300 m/g;12 kinds of resources has the raw fiber yield exceeding the control and 10 kinds of resources had the raw fiber yield≥2000 kg/ha;3 kinds of resources met the requirements of the high-yield and high-quality indicators(fiber fineness exceeding 2000 m/g and raw fiber yield≥2000 kg/ha),they were BD0718,BD1614 and BYL2.[Conclusions]These high-quality ramie resources can provide a rich resource base for the breeding of new ramie varieties.

Stability Analysis of Long-Span Continuous Rigid Frame Bridge with Thin-Wall Pier

During cantilever cast in construction of high-pier and large-span continuous rigid frame bridges, structural stability in the longest cantilevered stage is very important. Based on a practical design case of a large-span continuous rigid frame bridge in Wuhan, the longest span stability coefficient is calculated with linear-buckling and nonlinear-buckling methods, respectively. The influences of both geometrical nonlinearity and the dual nonlinearity of material and geometry are considered. Numerical results indicate that the nonlinear solution is necessary to stability analysis because linear buckling loads are much higher than those of nonlinear buckling. Thus, the edge fiber yield criterion is more convenient and faster than ultimate loading criterion when estimating nonlinear stability of structure, and can be used easily in the initial engineering design.

High day and night temperatures impact on cotton yield and quality——current status and future research direction

Heat waves,and an increased number of warm days and nights,have become more prevalent in major agricultural regions of the world.Although well adapted to semi-arid regions,cotton is vulnerable to high temperatures,particularly during flowering and boll development.To maintain lint yield potential without compromising its quality under high-temperature stress,it is essential to understand the effects of heat stress on various stages of plant growth and development,and associated tolerance mechanisms.Despite ongoing efforts to gather data on the effects of heat stress on cotton growth and development,there remains a critical gap in understanding the distinct influence of high temperatures during the day and night on cotton yield and quality.Also,identifying mechanisms and target traits that induce greater high day and night temperature tolerance is essential for breeding climate-resilient cotton for future uncertain climates.To bridge these knowledge gaps,we embarked on a rigorous and comprehensive review of published literature,delving into the impact of heat stress on cotton yields and the consequential losses in fiber quality.This review encompasses information on the effects of heat stress on growth,physiological,and biochemical responses,fertilization,cotton yield,and quality.Additionally,we discuss management options for minimizing heat stress-induced damage,and the benefits of integrating conventional and genomics-assisted breeding for developing heat-tolerant cotton cultivars.Finally,future research areas that need to be addressed to develop heat-resilient cotton are proposed.

Sequencing of the Cultivated Tetraploid Cotton Genome-Gossypium hirsutum

Cotton is an important cash crop in the world,and it plays an irreplaceable role in China's national economy.Cultivated upland cotton(Gossypium hirsutum L.) represents 95% of the world's cotton production,but it has a complex allotetraploid genome that contains at least 30000 genes in 2500