Genotypic Variation in Responses of Cassava (Manihot esculenta Crantz) to Drought and Rewatering: Root System Development

Abstract

Soil moisture condition is a major factor that affects root system development and thus, crop production. This study aimed to evaluate genotypic variations of cassava in root system structures and their responses to different soil moisture conditions by examining various root traits including production and elongation of adventitious roots and their laterals. Four pot experiments were conducted and different genotypes of various backgrounds were grown under well-watered, droughted, droughted to rewatered conditions. One field experiment was also conducted with selected genotypes till maturity. Results showed that substantial genotypic variations exist in root system structure, and the effects of the soil moistures were significant for most of the root traits. The principal component analysis (PCA) showed that the lateral root development mainly accounted for the variations in root system structure regardless of soil moisture conditions. The PCA on the differences between droughted and well-watered control, and droughted-rewatered and the control further indicated that the branching ability of adventitious roots was mainly responsible for the root system responses to drought as well as rewatering. Genotypic ranking in root system responses to drought was almost consistent among the pots and field experiments. Genotypicvariations in rooting depth were relatively small while those in horizontal spread were apparent in the field experiment.The ability to maintain adventitious root elongation under drought, resulting in relatively large horizontal spread of root system and to recover sharply from drought by lateral root branching may be related to good growth and yield performance under field.     

基于CFX的新型豆粕单螺杆挤出机数值模拟分析

单螺杆挤出机是加工以豆粕为原料的膨化食品行业中使用的关键设备。普通单螺杆挤出机存在混合不充分、比能耗低的缺点,为了提高其性能,运用ANSYS/CFX软件对具有三角屏障混炼元件以及反向螺纹元件的新型单螺杆挤出机的流道进行流场分析。研究分析豆粕在其流道中的运动情况,包括速度矢量图、速度流线图、宏观压力图,并和具有普通单螺杆元件挤出机进行对比分析,结果表明:新型组合式单螺杆挤出机的建压能力较好,可切断重排豆粕的速度流线,有利于豆粕更好地混合。研究结果可为单螺杆挤出机设计提供参考。     

Prediction and measurement of residual stresses in injection molded parts

Residual stresses were predicted by a flow analysis in the mold cavity and residual stress distribution in the injection molded product was measured. Flow field was analyzed by the hybrid FEM/FDM method, using the Hele Shaw approximation. The Modified Cross model was used to determine the dependence of the viscosity on the temperature and the shear rate. The specific volume of the polymer melt which varies with the pressure and temperature fields was calculated by the Tait’s state equation. Flow analysis results such as pressure, temperature, and the location of the liquid-solid interface were used as the input of the stress analysis. In order to calculate more accurate gap-wise temperature field, a coordinate transformation technique was used. The residual stress distribution in the gap-wise direction was predicted in two cases, the free quenching and the constrained quenching, under the assumption that the shrinkage of the injection molded product occurs within the mold cavity and that the solid polymer is elastic. Effects of the initial flow rate, packing pressure, and mold temperature on the residual stress distribution was discussed. Experimental results were also obtained by the layer removal method for molded polypropylene.     

GRASSLAND RECORDING. IV

The traditional method of calculating field output by the utilized-starch-equivalent (U.S.E.) system is compared with a recommended simpler and quicker method. The concept of calculating a U.S.E. factor is introduced and forms the basis for the new method. A monthly U.S.E. factor is used, in conjunction with monthly cow-day (CD.) records to calculate U.S.E. Savings of at least 50% may be expected. Agreement between the two methods is very close and the more seasonal nature of the calculation for sheep and non-milking cattle under the new method may be preferable.     

A GIS-aided two-phase grey fuzzy optimization model for nonpoint source pollution control in a small watershed

A method for allocating allowable ranges of total nitrogen (TN) load to nonpoint (diffuse pollution) sources in a watershed has been developed by adopting the two-phase grey fuzzy optimization approach. Competing goals of water quality management authorities and TN load dischargers at nonpoint sources such as paddy field, upland crop field, and residential area are described with linear imprecise membership functions including interval numbers. TN load discharged from each cell of the nonpoint sources is assumed to be transported along with surface, subsurface, and river flow under the conventional first-order kinetic removal with respect to distance. The travel length of the load is estimated with a digital elevation model in a geographic information system (GIS). Uncertainty of river discharge and self-purification coefficients appearing in the TN transport model is also expressed with interval numbers. The GIS-aided grey fuzzy optimization model developed here is applied to the Seimei River watershed, Japan. By solving the optimization model, the allowable load represented by an interval number at each cell is procured, which would be a scientific base for effluent control regarding nonpoint sources in the area.     

Seasonal fluctuation of groundwater in an evergreen forest, central Cambodia: experiments and two-dimensional numerical analysis

This study of a water cycle was conducted in an evergreen forest located in the Mekong River Basin in central Cambodia. At the observation site, we measured the dynamics of the spatial distribution of groundwater levels. The groundwater movement was analyzed two-dimensionally using boundary conditions and parameters that had been observed in the field. The climate in the research area is dominated by two seasons, which occur annually: a rainy and a dry season. The groundwater levels are generally high during the rainy season and low during the dry season. Groundwater levels were measured along a stream, which flowed through the study site. The streambed was visible at the head of the stream in January. At the next downriver well point, the streambed appeared in March. Finally, it became visible at all well points in April, meaning that surface runoff had disappeared temporarily and instead flowed underground during the ensuing dry period. Groundwater levels of the studied lateral flow perpendicular to the stream that seeped and infiltrated into the stream were 1.2–2.5 m deep (in April), which was the lowest level recorded for the year. During that period, the depth of the groundwater of the studied lateral flow fell by as much as 56 mm per month. In addition, the lateral flow groundwater infiltrated into groundwater of the stream during that period. The groundwater level fluctuation was estimated based on a two-dimensional analysis of lateral flow perpendicular to the stream using a numerical simulation model with soil physical parameters and observed boundary conditions. The observations of ground water fluctuations were well reproduced. Deep seepage of groundwater was estimated using a uniform boundary condition that allowed efflux through the bottom, estimated as being approximately 30 mm per year. The simulated deep seepage rate was considered plausible considering other hydrological components such as soil water storage fluctuation.     

开槽捏合块混炼元件在豆粕挤压加工中的应用及其流场研究

为了提高豆粕加工双螺杆挤出机的混合性能,采用ANSYS-CFX对带有开槽捏合块混炼元件的双螺杆挤出机流道进行三维流场分析,比较豆粨在开槽捏合块及普通捏合块挤出过程中的运动规律。包含速度场、压力场、加权平均剪切速率,以及挤出机流场的对比分析。结果表明:开槽捏合块元件相比于常规捏合块能够显著增强对豆粨的剪切速率,使剪切速率提高1.4倍,能够使轴向建压能力增强,在凹槽处形成背压区,增加豆粨在开槽处的运动时间,提高双螺杆挤出机的分散混合性能。     

基于图像和改进U-net模型的小麦赤霉病穗识别

为了快速、有效地监测小麦赤霉病的发生情况,利用数码相机对人工接种赤霉病菌的小麦田进行RGB图像获取,在图像预处理基础上,利用深度学习网络U-net来对人工标记好的发病麦穗图像进行训练。通过深度学习数据集的构建与测试,建立了基于RGB图像和改进U-net网络模型的小麦赤霉病识别与监测模型,并对模型识别结果进行了验证。结果表明,U-net可以很好地提取图像波段信息,但对于比较复杂的麦穗图像,在使用Keras方法进行图像语义分割时,需要对U-net网络结构进行改进,即在下采样部分加入Dropout层。与人工标记结果相比,模型识别结果的一致性较好,具有较高的监测精度。该模型平均精度为0.969 4,损失函数值为0.075 9,平均交并比MIoU为0.799。上述结果说明改进的U-net模型可以很好地识别和监测小麦图像中的发病麦穗,并在发病麦穗的分割上具有很好的效果     

Modeling paddy field subsurface drainage using HYDRUS-2D

All of steady and non-steady subsurface drainage equations were developed mostly based on water flow pattern in an ordinary field conditions. However, subsurface drainage in a paddy field is quite different from subsurface drainage in an ordinary field. Thus, it is necessary to develop new equations and mathematical models to design subsurface drainage system in a paddy field. The objective of this study was to apply the HYDRUS-2D model, based on the Richard’s equation, to simulate water flow under subsurface drainage in a paddy field for various drain depths (0.5, 0.75 and 1.0 m) and spacings (7.5 and 15.0 m), surface soil textures (clay loam and silty clay loam) and crack conditions. Simulation results were compared with two well-known drainage equations. The maximum drainage rate was obtained under 7.5-m spacings and 1-m depth. With increasing drain spacings, the drainage rate decreased. Drain spacings had more effect on drainage rate and water pressure head as compared to drain depth. Drainage rates calculated by the Hooghoudt’s and Murashima and Ogino’s equations were much lower than those calculated by the Richard’s equation. The Hooghoudt’s equation, developed for ordinary fields, did not perform well for paddy fields. This study also proved the importance of cracks in subsurface drainage system of paddy fields. HYDRUS-2D stands as a robust tool for designing subsurface drainage in a paddy field.     

Genotypic Variations in Response of Lateral Root Development to Fluctuating Soil Moisture in Rice

Abstract

Developmental plasticity in lateral roots may be one of the key traits for the growth of rice plants under soil moisture fluctuations. We aimed to examine responses in seminal root system development to changing soil moisture for diverse rice cultivars. Special attention was paid to the two different types of lateral roots ; the generally long, thick L type capable of branching into higher orders, and the non-branching S type. Plants were grown in half-split polyvinyl chloride tubes fixed with transparent acrylic plate for root observation under glasshouse conditions. When plants were grown first under drought conditions, then rewatered, the seminal root system development in terms of dry weight and total length was promoted as compared with plants grown under continuously well-watered conditions in IR AT 109 and Dular, drought tolerant cultivars. Promoted production of L type lateral roots mainly contributed to the development of the longer seminal root system. Plants exposed to soil submergence before they were grown under drought conditions did not show such promoted responses in these two cultivars. However, in KDML 105, a drought tolerant cultivar, the production of especially L type laterals was substantially promoted under drought and rewatered conditions. Honenwase was characterized by the shallow root system and great reduction in root system length when soil moisture becomes limited. These facts show that genotypic variations exist in the plastic response of rice seminal root system and that the L type lateral root plays a key role in manifestation of this plasticity.     

不同生育期喷灌对渭北旱地小麦产量及品质的影响

为明确喷灌对旱作小麦产量及品质的影响,试验以中麦175为材料,在小麦越冬期和拔节期进行喷灌处理,比较了喷灌处理与对照(未喷灌)间小麦产量、水分利用效率、光合特性及品质的差异。结果表明,越冬期和拔节期喷灌均能显著提高小麦产量,产量增幅为9.7%~36.3%,其中越冬期喷灌24mm+拔节期喷灌24mm处理增产效果最好。喷灌显著增加了穗数、穗粒数和千粒重。喷灌对小麦品质也有一定的影响,显著增加了籽粒硬度、吸水率、最大拉伸面积和沉降值,但对蛋白质含量、稳定时间等其他指标影响较小。说明合理的喷灌可在一定程度上增加旱地产量和改善品质。     

Development of molecular simulation methods to accurately represent protein-surface interactions: The effect of pressure and its determination for a system with constrained atoms

When performing molecular dynamics simulations for a system with constrained (fixed) atoms, traditional isobaric algorithms (e.g., NPT simulation) often cannot be used. In addition, the calculation of the internal pressure of a system with fixed atoms may be highly inaccurate due to the nonphysical nature of the atomic constraints and difficulties in accurately defining the volume occupied by the unconstrained atoms in the system. The inability to properly set and control pressure can result in substantial problems for the accurate simulation of condensed-phase systems if the behavior of the system (e.g., peptide/protein adsorption) is sensitive to pressure. To address this issue, the authors have developed an approach to accurately determine the internal pressure for a system with constrained atoms. As the first step in this method, a periodically extendable portion of the mobile phase of the constrained system (e.g., the solvent atoms) is used to create a separate unconstrained system for which the pressure can be accurately calculated. This model system is then used to create a pressure calibration plot for an intensive local effective virial parameter for a small volume cross section or "slab" of the system. Using this calibration plot, the pressure of the constrained system can then be determined by calculating the virial parameter for a similarly sized slab of mobile atoms. In this article, the authors present the development of this method and demonstrate its application using the CHARMM molecular simulation program to characterize the adsorption behavior of a peptide in explicit water on a hydrophobic surface whose lattice spacing is maintained with atomic constraints. The free energy of adsorption for this system is shown to be dramatically influenced by pressure, thus emphasizing the importance of properly maintaining the pressure of the system for the accurate simulation of protein-surface interactions.     

Permeability measurement of a circular braided preform for resin transfer molding

Permeability of the preform is one of key factors in design of RTM (Resin Transfer Molding) mold, determination of processing conditions, and modeling of flow in the mold. According to previous studies, permeability measured in the unsaturated fiber mats are higher than that in the saturated fiber mats by about 20 % because of the capillary pressure. In this study, permeabilities of several fiber preforms are measured for both saturated and unsaturated flows. A saturated experiment of radial flow has been adopted to measure the permeability of anisotropic fiber preforms with high fiber content, i.e., circular braided preforms. In this method, four pressure transducers are used to measure the pressure distribution. Permeabilities in different directions are determined and the experimental results show a good agreement with the theory. Since permeability is affected by the capillary effect, permeability should be measured in the unsaturated condition for the textile composites to be manufactured under lower pressure as in the Vacuum Assisted Resin Transfer Molding (VARTM).     

Validation of Diagnostic Methods for European Foulbrood on Commercial Honey Bee Colonies in the United States

One of the most serious bacterial pathogens of Western honey bees (Apis mellifera Linnaeus [Hymenoptera: Apidae]) is Melissococcus plutonius, the cause of the disease European foulbrood. Because European foulbrood is highly variable, with diverse outcomes at both the individual and colony levels, it is difficult to diagnose through visual inspection alone. Common lab diagnostic techniques include microscopic examination and molecular detection through PCR. In 2009, a lateral flow device was developed and validated for field diagnosis of European foulbrood. At the time, M. plutonius was thought to be genetically homogenous, but we have subsequently learned that this bacterium exists as multiple strains, including some strains that are classified as ‘atypical’ for which the lateral flow device is potentially less effective. These devices are increasingly used in the United States, though they have never been validated using strains from North America. It is essential to validate this device in multiple locations as different strains of M. plutonius circulate in different geographical regions. In this study, we validate the field use of the lateral flow device compared to microscopic examination and qPCR on larval samples from 78 commercial honey bee colonies in the United States with visual signs of infection. In this study, microscopic diagnosis was more sensitive than the lateral flow device (sensitivity = 97.40% and 89.47%, respectively), and we found no false positive results with the lateral flow device. We find high concurrence between the three diagnostic techniques, and all three methods are highly sensitive for diagnosing European foulbrood.     

Three dimensional FEM simulation for spinning of non-circular fibers

A finite element method is employed for a flow analysis of the melt spinning process of a non-circular fiber, a PET(polyethylene terephthalate) filament. The flow field is divided into two regions of die channel and spin-line. A two dimensional analysis is used for the flow within the die channel and a three dimensional analysis for the flow along the spin-line. The Newtonian fluid is assumed for the PET melt and material properties are considered to be constant except for the viscosity. Effects of gravitation, air drag force, and surface tension are neglected. Although the spin-line length is 4.5 m, only five millimeters from the spinneret are evaluated as the domain of the analysis. Isothermal and non-isothermal cases are studied for the flow within the die channel. The relationship between the mass flow rate and the pressure gradient is presented for the two cases. Three dimensional flow along the spin-line is obtained by assuming isothermal conditions. It is shown that changes in velocity and cross-sectional shape occur mostly in the region of 1mm from the die exit.     

Hydrogen sulfide removal by Thiobacillus thioparus bacteria on seashell bed biofilters

The aim of this research is to achieve an efficient and cheap methods to remove H2S from the factories emissions. Four serial cylinders are designed, 40 cm in height and 15 cm in diameter each. They are filled with bivalve seashells with 63% porosity which contains Thiobacillus thioparus bacteria to the maximum height of 27.5 cm. By mixing phosphoric acid and sodium sulfide, H2S gas is released and its concentration is measured as mg m(-3) before injecting into the cylinders. A permanent measuring instrument is equipped to control the gas coming out of the cylinders. In order to prevent the outdoor environment from pollution, first the gas is sent through two activated carbon columns and then sent through a ferrous chloride scrubber. Finally it is burnt directly by flames. There were 550 sample readings in 15 weeks. The changes in the discharge of the air which carries the gas are considered between 1-12 L min(-1) and the concentration of the influent pollutant is considered between 1-140 mg m(-3). Also the humidity in the atmosphere is fixed between 77-93% and the optimum temperature required for growing of the microorganisms is retained between 20.5-30 degrees C. After feeding the system for three weeks the efficiency started to increase so that by the end of the final week of this research the efficiency reached to 90% with the discharge of 6 L min(-1) of the carrier gas. The results achieved from this research show that because of not using Filamentous bacteria, clogging did not occur in the biological system in biofilters. The amount of head loss in cylinder was only 2 mm water and during this research, head loss was the same due to unclogging of filter. On the other hand the traditional methods are expensive in terms of using chemicals, carbon recycling and using fuel and etc. Therefore researchers have started new studies in this field. The above mentioned method, according to high efficiency, inexpensiveness and easiness of control and maintenance is considered one of the best methods.     

关中麦田产壳玉米秸秆密度与小麦赤霉病穗率的关系

为了准确预测关中地区小麦赤霉病的病穗率,采用田间模拟试验和田间调查相结合的方法,建立了麦田产壳玉米秸秆密度与穗表赤霉菌孢子数的关系模型y=1.115+2.506x,并在实验室前期关中小麦赤霉病病穗率预测模型的基础上,建立了基于麦田产壳玉米秸秆密度的小麦赤霉病预测模型。预测模型中产壳玉米秸秆密度参数的灵敏度变化范围为0.09~0.13,为中等灵敏参数。利用2014年关中15个代表县以及杨凌1986-1992年的实测数据对预测模型进行了评价,该模型的预测准确度在75%以上。综合来看,此预测模型使用简单,预测准确度高。     

Species specific primers for identification of Alternaria solani,in combination with analysis of the F129L substitution associates with loss of sensitivity toward strobilurins

A species specific forward primer was designed in order to identify the phytopathogenic fungus Alternaria solani, which causes early blight on potato. The reverse primer came from another survey of the American population of A. solani. The combination of these two primers can be used both as molecular identification of A. solani as well as sending the PCR product for sequencing in search for the F129L substitution associated with loss of sensitivity toward fungicides based on strobilurins. The diagnostic method has been successfully used when identifying the causal agent of lesions on potato leaflets during large field assays.     

Nonsteady plane-strain ideal forming without elastic dead-zone

Ever since the ideal forming theory has been developed for process design purposes, application has been limited to sheet forming and, for bulk forming, to two-dimensional steady flow. Here, application for the non-steady case was made under the plane-strain condition. In the ideal flow, material elements deform following the minimum plastic work path (or mostly proportional true strain path) so that the ideal plane-strain flow can be effectively described using the two-dimensional orthogonal convective coordinate system. Besides kinematics, schemes to optimize preform shapes for a prescribed final part shape and also to define the evolution of shapes and frictionless boundary tractions were developed. Discussions include numerical calculations made for a real automotive part under forging.     

Discharge estimation of the Shin-Yuan Canal using indirect method

This study presents an indirect method for estimating the discharge of the Shin-Yuan Canal. It includes a new tool of velocity measurement, a method of discharge computation, and some technology. When the Shin-Yuan Canal was built, the issue of discharge measurement was not considered. The Shin-Yuan Canal was co-constructed with the Wan-Dan Canal. Therefore, direct discharge measurement was impossible. This study indirectly estimated the discharge of the Shin-Yuan Canal by controlling the pump discharge through a pumping station. And a stage-discharge rating curve was created for continuous and real-time monitoring of canal discharge. In order to improve measurement accuracy and reliability, this study adopted the acoustic digital current meter (ADC) for discharge measurement. The probabilistic velocity distribution equation was used to accurately calculate the average vertical velocity and the area-velocity principle was used to estimate the water discharge of the Wan-Dan Canal. According to the measurement results, the discharge rating curve of the Shin-Yuan Canal could be accurately established with the precise device, ADC, and the technologies which could effectively measure velocity. This method should be promoted and applied to other similar discharge measurement and monitoring issues of irrigation canals.