Fifty-two winter wheat (Triticum aestivum L.). nine spring wheat, and 20 spelt (Triticum spelta L.) lines representing part of the European breeding germplasm, were assayed for RFLPs (restriction fragment length polymorphisms) with 56 wheat DNA clones and two barley cDNA clones. Objectives of this study were to (1) determine the level of variation for RFLPs in the wheat and spelt breeding lines, (2) characterize the genetic diversity within the European winter wheat germplasm, and (3) evaluate the usefulness of RFLP markers for pedigree analysis and the grouping of wheat and spelt lines of various origins. Seventy-three of the 166 RFLP loci detected with 58 probes and one restriction enzyme were polymorphic for the 81 lines. The percentage of polymorphic loci was greatest for the B genome (58%) and smallest for the D genome (21%). Among the 81 lines, 271 different RFLP bands were detected. RFLP band frequencies of the winter wheat lines differed considerably (greater than or equal to 0.5) from those of the spring wheat lines at five loci, and from those of the spelt lines at 17 loci. Eight cultivars that had a major impact as progenitors on the development of improved winter wheat cultivars accounted for 93% of the observed RFLP bands in winter wheat. Genetic distance (GD) estimates between two lines ranged between 0.01 and 0.21. Mean GD estimates within winter wheat (0.083), within spring wheat (0.108) and within spelt (0.096) were smaller than between spring and winter wheat (0.114), and greatest between winter wheat and spelt (0.132) and spring wheat and spelt (0.148). Principal coordinate analysis performed on GD estimates revealed a clear separation of wheat and spelt germplasm. Novel spelt lines with various proportions of wheat germplasm were positioned between wheat and traditional spelt lines. The spring wheat lines formed a distinct group at the periphery of the distribution of the winter wheat lines. Sub-groupings of the winter wheat lines according to the cluster analysis were in good agreement with their origin, and lines with common ancestors were grouped together.

52 winter wheat (Triticum aestivum L.), 9 spring wheat, and 20 spelt (Triticum spelta L.) lines representing part of the European breeding germplasm, were assayed for RFLPs (restriction fragment length polymorphisms) with 56 wheat DNA clones and two barley cDNA clones. Objectives of this study were to determine the level of variation for RFLPs in the wheat and spelt breeding lines, characterize the genetic diversity within the European winter wheat germplasm, and evaluate the usefulness of RFLP markers for pedigree analysis and the grouping of wheat and spelt lines of various origins. 73 of the 166 RFLP loci detected with 58 probes and one restriction enzyme were polymorphic for the 81 lines. The percentage of polymorphic loci was greatest for the B genome (58%) and smallest for the D genome (21%). Among the 81 lines, 271 different RFLP bands were detected. RFLP band frequencies of the winter wheat lines differed considerably (over 0.5) from those of the spring wheat lines at 5 loci, and from those of the spelt lines at 17 loci. Eight cultivars that had a major impact as progenitors on the development of improved winter wheat cultivars accounted for 93% of the observed RFLP bands in winter wheat. Genetic distance (GD) estimates between two lines ranged between 0.01 and 0.21. Mean GD estimates within winter wheat (0.083), within spring wheat (0.108) and within spelt (0.096) were smaller than between spring and winter wheat (0.114), and greatest between winter wheat and spelt (0.132) and spring wheat and spelt (0.148). Principal coordinate analysis performed on GD estimates revealed a clear separation of wheat and spelt germplasm. Novel spelt lines with various proportions of wheat germplasm were positioned between wheat and traditional spelt lines.

This paper presents grain yields of winter wheat in 3-field crop rotations in relation to forecrops (winter rape and pea) and doses of nitrogen (60, 100 and 140 kg/ha). The experiment was carried out since 1986 on black soil with the granulometric composition of light loam. Results obtained in 1987-91 prove a more favourable effect of pea as forecrop than winter rape on grain yield of winter wheat. N fertilization can be reducted on fertile soil without reducing the yields of winter wheat, when forecrop is pea

Winter wheat cultivars that are competitive with weeds help control weeds in crop rotations. Ten winter wheat cultivars were evaluated for interference with summer annual grasses in the wheat and the subsequent grain sorghum crop in a winter wheat-ecofallow sorghum-fallow rotation in which there are two 10-mo fallow periods and two crops in 3 yr during 1983 to 1987. The medium-tall (100 to 109 cm tall) and medium-statured (90 to 99 cm tall) winter wheat cultivars 'Buckskin', 'Siouxland', 'Lancota', 'Centurk 78', and 'Brule') were more competitive than medium-short (80 to 89 cm tall) and short (68 to 79 cm tall) cultivars ('Eagle', 'Homestead', 'Colt', 'Vona', and 'TAM 101'). Atrazine plus paraquat was applied to all cultivars 30 d after wheat harvest. When grain sorghum was planted in areas previously seeded with medium-tall and medium-statured winter wheat, summer annual grass weed biomass in sorghum was 61% less than in grain sorghum seeded into areas previously planted with medium-short and short wheat cultivars. Use of pendimethalin plus 2,4-D in winter wheat and glyphosate plus alachlor in grain sorghum eliminated differences in summer annual grass weed density and weed biomass among wheat cultivars. Sorghum grain yields were improved 7% when herbicides were used in the winter wheat and sorghum but value of the increase was less than cost of herbicides. Substituting less costly herbicides for herbicides used in this study still would not have been enough to pay for cost of herbicides for five cultivars. Grain sorghum grown on weed-free stubble of medium-tall and medium-statured winter wheat produced more grain than grain sorghum grown after medium-short and short-statured winter wheat by 5%. Volunteer wheat density during the fallow period following grain sorghum was lower in areas originally seeded to Centurk 78 and Siouxland wheat while volunteer wheat density was higher in areas planted to Homestead and Vona.

A field experiment was conducted on a brown soil to study the response of two winter wheat cultivars (Liwilla and Gama) and to increased concentration of cereals from 50 percent in a six-field crop rotation to 67 percent in three-field crop rotation and to continuous cultivation. The forecrops for winter wheat in three-field rotations were: oat, spring barley, spring wheat and field bean. Shortening rotation and increasing concentration of cereals of 50-60 percent decreased yields of winter wheat by 8.5 percent on average but the extent of negative depended on the kind of forecrops.

Much of the N applied to rainfed winter wheat (Triticum aestivum L.) is topdressed as granular fertilizer in late winter or early spring after growers evaluate over-winter survival and potential economic returns from N fertilization. Information is needed to determine the optimum timing for efficient use of topdressed N by winter wheat. This study evaluated the effect of three rates (0, 40, and 80 lb N/acre) of ammonium nitrate on winter wheat grain yield, N uptake, grain protein, and net income when topdressed at or near planting through heading (1 April) on silty clay and clay soils. Field experiments were conducted at five different sites during the 1985, 1987, 1988, 1991, and 1992 winter wheat growing seasons on Udorthentic Haplustoll and Udic Pellustert soils located in the North Texas Blackland. From 1985 through 1992, topdress applications were timed at planting, jointing (Feekes 6), booting (Feekes 10), and heading (Feekes 10.5) winter wheat growth stages. Maximum grain yields (56–61 bu/acre) resulted from single N topdressings of 40 lb/acre at jointing, 80 lb/acre applied at planting through jointing, or split applications of 40 lb/acre at planting and jointing. Grain protein concentrations were highest (15.3%) when N was topdressed at jointing and booting compared with planting and heading applications (14.9%). Highest grain N uptake (108 lb/acre) occurred with single N topdressings of 80 lb/acre from planting through booting stages, and with split N application. Optimum economic winter wheat grain yields were obtained with single, adequate N topdressings made at or near planting through prebooting stage (1 March). Fertilizer-N topdressed following booting resulted in grain yields that were 13 to 19% lower than observed with N topdressed prebooting. This was attributable to low available soil moisture from March through April. Water stress after booting increased winter wheat vegetative growth at the expense of grain yield, and probably reduced ammonium nitrate movement into the soil-plant-root zone. Research QuestionGranular N fertilizer topdressing is a safe, economical application method for rainfed winter wheat production. Research is lacking on the effectiveness of single preplant through late-spring and split N fertilizer topdressings at more than one application rate for rainfed winter wheat. The objective of this study was to evaluate the effect of three N rates (0, 40, and 80 lb/acre) topdressed from planting through grain ripening (Feekes growth stage 11.1) on winter wheat grain yield and protein content. Literature SummaryNitrogen applications should be timed when crop use of N is high. Winter wheat N uptake is most rapid from tillering (Feekes 5) through booting (Feekes 10) developmental growth stages with 80% of the total accumulation occurring before grain filling. Research has shown N applications after booting may not become positionally available to plant roots early enough to benefit vegetative growth or may contribute to excessive late-season vegetative growth at the expense of grain yield. Split N applications have the potential to provide an adequate supply of N to the plant throughout the growing season without risking large early-season N fertilizer losses via leaching or denitrification. Results of these studies have been inconsistent, however, and have varied with soil moisture availability, soil texture, winter vs. spring wheat, and N fertilizer form. Study DescriptionField experiments were conducted on five different sites from 1985 to 1992 at two locations in north-central Texas. Field sites had been previously cropped to winter wheat, then fallowed 5 mo prior to planting. Conventional tillage (shred, disc, and plow) was used for winter wheat seedbed preparation on Austin silty clay and Houston Black clay soils. Hard red winter wheat varieties, ‘Mit’, and ‘Collin’ were planted mid-November. Ammonium nitrate (34-0-0) was topdressed at 40 and 80 lb N/acre at or near planting, and at the jointing, booting, and heading stages plus a split application at planting and jointing stage. No supplemental irrigation was applied, and wheat grain yield, N uptake and grain protein, and net income were determined. Applied QuestionWhat was the optimum rate and time of topdressed N for rainfed winter wheat production? Optimum grain yield (56–61 bu/acre) resulted from single N topdressings of 40 lb/acre at jointing (Feekes 6), 80 lb/acre applied at planting through jointing, or split applications of 40 lb/acre at planting and jointing. Grain protein concentrations were highest (15.3%) when N was topdressed between jointing and booting developmental stages compared with planting and heading N applications. Fertilizer N topdressed following booting resulted in grain yields that were 13 to 19% lower than observed with N topdressed prebooting attributable to low available soil moisture following booting, which reduced movement of N into the soil-plant-root zone.

It was concluded that the weeds decreased yield of winter wheat from 9.8 to 23 or 513 to 1200 kg/ha grains. The weeding as protection means of winter wheat was more efficient in comparison to herbicides application for 151 kg/ha grains. Herbicides application in the jointing stage weaker affected on the weeds caused greater phytotoxicity and decreased grain yield of winter wheat in comparison with application ones in the tillering stage. Basagran DP and Lontrel 418-C were efficiently in decreasing weedness than Banvel DP and Banvel P-OHIS. Under strong weedness herbicides application is the only efficient means in the winter wheat protection.