Joint Selection for High Yield and Low Sensitivity in Winter Wheat (Triticum aestivum L.)

Early generation yield trials of families from a set of winter wheat crosses were grown in three contrasting environments chosen to represent differences in two important macro-environmental variables affecting the wheat, crop in Eastern England. Joint selection for high yield and low sensitivity to these macro-environmental variables over two seasons using the procedure of Brumpton et al. (1977) resulted in a group of genotypes which exhibited a much wider yield range than would have resulted from selecting for yield in each -environment separately. In spite of this, the top performing lines an yield trials grown in each of the environments during the next season exhibited good yield and stability over all three environments, demonstrating the feasibility of such a method for winter wheat breeding.     

Frost Resistance of Somaclones Derived from Triticum aestivum L. Winter Wheat Calli

Frost resistance was studied in SC₄ seedlings generated by self pollination from 31 (SC₄) plants of ‘GK Csongor’ winter wheat variety derived from resistance than ‘GK Csongor’. With respect to percentage survival, one family possessed significantly higher frost resistance as compared to the control at a temperature of -13°C In the case of regrowth analysis, 22 of the 31 families showed less growing capacity and 5 proved to be significantly better than ‘GK Csongor’. According to both testing methods, one family showed significantly higher frost resistance than the control.     

Agronomic and Physiological Study of Cold and Flooding Tolerance of Spelt (Triticum spelta L.) and Wheat (Triticum aestivum L.)

Flooding of soil occurs all over the world in areas of crop production. The resulting lack of available oxygen in the soil can hinder the establishment of field crops such as wheat ( Triticum aestivum L.) and thus lead to a decrease in yield. The current study compares the tolerance of spelt ( Triticum spelta L.) and wheat to wet and cold stress during germination and early growth. Two specific traits seem to be related to the superior early flooding tolerance of spelt: (1) fast growth of the coleoptile, which reaches the soil surface rapidly, thus reducing the time span of hypoxia sensitivity, independent of temperatures between 10 and 20 °C; (2) the improved physiological adaptation for coleoptile growth under hypoxia is probably due to lower oxygen consumption between germination and emergence. Because of this high level of flooding tolerance, spelt would also be a good source for breeding for stress tolerance in wheat. These findings will help to detect quantitative trait loci (QTL) for characters such as growth rate, flooding tolerance and oxygen consumption in future studies. A marker-assisted introgression of spelt into wheat is necessary to avoid combination with undesirable agronomic traits of spelt.     

小麦株高近等基因系的RAPD标记研究

采用RAPD技术, 以4个小麦株高近等基因系(分别含有rht、 Rht1、 Rht2、 Rht3基因)为材料, 筛选了296个单一随机引物(10个核苷酸)。 发现25个引物的扩增产物在近等基因 系间表现出特异性。 在6次重复试验中, 有18个引物的特异扩增片段不能重复, 6个引物 可以重复2～3次, 唯有OPAM01在全部试验中均能稳定重复, 其特异扩增     

Adjustment for Competition Between Genotypes in Single-Row-Plot Trials of Winter Wheat (Triticum aestivum)

Several statistical methods were investigated for improving yield estimation for 72 genotypes of winter wheat tested in a single-row-plot (SRP) trial. The different analytical models were compared using several criteria: the residual mean square fit; the standard error of differences of genotype means; the correlations of genotype means with means from six-row-plot (6RP) reference trial; the expected genetic gains relative to 6RP trial from selecting the 10 top yielding genotypes. There was no significant correlation between the unadjusted genotype means for SRP and 6RP. Genotype yields were positively correlated with height in SRP, but this correlation was reversed in 6RP. Using the mean height difference of a plot with its two neighbours as a covariate to adjust for competition in SRP reduced the standard error of difference of genotype means and substantially increased their correlation with the 6RP means. The predicted selection efficiency in SRP trial increased from zero, before adjustment, to 83 % of 6RP trial. Including the difference in heading date and the effect of guards at borders as covariates in the SRP analysis improved the residual mean square fit but had no effect on correlation with 6RP means or selection efficiency. A producer-competitor model in which individual competitor effects were estimated for each genotype gave a substantial improvement in fit over the covariate models but a much lower correlation with 6RP means and selection efficiency. Yield selection in early generation wheat trials based on single-row plots could be considerably strengthened by use of a plot covariate derived from height difference between neighbours.     

黄淮海麦区四省份小麦品种的农艺性状及遗传多样性分析

小麦品种的遗传多样性在育种工作中发挥着重要的作用。为了明确黄淮海麦区四省份小麦品种遗传多样性的基础,本研究以所收集的黄淮海麦区的河南、河北、山东和陕西四省的近十几年来(1992-2008年)审定的部分(42份)小麦品种为研究材料,以9个农艺性状为基础进行遗传性状的分析。结果表明,不孕小穗数的变异系数最大为61.39%,其次为有效分蘖和穗粒数,千粒重的变异系数最小为6.06%。河南、河北、山东和陕西四省的多样性指数分别为1.83,1.82,1.73和1.62,平均值为1.75。在此基础上,用最长距离法可将42份材料聚为三大类,但是第Ⅱ大类和第Ⅲ大类相差不大,这说明上述四省小麦品种遗传多样性在逐步提高的同时,其遗传基础仍需进一步拓宽。在性状选择上,首先对变异大的性状进行选择是非常重要的;在品种选择上,应注意选择产量、单株粒重和单株粒数均高的品种。     

The Growth in Culture of Detached Ovaries of Wheat (Triticum aestivum L. em. Thell)

Viable embryos have been recovered from fertilized wheat (Triticum aestivum) ovaries detached on the day of, or up to 7 days post-, anthesis and cultured aseptically fur up to 18 days. The most significant factors in determining the yield of embryos was the plating density, age and complexity of the explants. 26% of ovaries excised on the day of anthesis produced viable embryos if cultured as pairs of florets. The potential use of detached ovary cultures in gametophyte microinjection experiments, rescuing embryos from wide crosses and in chemically manipulating the early stages of embryo development are discussed.     

小麦株高近等基因系的RAPD标记研究

采用ＲＡＰＤ技术,以４个小麦株市基因近等基因系（分别含有rht、Ｒht1、Rht2、Rht3)为材料,对２９６个单一随机引物（１０个核苷酸）进行了筛选。发现２５个引我的扩增产物的近等基因系间表现出特异性,在６次重复试验中,有１８个引物的特异护增片段不能重复,６个引物可以重复２－３资,唯有ＯＰＡＭ０１在全部试验中均能稳定重复,其特异扩增版段ＯＰＡＭ０１１８６０可以作为rht基因的ＲＡＰＤ标记。     

Distribution and Origin of Hybrid Necrosis Genes in German Winter Wheat (Triticum aestivum L.) Cultivars

Hybrid necrosis in Triticum is known to be caused by the interaction of two complementary dominant genes. In the present paper, the genotypes for hybrid necrosis of 64 winter wheat cultivars are presented. 41 cultivars were found to possess the Ne₂ necrosis gene, whereas 23 cultivars were non-carriers. The Ne₁ gene was not found in any of the cultivars analyzed.     

Nitrate Assimilation and Nitrogen Harvest in Uniculm 'Gigas' Wheat (Triticum aestivum L.)

Contribution of the upper laminae designated as 7, 8 and 9 (flag), to the total reduced nitrogen was determined by two different methods; integration of nitrate reductase activity over the entire growing season of individual laminae, and laminae removal at ear emergence. The values obtained by these methods were: 20, 14, and 12 %, and 23, 15, 12 %, respectively. The in vivo nitrate reductase activity was relatively higher in the lamina 9, which contributed an extra 8 % towards total reduced nitrogen when the other laminae were removed from the shoot. No such compensatory response was observed when either lamina 7 or 8 was retained.     

Bread-Making Quality Indices in Triticum aestivum Progenies. Implications in Breeding for Better Bread Wheat

Bread-making quality indices (dough strength and dough mixing stability) in relation to flour protein content, glutenin/gliadin ratio, and high-molecular-weight (HMW) subunits of glutenin have been investigated in Triticum aestivum progenies during a three year agronomic trial. Dough strength (W) proved to be a fairly stable characteristic, slightly but positively correlated with flour protein content. High could be associated with a high glutenin/gliadin ratio as well as with the presence of specific HMW. subunits of glutenin, while high protein content tended to favour a balanced dough tenacity-extensibility ratio (P/L = 0.4—0.6). Satisfactory values of dough-mixing stability were frequently observed in association with good expression of W showing that the two quality traits may coexist without much difficulty in the same genotype. From the plant breeding standpoint the data suggest feasible to obtain high dough strength by concentrating in a genotype the HMW subunits of glutenin known to have a beneficial effect on W. However, very high W may present unfavourable P/L ratios. This possibility is enhanced when the flour has a low protein content which often occurs in high yielding genotypes.     

The Response of Anther Culture in a Genetically Wide Material of Winter Wheat (Triticum aestivum L.)

In a screening experiment with 215 different winter cultivars of Triticum aestivum L. for response in anther culture, pollen embryos or callus were obtained from 200 different cultivars and green plants from 93 different cultivars. On average, from the whole material, 1.3 green plants were obtained per 100 anthers cultured. Variance components estimated from replicates with selected parts of the plant material indicated that for the formation of pollen embryos from anthers, interactions between genotypes and replications were dominating, accounting for 45 to 50 per cent of the variation. Main effects from genotypes were less prominent, accounting for 25 to 30 per cent of the variation, and the replications showed relatively little effect, accounting, for about 4 to 12 per cent of total variation. Regeneration of plants from pollen embryos or callus was not significantly influenced by either genotype or replicates. The frequencies of plants regenerated being green, however, were influenced from both genotype and environments contributing 42.5 and 34.9 per cent of the total variation respectively, while only minor interactions between genotype and environments were indicated for this character.     

Effect of Mutagenic Treatments on Somaclonal Variation in Wheat (Triticum aestivum L.)

Different wheat genotypes were treated with gamma-rays, sodium azide (SA) and EMS before tissue culture and immature embryos from M₁ plants or plants shortly after exposure to gamma-rays were used to initiate callus culture. Thousands of plants were regenerated and used to investigate the effect of mutagenic treatments on the regenerated plants and somaclonal variation in the M₃R₂ and M₂R₂ generations. The results showed that mutagen-induced damage in terms of reduction in plant height, fertility and spike length were not outstanding in the regenerated plants as compared with the untreated control. In the M₃R₂ generation, only SA treatment had significantly higher frequencies of somaclonal variations than the control. Increases in the variation frequencies were observed when explant embryos were irradiated with 2.5 and 5 gy gamma-rays and the highest frequency appeared when embryos were exposed to 5 gy gamma-rays on the 5th day after anthesis. Increased variation spectra also resulted from mutagenic treatments and most of the variants recovered were unsuitable for plant improvement.     

Single and combined effects of colchicine, L-proline and post-inoculation low temperature on anther culture of wheat, Triticum aestivum L.

This investigation was undertaken to study the effects of colchicine, L-proline and a post-inoculation cold temperature of 14°C for 7 days, either as a single or as combined treatments, on the parameters of anther culture of the DH83Z118.32 wheat genotype. Results indicate that the addition of 100 mg/1 colchicine to the induction medium for a period of 3 days and at an incubation temperature of 28°C yielded the highest success index. This treatment, although it significantly reduced embryogenesis, improved embryoid quality so that not only the total regeneration, but also the percentage of green plantlets increased significantly, In addition, it raised the percentage of doubled haploids and, consequently, led to a significantly better final success index. Combining the colchicine treatment with a reduced post-inoculation temperature did not intensify its beneficial effect, although a treatment of reduced temperature alone was superior to normal temperature (28°C) for most parameters studied. The beneficial effects of adding L-proline (200 mg/1) to the induction medium, combined with a low temperature (10°C for 4 days) treatment, were diminished when this treatment was combined with a colchicine treatment.     

Culture selected somaclonal variation in five Triticum aestivum L. genotypes

Somaclones (R₃ and R₄ generations) regenerated from five winter wheat (Triticum aestivum L.) genotypes were evaluated for variation in agronomic and morphological characters. Immature embryos were used as initial explant material. Comparisons for plant height, top internode length, spike length, number of seeds per spike and 100 seed weight were made between the somaclones and their parents. Some morphological variations of stem and spike characteristics were registered which demonstrate that plant height and spike length can be changed by using immature embryo culture. The results obtained may be considered a biotechnological contribution to wheat plant improvement. This revised version was published online in August 2006 with corrections to the Cover Date.     

Identification of powdery-mildew-resistance genes in common wheat (Triticum aestivum L.). VI. Wheat cultivars grown in China

A total of 26 common wheat cultivars and advanced breeding lines grown in China were tested with a set of 11 differential powdery-mildew isolates. Seven cultivars were susceptible. Another seven cultivars showed the response pattern of resistance gene Pm2, either individually or in combination with genes Pm3d or Pm4a. Five cultivars expressed the resistance of gene Pm4b singly or in combination with Pm6. Another four cultivars exhibited the response patterns of genes Pm5, Pm6 and Pm8, respectively. Three cultivars, which included one breeding line with a pair of substituted chromosomes from Haynaldia villosa, presumably carrying the resistance gene Pm21, showed resistance-response patterns to all the isolates tested.     

Identification of Powdery Mildew Resistance Genes in Common Wheat (Triticum aestivum L.)

Major genes for resistance to powdery mildew were analysed in 24 Czechoslovakian wheat cultivars and, in part, in their parents. For this purpose individual isolates of the pathogen, able to differentiate host lines with known resistance genes, were selected. Eight of nineteen winter wheat cultivars do not possess any major resistance gene. Three cultivars have one and seven have two genes. One cultivar carries a combination of three genes (Pm2, Pm4b, Pm8). The most common resistance genes are Pm4b, Pm5 and Pm8. Pm2 is once combined with Pm6. Only one of five spring cultivars lacked a major resistance gene. Mlk is once present alone and twice combined with Pm5. There is one spring cultivar with a novel combination of three genes: Pm1, Pm5 and another gene needing further characterization. The observations are discussed with additional results of parent lines and further information on pedigrees.     

Performance of Spelt (Triticum spelta L.) and Wheat (Triticum aestivum L.) at two Different Seeding Rates and Nitrogen Levels under Contrasting Environmental Conditions

The aim of this investigation was to obtain information about differences between spelt and wheat in relation to their performance under low-input conditions. Two spelt varieties ( Oberkulmer, Hercule ) and two wheat varieties ( Anna, Iend ) were grown at two different seeding rates (S1 = 200; S2 = 400 kernels/m²) and two nitrogen levels (Nl = 80 kg N/ha; N2 = 110 kg N/ha) at two contrasting locations (Muri; altitude 459 m asl; Oberwallestalden: altitude 1011 m asl). No growth regulators and fungicides were applied.
The overall mean for the "husked" yield (grains and glumes) of spelt was not significantly different from the grain yield of wheat. At the higher site Oberwallestalden however, the "husked" yield of spelt was 10.5 % higher than the grain yield of wheat. Although the number of ears per m² was higher at S2 than at S1, spelt and wheat produced a similar yield at both seeding rates (spelt: S1 = 96 % of S2; wheat: S1 = 95 % of S2) due to the higher single ear weight at S1.
The reaction of spelt and wheat to nitrogen was similar. The yield was 10 % higher at N2 than at Nl for both species. The performance of spelt under low-input conditions was better than for wheat in marginal areas for cereal production only.     

伴生栽培小麦产量与品质性状的研究

为了解伴生栽培小麦产量和品质性状及合理开发利用伴生栽培小麦的优异性状,以6个伴生栽培小麦基因型和6个普通栽培小麦基因型为试验材料,对伴生栽培小麦产量与品质性状进行了研究。结果表明,伴生栽培小麦收获指数平均值为0.3823,普通栽培小麦比其高了28.0%,两者差异极显著;伴生栽培小麦单株穗数比普通栽培小麦多6.0穗,多出幅度为50.5%,两者差异极显著,千粒重平均值为26.38 g,普通栽培小麦是伴生栽培小麦的1.68倍,差异极显著,穗粒数差异不显著;6个伴生栽培小麦的蛋白质含量平均值为14.53%、湿面筋含量平均值为37.00%、沉降值的平均值为30.72%,均高于普通栽培小麦,差异极显著,水分为12.82%,小于普通栽培小麦,与普通栽培小麦比较差异显著。