Quantifying economic losses associated with levels of wheat streak mosaic incidence and severity in the Texas High Plains

Wheat streak mosaic (WSM), caused by the Wheat streak mosaic virus (WSMV), which is transmitted by the wheat curl mite (Aceria tosichella), is the most prevalent virus disease of wheat in the Texas High Plains. Infected plants initially exhibit mosaic symptoms, which lead to severe stunting, complete chlorosis and, in the most severe cases, eventually plant death. Wheat plants infected with WSMV have lower forage and grain yields and exhibit reduced water-use efficiency compared to non-infected plants. The disease impact on water-use efficiency raises an important issue of whether diseased fields should be irrigated as frequently as non-diseased fields. The issue becomes more relevant when energy costs and the dwindling water resources from the Ogallala Aquifer are taken into consideration. This study examined the potential economic losses due to WSM, using data collected from two fields in 2007 and 2009. A hand-held hyperspectral radiometer was used to quantify severity of WSM in multiple 1 m² plots along two transects, each stretching from the edges of the fields to their centers. Grain yield declined exponentially (R² = 0.79, P < 0.0001) with increasing disease severity, as measured by reflectance at 555 nm. For economic analysis, grain yield from each plot was used for determining cost adjustments and linked revenues in relation to WSM severity levels, which allowed calculations of potential profit reduction. The method enables one to compare losses associated with different levels of WSM severity to a baseline with little or no WSMV infection. Results show that losses from the disease are primarily an outcome of reduced revenue due to a decrease in grain yield, and, as expected, losses incurred per unit land area rapidly increase with increasing disease incidence and severity. Furthermore, producers incur additional marginal losses when irrigating fields with WSM because there is little or no return for irrigation inputs, as water-use efficiency of severely diseased wheat is drastically reduced. Results from this study are useful in estimating losses at differing levels of disease incidence and severity and represent the first step in development of an economic threshold for wheat streak mosaic.     

Wheat/maize or wheat/soybean strip intercropping: II. Recovery or compensation of maize and soybean after wheat harvesting

While early-maturing crops benefit from intercropping, late-maturing crops usually suffer growth penalties during the intercropping phase. It is possible, however, that recovery or compensation of the late-maturing crops occurs after the harvest of the early-maturing crops. Three field experiments were conducted at Baiyun in 1997 and at Jingtan in 1997 and 1998 to test the hypothesis in wheat/maize and wheat/soybean intercropping. The biomass and nutrient accumulation in intercropped soybean were significantly smaller than in sole soybean before wheat harvest but thereafter increased sharply at Jingtan site in 1997. The rates of dry matter accumulation in the intercropped maize (10.0–20.1 g/m² per day) were significantly lower than those in the sole maize (17.1–34.8 g/m² per day) during the early stage from 7 May to 3 August, while mostly intercropped with wheat. After 3 August, however, the rates of intercropped maize, increasing to 58.9–69.9 g/m² per day, was significantly greater than in sole maize (22.7–51.8 g/m² per day) at Baiyun site in 1997 and nutrient acquisition showed the same trends as growth. At Jingtan site in 1998, the disadvantage of the border row of intercropped maize resulted from interspecific competition diminished after wheat harvest and disappeared at maize maturity. It was concluded that there was indeed recovery of growth after wheat harvesting in wheat/maize and wheat/soybean intercropping. However, the recovery was limited under N₀P₀ treatment. The interspecific competition, facilitation and recovery are together contributed to yield advantage of intercropping.     

Rice straw mulching and nitrogen response of no-till wheat following rice in Bangladesh

Wheat (Triticum aestivum L.) cultivation in no-till soil of a postrice harvest field utilizes residual soil moisture and reduces the time period from rice harvest to wheat seeding in intensive rice-wheat cropping systems. Some of the major constraints in no-till wheat production are high weed infestation, poor stand establishment due to rapid drying of topsoil and low nitrogen use efficiency (NUE). A field experiment was conducted at the research farm of the Wheat Research Centre, Dinajpur, Bangladesh, for two consecutive years to overcome those constraints, to evaluate rice straw as mulch, and to determine the optimum application rate of nitrogen (N) for no-till wheat. The treatments included 12 factorial combinations of three levels of mulching: no mulch (M₀), surface application of rice straw mulch at 4.0 Mg ha⁻¹ that was withdrawn at 20 days after sowing (M₁), the same level of mulch as M₁ but allowed to be retained on the soil surface (M₂), and four nitrogen levels (control 80, 120 and 160 kg ha⁻¹). Rice straw mulching had a significant effect on conserving initial soil moisture and reducing weed growth. Root length density and root weight density of wheat were positively influenced both by straw mulching and N levels. N uptake and apparent nitrogen recovery of applied N fertilizer were higher in mulch treatments M₁ and M₂ as compared to M₀. Also mulch treatment of M₁ and M₂ were equally effective at conserving soil moisture, suppressing growth of weed flora, promoting root development and thereby improved grain yield of no-till wheat. N application of 120 kg ha⁻¹ with straw mulch was found to be suitable for no-till wheat in experimental field condition.     

Interactions between non-flooded mulching cultivation and varying nitrogen inputs in rice–wheat rotations

A 3-year field experiment examined the effects of non-flooded mulching cultivation and traditional flooding and four fertilizer N application rates (0, 75, 150 and 225 kg ha⁻¹ for rice and 0, 60,120, and 180 kg N ha⁻¹ for wheat) on grain yield, N uptake, residual soil N_min and the net N balance in a rice–wheat rotation on Chengdu flood plain, southwest China. There were significant grain yield responses to N fertilizer. Nitrogen applications of >150 kg ha⁻¹ for rice and >120 kg ha⁻¹ for wheat gave no increase in crop yield but increased crop N uptake and N balance surplus in both water regimes. Average rice grain yield increased by 14% with plastic film mulching and decreased by 16% with wheat straw mulching at lower N inputs compared with traditional flooding. Rice grain yields under SM were comparable to those under PM and TF at higher N inputs. Plastic film mulching of preceding rice did not affect the yield of succeeding wheat but straw mulching had a residual effect on succeeding wheat. As a result, there was 17–18% higher wheat yield under N0 in SM than those in PM and TF. Combined rice and wheat grain yields under plastic mulching was similar to that of flooding and higher than that of straw mulching across N treatments. Soil mineral N (top 60 cm) after the rice harvest ranged from 50 to 65 kg ha⁻¹ and was unaffected by non-flooded mulching cultivation and N rate. After the wheat harvest, soil N_min ranged from 66 to 88 kg N ha⁻¹ and increased with increasing fertilizer N rate. High N inputs led to a positive N balance (160–621 kg ha⁻¹), but low N inputs resulted in a negative balance (−85 to −360 kg ha⁻¹). Across N treatments, the net N balances of SM were highest among the three cultivations systems, resulting from additional applied wheat straw (79 kg ha⁻¹) as mulching materials. There was not clear trend found in net N balance between PM and TF. Results from this study indicate non-flooded mulching cultivation may be utilized as an alternative option for saving water, using efficiently straw and maintaining or improving crop yield in rice–wheat rotation systems. There is the need to evaluate the long-term environmental risks of non-flooded mulching cultivation and improve system productivity (especially with straw mulching) by integrated resource management.     

Predicting water absorption of wheat flour using high shear-based GlutoPeak test

Selection for water absorption, a fundamental wheat quality parameter, has been a challenge in wheat breeding programs due to limited wheat materials available for milling and consequent time-consuming farinograph test. Hence, a high shear-based method, which requires 8 g of flour and less than 10 min per test, was proposed to predict flour water absorption using the Brabender GlutoPeak instrument. Highly significant positive linear relationship (r² = 0.97) was found between GlutoPeak maximum torque and farinograph water absorption for 83 flour samples prepared with Bühler test mill from wheat lines under evaluation in the Canadian wheat variety registration trials. Similar strong correlation (r² = 0.96) was obtained from flours (n = 63) prepared with Quadrumat Junior laboratory mill using small amount of wheat. Flour prepared either with Bühler test mill or Quadrumat Junior mill can be used for predicting water absorption effectively. GlutoPeak maximum torque was found to be independent of dough strength (r² = 0.02) as measured by extensigraph. GlutoPeak test can be a powerful tool for rapid and reliable prediction of water absorption of wheat flour.     

Effects of harvest and sowing time on the performance of the rotation of winter wheat–summer maize in the North China Plain

Rotation of winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) is the prevailing double-cropping system in the North China Plain. Typically, winter wheat is planted at the beginning of October and harvested during early June. Maize is planted immediately after wheat and harvested around 25th of September. The growing season of maize is limited to about 100–110 days. How to rectify the sowing date of winter wheat and the harvest time of summer maize are two factors to achieve higher grain yield of the two crops. Three-year field experiments were carried out to compare the grain yield, evapotranspiration (ET), water use efficiency (WUE) and economic return under six combinations of the harvest time of summer maize and sowing date of winter wheat from 2002 to 2005. Yield of winter wheat was similar for treatments of sowing before 10th of October. Afterwards, yield of winter wheat was significantly reduced (P < 0.05) by 0.5% each day delayed in sowing. The kernel weight of maize was significantly increased (P < 0.05) by about 0.6% each day delayed from harvest before 5th of October. After 10th of October, kernel weight of maize was not significantly increased with the delay in harvest because of the lower temperature. The kernel weight of maize with thermal time was in a quadratic relationship. Total seasonal ET of winter wheat was reduced by 2.5 mm/day delayed in sowing and ET of maize was averagely increased by 2.0 mm/day delayed in harvest. The net income, benefit–cost and net profit per millimetre of water used of harvest maize at the beginning of October and sowing winter wheat around 10th of October were greater compared with other treatments. Then the common practice of harvest maize and sowing winter wheat in the region could be delayed by 5 days correspondingly.     

Does undersowing winter wheat with a cover crop increase competition for resources and is it compatible with high yield?

The sustainability of cropping systems can be increased by introducing a cover crop, provided that the cover crop does not reduce the cash crop yield through competition. The cover crop may be sown at the same time as a cash crop in the crop rotation. We carried out an experiment in 1999–2000 and 2000–2001 in the Paris Basin, to analyze the effects of simultaneously sowing winter wheat (Triticum aestivum L.) and red fescue (Festuca rubra L.), a turf grass. Competition between wheat and fescue was analyzed with one variety of red fescue, Sunset, and two varieties of wheat, Isengrain and Scipion, each sown at a density of 150 plants m^?2. In this study, we evaluated the effect of undersown fescue on wheat yield and analyzed the competition between the two species in detail. The undersown red fescue decreased wheat yield by about 12% for Isengrain (8.7 t ha^?1 for undersown Isengrain versus 9.8 t ha^?1 for Isengrain alone) and 7% for Scipion (7.4 t ha^?1 for undersown Scipion versus 8.0 t ha^?1 for Scipion alone). During the early stages of wheat growth (up to the ‘1 cm ear’ stage, corresponding to stage 30 on Zadoks’ scale), undersown fescue and fescue sown alone grew similarly. However, fescue biomass levels were much lower (5.6 and 4.7 g m^?2 for fescue grown alone and undersown fescue) than wheat biomass levels on the undersown plots (120 g m^?2 for Isengrain and 111 g m^?2 for Scipion). From the e1 stage onwards, the wheat canopy rapidly extended, whereas that of red fescue remained sparse. The time lag between the beginning of the rapid increase in LAI and PAR interception by wheat grown alone and that for fescue grown alone was 590 dd in the second year. This resulted in much slower growth rates for undersown fescue than for undersown wheat. Biomass production rate was therefore low for undersown fescue (12% those of fescue grown alone, on average, at the time of wheat harvest), as were levels of water and nitrogen use. Neither the water deficit that occurred during the second experiment nor the nitrogen nutrition status of the wheat on plots with undersown fescue significantly affected wheat biomass production after anthesis.The global interception efficiency index IG?_i indicated that the fraction of the PAR_o intercepted by the wheat during its growth (255 days) was 0.35.     

A rapid extensigraph protocol for measuring dough viscoelasticity and mixing requirement

The extensigraph is particularly useful in characterizing dough viscoelastic properties; however, testing throughput for standard method is low due to the prerequisite for farinograph water absorption, long dough resting and milling to prepare large amounts of flour. Therefore, a rapid extensigraph method was developed that reduced sample size (165 g wheat) for milling and more than tripled throughput. Wheat is milled in Quadrumat Junior mill with a modified sieving system. The resulting flour (100 g) was mixed with a pin mixer at constant water absorption to allow the evaluation of wheat genotypes at the absorption level they are expected to perform. Dough was subsequently stretched by an extensigraph after 15 min of floor time and 30 min resting. Strong correlations for extensigram R_max (r > 0.93), extensibility (r > 0.64) and area (r > 0.88) were found for the proposed method compared to the standard method. Mixing parameters (time and energy) obtained during dough preparation provided further information about dough strength and mixing requirement. By significantly reducing sample size requirement and increasing testing throughput, this rapid extensigraph method can be widely adopted in milling and baking industry and meets the need for a fast evaluation of dough strength in breeding trials.     

Protein Content of Single Kernels of Wheat by Near-Infrared Reflectance Spectroscopy

Protein content is well known to affect the functional properties of processed wheat products. Traditionally performed on aliquots (0·25–2·2 g) from samples ranging in size from 30–40 g (for combustion and Kjeldahl analyses) to several hundred grams (for whole-grain near-infrared analysis), these methods inherently do not provide information on single-kernel protein variability. Inspection procedures by the United States Department of Agriculture for grading and classification of wheat are undergoing change to provide the processor or end user with information on the variability of several single-kernel properties including hardness, moisture, weight, and wheat class. The present study has focused on demonstrating the feasibility of measuring crude protein content of single wheat kernels by near-infrared reflectance. More than 300 commercial wheat samples from the 1992 U.S. harvest, representing five (hard red winter, hard red spring, soft red winter, hard white, and soft white) of the six (durum excluded) market classes were chosen, from which 10 kernels were randomly selected and handled on a single-kernel basis. Handling consisted of reflectance scanning (1100–2498 nm), drying (for moisture compensation), and combustion (for reference protein-content determination). Partial least squares and multiple linear regression models, when applied to samples excluded from calibration, demonstrated standard errors of performance ranging from 0·462 to 0·720% protein depending on the modeling technique, number of classes used to develop the model, and the wheat class tested. The pooling of wheat classes to produce a general model did not diminish model accuracy. Best results were achieved with an 1100–1400-nm region. Model performance worsened as the wavelength region widened or as the minimum wavelength shifted from 1100 nm to higher values.     

Physiological determinants of maize and sunflower grain yield as affected by nitrogen supply

Utilisation of nitrogen (N) has been closely related to increases in crop productivity. However, not all crops respond similarly and the objective of this study is to identify physiological processes that determine responses to N supply for maize and sunflower. Grain yield in maize (range: 210–1255 g m⁻²) was greater and more responsive to N supply than in sunflower (106–555 g m⁻² in carbohydrate equivalents) over a wide range of total N uptake (3–>20 g N m⁻²). In maize, differences in grain yield among levels of N supply were associated more with variation in biomass than in harvest index. In sunflower, differences in grain yield (in carbohydrate equivalents) among levels of N supply were related similarly to variation in both biomass and harvest index. The decrease in biomass production with decreasing N supply was associated with decreases in both radiation interception and radiation use efficiency (RUE). Decreased interception was due to effects of N supply on reducing canopy leaf area, whereas the reduced RUE was associated with decreased SLN. Total biomass production in maize was more responsive to N supply than in sunflower. The major determinants of the differences in response of biomass accumulation to N supply found between maize and sunflower are: (i) sunflower tends to maintain SLN with increase in partitioning of N to leaves under N limitation whereas maize tends to maintain leaf area with increase in partitioning of biomass to leaves and (ii) the ability of maize to maintain N uptake following cessation of leaf production.     

Influence of solar drying and storage conditions on microstructure,crack propagation and nano-hardness of paddy and wheat

The influence of hybrid solar drying (HSD) and storage conditions on microstructure, crack propagation, nano-hardness and milling indices of paddy and wheat grains were investigated. Milling yield and head rice yield of dried paddy was 71.48% and 72.42%, which was further increased by 1–1.26% and 3.12–4.65%, respectively. Flour yield from dried wheat was found to be 77.30% and was reduced by 3.5–7.7% after 180 days of storage. Maximum nano-hardness of 0.15 ± 0.02 GPa was obtained for rice stored at 5 °C, whereas, for wheat, nano-hardness, elastic modulus, and peak load values gradually reduced with a storage time of 180 days. Micro-X ray computed tomography images revealed the pore size of paddy and wheat samples to be in the range of 0.01–0.8 mm³. Micrographs showed a compact paddy surface, whereas wheat endosperm witnessed cell disruption and agglomeration.     

Evaluation of post-emergence herbicides for the control of wild oat (Avena fatua L.) in wheat and barley in Argentina

Wild oat (Avena fatua L.) is the most troublesome weed in cereal crops in Argentina. With the aim of studying the effects of different herbicides, doses, and wild oat growth stage at application on weed control and crop yield, field experiments were conducted in wheat and barley crops during three growing seasons in the south of Buenos Aires Province, Argentina. Treatments were post-emergence applications of new herbicide, pinoxaden + cloquintocet mexyl (5%-1.25%), at doses that ranged from 20 g to 60 g a.i. pinoxaden ha⁻¹, applied at two to three leaves and the beginning of tillering of wild oat. In addition, standard treatments were included and applied at the same wild oat growth stages. Diclofop methyl at 511 g a.i. ha⁻¹ and fenoxaprop-p-ethyl at 55 g a.i. ha⁻¹ were applied in barley. In wheat, diclofop methyl was replaced by clodinafop-propargyl + cloquintocet mexyl (24%-6%) at 36 g a.i. clodinafop-propargyl + 9 g cloquintocet mexyl ha⁻¹ and in 2008/09 wheat experiments, iodosulfuron plus metsulfuron methyl (5%-60%) at 3.75 g a.i. ha⁻¹ + 3 g a.i. ha⁻¹ also was included. In both crops, pinoxaden at 30 g a.i. ha⁻¹ and at higher rates, fenoxaprop-p-ethyl and clodinafop-propargyl gave the best control of wild oat. In 2006/07 wheat crops, treatments applied at tiller initiation provided better control than the early timing averaged across herbicides. However, wheat yield generally was greater with early application. In barley, wild oat control and crop yield were similar regarding time of application. Variations in crop yield were correlated with grain number m⁻² both in wheat and barley, but relationships between both grain number and spikes m⁻² and with grains per spike were identified only in wheat.     

Ecophysiological determinants of biomass and grain yield of wheat under P deficiency

Grain yield of crops can be expressed as a function of the intercepted radiation, the radiation use efficiency and the partitioning of above-ground biomass to grain yield (harvest index). When a wheat crop is grown under P deficiency the grain yield is reduced but it is not clear how these three components are affected. Our aim was (i) to identify which of these components were affected in spring bread wheat under P deficiency at field conditions and (ii) to relate the grain yield responses to processes of grain yield formation during the spike growth period. Three field experiments were conducted in the potentially high wheat yielding environment of southern Chile. All experiments had two levels of P availability: with (155 kg P ha⁻¹) or without P fertilization (average soil P-Olsen concentration of 10 ppm, a medium level of P availability). High wheat grain yields were obtained varying between 815 and 1222 g m⁻² with P applications. Experiments showed a grain yield reduction caused by P deficiencies of 35, 16 and 18% in experiments 1, 2 and 3, respectively. This was related (R² = 0.99, P < 0.01) to a reduction in the total above-ground biomass at harvest and not to the harvest index. Reductions in above-ground biomass were due to a reduction in radiation intercepted under P deficiency without effecting radiation use efficiency. Grain number per square meter was the main yield component (R² = 0.99, P < 0.01) that explained the grain yield reduction caused by the P deficiency which was due to low spike biomass at anthesis (R² = 0.96, P < 0.05). The reduction in spike biomass at anthesis was related (R² = 0.86, P < 0.01) to reductions in crop growth rate during the spike growth period as a consequence of a lower radiation intercepted during this period. This study showed that under high wheat yield conditions the main effect of a P deficiency on grain yield reduction was a negative impact on the total above-ground biomass due to the negative impact on intercepted radiation, particularly during the spike growth period, affecting negatively spike biomass at anthesis and consequently grain number and yield.     

Detection of powdery mildew in two winter wheat cultivars using canopy hyperspectral reflectance

To determine the most sensitive spectral parameters for powdery mildew detection, hyperspectral canopy reflectance spectra of two winter wheat cultivars with different susceptibilities to powdery mildew were measured at Feekes growth stage (GS) 10, 10.5, 10.5.3, 10.5.4 and 11.1 in 2007–2008 and 2008–2009 seasons. As disease indexes increased, reflectance decreased significantly in near infrared (NIR) regions and it was significantly correlated with disease index at GS 10.5.3, 10.5.4 and 11.1 for both cultivars in both seasons. For the two cultivars, red edge slope (dr_red), the area of the red edge peak (Σdr_{680−760 nm}), difference vegetation index (DVI) and soil adjusted vegetation index (SAVI) were significantly negatively correlated with disease index at GS 10.5.3, 10.5.4 and 11.1 in both seasons. Compared with other parameters, Σdr_{680−760 nm} was the most sensitive parameter for powdery mildew detection. The regression models based on Σdr_{680−760 nm} were constructed at GS 10.5.3, 10.5.4 and 11.1 in both seasons. These results indicated that canopy hyperspectral reflectance can be used in wheat powdery mildew detection in the absence of other stresses resulting in unhealthy symptoms. Therefore, disease management strategies can be applied when it is necessary based on canopy hyperspectral reflectance data.     

Antioxidant properties of wheat and rye bran extracts obtained by pressurized liquid extraction with different solvents

Rye and wheat brans are valuable sources of bioactive compounds, which could be used for the development and commercialization of high added value functional ingredients such as dietary antioxidants. The aim of this study was to evaluate antioxidant potential of rye and wheat bran using different polarity solvents. Cereal brans were ground to four different particle size fractions and extracted at 10.3 MPa pressure and 80 °C temperature by consecutive application of hexane, acetone and methanol:water (80:20%). The highest extract yield was obtained from rye bran using methanol-water; particle size in most cases had a significant effect. Antioxidant potential of extracts was assessed by ABTS^+•, DPPH^• scavenging, ORAC and total phenols content (TPC) assays. Extraction solvent had a major influence on TPC and antioxidant activity of the extracts. The most active extracts were obtained using methanol:water; rye bran extracts, in general, were stronger antioxidants than wheat bran extracts. For the majority of assays, reduction of particle size resulted in higher antioxidant activity values. However, ABTS^+• scavenging was found to decrease by decreasing particle size of rye bran used for extraction.     

Effect of heating temperature on the particle size distribution in waxy wheat flour

The particle size of waxy (amylose-reduced) wheat (Triticum aestivum L.) starch was determined at isothermal temperatures by laser diffraction analysis. Flour samples were suspended in deionized water at temperatures ranging from 30 to 90 °C for 20–60 min. At 30 °C, all of the flour particles exhibited trimodal size distributions, i.e., the particles in the first, second, and third modes were <10 μm, 10–50 μm, and 51–300 μm, respectively. Control experiments with isolated starch indicated that the first and second modes were associated mainly with starch granules, whereas the third mode may have been related to gluten and gluten adhesion. The particle size distributions of waxy segregant wheat flours were temperature dependent. At 60 °C, there were significant changes in the particle size and distribution of waxy flours, which indicated the swelling of starch granules in response to elevated temperature. As the temperature increased, the peak particle size of waxy segregant wheat flours increased in different ways. The results suggest that variations in the swelling properties of selected waxy genotype flours may be due to the strength of starch–protein interaction and the capacity for starch granule gelatinization.     

Applications of pre-emergent pyroxasulfone,flufenacet and their mixtures with triallate for the control of Bromus diandrus (ripgut brome) in no-till wheat (Triticum aestivum) crops of southern Australia

Four field experiments were conducted over a three-year period in Victoria and South Australia to investigate the effectiveness of pre-emergence (PRE) applications of pyroxasulfone, flufenacet and their mixtures with triallate for the control of Bromus diandrus in spring wheat. Herbicide mixtures of pyroxasulfone plus triallate and flufenacet plus triallate applied PRE to wheat provided consistently high levels of B. diandrus control (≥85%). In contrast, applications of pyroxasulfone and flufenacet applied alone along with trifluralin plus metribuzin (a common farmer practice in southern Australia) provided more variable control of B. diandrus (33–90%). Pyroxasulfone plus triallate treatments had a much lower (≤47 panicles m⁻²) panicle density of B. diandrus than trifluralin plus metribuzin (42–318 panicles m⁻²) and the non-treated control (118–655 panicles m⁻²). PRE herbicides which were safe to spring wheat and provided the greatest level of control of B. diandrus resulted in significantly (P < 0.05) higher grain yields at Culgoa (120%) and Gama (13%) than non-treated wheat (720 and 1740 kg ha⁻¹). Although flufenacet was effective against B. diandrus, crop phytotoxicity at the higher dose (900 g ai ha⁻¹) reduced spring wheat grain yield. Based on these results, PRE pyroxasulfone plus triallate could play an important role in the management of B. diandrus in spring wheat. However, high cost of these herbicides (AUS$35-$70 ha⁻¹) may limit their adoption in low rainfall and low yielding wheat environments in southern Australia where B. diandrus is most prevalent.     

Effect of particle size and addition level of wheat bran on quality of dry white Chinese noodles

Wheat bran is one of the major dietary fiber sources widely used in the food industry in order to produce fiber-rich foods. The effects of particle size and addition level of wheat bran on the quality of flour and of dry white Chinese noodles (DWCN) were investigated. Results suggested that increasing wheat bran concentration and particle size decreased midline peak value (MPV). However, the MTxW and MPT increased as particle size increased. Peak viscosity, trough, final viscosity, area of viscosity, breakdown, and setback of blends decreased significantly with increasing bran levels from 5% to 20%, but there were no significant differences in the impact of particle size on pasting properties. For the 5% and 10% addition levels, there was no distinct effect in breaking strength of the noodles when bran size was 0.21 mm and 0.53 mm. Hardness, gumminess and chewiness of cooked DWCN showed a downtrend with increasing addition levels and particle size, while adhesiveness showed uptrend. The total score of DWCN showed a downtrend with increasing of addition level and particle size. For the 5% bran level, the scores of cooked DWCN were more than 83 when wheat bran particle size was 0.21 mm and 0.53 mm. By using 5–10% fine bran or using 5% medium bran in wheat flour, it is possible to satisfactorily produce fiber-rich DWCN.     

Model predictions of winter rainfall effects on N dynamics of winter wheat rotation following legume cover crop or fallow

Winter rainfall in a Mediterranean region varies from year to year. Both release of inorganic N from soil organic matter (SOM) or a legume cover crop (LCC) and subsequent nitrate movement in the soil profile are strongly affected by winter rainfall, through its effects on soil water status and on vertical flux. N accumulation of a LCC also varies over years due to weather effects on growth. Thus, these two factors need to be taken into account for efficient use of SOM-N and LCC-N in a wheat (Triticum aestivum L.) rotation. To determine how winter weather might affect the performance of wheat-fallow rotations that include an LCC grown and incorporated during the fallow year, we used the CERES-wheat model and a 46-season weather record to simulate N dynamics of 2-year unfertilized and irrigated winter-LCC wheat systems with high LCC (236 kg N ha⁻¹) or low LCC (118 kg N ha⁻¹) inputs. Unfertilized and fertilized fallow-wheat controls were also simulated. Within a given LCC input value, coefficients of variation for total seasonal N supply (the sum of predicted wheat N uptake, N leaching and inorganic soil N at wheat maturity) over years were <15%, despite the fluctuating winter rainfall (CV 48%). Average N leaching was predicted to be highest in the high LCC input system (108 kg N ha⁻¹), followed by the low LCC input system (86 kg N ha⁻¹) and midseason-intensive and planting-intensive fertilized wheat-fallow systems (82 and 72 kg N ha⁻¹, respectively), and least in the unfertilized wheat-fallow system (54 kg N ha⁻¹). N leaching exceeded 100 kg N ha⁻¹ in 4, 20, 16, 18, and 29 seasons out of 46 seasons, respectively, in the unfertilized and planting-intensive and midseason-intensive fertilized wheat-fallow rotations and in wheat rotations with low and high LCC inputs. There was no difference in predicted wheat yield among the four systems with N inputs from fertilizer or LCC, but yield was lower in the unfertilized wheat-fallow rotation. If the goal of use of LCC was to attain the same yield level as high LCC input or fertilized wheat system while diminishing the risk of N leaching, the low LCC input case met this goal in the short term. However, a simple balance sheet using the model showed that the N balance of the low LCC input system was −147 kg N ha⁻¹ season⁻¹, if we assumed 50% of LCC-N was derived from atmospheric fixation. The low-LCC-input system could therefore fail to maintain inherent soil N fertility in the long term unless nearly 100% LCC-N was derived from fixation.