AN EVALUATION OF AN ELECTRONIC INSTRUMENT FOR PASTURE YIELD ESTIMATION

A model of the electronic instrument described by Campbell et al . (3) was built at the Grassland Research Institute and was found to behave in a very similar way to their New Zealand model. A considerable amount of field work was undertaken with it in 1964 and this demonstrated that no general relationship of acceptable accuracy had yet been found; nor could it be sufficiently improved by the inclusion of the meteorological and botanical factors recorded. This forces one to a consideration of double-sampling techniques, which appear worth while; they will be discussed in Part 2 of this paper.     

An improved electronic capacitance meter for estimating herbage mass

An improved electronic capacitance pasture meter is described, and data on its calibration and use in a grazing trial are presented. The instrument is light (1·4 kg) and portable, and uses integrated circuits to record the readings from a number of sampled sites. It has a digital display and can be constructed for a modest cost. The meter is mainly responsive to the surface area of the herbage and hence it is less sensitive to variations in moisture content of the pasture than previous meters. Thus it can be calibrated to measure the mass of herbage dry matter to ground level and reduces the need to collect and dry herbage samples for frequent recalibration of the instrument.     

A rapid method of testing plants in the field for potato virus X

American Journal of Potato Research - A method is described whereby a team of four people can use a variant of the serological precipitin reaction to test over 125 plants an hour in the field for...     

AN ELECTRONIC INSTRUMENT FOR PASTURE YIELD ESTIMATION

This is a preliminary report on an instrument being developed for the measurement of pasture yield in situ . In essence the instrument is an electrical capacitance measuring unit in which the introduction of herbage to a measuring head causes a change in the electrical capacitance of the system. This capacitance change is measured at a radio frequency and used as an indicator of the mass of herbage contained within the measuring head.
The development and construction of the instrument is described and data are presented for 15 calibration series in which frequency change has been related to pasture yield.
Within series the instrument accounts for approximately 90% of the variation in pasture sample yield measured either as wet, dry or organic matter. However, significant differences exist between series. These differences would give rise to bias if pasture yield were estimated from a prediction equation derived from the pooled data.
Possible sources of the differences between series are discussed and avenues for further development indicated.     

便携式高油酸花生鉴定仪的研制

高油酸花生以其营养价值高、储藏期长等优点深受消费者和加工企业的喜爱。但是,高油酸花生和普通油酸花生并不能直观区分,必须借助仪器检测油酸含量。其中,气相色谱仪和近红外光谱仪是目前最常用的两类仪器,但是体积大、质量重、造价高,而且需要专业实验室和专业人员操作,限制了其在中小型花生生产和加工企业中的应用。本研究基于花生油折光指数与温度（R²=0.999）和油酸含量（R²=0.802）显著负相关的原理,建立了利用折光指数鉴定高油酸花生的数学模型,并研发了一款便携式高油酸花生鉴定仪。利用该仪器检验了30个花生品系是否为高油酸花生,鉴定结果均与其油酸含量化学值相一致,准确率为100%。该仪器的研制填补了快速、低价、便携式高油酸花生检测仪的空白,为促进高油酸花生产业发展提供了一种简便易行的检测设备。     

An empirical statistical model for predicting the yield of herbage from legume-grass swards within organic crop rotations based on cumulative water balances

Multi-species legume-grass swards play a key role in organic farming systems as a source of forage and of symbiotically fixed nitrogen (N). Forage and N balances, based on site-specific data on dry matter (DM) yields of herbage, are useful planning tools in describing forage and N supply at the field and farm level. In practice, measurements of DM yield are often imprecise or missing, and thus a weather- and site-specific assessment of DM yield is required. An empirical model to predict DM yield from legume-grass swards was developed based on weather and soil data commonly available at field and regional scales. The main underlying hypothesis was that water use, calculated from cumulative water balances, can be used as a predictor of DM yield. The model was calibrated with data from a multi-year field experiment in Müncheberg, north-east Germany and was tested with data from other countries of Europe. In the calibration data set, highly significant linear relationships were found between water use and DM yield for DM yield of single harvests and for annual DM yield. The only additional variable significantly improving the prediction of DM yield was cut number. For the validation data set the DM yield for single cuts and annual yields was predicted with a similar accuracy as found with other models requiring the use of more information. The models described offer a straightforward weather- and site-specific means of predicting DM yield with a satisfactory level of precision, especially for annual DM yields, and thus can help to reduce planning failures concerning forage and N supply in organic farming systems in Europe.     

Development of a Human-Clothing-Environment simulator for dynamic heat and moisture transfer properties of fabrics

A vertical skin model with two detachable environmental chambers was developed to simulate a Human-Clothing-Environment system and to evaluate heat and moisture transport properties of textile materials under severe conditions and during transient states. The construction of the system was described and data reproducibility and accuracy of the instrument were verified by using PEG treated nonwovens. Also advantages over a traditional static type experiment were demonstrated based on a series of experiments.     

Genetic and environmental analysis of NIR feed quality predictions on genotypes of barley (Hordeum vulgare L.)

This study investigated the use of NIR feed quality equations, developed from a multi-cereal calibration set, including barley, on barley breeding lines and commercial cultivars. The resultant predictions were then analysed to ascertain genetic and or environmental affects. The calibrations were developed by a third party, using a NIRSystems 6500 (master) instrument. The barley spectra we used were also from the same model of instrument, which had been spectrally standardised to match the master instrument. The breeding lines and commercial cultivars used were obtained from a field trial series which combined intermediate and advanced breeding lines, grown at 11 environments over two seasons. The results indicated there were significant (P < 0.05) genetic and environmental effects on a broad range of feed quality related traits; including metabolisible energy, digestible energy and apparent metabolisible energy. Other feed traits such as acid detergent fibre, neutral detergent fibre, β-glucan and starch also showed significant (P < 0.05) genetic and environmental affects. There was a high level of heritability for most traits, ranging from 70 to 90%. The results identified a number of strongly correlated traits when analysed by factor analysis. These included starch and the energy traits. There were no strong associations between particular cultivars and the NIR predicted feed traits. The results from this study highlighted NIR equations for predicted feed quality that can provide data to assist selection of barley breeding lines. In addition, the analysis also showed the genetic and environmental effects that could be expected to be observed in a broad range of barley breeding material and commercial varieties. This information can be combined in breeding programs to identify robust barley lines that would be suited to specific animal feed classes.     

水稻赖氨酸含量测定方法改进及其最优动态分类研究

赖氨酸是水稻营养成分中第一限制性氨基酸。为优化赖氨酸的测定方法,设置了本试验,通过超声振荡器取代普通振荡器,进行300W超声功率下酰化用时及染料结合反应用时的研究。结果表明,最佳酰化用时为15 min,染料结合用时为90 min。与国标法相比,优化后的方法酰化用时变长、染料结合用时变短,测定总用时明显缩短,但测定结果和试验精度更高。可见,采用超声波振荡代替传统振荡器振荡能改进赖氨酸的测定方法。另外,采用最优动态聚类法对赖氨酸含量进行分类,能防止人为分类的不确定性,做到分类方案的最优化。     

Sensory and instrumental measurement of french fry limpness

An instrument is described for measuring the apparent rupture stress and apparent elastic modulus of French fries objectively to evaluate French fry limpness. The fries are bent at a constant rate and the force and deflection recorded during this process. The instrumental results agree with sensory tests. Both instrumental and sensory tests indicate that French fry limpness and specific gravity of the fry are related.     

尾叶香茶菜化学成分测定分析

采用分光光度法对尾叶香茶菜不同部位的黄酮和多糖进行测定分析,实验表明,尾叶香茶菜不同部位的总黄酮和多糖含量差异较大,该植物的黄酮类化台物主要存在于叶中,而多糖主要存在于根部;同时采用原子吸收分光光度法和原子荧光分光光度法测定尾叶香茶菜中无机元素含量,结果表明:尾叶香茶菜中存在多种无机元素,各元素的相对含量各有不同。     

Spatial heterogeneity and other sources of variance in sward height as measured by the sonic and HFRO sward sticks

Measurements of undisturbed sward surface height (sward height) were made using the HFRO and sonic sward sticks at 20 cm intervals along 100 m transects laid across paddocks grazed by either sheep, cattle or goats. Measurements of sward height were also made at 5 cm intervals along 10 m transects laid across the same paddocks using the HFRO sward stick alone. The variance of the measurements from each transect was partitioned across the range of spatial scales of roughness present using spectral analysis. The variance of the sward surface height appeared to be dominated by variation with spatial scales of less than 1 to 2 m. The variances of measurements made with the two sward sticks were similar despite the greater sampling area of the sonic sward stick. This was due to the presence of variation at spatial scales much larger than the sampling area of either instrument and to a greater contribution from non-spatially related sources to the variance of the sonic sward stick measurements. The use of weighted disc meters for obtaining the mean height of continuously grazed sward deserves re-examination, while automation of the sonic sward stick may be worthwhile if the spatial distribution of herbage is to be described.     

Evaluating a dual-frequency-phase-shift soil moisture and electrical conductivity sensor

For soil water and solute transport research, time domain reflectometry (TDR) has been commonly used since its introduction to soil research in 1980 by Topp and his colleagues. Although TDR seems to be very versatile for laboratory and field experiments, it requires modest user skills for accurate measurements and the instrument itself is still expensive. A new soil moisture and electrical conductivity (EC) sensor was recently developed at a reduced cost. The new sensor independently measures soil water content, and soil bulk electrical conductivity using frequency phase-shift techniques, and soil temperatures using a thermistor. We evaluated the new sensor for measurements of water content, and EC using three different sensors in variably saturated soils. There was little deviation among the units for water content measurement except at near saturation. Separate exponential curves provided good calibrations for all the soils used in the full range of water content between air-dry and saturation. In saline water up to 54 mS m^?1, the mV output in the EC measurement mode was linearly related to solution EC. Although slopes were quite similar among the three sensors, the intercepts differed from the manufacturer’s calibration. The calibrations for volumetric water content and electrical conductivity provided by the manufacturer were not good enough for any use. The temperature effect on volumetric water content could be negligible or easily compensated with a simple formula. Little EC dependency of the sensor on volumetric water content was observed.     

A system for rapid freezing of pasture samples in the field

A system for rapid freezing and containment of pasture and forage samples in the field is described. Core temperatures of pasture samples of 2–5 kg mass can be reduced to below 0°C in a few minutes using liquified carbon dioxide in the ratio of 1 to 2 kg carbon dioxide to 1 kg of green plant material. Changes in the pH of the plant extract were very small ( ca. 0 1 pH unit). The system is especially suitable for use in areas remote from normal laboratory facilities, where rapid freezing of herbage samples is essential.     

A methodology for characterization and analysis of plant functional composition in grassland‐based farms

Understanding the relationships between farmers' land‐use and management decisions, and plant diversity is a challenge. It requires characterization of plant diversity within and between fields and investigation of land‐use allocation to fields. To analyse how grassland functional composition [mean plant trait and functional diversity index (FD)] varies according to scale (field, land‐use type: cutting, grazing, farm), grasslands were characterized according to leaf dry‐matter content (leaf DM) and FD computed from leaf DM values. A leaf DM‐αFD framework was used to analyse how leaf DM‐based plant strategies were distributed at land‐use type and farm scales (βFD). The study was conducted on eight dairy and beef farms (169 grasslands) differing in their stocking rate. At field and land‐use type scales, leaf DM was significantly decreased and increased with N fertilizer rate and field elevation respectively. It was significantly higher for grazing than for cutting. At the farm scale, the main differences between farms resulted from differences in plant strategy distribution between land‐use types within a farm and among farms for a given land‐use type in relation to management intensity. Farms that contributed the most to αFD had the highest stocking rate, and those which had the most contrasting grasslands for management intensity had the highest βFD. Management practices need to be examined at a land‐use type scale for evaluating the within‐ and between‐field plant functional compositions. By contrast, the value of the analysis was reduced if data were collected and averaged at the farm scale.     

水稻氮素营养诊断方法研究进展

目前水稻氮素营养诊断方法主要有外观诊断、化学诊断与现代氮素营养诊断。外观诊断包括颜色诊断和长势长相诊断;化学诊断包括全氮诊断和硝酸盐诊断;现代氮素营养诊断包括叶绿素仪测量、机器视觉和高光谱遥感。本文对各诊断方法及近来年相关应用成果进行阐述,同时分析了各技术方法的优缺点,以为研究学者提供参考与思路。     

Large deformation stress relaxation and compression-recovery of gluten representing different wheat classes

Despite the great variety of physicochemical and rheological tests available for measuring wheat flour, dough and gluten quality, the US wheat marketing system still relies primarily on wheat kernel hardness and growing season to categorize cultivars. To better understand and differentiate wheat cultivars of the same class, the tensile strength, and stress relaxation behavior of gluten from 15 wheat cultivars was measured and compared to other available physicochemical parameters, including but not limited to protein content, glutenin macropolymer content (GMP) and bread loaf volume. In addition, a novel gluten compression–relaxation (Gluten CORE) instrument was used to measure the degree of elastic recovery of gluten for 15 common US wheat cultivars. Gluten strength ranged from 0.04 to 0.43 N at 500% extension, while the degree of recovery ranged from 5 to 78%. Measuring gluten strength clearly differentiated cultivars within a wheat class; nonetheless it was not a good predictor of baking quality on its own in terms of bread volume. Gluten strength was highly correlated with mixograph mixing times (r = 0.879) and degree of recovery (r = 0.855), suggesting that dough development time was influenced by gluten strength and that the CORE instrument was a suitable alternative to tensile testing, since it is less time intensive and less laborious to use.     

MECHANICAL MEASUREMENT OF GRAZING TIMES OF SHEEP AND A BIAS IN VISUAL ASSESSMENT

A mechanical device to record time spent in grazing by sheep is described and the results of tests of its performance under field conditions are given. There was good agreement between mecbanicai and visual records under field conditions, and observations made during tbe tests indicate a possible source of bias where visual records are made by an observer watching a group of animals.     

Continuous electronic on-line cookness tester for potatoes

An on-line instrument was developed to continuously measure the amount of cooking received by potatoes during processing. It correlates with our earlier work in which a batch back extrusion tester was used to develop a model for cooking. As a prototype, the on-line instrument was used in place of the conventional ricer in the instant potato flake process; but should be applicable to other food processes to optimize the amount of cooking a food product undergoes during processing.