Evaluation of N Fertilizer Rate and Timing and Wheat Cultivars on Soil Residual Nitrates

Nitrogen (N) fertilizer management for production of bread quality wheat may increase nitrate residues in the soil. To assess soil nitrate levels associated with bread quality wheat ( Triticum aestivum L.) production in Eastern Canada, an experiment was conducted for 2 years at each of two sites in Québec. Four cultivars (Columbus, Katepwa, Max and Hege 155-85), four N levels (0, 60, 120 and 180 kg N ha⁻¹) and two N timings (all at seeding time or 60 % at seeding and 40 % at anthesis) were combined in a factorial arrangement on a Bearbrook clay and a Ste-Rosalie clay. Residual soil NO₃-N levels were measured in the 0–20 and 20– 60 cm soil layers. The cultivars used have potential as bread wheats. Cultivar effects on soil nitrate levels existed only in the Ste-Rosalie soil, suggesting that the cultivars used were better adapted to the conditions on the Bearbrook soil. Changes in soil NC₃N levels over winter indicated that mineralization had occurred. Calculated balance-sheet values were larger than measured residual NO₃-N in the autumn of each year, indicating that NO₃-N was lost from the systems, possibly due to denitrification. Potential increases in, and thus potential pollution from, residual soil NO-N existed only at the 180 kg N ha⁻¹ level. Overwinter changes in soil NO₃-N levels were proportional to the inverse of the fall NC₃N levels. Differences between sites were large for many of the variables measured.     

Genetic improvement of spring barley cultivars grown in eastern Canada from 1910 to 1988

Summary Spring barley is an important feed crop in eastern Canada, and the development of high-yielding, high grain protein cultivars is desirable. This study was conducted to assess the impact of breeding on the yield and protein aspects of cultivar development, and to identify related changes in plant characteristics which may have been altered over time. A 3-year field experiment was conducted to evaluate twenty six-rowed spring barley genotypes representing the majority of cultivars developed from 1910 to 1988 for eastern Canada. The yields of barley cultivars released from 1935 to 1988 increased at a rate of about 0.03 t ha^-1 yr^-1, and showed no evidence of having reached a plateau. Increases in yield were associated with higher total dry matter production and harvest index, reduced plant height and increased lodging resistance. No consistent change in main stem or tiller yield components was observed. Grain protein concentration decreased progressively with time, especially with the newer cultivars. Reduction in grain protein concentration was not associated with lower protein content on a per grain basis, but rather with an increase in the amount of non-structural carbohydrate per grain. Total plant and grain N accumulation showed positive trends with time. No trends were observed for N harvest index, apparent post-heading N uptake, N retranslocation, and retranslocation efficiency. Thus, while the newer cultivars accumulated more total and grain N, proportional N partitioning to the grain was not altered.     

Grain yield and quality: does there have to be a trade-off?

The effect of agronomic practices and cultivars on grain yield, grain protein and small grain sievings was examined in field experiments over four years in the winter rainfall wheatbelt of Western Australia. Rotation with legume crops and pastures was the main factor responsible for increasing grain protein percent. Grain proteins were increased by 4-5% for crops grown in good legume pasture rotations compared to continuous wheat rotations, but only by 1-2% by factors such as delayed sowing time, applied nitrogen, cultivar or grass weed control. In legume based rotations, wheat crops sown at their highest yielding times produced proteins in the appropriate ranges for premium paying grades. Applying N fertilisers up to the optimum rates for yield did not result in proteins below the levels required for premium paying grades, except for hard wheats at >11.5% grain protein. Legume rotations and appropriate soil types were required for hard wheats to exceed 11.5% at economic N rates. The yield penalty often associated with high quality cultivars has been reduced or eliminated in the modern cultivars used in the experiments. Some longer season cultivars only produced grain proteins >10% if sown after their optimum time for yield, but sowing at optimum time reduced the probability of producing small grain sievings. Some cultivars were more susceptible than others to producing excessive sievings, especially those with inherently smaller than average seed size. Seed rates up to the optimum for grain yield did not result in excessive small grain sievings except where the site was highly fertile, where the crop was sown too late for optimum yield or where too much N fertiliser was used. This revised version was published online in August 2006 with corrections to the Cover Date.     

氮肥运筹方式对豫单2002产量及品质的影响

【研究目的】该研究旨在为豫单2002的推广应用提供施肥技术支撑,为高产高蛋白夏玉米氮肥合理运筹肥提供理论与技术依据。【方法】在豫北潮土区高产田块上,采用田间试验,设N0（不施氮肥）、N1（攻杆肥100%）、N2（攻穗肥100%）、N3（攻杆肥40%+攻穗肥60%）,N4（攻杆肥30%+攻穗肥50%+攻粒肥20%）五个处理开展研究。【结果】结果表明：氮肥不同运筹方式增产效果差异显著,其中N3处理增产效果最好,其次是N1处理和N4处理,N2处理增产效果最小;分次施肥有于提高籽粒粗蛋白含量,且随着施肥次数的增加,籽粒粗蛋白含量呈上升趋势;分次施肥亦有利于提高籽粒蛋白质产量,不同处理以N3最佳,其次为N4;氮肥不同运筹方式肥料利用率差异显著,其中N3处理最高,其次为N4和N1处理,而N2最低。【结论】N3处理由于有效地促进了植株对氮素的吸收利用,增加显著地产量和提高了籽粒蛋白质产量,一定程度上提高了籽粒蛋白质含量,因而为最佳氮肥运筹方式。     

The use of grain protein deviation for identifying wheat cultivars with high grain protein concentration and yield

The relationship between grain protein concentration and grain yield in different cultivars of winter wheat was examined in a series of field experiments carried out over three years, in which 13, 12 and 8 cultivars were studied in each year, respectively. The plants were grown at sites located in Shropshire, west-central England, in years 1 and 2, and at three other locations in eastern England in year 3. Above ground plant samples were collected at an thesis and again at maturity, when they were separated into grain and straw, and analysed for dry matter and N content. Analysis of residuals from regression of grain protein concentration on grain yield (grain protein deviation, GPD) showed that some cultivars had a higher grain protein concentration than was predicted from grain yield alone. It was deduced that the capacity to accumulate a higher grain protein concentration than predicted from grain yield is under genetic control and thus may be improved through breeding. Other factors (weight of N accumulated in the biomass at anthesis, weight of N accumulated in the biomass between anthesis and maturity and the concentration of N remaining in the straw at maturity) were added step-wise into the regression to enable statistical analysis of their relative contributions to grain protein. High GPD may be achieved through increased N accumulation after anthesis, combined with efficient re-translocation of vegetative N reserves. The use of GPD provides a selection criteria in wheat breeding programs to screen for increased grain protein concentration without a concurrent grain yield reduction. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of Phaeosphaeria nodorum-induced seed shrivelling on subsequent wheat emergence and plant growth

Summary The bread wheat cultivars Pasqua and Katepwa, and durum wheat cultivars Kyle and D8257 were used to test the effects of sowing Phaeosphaeria nodorum-shrivelled seed. In a controlled environment, emergence, tillering, and dry weight of seedlings were compared at two sowing depths. Emergence, tillering and plant dry weights were also determined in field plots in 1992 and 1993, as were yield and thousand kernel weight (TKW) in plants inoculated with P. nodorum. Under controlled conditions the level of shrivelling did not affect emergence at depths of 25 mm and, except for Katepwa, 50 mm. Deeper seeding reduced emergence regardless of the level of shrivelling. Seeding depth did not affect dry weight of roots and shoots and the effect on tillering was inconsistent in the two years. Dry root weight was positively correlated with original seed size and decreased with level of shrivelling. In the field, seedling emergence of severely shrivelled seed was significantly lower in Katepwa and Pasqua. Tillers per plant appeared to increase with increased level of shrivelling, but was significant only for D8257 in one year. Dry tiller weight was inversely related to tillering and decreased consistently with level of shrivelling. Excepting Pasqua, in one year, yield and TKW did not differ between plots originating from plump or shrivelled seed. Inoculation with P. nodorum caused a significant reduction in TKW and yield in all cultivars but Kyle. Seed shrivelled due to P. nodorum was in general found to be as suitable as plump seed for growing a wheat crop.     

Nitrogen uptake and nitrogen harvest index in durum wheat cultivars varying in their grain protein concentration

Summary In a field experiment, plant (excluding roots) and grain nitrogen at harvest were estimated in 15 durum wheat cultivars varying in their grain protein concentration. They showed significant variation in grain yield, grain protein concentration, biological yield, total plant nitrogen at harvest and residual nitrogen in straw. Harvest index and nitrogen harvest index were calculated from this primary data. Nitrogen harvest index varied from 57 to 83%. Plant nitrogen showed significant positive correlation with biological yield, grain yield and grain protein yield, but the correlations with grain protein concentration, harvest index and nitrogen harvest index were not significant. Nitrogen harvest index was positively correlated with harvest index indicating that the distribution of N between straw and grain to a large extent, but not entirely, depends upon the partitioning of dry matter between the two. Grain protein concentration was neither correlated significantly to plant nitrogen nor to nitrogen harvest index.     

Analysis of Wheat Cultivar Differences in Grain Yield, Grain Nitrogen Yield and Nitrogen Utilization Efficiency.

More detailed information on the causes of yield variability among wheat cultivars is needed to further increase wheat yield. Field studies were conducted in Northern Greece over the two cropping seasons of 1985—1986 and 1986—1987 to assess the effects of nitrogen fertilizer and application timing of the various component traits that determine grain yield, grain nitrogen yield and nitrogen utilization efficiency of two bread ( Triticum aestivum L.) and two durum ( Triticum durum Desf.) wheat cultivars, using yield and yield component analysis. Nitrogen at a rate of 150 kg ha^-1 was applied before planting or 100 N kg ha^-1 before planting and then 50 N kg ha^-1 top dressed at early boot stage. Nitrogen and cultivars affected all traits examined, while split nitrogen application affected only some of the traits. Grain yields in the most cases were correlated with number of grains per unit area and grain weight and grain nitrogen yields in all cases with grain number per unit area. The contribution of the number of grains per spike to total variation in grain yield among cultivars was almost consistent (37 to 55 %), while the contribution of grain weight was more significant (up to 55 %) in high yields (>6.500kg ha^-1) and number of spikes per unit area (>500). The number of grains per spike contributed from 60 to 83 % to the total variation in grain nitrogen per spike. Increased grain nitrogen concentration resulted in a reduction of its contribution in grain nitrogen yield variation. Nitrogen utilization efficiency was higher during grain filling than during vegetative biomass accumulation. The contribution of nitrogen harvest index to the variation of utilization efficiency for grain yield was higher in plants receiving nitrogen application.     

Effect of heat shock during grain filling on protein composition and technological quality of wheats

In southern Europe, the Mediterranean climate offers a unique opportunity for the production of high quality wheats, which are lacking in the European Economic Union. It is also responsible for the remarkable variability in both wheat yield and quality from year to year and from location to location. In this paper, the effects (in recent years) of the Mediterranean climate in Italy on grain yield and quality of bread and durum wheats are summarised with particular regard to high temperatures. Nitrogen fertilisation rate and timing were investigated in five cultivars grown at six sites. The impact of high temperature was evaluated in open field and pot experiments by imposing different temperature regimes during grain filling. Viscoelastic properties were evaluated with the Chopin alveograph for field experiments and with a Promylograph T3 apparatus for pot experiments. Protein composition was evaluated by SE-HPLC (size exclusion high performance liquid chromatrography). Agronomic trials indicated that high quality wheats can be obtained in a wide range of growing conditions. Viscoelastic properties were significantly affected by the temperature treatments. Short episodes of daily maximum temperatures above 35 °C caused a 'weakening' in both durum and bread wheat. High temperatures seemed to affect mainly the composition of the polymeric fraction (soluble/insoluble polymers) without influencing their synthesis. This revised version was published online in August 2006 with corrections to the Cover Date.     

Can Leaf Chlorophyll Measures at Differing Growth Stages be used as an Indicator of Winter Wheat and Spring Barley Nitrogen Requirements in Eastern Canada?

Plant need-based N management approaches may increase the efficiency of N fertilizer application in wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). The leaf chlorophyll concentration estimated through the SPAD-502 meter gives a relative assessment of N status in crop. Field trials were conducted near St John's, Newfoundland, between 1997 and 2000 to describe the relationship between winter wheat and spring barley grain yield, protein content, protein yield and SPAD measurements, as affected by differential stage of crop growth, seeding rate and topdress N fertilizer. Grain yield, protein content, and protein yield of winter wheat and spring barley exhibited linear responses to increasing N topdress application rate. SPAD-502 values were moderately to highly positively correlated with grain yield, protein content, and protein yield as a result of increasing topdress N fertilization, and moderately negatively correlated as a result of increasing seeding rate. It may be difficult to make an N-application rate recommendation based on SPAD measurements, as a critical SPAD value may vary among years, locations, cultivars and soil characters.     

Post-harvest Evaluation of Nitrogen Sufficiency for Small-grain Cereals by Measuring Grain Protein Concentration

Nitrogen (N) fertilizer is an important and expensive input in small-grain cereal production, and growers therefore should aim to optimize its use. Possibilities for using grain protein concentration for post-harvesr evaluation of N sufficiency were determined in this study. Field experiments including spring wheat ( Triticum aestivum L.), spong barley ( Hordeum vulgare L) and spring oats ( Avena sativa L.), and various rates of N fertilizer application were conducted in southern and western-Finland over 2 years. Grain yield and grain protein were positively correlated and firred quadratic regression models. Both critical and optimum levels for grain protein concentration were determined by Cate-Nelson analysis Critical values were 12.2 for wheat, 10.2 for barley and 10.9 for oats, and corresponding optimum values were 13.3, 11.1 and 12.7, respectively. The accuracy of the method was tested using results from on-farm spring wheat trials. The results indicated that N fertilizer uptake and grain yield were best in held where gram protein concentration exceeded the critical values but not the optimum. Growers should use more intensive N fertilization management if grain protein concentration does not exceed critical values. Grain protein concentrations above optimum values indicate over-fertilization for maximum grain yield. Analysing previous research data to identify the "critical level" of grain protein concentration is not difficult, and will provide powers, extension personnel, and fertilizer dealers with a cost effective means of evaluating the efficiency of N use by the crop and for developing N fertilization recommendations.     

Nitrogen Fertilizer and Protein, Lipid, and Non-structural Carbohydrate Concentrations During the Course of Maize Kernel Filling

A field experiment was carried out at four location-years in Southwestern Quebec, Canada in 1990 and 1991, to evaluate the effects of nitrogen (N) application on protein, lipid, non-structural carbohydrate (NSC), and remaining grain components concentrations of maize ( Zea mays L.) grain during kernel development. Three N fertilizers (ammonium nitrate, urea, and calcium ammonium nitrate) were compared for plants receiving pre-plant incorporated N fertilizer at 180 kg ha^-1 as well as a control which received no N fertilizer. The results indicated that between 20 and 30 days after pollination (DAP) protein concentration of maize kernels declined sharply, thereafter only slightly, irrespective of the treatment. At most stages and in all four location-years protein concentration was raised significantly by N-application without clear difference between N-fertilizer sources. At 20 DAP seeds of N-fertilized plants contain 25.5 mg g^-1 more than those without N-application (control); later on, this difference was lower (12.8 mg g^-1) but remained constant over time if averaged over N-sources and location-years. At most growth stages and in most location-years the lipid concentration did not respond to N fertilizer application. Lipid concentration followed an "N" shaped curve over the course of grain development. Non-structural carbohydrate (NSC) concentration increased significantly during grain filling and showed little effect due to N application. However, at most growth stages in the four location-years, the concentration of remaining grain components tended to decline with N application. A significant negative correlation existed between the changes in protein concentration and NSC concentration during kernel development.     

Polymorphism of waxy proteins in Iberian hexaploid wheats

A collection of 130 cultivars of bread wheat, 332 landraces of bread wheat and 144 spelt wheats was analysed for waxy proteins in the grain. The electrophoretic patterns showed very low polymorphism and most of the hexaploid wheats had the Wx-Ala, Wx-D1a and Wx-B1 alleles of ‘Chinese Spring’. Two alleles were detected at Wx-A1 (Wx-A1a, and Wx-A1b (null)), the latter was present in only 5.1% of the bread wheat landraces and 7.6% ofthe spelt wheats. No allelic variation was found at the Wx-D1 locus and all the hexaploid wheats had the Wx-D1a allele. Wx-B1 was the most polymorphic locus, with three alleles detected: Wx-B1a, Wx-B1b (null) and Wx-Blc coding for a Wx-B1 protein with a slightly different mobility from Wx-B1a. The null Wx-B1b allele was found in 10.8% of the bread wheat cultivars, 21.4% of the bread wheat landraces and 12.5% of the spelt wheats. Among the 604 hexaploid wheats analysed, only two bread wheat landraces (0.6%) and two spelt wheats (1.4%) had the null allele at both Wx-A1 and Wx-B1 loci.     

Phosphorus Accumulation and Translocation in Wheat as Affected by Cultivar and Nitrogen Fertilization

To improve nutrient management strategies in wheat more information is needed about the interaction effects among nutrients in their uptake and redistribution in the plants, in relation to different genotypes. Therefore, two bread ( T. aestivum L.) and two durum ( T. durum Desf.) winter wheat cultivars were grown in the field for 2 years (1986, 1987) in a silty-clay soil under different nitrogen (N) levels, in Northern Greece. Nitrogen at a rate of 150 kg ha⁻¹ was applied before planting or 100 kg ha⁻¹ before planting and then 50 kg ha⁻¹ at early boot stage. Cultivar differences in phosphorus (p) concentration were observed only in vegetative parts but not in the grain. Maximum p accumulation was observed either at anthesis or at maturity. During grain filling dry matter and p accumulation in the grain followed almost the same pattern. Phosphorus translocation efficiency of the cultivars at the 2 years ranged from 70.7 to 84.3 % and the amount of p in the grain derived from translocation 52 to 100 %. Phosphorus translocation efficiency was weakly correlated with p content in grain only in 1986, while phosphorus harvest index (PHI) was positively correlated with harvest indst (HI) both years (r = 0.82** in 1986 and 0.75** in 1987). Nitrogen application mainly affected p accumulation of the cultivars via its effect on biomass production. The split N application promoted slightly the p uptake in 1987 and this resulted in the reduction of both the contribution of the translocated p to the grain and the efficiency of p utilization for total biomass. Results indicated that p accumulation and translocation and the efficiency of p utilization in wheat were mainly determined by the genotype in relation to environmental condition of growth.     

Grain Protein Quality in Response to Changes in Pre-anthesis Duration in Wheats Released in 1940, 1964 and 1994

Grain protein content is one of the most important attributes in bread making quality. Several studies have reported that the type of, and the balances between, storage protein (i.e. gliadins and glutenins) are also relevant. Generally, the modern cultivars present less grain protein content than their predecessors, suggesting that breeding may have reduced baking quality while improving yield. Furthermore, there is little information on whether, and eventually how, breeding influences the types of protein synthesized in the grains, and the sensitivity of the type of protein and baking quality to changes in the environment. This study aimed to determine the stability in baking quality in wheat cultivars released at different eras to variation in the duration of the pre-anthesis period without changes in the sowing date. The experiment studied the combination of three cultivars released in 1940, 1964 and 1994 at two different durations from sowing to anthesis (because of exposure to different photoperiods during stem elongation in the field). Modern cultivars showed lower grain protein content than the oldest ones (11 vs. 14 %). There were no correlation between grain protein content and baking quality (assessed by Zeleny test), indicating that protein type is more important than grain protein content. Gliadins were more variable than glutenins because of differences between cultivars and flowering dates. Wheat breeding also seemed to have improved the stability of quality variables in response to environmental variation during the pre-anthesis period (when yield potential is being determined).     

氮素分期优化管理对冬小麦产量和籽粒品质的影响

采用田间试验,对氮素分期优化管理方法对小麦籽粒品质的影响进行了研究,以期为高产、优质、资源高效、环境保护等多重目标并重的养分资源优化管理提供理论依据.结果表明:氮素供应量最优的处理(冬小麦返青期氮素供应量即0～60 cm土壤Nmin+肥料氮为90 kg/hm2,拔节期追氮量即施用肥料氮30 kg/hm2)的冬小麦籽粒产量和其他氮素供应量处理没有显著差异;氮素供应量最优的处理冬小麦籽粒的粗蛋白和面筋含量显著低于在返青期和拔节期供氮量都高的处理(冬小麦返青期氮素供应量即0～60 cm土壤Nmin+肥料氮为150kg/hm2、拔节期追氮量即施用肥料氮90kg/hm2),但与其他处理相比差异不显著;以高产、资源高效和环境保护为前提的冬小麦氮肥分期优化施用量获得了最高产量的同时兼具较好的小麦籽粒品质.     

Nitrogen Level and Seeding Rate Effects on the Performance of Hulled Wheats (Triticum monococcum L., T. dicoccum Schubler and T. spelta L.) Evaluated in Contrasting Agronomic Environments

Effects of the nitrogen level and of the seeding rate on the performance of Triticum monococcum L., T. dicoccum Schübler and T. spelta L. (hulled wheats, together referred as 'farro') in comparison with bread wheat (variety Eridano) were evaluated. Field trials were conducted in five contrasting environments located in the north and central areas of Italy. Eridano mean grain yield was 3.86 t ha⁻¹, resulting the highest in all the field trials. T. spelta, T. dicoccum and T. monococcum net grain yield was 2.71 t ha⁻¹, 2.371 ha⁻¹ and 1.06 t ha⁻¹, respectively. Significant differences in all the evaluated parameters were observed among the species as well as among the environments. Biomass yield, grain protein and SDS sedimentation values of the hulled wheats were significantly influenced by nitrogen, which had no effect on grain yield. The results show the necessity to breed hulled wheat varieties adapted to the Italian environments and competitive with the bread wheat productivity in the marginal areas.     

人工合成六倍体小麦后代衍生群体Waxy蛋白亚基的分子标记

四倍体小麦与节节麦杂交培育的人工合成六倍体小麦已广泛应用于国内外小麦品种改良。以引自CIMMYT的Syn768、Syn769和Syn780人工合成六倍体小麦分别与中国四川成都平原主栽普通小麦品种杂交、回交的BC2F2:6后代群体中选育的113份优良高代系为材料,采用SSR特异引物的PAGE凝胶电泳对其Waxy蛋白亚基缺失类型进行了研究。结果表明,在所检测的121份材料中,8份材料缺失Waxy-B1型蛋白亚基,占全部材料的6.6%;没有检测到其他类型的缺失体。从每个人工合成六倍体小麦亲本材料所形成的后代衍生群体来看, Waxy-B1缺失体频率各不相同,说明Waxy蛋白亚基缺失类型在人工合成六倍体小麦后代衍生群体材料中的表现存在着随机性,与亲本的基因型状况关系极大。通过研究人工合成六倍体小麦与普通小麦杂交后代的Waxy蛋白亚基缺失类型,有助于提高分子标记育种效率。     

Effect of Integration of Fertilizer and Green Manure Nitrogen on Yield Attributes, Nitrogen Uptake and Yield of Lowland Rice (Oryza sativa L.)

Field experiments were conducted at Tamil Nadu Rice Research Institute, Aduthurai, India, during the wet seasons of 1992 and 1993 to study the effect of full and partial substitution of fertiliser N with green manure N (Sesbania rostrata) on nitrogen uptake, yield attributes and yield of rice. The experiment consisted of eight treatments with two levels of N (100 and 200 kg ha⁻¹) and three sources of N application viz., fertilizer, integrated (1:1 fertilizer and green manure N) and green manure N compared to the recommended practice (150 kg fertilizer plus 6.25 t ha⁻¹ (72 kg N) green manure) and a no N control. Nitrogen application markedly increased the N uptake. Combined use of the two N sources at 200 and 222 kg N ha⁻¹ and of single fertilizer N at 200 kg N ha⁻¹ recorded the maximum N uptake, increased the yield attributes such as number of panicles per unit area, weight per panicle, number of total and filled grains per panicle and test weight. At 200 kg N ha⁻¹ full substitution of N by green manure reduced the grain yield but only partial substitution of N by green manure resulted in almost similar yield as single fertilizer N. Thus 200 kg N ha⁻¹ applied in equal proportions of fertilizer and green manure N can be recommended for medium duration rice cultivars.