The effect of tillage system and residue management on grain yield and nitrogen use efficiency in winter wheat in a cool Atlantic climate

The effects of soil tillage and straw management systems on the grain yield and nitrogen use efficiency of winter wheat (Triticum aestivum L. em. Thell.) were evaluated in a cool Atlantic climate, in central Ireland between 2009 and 2011. Two tillage systems, conventional tillage (CT) and reduced tillage (RT) each with and without incorporation of the straw of the preceding crop, were compared at five levels of fertiliser N (0, 140, 180, 220 and 260 kg N ha⁻¹).CT had a significantly higher mean grain yield over the three years but the effect of tillage varied between years. Yields did not differ in 2009 (Year 1), while CT produced significantly higher grain yields in 2010 (Year 2), while RT produced the highest yields in 2011 (Year 3). Straw incorporation had no significant effect in any year.Nitrogen application significantly increased the grain yields of all establishment treatment combinations. Nitrogen use efficiency (NUE) ranged from 14.6 to 62.4 kg grain (85% DM) kg N ha⁻¹ and decreased as N fertiliser rate was increased.The CT system had a significantly higher mean NUE over the three years but the effect of tillage varied with years. While there was no tillage effect in years 1 and 3, CT had a significantly higher NUE than RT in year 2. Straw management system had minimal effect on NUE in any year.The effect of tillage and N rate on soil mineral N content also varied between years. While there was no tillage effect in years 1 and 3, RT had significantly larger soil N contents than CT in the spring before N application, and post-harvest in year 2. N application rates had no effect on soil N in year 1, increased residual N content in year 2 and had an inconsistent effect in year 3. Straw management had no significant effect on soil mineral N content.These results indicate that RT establishment systems can be used to produce similar winter wheat yields to CT systems in a cool Atlantic climate, providing weather conditions at establishment are favourable. The response to nitrogen is similar with both tillage systems where the crop is successfully established. Straw management system has very little effect on crop performance or nitrogen uptake.     

Residual nitrogen effect of clover-ryegrass swards on yield and N uptake of a subsequent winter wheat crop as studied by use of N methodology and mathematical modelling

The residual effect of 2-year-old swards of clover-ryegrass mixture and ryegrass in monoculture on yield and N uptake in a subsequent winter wheat crop was investigated by use of the ¹⁵N dilution method and by mathematical modelling. The amount of N in the wheat crop, derived from clover-ryegrass residues was 25–43% greater than that derived from residues of ryegrass which had been growing in monoculture. Expressed in absolute values, the N uptake in the subsequent winter wheat crop was 23–28 kg N ha ⁻¹ greater after clover-ryegrass mixture than after ryegrass in monoculture. Up to about 54 kg N ha⁻¹ of the N mineralised from the clover-ryegrass crop was calculated to be leached, whereas only 11 kg N ha⁻¹ was leached following ryegrass in monoculture.     

Grain nitrogen content of winter bread wheat (Triticum aestivum L.) as related to crop management and to the previous crop

Low-input management for wheat production (less fungicide, low nitrogen rate) could affect grain protein content. The impact of the previous crop could also be a determining factor for wheat quality. A long-term field experiment located near Toulouse (southwestern France), comparing different rotations and management schemes from 1984 to 1993, was used to assess the effect of N availability and diseases on grain nitrogen concentration (GNC) of wheat. GNC ranged from 1.6 to 2.8%, increasing with the input level in 5 years out of 10, as the result of higher nitrogen levels and crop protection with fungicides. Leaf brown rust, high temperatures and water shortage, which affected dry matter accumulation during grain filling, were responsible for high GNC. GNC was generally correlated with N uptake when nitrogen availability was the main limiting factor and to the nitrogen harvest index (NHI) when foliar diseases or drought limited grain production. N uptake in the absence of N fertiliser ranged from 20 to 200 kg ha⁻¹ depending on the previous crop. GNC was closely related to the nitrogen nutrition index (NNI) at anthesis.     

Modeling the effect of cultivar resistance on yield losses of winter wheat in natural multiple disease conditions

The use of winter wheat (Triticum aestivum L.) cultivars resistant to diseases may make it possible to reduce yield losses without the need to use fungicides, which are expensive and may damage the environment. The cultivar resistances favored depend on the region considered and the nature of the most widespread diseases in that region. We have constructed a statistical linear model for the estimation of relative yield loss due to diseases, making it possible to assess the effects of winter wheat cultivars in various disease conditions. We considered the interactions “potential disease intensity × winter wheat cultivar” for four main fungal diseases: septoria tritici blotch (Mycosphaerella graminicola), brown rust (Puccinia triticina), yellow rust (Puccinia striiformis) and powdery mildew (Erysiphe graminis). This model can therefore be readily adapted to different regions with diverse combinations of these diseases. The potential intensity of each disease in each trial was calculated based on the symptoms observed on susceptible cultivars not treated with fungicide. The cultivar effect was characterized by the ratings of cultivar susceptibility to each disease and by cultivar earliness. The parameters of the model were estimated from 276 wheat cultivar trials carried out over 12 years (1991–2002) in the major wheat-growing areas of France. This model can help to choose from the cultivars resistant to several diseases (but very rarely resistant to all the diseases), those cultivars best adapted to a given environment, according to the hierarchy of potential disease intensities encountered.     

The Effect of Improved Management on the Yield and Nitrogen Content of Legume Hay/Barley Crop Rotations in West Asia

In the light of growing governmental support in west Asia and north Africa for policies which either discourage cereal monoculture or encourage fallow replacement by farmers, two experiments were conducted in northern Syria. These were designed to evaluate and quantify the effect of agronomic interventions on the productivity and nitrogen content of legume hays, and the subsequent residual effects of these interventions on the yield and nitrogen content of a following barley crop. Quantitative estimates of the residual effects of legume hays, when grown under rainfed conditions, on the N uptake of barley are rarely available for the region at large.
The major management effects on the productivity of legume hays were the addition of phosphate fertilizer and a reduction in row spacing. Positive residual effects on the yields of following barley crops were shown to be small but not insignificant. They could be considered to be important influences in the sustained production of barley in legume hay-barley crop rotations.
It is suggested that the results give further positive evidence that farmers in west Asia will not resist the introduction of improved crop rotations including legumes in place of their current fallow-barley or continuous barley crop sequences.     

The effect of water and nitrogen availability during grain filling on the timing of dormancy release in malting barley crops

Pre-harvest sprouting (PHS) causes immediate loss of seed viability, making barley (Hordeum vulgare L.) grains worthless for malting purposes. Grain dormancy release rate in barley crops is genetically and environmentally controlled. A 2 year experiment was conducted to evaluate the effect of soil nitrogen and water availability during grain filling on the dormancy release pattern (and then on the PHS susceptibility) for five malting barley commercial cultivars. Drought and well-irrigated control treatments were imposed from anthesis onwards, and contrast nitrogen fertilization treatments were applied at tillering. Nitrogen availability showed no effects on dormancy release. Drought during grain filling accelerated dormancy release with respect to well-irrigated control in 2004, but not in 2005 year. Mean temperatures during the last stages of grain filling were much higher (ca. 6°C) in 2005 than in 2004, indicating that high-dormancy loss promoting temperatures had masked drought effects on dormancy release.     

水氮配置对华北冬小麦-夏玉米种植体系氮素利用及土壤硝态氮残留的影响

针对华北平原冬小麦-夏玉米轮作体系存在过量的水、氮投入问题,本研究于2008 -2010年在河北吴桥设置了传统水氮、传统水氮调整、节水减氮和最少水氮4个水氮模式,以分析减少水氮投入后冬小麦-夏玉米体系的产量、氮素利用和土壤氮残留情况.结果表明:与传统水氮相比,节水减氮模式的氮肥投入量下降55％,水分投入量下降36.6％...     

The effect of the homoeologous group 5 chromosomes with different vrn loci on growth phases and quantitative characters of wheat

The differences between effects of homoeologous group 5 chromosomes on growth phases and agronomic characters were studied by using reciprocal substitution lines between a winter wheat cultivar with a high vernalization requirement (Mironovskaya 808) and one with lowvernalization requirement (Bezostaya 1), in which the presence of different recessive vrn alleles is supposed. The two cultivars and the substitution lines Mironovskaya 808 (Bezostaya 1 5A), Mironovskaya 808 (Bezostaya 1 5B), Mironovskaya 808 (Bezostaya 1 5D), Bezostaya1 (Mironovskaya 808 5A), Bezostaya 1 (Mironovskaya 808 5B),Bezostaya 1 (Mironovskaya 808 5D) were grown at 10 different sowing dates. The results showed that differences between the homoeologous group 5 chromosomes of Mironovskaya 808 and those of Bezostaya 1influenced the growth phases in addition to the impact by the genetic background and sowing date. We inferred from the analysis and comparison of their effect on vernalization response that vrn loci on these chromosomes influence growth phases. It is probably due to pleiotropic effects of the loci. The rare occurrence of significant interactions between group 5 chromosomes × sowing dates probably indicates independence of their effect. Agronomic characters were also markedly influenced by sowing date and the difference in backgrounds between Mironovskaya 808 and Bezostaya 1. A significant impact by at least two of the chromosomes on almost all studied characters was detected. The chromosomes affected the combined characters in the order5D>5B>5A and the positive value of the differences suggests that a content of Mironovskaya 808 chromosomes is more advantageous. It was possible to find certain indices in some agronomic traits, supporting the idea that the expression of some characters can also be connected to vernalization requirement and thus to the expression of the vrn loci. This supposition is most probable in the number of tillers and number of spikes. In some traits significant interactions occurred between homoeologous group 5 chromosomes × genetic background. Sporadic and low significance between homoeologous group 5 chromosomes × sowing dates suggest that the genetic effect of these chromosomes is independent of environmental conditions. This revised version was published online in July 2006 with corrections to the Cover Date.