Spring Wheat Grain Yield Research Articles

Adaptations for growing wheat in the drying climate of Western Australia

This study investigated the effects of predicted changes in rainfall distribution in marginal (≤325 mm annual rainfall) parts of the south-west Australian wheatbelt and options for management and adaptation of the wheat crop. Field experiments with rain-out shelters and irrigation were conducted in 2008 and 2009 to investigate the interactions of rainfall distribution, row spacing, genotype and timing of nitrogen application on growth, water use and grain yield of spring wheat. Water storage before seeding showed potential to maintain or increase yields despite lower in-season rainfall. Widening row spacing reduced biomass and slowed water use but did not increase grain yield, because of increased soil evaporation and water left in the soil at crop maturity. The Agricultural Production Systems Simulator (APSIM) wheat model was used to investigate the effects of recent and projected climate change on yield in relation to row spacing, phenology and nitrogen. Two climate-change scenarios were applied to historical climatic data to create two plausible future climates (‘optimistic’ and ‘pessimistic’) for the year 2030. None of the strategies tested increased wheat yield under the predicted climate scenarios. Simulated yields at wider row spacings were consistently lower due to insufficient biomass, increased soil evaporation and the inability of the crop to use all of the available water before maturity. Simulated yields of short-season genotypes were always greater than yields of longer season genotypes. Nitrogen regimes had little effect in this study. This study points to several genotypic traits that could improve the performance of wheat grown at wider row spacings. These include early vigour to reduce soil evaporation and increase competition with weeds, greater tillering/biomass to reduce limitation by sink size, and a vigorous root system with appropriate lateral spread and growth to depth to access available soil water.

Response of Grain Yield and Protein Content of Wheat Varieties to Different Levels of Fertilizers

The grain yield and protein content of winter and spring wheat are significantly influenced by the technological factors, by variety, meteorological conditions and interaction between them. The field experiment was conducted to evaluate the effect of different levels of fertilization on grain yield and quality indices in winter and spring wheat and to compare of their values. The quality of the grain was determined based on meal analysis. Nitrogen application improved protein content and also increase the grain yield until level when is appear the negative correlation between two characters. The experimental date from this paper is about adaptability of 25 winter wheat and 22 spring wheat varieties local and foreign in two years and two level of fertilization on the local conditions at Turda. The experiments were conducted over two years, 2011 and 2012, at Agricultural Research and Development Station Turda, which are characterized with a high rainfall and temperatures favourable for winter wheat and spring wheat crops. The trials were conducted under quadratic lattice design with repeated the basic scheme. Each of both basic scheme consisting of 3 replications permitted to create two levels of fertilization. So, including the years as factors was possible to consider our experiment as an three factorial one (years- cultivars- fertilization). The effect of fertilization is reflected on increase grain yield and qualitative of these. By analysis of variance could be highlighted the influences of year, level of fertilization and cultivars, and also the interactions between these.

Impact of corn residue on yield of cool-season crops

AbstractSynergy between dry pea and corn can reduce the density of corn needed for optimum yield. Lower crop density may accrue an additional benefit, as after-harvest residues of corn lying on the soil surface can reduce yield of crops planted the next year. This study evaluated impact of corn residue levels on growth and yield of three cool-season crops in no-till. Corn was grown at two densities, 52,000 and 73,000 plants ha−1, leading to after-harvest residue levels designated as low and high residue. Residue quantity on the soil surface differed by 21%. Controls were included for each residue level by burying residue with tillage. Spring wheat, dry pea and red clover were planted the following year. Grain yield of spring wheat and dry pea and forage yield of red clover were reduced 13–33% by residue on the soil surface. However, yield of cool-season crops were 10–18% higher in the low-residue treatment compared with high residue. Furthermore, yield loss because of weed interference in spring wheat and red clover was greater with high residue. Of the three crops, spring wheat was the least affected by corn residue on the soil surface. One contributing factor to lower yield with high residue was reduced crop seedling establishment. Producers may be able to reduce the negative impact of corn residue on following crops in no-till systems by using synergistic crop sequences in the rotation.

Downy Brome (Bromus tectorum) Competition and Control in No-Till Spring Wheat

Downy brome is one of the leading plant pests in winter wheat and no-till spring wheat in many areas of the country. It has recently been studied in North Dakota where it is emerging as a serious crop competitor. Downy brome plants produced up to 60 tillers and more than 7,500 seeds when no control measures were used and densities were less than 2 plants m−2. Experiments focusing on herbicide-application timing identified differences in downy brome control and the grain yield of spring wheat. Regardless of fall or spring application timing, glyphosate applied PRE to wheat completely controlled downy brome in 2007. In 2008, control was not achieved with the earliest glyphosate-application timings because of late-emerging plants. When comparing fall and spring application timings of other herbicides, imazapic provided at least 79% control at each timing and location, resulting in the highest imazamox-resistant spring wheat yield. In general, herbicides performed better when applied in fall than they did when applied in spring. When herbicides were applied POST, imazamox provided the greatest downy brome control and usually caused the largest numerical reduction in downy brome biomass, seed, and stem number. If downy brome was left untreated, regression analysis predicted approximately 2,000 stems m−2could result in total yield loss of spring wheat.

Soil Nutrients and Grain Yield Performance in Spring Wheat (<i>Triticum aestivum</i>) as Influenced by Regulated Deficit Irrigation

A field trial was conducted in 2007 and 2008 to investigate the difference in soil nutrients and grain yield of spring wheat (Triticum aestivum) as influenced by regulated deficit irrigation (RDI) in an arid area. Three RDI treatments and a no-water-deficit control (CK) were designed to subject wheat to various degrees of soil water deficit at different crop developmental stages. Significant differences (p<0.05) occurred in soil organic matter (SOM) and soil available potassium (SAK) contents in both growing seasons, but no difference (p>0.05) occurred among the RDI treatments. Meanwhile, no differences were found in soil total nitrogen (STN) and soil total phosphorus (STP) contents among the treatments and CK. SOM content was improved by 6.2% to 7.2% in RDI treatments than in the CK over the two growing seasons, while the STN, STP, and SAK contents were increased by 1.2% to 2.5%, 1.4% to 5.6%, and 9.0% to 11.2%, respectiely. The STP (t=10.900, p<0.001), soil available phosphorus (SAP, t=8.894, p<0.001), and SAK (t=11.706, p<0.001) contents in 0~40 cm soil layer at wheat harvest were significantly lower in 2008 than in 2007, while the SOM (t=-2.513, p<0.05) and STN (t=-9.950, p<0.001) contents were significantly higher in 2008. Soil organic C, STN, and SAP balance was greatly influenced by RDI in two growing seasons. Compared to the no-water-deficit control, grain yields over the two years were respectively improved by 16.5% to 24.9% in RDI plots.The relationship between grain yield and the soil nutrients was described as y=15843.4 +713.3SOM-20989.1STN+38.7SAN-15.0SAP-39.7SAK (R2=1, p<0.001).

A long-term sensitivity analysis of the denitrification and decomposition model

Although sensitivity analysis (SA) was conducted on the DeNitrification–DeComposition (DNDC) model, a global SA over a long period of time is lacking. We used a method of Bayesian analysis of computer code outputs (BACCO) with the Gaussian emulation machine for sensitivity analysis software (GEM-SA) to conduct a long-term SA of DNDC for predicting the annual change of soil organic carbon (dSOC), nitrous oxide emission (N2O) and grain yield of spring wheat. Twenty seven non-weather input parameters with wide ranges were selected for SA using weather data recorded from Three Hills, Alberta over 86 years (1921–2006). The SA had two steps: 1) a preliminary BACCO GEM-SA was conducted to identify a more accurate emulator sampling method and to screen out parameters with insignificant influence on model outcomes; and 2) final BACCO GEM-SA was conducted with optimal input design set for emulator training runs varying only the significant input parameters. Results indicated that the Maximin Latin Hypercube sampling method outperformed the LP-τ method with higher emulator accuracy. Most of the 27 input parameters contributed little to the three outputs by the first step BACCO GEM-SA. In the second step of BACCO GEM-SA there were only three (in the case of dSOC) and six (in the cases of N2O and yield) input parameters whose influence contributed to more than 10% of the total output variances by their total effects. Among the selected parameters, initial soil organic carbon and clay content are very important and were important in determining results for all three outputs. Sensitivities of some parameters, such as clay content and urea fertilizer amount changed dramatically over the years. This indicates that a single year SA may overestimate or underestimate a long-term parameter effect on the model prediction. The two-step procedure with the BACCO GEM-SA method improved the accuracy of SA and provided important information for model validation and parameterization.

Wheat yield response to line source sprinkler irrigation and soil management practices on medium-textured shallow soils of arid environment

A field experiment was conducted for 3 years to evaluate the effect of deficit irrigation under different soil management practices on biomass production, grain yield, yield components and water productivity of spring wheat (Triticum estivum L.). Soil management practices consisted of tillage (conventional and deep tillage) and Farmyard manure (0 and 10 t ha -1 FYM). Line source sprinkler laterals were used to generate one full- (ETm) and four deficit irrigation treatments that were 88, 75, 62 and 46 % of ETm, and designated as ETd1 ,E Td 2, ETd3 ,a nd ETd 4. Deep tillage significantly enhanced grain yield (14-18 %) and water pro- ductivity (1.27-1.34 kg m -3 ) over conventional tillage. Similarly, application of FYM at 10 t ha -1 significantly improved grain yield (10-13 %) and water productivity (1.25-1.31 kg m -3 ) in comparison with no FYM. Grain yield response to irrigation varied significantly (5,281-2,704 kg ha -1 ) due to differences in soil water contents. Water productivity varied from 1.05 to 1.34 kg m -3 , among the treatments in 3 years. The interactive effect of irriga- tion 9 tillage practices and irrigation 9 FYM on grain yield was significant. Yield performance proved that deficit irri- gation (ETd2) subjected to 75 % soil water deficit had the smallest yield decline with significant water saving would be the most appropriate irrigation level for wheat production in arid regions.

Effect of fertilization with farmyard manure, municipal sewage sludge and compost from biodegradable waste on yield and mineral composition of spring wheat grain

Both deficiency and excess of mineral components in cereal grain may impair its biological value, later interfering with the metabolic processes occurring in animal and human organisms. Potential accumulation of undesirable components in biomass should be taken into consideration since such compounds occur in large amounts in waste material. Therefore, it is necessary to assess the effect of waste-based fertilizers on both the amount of generated biomass and its chemical composition. The present investigations were conducted to determine the effect of fertilization with farmyard manure, municipal sewage sludge and compost from biodegradable materials on the yield and mineral composition of spring wheat grain. The field investigations ran for three years. Nitrogen in wheat grain was assessed using Kjeldahl’s method, phosphorus by colorimetry, sulphur, copper, manganese and zinc by the ICP-AES method, and potassium, magnesium and sodium by flame photogrammetry. In the first year, organic fertilizers were observed to be less stimulating to yield formation than mineral fertilizers. Although the uptake of N, P and K from the applied organic fertilizers was impeded, their deficiency in wheat grain was preventable by balancing doses of these components. Despite different amounts of magnesium, sodium and sulphur applied to the soil with the fertilizers, the concentrations of these elements in grain were considerably stable in the years of the investigations. Copper and manganese concentrations in wheat grain were deficient, which significantly depressed grain fodder value and might indirectly determine the crop yield.

Contribution of CIMMYT Wheat Germplasm to Genetic Improvement of Grain Yield in Spring Wheat of Sichuan, Yunnan, Gansu, and Xinjiang Pro-vinces

研究历史品种产量潜力变化规律有助于提高小麦育种水平。2007—2009连续2年度将来自四川、云南、甘肃和新疆的代表性59个品种分别种植在四川成都、云南丽江、甘肃武威和新疆昌吉，在肥水供应充足、控制病虫害和倒伏的条件下分析了产量和相关农艺性状的变化趋势。结果表明，四川、云南、甘肃和新疆品种的产量随育成年份显著增加，年遗传增益分别为0.73%、0.34%、0.58%和1.43%。产量遗传增益四川品种表现与产量构成因子关系不密切；云南品种主要表现为减少穗数和增加穗粒数；甘肃品种主要表现为增加穗粒数；新疆品种主要表现为增加主穗粒重和收获指数，并与成熟期提早及株高降低有一定关系。各地区品种中 Rht-B1b 和 Rht-D1b 矮秆基因均来自CIMMYT种质，其产量潜力的提高主要得益于CIMMYT种质的引进和有效利用，在四川和云南，CIMMYT种质的主要贡献是提高品种的条锈病抗性；而在甘肃和新疆，其被利用的主要特性是矮秆、高产、穗粒数多及广泛适应性。

Association of Fhb1 and Qfhs.ifa-5A in Spring versus Winter Growth Habits in Bread Wheat (Triticum aestivum L.)

Fusarium head blight (FHB) is a major disease that reduces grain yield and quality of winter and spring wheat in eastern South Dakota. This study was conducted to determine the association of FHB resistance QTLs (Fhb1 and Qfhs.ifa-5A) to spring and winter growth habits of bread wheat. Four genotypes consisting of susceptible winter wheats ‘Nekota’ and ‘2137’ and moderately resistant spring wheats ‘ND2710’ and ‘BacUp’ were crossed and populations derived from the crosses were separated into spring and winter types following cold treatment of seedlings at -70C for 1 h. A total of six SSR markers (Fhb1 markers: Xgwm389, Xgwm493 and STS256; Qfhs.ifa-5A markers: Xgwm293, Xgwm304 and Barc186) were used to genotype the populations. A chi-square analysis deviating from a 1:1 ratio showed that there were significant differences in the percentage of genotypes containing homozygous marker alleles for Fhb1 and Qfhs.ifa-5A between spring and winter types in the population ND2710/2137, ND2710/Nekota and BacUp/2137. The percentage of genotypes with homozygous marker alleles for Fhb1 was lower in the spring types in the populations ND2710/2137 and ND2710/BacUp. In contrast, the spring types in the population ND2710/Nekota had a higher percentage of genotypes containing homozygous marker alleles for Qfhs.ifa-5A compared with the winter types. The results indicated that Fhb1 was not necessarily associated with the spring growth habit; whereas, Qfhs.ifa-5A was not necessarily associated with the winter growth habit.

Contribution of CIMMYT Wheat Germplasm to Genetic Improvement of Grain Yield in Spring Wheat of Sichuan, Yunnan, Gansu, and Xinjiang Provinces

Information on advances in wheat (Triticum aestivum L.) productivity is essential for genetic improvement on yield potential. Four yield potential trials with totally 59 leading cultivars from Sichuan, Yunnan, Gansu, and Xinjiang, China were conducted using a randomized complete block design with 3 replications under controlled environments in 2 successive cropping seasons from 2007 to 2009. The experimental sites were located in Chengdu in Sichuan, Lijiang in Yunnan, Wuwei in Gansu, and Changji in Xinjiang. Molecular markers were used to detect the presence of dwarfing genes and 1B/1R translocation. The results indicated that the annual genetic gains in yield were 0.73% in Sichuan, 0.34% in Yunnan, 0.58% in Gansu, and 1.43% in Xinjiang. There was no obvious trend of yield component improvement for yield increase in Sichuan; while reduced spikes per square meter and increased kernels per spike were the main factor for yield increase in Yunnan; increased kernels per spike were the main factor for yield increase in Gansu; and increased kernel weight of main spike and harvest index were the main factor for yield increase in Xinjiang, together with the contribution from reduced plant height and earlier maturity. It also indicated that the dwarfing genes Rht-B1b and Rht-D1b were all from International Maize and Wheat Improvement Center (CIMMYT) lines, and the significant progresses of genetic gain in yield in the 4 provinces were mainly due to the direct and indirect use of CIMMYT germplasm. Stripe rust resistance was the main contribution of CIMMYT germplasm in Sichuan and Yunnan; while CIMMYT germplasm contributed to high yield potential with high kernel number per spike, short plant height, and wide adaptability in Xinjiang and Gansu.

Pedigree Selection for Grain Yield in Spring Wheat (Triticum aestivum L.) under Drought Stress Conditions

Pedigree Selection for Grain Yield in Spring Wheat (Triticum aestivum L.) under Drought Stress Conditions

Response to Pedigree Selection for Earliness and Grain Yield in Spring Wheat under Heat Stress

The objectives of this study were to estimate the response to direct selection for early heading and grain yield under favourable and stress environments and to study the correlated response of other studied traits. Two cycles of pedigree selection for earliness and grain yield/plant were completed on a segregating population of wheat in the F3-F5 generations. Selection for each trait was, separately and over environments, practiced at favourable, stress and over environments. After two cycles of selection for earliness, the realized gain reached to -2.19, -1.85 and -1.72% from the bulk samples for selection under favourable, stress and over environments, respectively. The realized gains from selection for increasing grain yield/plant were 17.32, 24.16 and 7.48% from the bulk samples for selection under favourable, stress and over environments, respectively. The antagonistic selection was more efficient than synergistic selection in changing the mean and in decreasing the sensitivity to environments. Selection for earliness was accompanied by undesired decrease in all correlated traits over the bulk sample at favourable, stress and over environments. However, selection for grain yield/plant was accompanied by late in days to heading and decrease in 1000-grain weight from the bulk sample at favourable, stress and over environments. Two families; No. 58 and No. 50 could be considered the best selected families resulted from selection for earliness and grain yield/plant, respectively which earlier and higher than the bulk sample under different environments. Pedigree selection for either earliness or grain yield/plant was effective in isolating genotypes for early heading and high grain yield.

Comparative Efficacy of Different Weed Management Strategies in Wheat

Weed management programs should focus on environmental safety along with benefits to the farmer. We evaluated the effects of various weed control methods: ?daab? practice (stale seed bed technique), manual hoeing, and the chemical method (mixture of Buctril Super 60EC [bromoxynil + MCPA] 0.45 kg ai ha-1 and Puma Super 75EW [fenoxaprop-P-ethyl] 0.75 kg ai ha-1) in combination with different planting geometries: 22.5 cm apart single row, 22.5 cm apart crisscross double row, 30 cm apart single row and broadcast sowings on weed control and grain yield of spring wheat (Triticum aestivum L.) var. Sehar 2006 at the University College of Agriculture, University of Sargodha, Pakistan, during the winters of 2009 and 2010. The chemical method, manual hoeing and ?daab? practice gave 71.44%, 30.69% and 28.60% weed controls resulting in 11.79%, 11.09% and 4.95% increases in grain yield above that of the weedy control, respectively. The 22.5 cm apart single row sowing in combination with chemical weed control proved to be the best regarding weed control (87.23%), grain yield (4073 kg ha-1) and number of fertile tillers m-2 (509.5), whereas wheat plant height (108.2 cm), number of grains spike-1 (45.90) and 1000 grain weight (45.23 g) were higher in 30 cm apart single row sowing in interaction with manual hoeing. Grain yield showed a significant negative (b = -152.8) and positive (b = 3.21) correlation with weed biomass and fertile tillers m-2, respectively. Chemical weed control, ?daab? practice and manual hoeing gave cost:benefit ratios of 2.50, 1.95 and 1.14, respectively. Although the chemical method seems the most profitable, the ?daab? practice was found to be the most advantageous if environmental concerns were taken into consideration.

Application of the DNDC model to predict N2O emissions from sandy arable soils with differing fertilization in a long‐term experiment

AbstractModeling crop growth and soil N dynamics is difficult due to the complex nature of soil–plant systems. In several studies, the DNDC model has been claimed to be well‐suited for this purpose whereas in other studies applications of the model were less successful. Objectives of this study were to test a calibration and validation scheme for DNDC‐model applications to describe a field experiment with spring wheat on a sandy soil near Darmstadt (SW Germany) using different fertilizer types (either application of mineral fertilizer and straw—MSI; or application of farmyard manure—FYM) and rates (low—MSIL, FYML; and medium—MSIM, FYMM). The model test is based on a model parameterization to best describe the case MSIL and applies this parameterization for a retrospective simulation of the other cases (MSIM, FYML, FYMM) including crop growth and N2O emissions. Soil water contents were not accurately simulated using either the DNDC default values for a loamy sand or for the next finer texture class or using results from the pedotransfer function provided by ROSETTA. After successful calibration of the soil water flow model using a soil texture class that led to the best fit of the measured water content data, grain yield of spring wheat and cumulative N2O emission were slightly underestimated by DNDC and were between 91% and 86% of the measured data. A subsequent calibration of the yields and cumulative N2O emissions from soils of the MSIL treatment gave a good prediction of crop growth and N2O emissions in the MSIM treatment, but a marked underestimation of yields of the FYM treatments. Cumulative N2O emissions were predicted well for all MSI and FYM treatments, but seasonal dynamics were not. Overall, our results indicated that for the sandy soil in Germany, site‐specific calibration was essentially required for the soil hydrology and that a calibration was useful for a subsequent prediction where greater amounts of the same fertilizer were used, but not useful for a prediction with a different fertilizer type.

Responses of Spring Wheat and Soybean to Subsurface Drainage in Northwest Minnesota

The advantages and adoption of subsurface drainage are well documented in many parts of the Upper Midwest. The adoption of subsurface drainage in the northern half of Minnesota, in particular the Red River of the North Basin (RRB), has been relatively small compared with other intensively drained regions of the Upper Midwest. The objectives of this research were to measure the effect of subsurface drainage on grain yield and grain quality of spring wheat (Triticum aestivum L.) and soybean [Glycine max (L.) Merr.] in the RRB. Experimental sites were established near Brooks and Crookston, MN. At each site subsurface drainage was installed based on drainage coefficients of 6.3, 12.7, and 19 mm d−1 of excess soil water. The grain yield of both wheat and soybean did not improve with subsurface drainage. In contrast to grain yield, grain protein in both wheat and soybean increased. The grain protein increased linearly in spring wheat as the drainage coefficient increased. In soybean, grain protein showed a quadratic response to the increase in the drainage coefficient. A correlated response to the increase in grain protein was detected with the quadratic decrease in oil content in soybean. These results suggest that subsurface drainage as a means to supplement the predominant system of land leveling and surface drainage may have limited applicability in the RRB as subsurface drainage did not improve grain yield of spring wheat or soybean, greatly limiting the economic feasibility of subsurface drainage.

Effects of perennial fodder crops on soil structure in agricultural headlands

AbstractIn agricultural headlands, rooting and yield of crops may be limited because of soil‐structure changes as a consequence of multiple passes of turning machinery. We hypothesized that perennial forage crops can substantially alter soil structure in agricultural headlands. On one experimental field and two commercial farms on Haplic Luvisols from respectively loess and sandy loess in the Lower Rhine Bay (Germany), we investigated how 4 y of continuously grown grass/clover or alfalfa affected soil structure and the performance of subsequent spring wheat. Compared with a crop rotation with annual plowing to 30 cm soil depth, perennial forage crops led to increased soil C content (+1.3% to +22.8%) and N content (+4.2% to +15.1%), higher densities of medium and coarse biopores at a depth of 35 cm, more large water‐stable soil macroaggregates, higher biomass and abundance of anecic earthworms, and higher grain yield and grain protein content of spring wheat grown as the following crop. Root‐length density of spring wheat in the subsoil was not affected by the preceding perennial fodder crops in two of the three field trials. We concluded that besides increasing N input to the soil, perennial cropping of grass/clover or alfalfa has effects on soil structure that may substantially reduce yield losses in agricultural headlands.

The effect of tillage system and forecrop on the yield and values of LAI and SPAD indices of spring wheat

Catch crops cultivated for producing green manure are the reason for modifications in soil tillage. The objective of the present study was to determine the yields of two spring wheat cultivars, as well as the values of LAI and SPAD indices in relation to the method of tillage and use of a forecrop. A field experiment was carried out over the period of 2005–2007 at the Experimental Station in Prusy near Krakow (Poland). It included the following research factors: (i) a tillage system: simplified and conventional, (ii) forecrop: faba bean, stubble crop (white mustard) after faba bean, (iii) cultivars of spring wheat (Bryza and Zebra). These spring wheat cultivars reacted the same way to the tillage variants applied. Crop residue of faba bean and stubble crop leave the soil rich in mineral nitrogen; owing to this fact, it is possible to obtain high grain yield of spring wheat (6.71 Mg ha −1) with relatively low application of nitrogen fertilization (60 kg N ha −1). Cultivation of white mustard as a stubble crop after faba bean is a valuable solution not only in terms of protecting the soil environment by immobilizing nitrate nitrogen, but also because it results in a significant increase in wheat yields, especially under simplified soil tillage conditions. The simplified soil tillage resulted in a decrease in the wheat yield by 12.6% on average, while with the stubble crop incorporated it was possible to increase the wheat grain yield by 18.2%.

Genetic gains for grain yield in high latitude spring wheat grown in Western Siberia in 1900–2008

Short season high latitude (50°N–56°N) spring wheat ( Triticum aestivum L.) is grown on approximately 7 million ha in Western Siberia with average yield of 1.5–2.0 t/ha. A historical set of 47 varieties developed and grown in the region between 1900 and 2000 was evaluated at a trial in Siberian Research Institute of Agriculture (Omsk) in 2002–2008. The genetic gains for grain yield and associated changes in agronomic traits were analyzed for three maturity groups (early, medium and late) and four breeding periods (before 1930, 1950–1975, 1976–1985 and after 1985). The overall yield was 3.71 t/ha for modern varieties versus 2.18 t/ha for old varieties representing 0.7% increase per year in the course of 100 years. The genetic gains between the breeding periods indicated that the rate of progress for the early and medium maturity groups was more or less comparable from one breeding period to the other. For the late maturity group there was an obvious and sharp decline in genetic gain with time. Modern varieties were also characterized by average response to environmental mean and good grain yield stability evaluated according to Eberhart and Russell (1966). Thousand kernel weight and number of grains per unit area were linearly correlated with grain yield and genetic gain over time suggested their importance for breeding progress. Resistance to leaf rust in some modern varieties sustained and contributed to stability of genetic gains. The yield increase over time was not associated with plant height reduction and incorporation of Rht genes. The maturity range of the newer varieties is narrower compared to old germplasm as they tend to belong to medium maturity group. Translocation 1B.1R had limited contribution to Western Siberian germplasm being observed in only three varieties. The increase in adaptation, yield potential and its stability has been reached due to gradual accumulation of favorable genes through diverse crosses, robust selection and testing system. Resistance to leaf rust and other prevalent pathogens is of paramount importance for future progress.

THE EFFECTIVENESS OF DIAZOPHIT APPLICATION IN DIFFERENT FERTILIZATION SYSTEMS AT CULTIVATION OF SPRING WHEAT

It was established, that the increase of a grain yield of spring wheat at diazophit application makes about 8.6 up to 19,8 % depending on the fertilization system. Yield gain by the use of biopreparation was more cost efficient than from the use of mineral fertilizers. Energy efficiency of diazophit inoculation is the largest in the system with the minimal norm of mineral fertilizers. It had exceeded the control on 19,6 %.