Improving crop vigor can suppress growth of weeds present in the crop. This study examined the impact of preceding crop and cultural practices on rye growth in winter wheat. Preceding crops were soybean, spring wheat, and an oat/dry pea mixture. Two cultural treatments in winter wheat were also compared, referred to as conventional and competitive canopies. The competitive canopy differed from the conventional in that the seeding rate was 67%% higher and starter fertilizer was banded with the seed. The study was conducted at Brookings, SD. Rye seed and biomass production differed fourfold among treatments, with winter wheat following oat/pea being most suppressive of rye growth. Rye produced 63 seeds/plant in winter wheat with a competitive canopy that followed oat/pea, contrasting with 273 seeds/plant in conventional winter wheat following spring wheat. Yield loss in winter wheat due to rye interference increased with rye biomass, but winter wheat was more tolerant of rye interference following oat/pea compared with the other preceding crops. Regression analysis indicated that winter wheat yield loss at the same rye biomass was threefold higher following spring wheat or soybean compared with oat/pea as a preceding crop. Winter wheat competitiveness and tolerance to rye can be improved by increasing the seeding rate, using a starter fertilizer, and growing winter wheat after an oat/pea mixture.Nomenclature: Dry pea, Pisum sativum L.; oat, Avena sativa L.; rye, Secale cereale L.; soybean, Glycine max (L.) Merr.; wheat, Triticum aestivum L.

The influence of autumn, spring and total amount of rainfall on grain yield of winter wheat was investigated in monoculture and two crop rotation. The investigations are related to fifteen-year period. The type of soil on which the sort of winter wheat Pobeda was grown, under conditions of natural water regime was luvic chernozem. Winter wheat yields in investigated years were statistically and significantly different. On the basis of correlation and regression dependance of obtained grain yields of winter wheat on spring, winter and total amount of rainfall it was found that increasing the amount of autumn rainfall, grain yield was decreasing, especially in monoculture. However, increasing spring and total amount of rainfall, wheat grain yield increased in both investigated systems of growing. It means that in examined area (central part of Serbia) there is a sufficient amount of rainfall in winter period and that every increasing of the amount can decrease grain yield or even endanger wheat production. Therefore, the reason for lower grain yield of winter wheat in examined area was mainly lack of precipitation in spring period, when water is the most necessary for plants.

The success of winter × spring wheat hybridization programmes depends upon the ability of the genotypes of these two physiologically distinct ecotypes to combine well with each other. Hence the present investigation was undertaken to study the combining ability and nature of gene action for various morpho-physiological and yield-contributing traits in crosses involving winter and spring wheat genotypes. Five elite and diverse genotypes each of winter and spring wheat ecotypes and their F ₁ (spring × spring, winter × winter and winter × spring) hybrids, generated in a diallel mating design excluding reciprocals, were evaluated in a random block design with three replications. Considerable variability was observed among the spring and winter wheat genotypes for all the traits under study. Furthermore, these traits were highly influenced by the winter and spring wheat genetic backgrounds, resulting in significant differences between the spring × spring, winter × winter and winter × spring wheat hybrids for some of the traits. The winter × spring wheat hybrids were observed to be the best with respect to yieldcontributing traits. On the basis of GCA effects, the spring wheat parents HPW 42, HPW 89, HW 3024, PW 552 and UP 2418 and the winter wheat parents Saptdhara, VWFW 452, W 10 and WW 24 were found to be good combiners for the majority of traits. These spring and winter wheat parents could be effectively utilized in future hybridization programmes for wheat improvement. Superior hybrid combinations for one or more traits were identified, all of which involved at least one good general combiner for one or more traits in their parentage, and can thus be exploited in successive generations to develop potential recombinants through various breeding strategies. Genetic studies revealed the preponderance of additive gene action for days to flowering, days to maturity and harvest index, and non-additive gene action for the remaining six traits.

In Latvia, there are almost no data on the influence of soil agrochemical parameters (phosphorus and potassium content, pH KCL) on development and yield of winter wheat using precision agriculture methods. Investigations were carried out in Research and Study farm "Vecauce" in 2005-2007. The aim of this study was to clarify the effect of soil agrochemical properties on development and yield of winter wheat in production conditions. Soil reaction and phosphorus content were showed significant effect on the winter wheat yield in 2006, when the yield level was 7.50-9.20 t haE-1. Coefficient of tillering and fresh weight of winter wheat plants in both trial years was significantly higher when soil reaction and phosphorus content were above the medium range. Area of flag leaf had significant effect on the winter wheat grain yield in 2006 with the yield level from 7.02-9.02 t haE-1 and in 2007 with the yield level from 3.53-7.05 t haE-1.

In winter wheat (Triticum aestivum L.), the stem begins to elongate after the vernalization requirement is satisfied during winter and when favorable temperature and photoperiod conditions are attained in spring. In this study, we precisely measured elongation of the first extended internode on 96 recombinant inbred lines of a population that was generated from a cross between two winter wheat cultivars, Jagger (early stem elongation) and 2174 (late stem elongation). We mapped a major locus for stem elongation to the region where VRN-A1 resides in chromosome 5A. Visible assessment of winter dormancy release was concomitantly associated with this locus. VRN1 was previously cloned based on variation in vernalization requirement between spring wheat carrying a dominant Vrn-1 allele and winter wheat carrying a recessive vrn-1 allele. Both of two winter wheat cultivars in this study carry a recessive vrn-A1 allele; therefore, our results suggest that either VRN-A1 might invoke a new regulatory mechanism or a new gene residing close to VRN-A1 plays a regulatory role in winter wheat development. Phenotypic expression of the vrn-A1a allele of Jagger was more sensitive to the year of measurement of stem elongation than that of the vrn-A1b allele of 2174. In addition to QSte.osu.5A, several loci were also found to have minor effects on initial stem elongation of winter wheat. Seventeen of nineteen locally adapted cultivars in the southern Great Plaints contained the vrn-A1b allele. Hence, breeders in this area have inadvertently selected this allele, contributing to later stem elongation and more conducive developmental patterns for grain production.

Evaluation of yielding, nutrient status and efficiency of nutrient uptake by selected modern and old winter wheat cultivars in organic crop production system was the aim of the research. The research was based on a special field experiment established in 1994 at the Experimental Station in Osiny on a grey-brown podzolic soil in which different crop production systems (organic, integrated and conventional) are compared. The research was conducted in 2005-2007 on the field of winter wheat in the organic system. Six different cultivars of common winter wheat (Mewa, Roma, Kobra, Sukces, Zyta and Korwetta) and one cultivar of spelt winter wheat (Schwabenkorn) were compared. Moreover 3 old cultivars of winter wheat were taken into account: Wysokolitewka Sztywnosłoma, Kujawianka Wieclawicka, Ostka Kazimierska. The largest and the most stable grain yields of winter wheat were noted for modern cultivars. Among them Zyta (4.36 t/ha), Sukces and Roma (4.05 t/ha) gave the largest yields. Old winter wheat cultivars yielded on the level of about 1,5 t less in comparison to modern ones. The results of the research showed that modern, quality cultivars Zyta and Sukces, as well as husky cultivar Mewa are better adapted for organic farming than old ones. Old cultivars are worse adapted, because they give smaller yields and their leaves are more infested by fungal pathogens. An important criteria of cultivar selection for organic farming should be firstly high resistance on fungal pathogens and secondly ability to effective uptake of nutrients and their distribution to generative parts of plant

Improved winter wheat (Triticum aestivum L.) cultivars are needed for the diverse environments in Central and West Asia to improve rural livelihoods. This study was conducted to determine the performance of elite winter wheat breeding lines developed by the International Winter Wheat Improvement Program (IWWIP), to analyze their stability across diverse environments, and to identify superior genotypes that could be valuable for winter wheat improvement or varietal release. One hundred and one advanced winter wheat breeding lines and four check cultivars were tested over a 5-year period (2004-2008). Grain yield and agronomic traits were analyzed. Stability and genotypic superiority for grain yield were determined using genotype and genotype x environment (GGE) biplot analysis. The experimental genotypes showed high levels of grain yield in each year, with mean values ranging from 3.9 to 6.7 t ha(-1). A set of 25 experimental genotypes was identified. These were either equal or superior to the best check based on their high mean yield and stability across environments as assessed by the GGE biplot analysis. The more stable high yielding genotypes were ID800994.W/Falke, Agri/Nac//Attila, ID800994W/Vee//F900K/3/Pony/Opata, AU//YT542/N10B/3/II8260/4/JI/Hys/5/Yunnat Esskiy/6/KS82W409/Spn and F130-L-1-12/MV12. The superior genotypes also had acceptable maturity, plant height and 1,000-kernel weight. Among the superior lines, Agri/Nac//Attila and Shark/F4105W2.1 have already been proposed for release in Kyrgyzstan and Georgia, respectively. The findings provide information on wide adaptation of the internationally important winter wheat genotypes, and demonstrate that the IWWIP program is enriching the germplasm base in the region with superior winter wheat genotypes to the benefit of national and international winter wheat improvement programs.

The title method includes: 1. Agrochemical field mapping and development of an agrochemical certificate on humus content, nitrification ability, labile phosphorus and exchange potassium and other elements contents; 2. Winter wheat crops condition estimation after wintering with determination of bushing factor, density of standing and moisture and mineral nitrogen content within 1-m layer; 3. Winter wheat yield forecast and provision of recommendations on dosage, timing and methods of nitrogen fertilizers introduction; 4. Winter wheat nitrogen nutrition on-line control and regulation on the basis of vegetable diagnosis and field grouping by raw gluten content in grain.

Comparison of economic efectivity of the winter wheat (Triticum aestivum L.) and winter spelt (Triticum spelta L.) growing in organic farming systems. The differences of yield of two species wheats in organic farming system and factors are evaluated. In relation to standart technological procedures in farming systems are defined costs for area nad for production unit. Structure of costs on production, price differences between the winter wheat and winter spelt are analysed.