Sheep grazing and defoliation of contrasting varieties of organically grown winter wheat with and without undersowing

Field experiments in Gloucestershire, UK, in the 1990–91, 1991–92, 1993–94 and 1994–95 growing seasons explored the merits of grazing in spring a traditional tall wheat (Triticum aestivum) variety, Maris Widgeon, with more modern shorter varieties. In the first 2 years, defoliation was achieved by mowing at 7 cm in March and/or April. In the second 2 years, varieties sown at two sowing dates were grazed by sheep at a stocking rate of 42 × 50 kg sheep ha^?1 for 3 or 4 days in March. Defoliation reduced crop height and interception of photosynthetically active radiation (PAR). In 1991–92, mowing significantly reduced grain yield of some of the shorter varieties but not of Maris Widgeon. This interaction was related to the amount of PAR intercepted. In this year, mowing improved the establishment of undersown white clover (Trifolium repens) and perennial ryegrass (Lolium perenne), but in subsequent years the conditions were much drier and undersowing failed. In the last two experiments, grazing in March did not significantly reduce grain yield of any variety. The quality of the forage eaten by the sheep had a modified acid-detergent fibre (MADF) content of less than 300 g kg^?1 dry matter (DM) and a crude protein (CP) content of more than 200 g kg^?1 DM in both seasons. Yield of DM and calculated metabolizable energy (ME) of different varieties removed by the sheep interacted strongly with sowing date. September-sown Maris Widgeon provided ≈ 0·7 and 0·3 t DM ha^?1 (or 7·8 and 3·4 GJ ME ha^?1) in March 1994 and March 1995 respectively. However, the shorter wheat varieties, Hereward and Genesis, only provided 0·3 and 0·1 t DM ha^?1 when sown at the same time in the 2 years. At later sowing dates all of the varieties only provided about 0·1 t DM ha^?1 when sown in October 1993, or 0·01 t DM ha^?1 when sown in November 1994. Sheep grazing reduced total weed biomass in June, and reduced the emergence of weed seedlings from soil samples collected after the wheat harvest. Effects of defoliation on foliar infection by Septoria tritici were inconsistent.     

Response of common wheat varieties to organic and conventional production systems across Italian locations,and implications for selection

Specific breeding for organic systems may help reduce their yield gap relative to conventional systems by exploiting genotype × system (GS) interaction. Likewise, specific breeding for distinct subregions within a region could capitalize on genotype × location (GL) interaction. Grain yield and test weight of common wheat varieties were evaluated under organic and conventional systems in ten locations spanning from northern to southern Italy, with the objectives of: (i) comparing production systems; (ii) investigating the extent of GS and GL interactions and their relationship with genotypic and environmental characteristics; and (iii) preliminarily comparing, in terms of predicted selection gains, different strategies to cope with GS and GL effects. These effects were investigated in the 2-year Data set 1 including seven genotypes. GS effects were also assessed in the annual Data sets 2 and 3 including 13 and 11 genotypes, respectively. The yield reduction of organic systems relative to conventional ones averaged 28% in Data set 1, 29% in Data set 2 and 14% in Data set 3. Organic systems also tended to a modest test weight reduction. Genetic correlations between systems ranged from high to very high (0.88 ≤ r_g ≤ 0.98) for yield and test weight, owing to nil or limited GS interaction. Broad-sense heritability tended to be higher in conventional systems than organic ones for yield in two data sets (mainly due to lower experimental error) while being similar in the two systems in the other cases. Predicted selection gains suggested nil (yield) or very modest (test weight) advantage of direct selection in organic systems relative to indirect selection in conventional systems, when targeting organic systems. The scope for selection only in conventional systems was reinforced when comparing predicted gains for selection scenarios which target both systems in relation to their foreseeable marketing importance. GL effects for yield and test weight were significant and were modeled by additive main effects and multiplicative interaction analysis. Site classification based on GL effects for yield revealed a larger subregion A including northern and central Italy and a smaller subregion B comprising southern Italy, accordingly with previous, independent studies. Yield selection only in subregion A (with indirect selection gain for subregion B) implied slightly higher predicted gain for A (+4%) and much lower gain for B (−24%) relative to independent, direct selection in each subregion. Selection for specific geoclimatic subregions may have greater importance than selection for specific production systems.     

EST-SSR标记在45份冬小麦品种遗传多样性分析和新品种测试应用中的研究

本研究利用21对小麦EST-SSR引物对45份黄淮海地区新育成冬小麦品种的遗传多样性进行了分析。在23份新育成品种中,共检测到61个位点,每个位点的等位基因个数在2-8之间,平均2.90;基因遗传多样性指数在0.08-0.79之间,平均为0.38。23份新育成品种的遗传距离在0.12-0.69之间, 平均为0.40。在23份亲本品种中,共检测到63个位点,每个位点的等位基因个数在2-7之间,平均3.00;基因遗传多样性指数在0.08-0.79之间,平均为0.43,23份亲本品种的的遗传距离在0.09-0.81之间, 平均为0.46。新育成品种遗传多样性低于其亲本品种。聚类分析表明,45份品种可分为6个类群,部分申请品种和近似品种聚在一起,但其他申请品种和近似品种并未聚在一起,其中有些甚至距离较远。据此认为EST-SSR标记用于DUS测试中近似品种的选择是可行的。     

Wheat-flour dough extensibility as a discriminator for wheat varieties

The extension testing of wheat-flour dough has become one of the key cereal chemistry links to end product quality assessment, because of its perceived relevance to baking performance, and because of the various correlations that have been inferred and assumed since the extensibility of a dough was first investigated in the late 19th century. As a consequence, from a plant breeding perspective, there is a need to understand and interpret the extensibility of a dough in terms of the molecular dynamics occurring during its extension, not only as it relates to its baking, but also to the HMW/LMW glutenin and gliadin composition of the wheat. The focus of this paper is the direct measurement of extensibility on a micro-extension tester. The theoretical justification is that the resulting extensogram represents an encapsulation of the extensional rheology of the dough. The paper reports on a graphical and statistical analysis of extension tests performed on eight representative flours. They yield validation for the conclusion that the historic assessment of extensibility as Ext_Rupture should be replaced by Ext_Rmax and the difference Ext_Rupture−Ext_Rmax. It is relatively easy to obtain accurate estimates of R_max, Ext_Rmax and Ext_Rupture from electronically recorded extensograms. Among other things, it is established that, in terms of the glutenin classification of flours based on electrophoresis, HPLC or DNA markers, R_max yields a far better differentiation than is achieved with either Ext_Rupture or Ext_Rmax. It follows, as a corollary to such results, that the extensions to the earlier rheological phases in an extensogram are just as, if not more, important in identifying connections between the gluten composition of wheat varieties and the traditional Ext_Rupture and R_max. In particular, it is shown that, like R_max, the scaled difference R_max/(Ext_Rupture−Ext_Rmax) represents an alternative strategy to relate quality to the glutenin composition of wheat varieties, determined by electrophoresis, HPLC and DNA markers.     

The influence of weeds on polyphagous arthropod predators in winter wheat

In 1980 and 1981, pitfall traps and an insect vacuum net were used to sample polyphagous predators in plots of winter wheat treated or not treated with herbicides. Dense populations of broad-leaved and grass weeds occurred in untreated plots. Significantly more large carabids (Pterostichus melanarius and P. madidus) were caught in pitfall traps in treated than in untreated plots, where their activity may have been reduced by the vegetation. Numbers of the carabids Loricera pilicornis, Agonum dorsale and Amara species, of the staphylinids Philonthus cognatus, Tachinus signatus, Tachyporus species and Aleocharinae and of larvae of both families were significantly reduced by herbicide treatments. Some species were unaffected by the treatments. Cereal aphids were sparse during the trials and their numbers were unaffected by herbicide treatments. In 1981, more Sitobion avenae occurred on the cultivar Maris Huntsman than on Kador.     

DNA-based methods for identification and quantification of small grain cereal mixtures and fingerprinting of varieties

The composition of cereal-based foods is a key factor in determining the quality and safety of the final product while the reliable identification of cereal species and cultivars are essential for the handling, marketing and processing of grain and for the protection of plant breeders' rights. Analytical methods have therefore been developed and applied to identify and quantify cereal species in food products and also to fingerprint and identify grain at the genotype and variety levels. DNA-based methods for the detection and quantification of mixtures of small grain cereals are reviewed, together with the recent development of molecular markers for varietal fingerprinting.     

The economics of fungicide use in winter wheat in southern Sweden

In southern Sweden, fungicide treatment of winter wheat is prevalent and recommended almost routinely against leaf blotch diseases. However, yield increases and hence the resulting net returns from fungicide use are highly variable within and between years. These variations raise questions about whether, when and how fungicides should be used. To help answer these questions, a thorough economic evaluation of fungicide use was carried out, based on results from untreated plots and fungicide-treated plots in trials in farmers' fields, 1983–2007. Scenarios with varying grain prices and costs of fungicide treatment were evaluated and examined. Doubling and tripling the grain price led to the largest impact on the net return from fungicide treatment, followed by increasing cost of the fungicide. Other costs were of minor importance. The mean net return from fungicide use was no more than 12 € ha⁻¹ over the 25 years (2008 grain prices and costs used in calculations). Furthermore, the mean net return was negative in 10 years and less than 50% of the entries were profitable to treat in 11 years. Changes over time and changes in controllable factors (e.g. fungicide and cultivar choice, crop rotation, techniques) and uncontrollable factors (e.g. emerging and new diseases, price relations) influenced the profitability of fungicide use. Fungicide use was in fact more profitable (mean net return 21 compared with 3 € ha⁻¹) during the latter part of the period (1995–2007) than in the earlier part (1983–1994). Improved decision support systems in a holistic framework based on sound economics are urgently needed.     

The economic consequences of integrating whole-crop wheat with grass production on dairy farms in the UK: a computer simulation

Harvesting techniques, which involve simultaneously preserving and upgrading mature crops of whole cereals using an alkali, have been developed. When treated crops have been fed to sheep and cattle, satisfactory intakes and growth rates have been observed. With the possibility of falling cereal prices, such an end-use for grain crops may be attractive in the future. Accordingly, a mathematical model of the production, harvesting and utilization of whole-crop wheat and grass silage has been developed to examine the economic implications. Using the model, the comparative costs of growing and feeding alkali-treated whole-crop wheat in place of grass silage for winter milk production have been examined.
A milk production system based on whole-crop wheat rather than grass silage is estimated to improve profits by up to £130 per cow. However, the improvement in profitability is very sensitive to assumptions about the uses for surplus land or silage arising from such a switch. Furthermore, for physiological reasons it may be prudent to restrict the quantity of whole-crop wheat fed to about 50% of the total forage intake. Thus, whole-crop cereals may best be seen as a complement to rather than a substitute for grass silage. However, in the absence of data on feeding dairy cows with treated wheat silage, research is required before the computer simulations can be corroborated.     

The influence of weeds on aphid-specific natural enemies in winter wheat

Aphid-specific predators, aphid parasitoids and aphid-pathogenic fungi were sampled in 1980 and 1981 in plots of winter wheat treated or not with herbicides. Aphids and their natural enemies were also sampled from three abundant weed species. Aphid-specific predators were scarce in both years of the study, probably because of the scarcity of cereal aphids in the experimental plots, and no significant treatment effects on this group were recored. The syrphid, Platycheirus manicatus, was the only predator recorded from the weeds. Cereal aphids and the weed aphids, Brachycaudus helichrysi and Cryptomyzus galeopsidis, were attacked by the same species of aphid-pathogenic fungi but by different parasitoids. In the first year more Sitobion avenae were infected by fungal pathogens in weedy plots than in treated plots, either because of higher humidity or because of the spread of infection from weed aphids, or a combination of both. Weed removal had little effect on those parasitoid species which attacked cereal aphids. The small populations of cereal aphids which were present in the plots were unaffected by herbicide treatments.     

A stochastic modelling approach for real-time forecasting of winter wheat yield

Crop simulation models are receiving increasing use in agriculture and are recommended as multipurpose tools in research and farm management. Of one particular interest to crop growers is the possibility of applying crop models for real-time yield forecasting. This investigation evaluated the utility of the SUCROS model for site-specific real-time crop biomass and grain-yield forecasting. A stochastic forecasting approach was used combining generated weather data with observed data for model updating. The forecast procedure was tested with field data collected at four sites in the UK over two growing seasons. The results showed that across all site-years, the model is able to forecast the final biomass and grain yield with <10% bias. There was no significant difference between observed and forecasted biomass and grain yield for forecasts made at anthesis or milky grain stage although earlier forecasts did show significant differences. The ranking of the observed and forecast biomass and grain yield were also highly correlated for the later forecasts.     

Rapid DNA-based identification of wheat and barley varieties

Micro-fluidic capillary electrophoresis methodology was developed to analyse grain DNA composition, thus to provide unequivocal distinction between varieties of wheat (Triticum aestivum L.) and of barley (Hordeum vulgare L.). This ‘Lab-on-a-chip’ technology complements protein composition analysis by micro-fluidic capillary electrophoresis, which is already in routine use for variety identification. Whereas it had been difficult to distinguish between some varieties by protein analysis using the Lab-on-a-chip system, distinctions proved to be possible using a combination of DNA extraction and microsatellite analysis, taking advantage of the speed and convenience of DNA chips. Several combinations of microsatellites permitted the DNA analysis system to provide distinction between two wheat varieties and between all but two (Chebec and Schooner) of the main eleven Australian barley varieties (Arapiles, Baudin, Barque, Chebec, Gairdner, Grimmett, Lindwall, Parwan, Schooner, Skiff and Sloop).     

Rapid DNA-based identification of wheat and barley varieties

Micro-fluidic capillary electrophoresis methodology was developed to analyse grain DNA composition, thus to provide unequivocal distinction between varieties of wheat (Triticum aestivum L.) and of barley (Hordeum vulgare L.). This ‘Lab-on-a-chip’ technology complements protein composition analysis by micro-fluidic capillary electrophoresis, which is already in routine use for variety identification. Whereas it had been difficult to distinguish between some varieties by protein analysis using the Lab-on-a-chip system, distinctions proved to be possible using a combination of DNA extraction and microsatellite analysis, taking advantage of the speed and convenience of DNA chips. Several combinations of microsatellites permitted the DNA analysis system to provide distinction between two wheat varieties and between all but two (Chebec and Schooner) of the main eleven Australian barley varieties (Arapiles, Baudin, Barque, Chebec, Gairdner, Grimmett, Lindwall, Parwan, Schooner, Skiff and Sloop).     

An improved water-use efficiency for winter wheat grown under reduced irrigation

Single irrigation, compared to the conventional four or five irrigations, has been practised in northern China on winter wheat on a relatively large scale since 1991. In a field study, irrigation was reduced from normally four times (I₄, 4×75 mm) to one (I₁, 75 mm at the end of the second internode elongation) in an area with an annual rainfall of about 600 mm. A control without irrigation (I₀) was also included. Late sowing and early soil drying at seedling stage resulted in a relatively deep root system. Leaf area index, the size of upper leaves and the length of base internodes were also significantly reduced under I₁, but kernel number per panicle was not reduced, suggesting that the development of inflorescence was not disrupted. During the active grain-filling stage, it was found that leaf water potential under I₁ was maintained similar to that of I₄, while daytime stomatal conductance was substantially reduced. Leaf temperature was increased, indicating an inhibited leaf transpiration. Early senescence was induced in I₁ and I₀ crops and resulted in a substantially lower kernel weight. Although the grain yield of I₁ was reduced by about 15% from I₄, the water-use efficiency (WUE) for total water consumption was increased by 24–30%. Single irrigation can potentially make wheat cropping sustainable in this area in terms of water usage and prevent further depletion of the underground water resource. Explanations for the small or zero reduction in yield are: (1) the encouraging development of a deep root system that enabled the plants to use more water at depth (below 1 m), which is recharged annually by the relatively high summer rainfall. (2) A large portion of root system in the drying soil and its induced shoot physiological changes, that is, reduced leaf expansion and stomatal conductance, which helped the plants to establish a better canopy structure with a much reduced water consumption. (3) An improved harvest index.     

Reconciling alternative models of phenological development in winter wheat

Simulation of the timing of anthesis in wheat crops is achieved using two very different approaches. The older of these simulates progress to flowering by calculating the duration of phases between significant events on the shoot apex. The alternative method tracks development through leaf appearance, using the prediction of final mainstem leaf number to control the duration of the phase from emergence to flowering. Although these methods appear to differ substantially, we show in this paper that the number of leaves on the mainstem when the stage of terminal spikelet occurs is extremely tightly coupled to final mainstem leaf number. We conclude that accurate prediction of the terminal spikelet stage or similar prediction of mainstem leaf number amount to the same thing, so reconciling the methods.     

适应贵州黄壤生长的氮高效油菜品种筛选

为筛选适宜贵州黄壤水旱轮作和旱地轮作种植的氮高效冬油菜品种,2018-2019年在贵州省遵义市播州区和毕节市黔西县开展田间试验,以26个不同的冬油菜品种为材料,设置4个氮素水平（0、45、135和180 kg/hm²）,探讨品种间在生长、养分吸收及利用效率上的差异。结果发现,两种轮作种植情况下,所有品种的产量随施氮量的增加而增加,在施氮180 kg/hm²时,旱地轮作的产量、产值和经济效益以德油杂11号最优,分别达到3130 kg/hm²、 15 650元/hm²和9998元/hm²,水旱轮作的产量、产值和经济效益也以德油杂11号最优,分别达到2767 kg/hm²、13 835元/hm²和8183元/hm²。生物量也以德油杂11号最大。旱地轮作种植冬油菜,氮素农学效率随施氮量增加呈先增加后降低的趋势,在135 kg/hm²时达到最大值;各品种氮素偏生产力随施氮量增加而降低;氮素吸收效率也随着施氮量的增加而降低。旱地轮作种植冬油菜,产量、养分吸收和氮素利用效率均优于水旱轮作种植。推荐德油杂11号、黔油早2号、龙庭1号、庆油1号、金油8号、庆油3号、金农油1号、黔油早1号为较适宜的旱地种植品种,德油杂11号、黔油28号、广源68、庆油3号、华龙油1号、龙庭1号、庆油1号、渝油28为较适宜水旱轮作种植的品种;并认为冬油菜的氮肥管理应该根据轮作模式做调整。     

Nutritional evaluation of some commercial wheat varieties grown in Pakistan

The nutritive value of some commercial wheat varieties grown in Pakistan was measured chemically, including amino acid analysis, and biologically in N-balance experiments with growing rats. The protein content ranged from 13.2% in Punjab-83 to 16% in Barani-83. Lysine per 100g protein varied between 2.46 and 2.75%. The available carbohydrate ranged from 67.3 to 74.7%. Iron content was highest in Sonalika while the concentration of zinc and manganese was highest in Sarhad-82. The protein digestibility (TD), biological value (BV) and net protein utilisation (NPU) varied between 92–95%, 56–68% and 53–65% respectively. Level of wheat protein was negatively correlated with available carbohydrate (r=–0.93), lysine per unit protein (r=–0.67) and BV (r=–0.76). The lysine content (g/16gN) of commercial wheat varieties showed a positive correlation (r=+0.95) with the BV. The protein quality was lowered in varieties having higher content of protein.     

Determining the spirit yield of wheat varieties and variety mixtures

Four winter wheat varieties and the four possible three-component mixtures derived from them were included in a trial in Scotland. The site produced low grain protein levels and there were significant yield and specific weight differences between varieties. The variety Deben significantly out-yielded the varieties Claire and Riband, both with and without fungicide treatment, but produced grain with significantly lower spirit yield than Claire. Protein contents and thousand corn weights were good predictors of spirit yield in a reference population of wheat samples, but thousand corn weights did not correlate with spirit yield in the trial, as Claire combined small grain with high spirit yield. The relationship between protein and spirit yield was shown to change at lower protein levels and to differ between varieties. Reduction in spirit yield as protein increased was greater in Deben than in a better distilling variety like Consort. A rapid means of predicting spirit yield, based on small-scale measurement of hot water extract and protein content, was devised and a good association between predicted and measured spirit yield was observed in both the reference population and the trial. Mixtures containing cvs. Claire and Deben did not demonstrate the adverse effects on yield and spirit yield observed, respectively, for these varieties, and a mixture comprising cvs. Claire, Consort and Deben significantly out-yielded Claire and gave higher spirit yields than Deben. These benefits, together with the potential yield stability and disease reduction characteristics of wheat mixtures, make them a viable commercial option for distilling.     

Molecular characterization of storage proteins for selected durum wheat varieties grown in different environments

The variations of the amounts of individual high molecular weight glutenin subunits (HMW-GS), of the ratios HMW-GSy to HMW-GSx and HMW-GS to low molecular weight glutenin subunits (LMW-GS) and of protein content were evaluated for eight durum wheat cultivars in two regions using four fertilizer combinations during two successive years. All measured parameters showed significant variation with genotypes (G), environments (E) and fertilizers (F). The interaction E × G × F was highly significant for glutenin amount variation. Amongst cultivars possessing HMW-GS 20, landraces seem to better value the N-fertilizer use for the accumulation of HMW-GSy than high yielding cultivars. Both HMW-GSy to HMW-GSx and HMW-GS to LMW-GS ratios were found to be positively correlated (p < 0.05) with total protein content.     

Environmental modification of hard red winter wheat flour protein composition

The intrinsic processing quality of wheat (Triticum aestivum L.) cultivars is modified significantly by cultural conditions and climate. In an attempt to understand the biochemical basis of such variation, environmental modification of flour protein content and composition was measured. Thirty hard red winter wheat cultivars and experimental lines were grown at 17 Nebraska environments during 1990 and 1991. Environmental conditions, including grain filling duration, temperature and relative humidity during grain filling, were monitored. Grain yield and test weight also were determined as environmental indicators. Significant linear correlations between flour protein content, as measured by near-infrared spectroscopy, were observed only with the duration of grain filling. Protein quality, as measured by SDS sedimentation volumes and size-exclusion high-performance liquid chromatography, was highly influenced by the frequency of high temperatures during grain filling and by the relative humidity. Observed ranges in genotypic responses (variance) at locations also were altered by environmental factors. Optimal protein quality, as determined by SDS sedimentation volumes, was observed with exposure to less than 90 h of temperature greater than 32°C during grain filling. Protein quality declined with exposure to a greater number of hours of elevated temperature.