Identification of bread wheat,durum wheat and barley cultivars adapted to dry areas of Southern Italy

Summary Among the cultivars of bread wheat, durum wheat and barley grown in the South of Italy, genetic variation for adaptation to the high temperature and drought stress conditions typical of the Mediterranean environment has been found.The basic data have been extrapolated from 5 years of Italian national network cultivar trials, where 20–30 cultivars were grown in replicated plot trials in 30–50 locations per year, including some where stress strongly affected grain yield.After careful identification of the most representative years and testing sites it was possible to characterise the cultivars on the basis of the grain yield in stress conditions and the Fischer & Maurer (1978) susceptibility index and to find genotypic differences sufficiently repeatable in years.The cultivars giving the best yield under stress associated with low susceptibility indices were in bread wheat: Etruria, Spada, Pandas, Centauro, Oderzo, Costantino and Gladio, in durum wheat: Aldura, Arcangelo, Adamello, Vespro and Capeiti, in barley: Fleuret, Barberousse, Jaidor, Express, Trebbia, Georgie, Dahlia, Criter and Magie.     

Responses of wheat and barley genotypes to toxic concentrations of soil boron

Summary The growth and yield of seven wheat and two barley cultivars or lines, previously found to show different degrees of boron tolerance under field conditions, were compared in a pot experiment at a range of soil boron treatments. Soil treatments ranged up to 150 mg/kg applied B. Extractable B in soils ranged up to 103 mg/kg.At the highest B treatment seedling emergence was delayed, but the percentage emergence was not reduced. The degree of boron toxicity symptom expression varied between the wheat cultivars and lines, with the two most tolerant, Halberd and (Wq^*KP)^*WmH)/6/12, displaying the least symptoms.The concentration of boron applied to the soil which produced a significant depression of growth and yield varied between cultivars. For example, the yield of (Wq^*KP)^*WmH)/6/12 was not affected at the 100 mg/kg applied boron treatment, while the grain yield for (Wl^*MMC)/W1/10 was significantly reduced at the 25 mg/kg treatment.There was a linear increase in boron concentration in tillers at the boot-stage with increasing concentration of boron in the soil. The most boron tolerant genotypes had the lowest tissue boron concentrations in each of the treatments. Halberd and (Wq^*KP)^*WmH)/6/12 had approximately half the boron concentrations of the more sensitive genotypes at the 25 and 50 mg/kg treatments. Differential tolerance of boron within the tissue was also observed. Both Stirling and (Wl^*MMC)/W1/10 had significantly reduced total dry matter and grain yields at the 25 mg/kg treatment, while the concentrations of boron in boot stage tillers at this treatment were 118 and 100 mg/kg, respectively. On the other hand, Halberd and (Wq^*KP)^*WmH)/6/12 had tissue boron concentrations of 144 and 131 mg/kg, respectively, at the 50 mg/kg treatment but yield was unaffected.The relative responses in the pot experiment, for wheat, were in close agreement with field results. Halberd and (Wq^*KP)^*WmH)/6/12 had the highest grain yields, with the lowest concentrations of boron in the grain when grown under high boron conditions in the field. In pots these two genotypes proved to be the most tolerant of boron. For barley the advantage in grain yield in the field, expressed by WI-2584 compared with Stirling, was not repeated in pots. WI-2584 was, however, more tolerant than Stirling on the basis of total dry matter production.The results show that useful variation in boron tolerance exists among wheat, and that breeding should be able to provide cultivars tolerant to high levels of boron.     

The effect of temperature on seed set and embryo development in reciprocal crosses of wheat and barley

Summary The effect of temperature on seed set and embryo development in reciprocal crosses of barley and wheat was assessed in crosses involving two spring barley varieties (Betzes, Martonvásári 50) and one wheat variety (Chinese Spring). Detached tillers placed in nutrient solution were pollinated in controlled environments at constant day-night temperature regimes (12, 15, 18 and 21° C) with a light intensity of 30,000 lux and a relative humidity of 80%. When barley was used as the female, lower temperatures (12 and 15° C) produced the maximum seed set, whereas for the reciprocal cross, the highest temperature (21° C) produced the best seed set in the Chinese Spring × Betzes combination.Low temperature retarded the embryo development. The highest numbers of hybrid plants were produced at 18° C and 21° C in the barley × wheat cross and in the wheat × barley cross, respectively. Embryos of about 1.5 mm length in the barley × wheat cross, and of about 1.0 mm length in the wheat × barley cross germinated successfully. The smallest embryo giving rise to hybrid plants was 0.57 mm in the barley × wheat cross and 0.51 mm in the wheat × barley cross.     

Analysis of adaptation of barley,triticale, durum and bread wheat under Mediterranean conditions

Summary Yield data obtained from a comparative small grain cereals trial, grown for five consecutive growing seasons at a total of 23 environments in Cyprus, were subjected to regression analysis. Within each environment, yield trials consisted of a standard set of three cultivars or elite lines of barley, triticale, durum and bread wheat. The regression coefficient (b) of crop mean on the environmental index (I) and the mean square deviation from regression (sd²) were calculated for each crop. Each crop tended to have its own characteristic value of sd² and its magnitude was an excellent indicator of specific crop-environment interaction. The causes of large sd², for two of the four crops, were the susceptibilith of barley to lodging, when favourable conditions were encountered at high yielding environments, and triticale dependence on late season precipitation. Durum wheat and triticale had an average response to different yielding environments (b>1.19) and both were significantly different from those of bread wheat (1.08) and barley (0.54). Hence, barley, bread and durum wheat are specifically adapted to low, average and high yielding Mediterranean environments, respectively. The cultivation of triticale at the expence of durum wheat is not feasible. Furthermore, interactions between crops and environments demonstrated by the regression parameters, should constitute the basis for decision making, regarding crop adaptation in a region. The average yield in all environments should not be considered as a proper criterion for adaptation. In this study, triticale had a similar mean grain yield (3,842 kg/ha) to that of bread wheat, but was significantly higher yielding than barley or durum wheat (5 and 7%, respectively).     

Applications of pedigree-based genome mapping in wheat and barley breeding programs

The aim of the pedigree-based genome mapping project is to investigate and develop systems for implementing marker assisted selection to improve the efficiency of selection and increase the rate of genetic gain in breeding programs. Pedigree-based whole genome marker application provides a vehicle for incorporating marker technologies into applied breeding programs by bridging the gap between marker–trait association and marker implementation. We report on the development of protocols for implementation of pedigree-based whole genome marker analysis in breeding programs within the Australian northern winter cereals region. Examples of applications from the Queensland DPI&F wheat and barley breeding programs are provided, commenting on the use of microsatellites and other types of molecular markers for routine genomic analysis, the integration of genotypic, phenotypic and pedigree information for targeted wheat and barley lines, the genomic impacts of strong selection pressure in case study pedigrees, and directions for future pedigree-based marker development and analysis.     

Long-term association of locations for testing spring bread wheat

Summary The International Spring Wheat Yield Nursery (ISWYN) has been distributed annually since 1964 and the results provide a base for investigating relationships among locations. Ordination and clustering of locations was conducted using 26 years of grain yield data. Ordination and clusters based on the discrimination of germplasm were compared with mega-environments, which are groupings of locations defined by CIMMYT on the basis of climatic factors and perceptions of major biotic and abiotic stresses. Discrepancies among mega-environmental groupings, clusters and ordinations may identify locations for which major stresses affecting wheat yield are yet unidentified.Major environmental discriminators were latitude and the presence or absence of stress, although there was little association of locations due to limited moisture availability. We identified two major spring wheat environments, typified as Asian and European, and suggest the mega-environmental classification does not explain all significant associations among locations. Location groupings based on discrimination of germplasm should be considered in parallel to mega-environments on a regular basis and we propose breeding for a base of broadly adapted germplasm to which specific stress tolerances are incorporated.Abbreviations CIMMYT International Maize & Wheat Improvement Centre - ISWYN International Spring Wheat Yield Nursery - WANA West Asia and North Africa     

A recurrent selection programme for grain yield in winter barley

Summary The effect of a recurrent selection procedure was evaluated in a winter barley (Hordeum vulgare L.) population. Cycle zero (C₀) was initiated by crossing six high yielding winter barley cultivars with the short straw cv Onice. The F₁'s were crossed according to a diallel scheme without reciprocals. A total of 750 S₀ plants were derived and evaluated; 329 S₀ plants were selected and their progenies (S₁ lines) tested. Fifteen S₁ lines were chosen and used as parents of cycle 1 (C₁), by producing 105 F₁ hybrids which simulated a random mating offspring. One hundred and three randomly chosen S₁ lines belonging to C₀, and 103 S₁ lines belonging to C₁, were evaluated at two locations.For grain yield a significant difference between cycles was observed. From C₀ to C₁ the grain yield increased with 307 g/m². This increase was due to a higher number of seeds per m². For plant height, heading date and 100-kernel weight no differences between cycles were observed.The positive results obtained in this study indicate the potential usefulness of recurrent selection for developing parents or lines superior for grain yield, with little change in other important agronomic traits.     

The effect of gibberellic acid on male fertility in bread wheat

Summary The effect of gibberellic acid (GA₃) on male fertility was investigated in wheat. Greenhouse and field experiments were carried out. GA₃ induced high levels of male sterility both in gibberellin (GA)-sensitive and GA-insensitive genotypes. The optimum concentration was 2000 ppm of GA₃ when applied at successive sprays. The critical period for GA₃ treatment, in the general sense, extended from glume differentiation to premeiotic interphase in the oldest florets of the spike, though differences were found between GA-sensitive and GA-insensitive genotypes in the extension of this period. The effect of GA₃ on plant height was also studied. The potential use of GA₃ as a chemical hybridizing agent in wheat breeding is discussed.Abbreviations GA gibberellin - GA₃ gibberellic acid - ms male sterility Scientific Paper GEN-810 of the Instituto de Gen]'etica, CICA, INTA, Castelar, Argentina     

Selection for yield in small plots of spring wheat

Summary Four selection experiments were sown: single-row plots with single row-spacing (20 cm), single-row plots with double row spacing (40 cm), three-row plots and six-row plots both with single row-spacing (20 cm). Selection entries were mimiced by 16 different varieties or advanced breeding lines, which were also sown in a yield trial. Each experiment was laid out as a 4-times replicated randomized block design. Row length was 2 m. Alley borders and border-rows of multiple-row plots were harvested separately to evaluate the effects of different harvesting procedures on the selection efficiency. Removal of alley borders was found to be disadvantageous, since the gain in precision was more than offset by the loss in sampled area. Wide spacing of single-row plots improved the selection efficiency in comparison with normal spaced single-row plots. In multiple-row plots the selection efficiency was not improved by harvesting only the central rows.For gross plot yield (= yield of net plot + yield of alley borders) the differences in selection efficiency between the various selection plot-types were explained on the basis of the genetic variance, the environmental variance and the coefficient of genetic correlation with farm yield as determined in the yield trial.     

Tolerance to paraquat is correlated with the traits associated with water stress tolerance in segregating F2 populations of barley and wheat

To identify scorable marker traits that can be used in cereal breeding programs for selecting drought tolerant individuals, we investigated the correlation among the drought-associated traits in two F₂ populations derived from the crosses made between drought tolerant and sensitive barley and wheat parental genotypes. The parental genotypes of these crosses also differed by at least three other traits – paraquat tolerance, leaf size, and the relative water content. These three traits were scored in two F₂populations of 80 individuals for each barley and wheat cross. Analysis of results indicated that the enhanced tolerance to paraquat was correlated with reduced leaf size and increased relative water content, two traits associated with water stress phenotypes of the drought tolerant barley and wheat parents. Our results suggested that the selection based on paraquat tolerance istechnically less demanding and thus useful for rapid screening of individuals for enhanced drought tolerance in segregating populations. This revised version was published online in August 2006 with corrections to the Cover Date.     

Quantitative trait loci for grain yield and yield components in a cross between a six-rowed and a two-rowed barley

Summary The positions of quantitative trait loci (QTL) for yield and yield components were estimated using a 85-point linkage map and phenotype data from a F₁-derived doubled haploid (DH) population of barley. Yield and its components were recorded in two growing seasons. Highly significant QTL effects were found for all traits at several sites in the genome. A major portion of the QTL was found on chromosome 2. The effect of the alleles in locus v on thousand grain weight and kernels per ear explained 70–80% of the genetic variation in the traits. QTL × year interaction was found for grain yield. Several different QTL were found within the two-rowed DH lines compared to those found in the six-rowed DH lines. Epistasis between locus v and several loci for yield and yield components indicates that genes are expressed differently in the two ear types. This may explain the difficulties of selecting high yielding lines from crosses between two-rowed and six-rowed barley.Abbreviations DH doubled haploid - QTL quantitative trait locus/loci - RAPD random amplified polymorphic DNA - RFLP restriction fragment length polymorphism - T. Prentice Tystofte Prentice - V. Gold Vogelsanger Gold     

Transgressive segregation in inter and intraspecific crosses of barley

Summary Six populations of F₂-derived lines of barley and their parents were evaluated for heading date, plant height, grain yield, bundle weight, and harvest index in a replicated experiment in the field. These data were used to estimate the minimum number of effective factor pairs segregating for each trait, the number of favorable factors contributed by each parent in a cross, and the frequencies and magnitudes of transgressive segregates.Heading date, plant height, and harvest index were controlled by three to four effective factor pairs, whereas grain yield and bundle weight were controlled by five or more.All three H. spontaneum strains used in our study contributed one or more useful genes for each of the traits, grain yield, heading date, plant height, bundle weight, and harvest index. Therefore, it seems that H. spontaneum can be a useful source of favorable genes for quantitative traits, especially for grain yield, which could be incorporated into barley varieties readily by backcrossing. Transgressive segregates for grain yield in the interspecific crosses may provide the basic materials for improving the productivity of cultivated barley varieties.Journal Paper No. J-9760 of the Iowa Agric. and Home Econ. Exp. Stn., Ames, IA 50011. Project 2227. Supported in part by a grant from the Science and Education Administration-Cooperative Research, United States Department of Agriculture.     

Influence of variety, seed position and seed source on screening for coleoptile length in bread wheat (Triticum aestivum L.)

A study was conducted to evaluate the usefulness of somaclonal variation as a means to obtain powdery mildew resistance in the background of an agronomically elite, high-yielding barley (Hordeum vulgare L.) cultivar. A total of 170 R_o-derived lines were regenerated from embryo-induced callus of the barley cultivar Léger. Forty-five lines were selected and evaluated in replicated field plots at two locations in Eastern Canada. In comparison with Léger, one of the 45 lines was higher yielding, one produced a greater test weight, two had a greater seed weight, and one was shorter in plant height. Three lines were found to segregate for resistance to powdery mildew (Erysiphe graminis DC ex Merat f. sp. hordei EM). Many of the single-plant selections from the three resistant lines showed resistance to powdery mildew under field conditions for two years. Three lines were eventually promoted to the official registration tests in Ontario. One of the three lines was subsequently registered as a new cultivar (AC Malone) in Canada. To our knowledge, AC Malone is the world's first barley cultivar selected from somaclonal variation. The results of this study demonstrate that it is possible to obtain high- yielding or disease-resistant lines from callus culture in barley. This revised version was published online in August 2006 with corrections to the Cover Date.     

The relation between grain yield and some related traits of spring barley (Hordeum vulgare L.) and their usefulness in a breeding program

Summary The objective of this study was to evaluate traits which can facilitate and improve selection for grain yield of spring barley. Five experiments were conducted in different environments to measure grain yield and yield related traits of breeding lines and exotic varieties. Differences for rate of canopy expansion were significant and offer the opportunity to select for a high weed suppressing potential but there was no relation to grain yield. Dry matter yield/m² at anthesis and its water-soluble-carbohydrate content were not correlated with grain yield/m² and number of grains/m². Variation in biomass among breeding lines with a similar development and plant height was small. Biomass standardized for plant height was stable across environments and showed a good correlation with number of grains and grain yield. The contribution of pre-anthesis assimilation to grain yield was only important under low yielding experimental conditions, but the differences among the genotypes for this trait were inconsistent. It may be difficult to select genotypes with a high potential contribution of pre-anthesis assimilation to grain yield.     

Differential responses of bread wheat characters to high temperature

Summary Agronomic and yield data were collected from two trials each containing 16 bread wheat genotypes, planted two years under late sowing conditions of high temperature (above 30° C) and one year under a normal sowing time environment. The aim was to study the character response and yield correlations with yield components and other characters under high temperature conditions with full irrigation. The results show that yield, seeds per spike, biomass, and plant height are more thermo-sensitive than spike number per square meter, 1000 kernel weight, and test weight. The grain-filling rate was more temperature-sensitive than days to anthesis and duration of grain-filling. Simple phenotypic correlation analysis indicated that yield was highly and positively correlated with seeds per spike, biomass, and harvest index (HI), independent of seasons and genotypes under high temperatures. The seeds per spike accounted for variation of yield ranging from 35.2 to 78.1%. Effect of earliness on the yield under high temperature was highly dependent on the temperature regime during the heading stage. Grains per spike, biomass, HI, and test weight could be considered potential selection criteria for yield under high temperature. Analysis of yields under normal and late sowing conditions failed to reveal any association between the yield potential in normal sowing date and the performance of varieties under high temperature.     

Flag leaf area in five spring wheat crosses and the relationship to grain yield

Summary Five spring wheat crosses were evaluated over a 6-year period using comparisons between F₂ and F₃ data and between near-isogenic F₄ populations selected for flag leaf area. Nonsignificant r values for F₂ vs. F₃ flag leaf measurements may be due to the effect of environment on flag leaf area, but are probably also an indication of low heritability for this plant character. Near-isogenic populations selected on the basis of flag leaf area showed little difference in grain yield, an indication that other plant parts must be more influential in determining grain yield. Flag leaf area, by itself, appears not to be a good index to plant performance.Joint contribution of ARS/USDA and the Montana Agricultural Experiment Station. Published with approval of the Director of the Montana Agricultural Experiment Station as Paper No. 725. Journal Series. Use of data from Research Centers at Moccasin. Havre. Huntley, and Kalispell is gratefully acknowledged.     

Grain yield and its components in spring barley under row and hill plot conditions

Twenty homozygous barley lines were grown in row and hill plots at two locations in Ontario in 1973. The hill plots were of two spacings –30×30 cm and 45×45 cm between hills. Within each spacing, three seeding rates were used i.e. 15, 25 and 35 seeds per hill. Grain yield and three of its components, namely; number of seeds per spike (NSS), number of spikes per plot (NSP) and seed weight (SW) were studied. It was concluded that both NSS and SW could be evaluated in hill plots. NSS was found to be an important component of grain yield and its relationship with grain yield was unaffected by plot types and locations. SW also remained unaffected by plot types and seeding rates but as a component of grain yield it was the least important of the three components measured. The correlation between SW and grain yield could be changed by locations. NSP was as important as NSS as a component of grain yield, and was highly correlated with grain yield. Unlike NSS, NSP could not be efficiently evaluated in hill plots since its correlation between row and hill plots was generally lower.     

Chromosomal location of genes controlling grain size in a large grained selection of wheat (Triticum aestivum L.)

Summary Grain size in wheat is the most stable yield component and has a favorable effect on flour yield. To identify the chromosomes associated with the large grains of line G603-86, (grain weight over 60 mg and grain length of about 9 mm), F₃ lines, extracted from F₂ populations obtained from F₁ monosomics of crosses between G603-86 (P₁) and the monosomic set of Favorit (P₂) were tested in the field. ANOVA showed significant differences among parents for grain weight and grain length, but not for grain width or the factor expressing the difference in grain form and density. Homoeologous groups had significant effects on grain weight and on all components of grain weight, while genomes were not significantly different for any of these characters. Grain weight was significantly increased by chromosomes 6D and 4A of G603-86. Grain length was significantly increased by chromosomes 4A, 4B, 2B, 3A and 1B, grain width by chromosomes 1A and 1B, and the factor form-density by chromosomes 6D and 6A. The high grain size in G603-86 results from the effects of genes located on many chromosomes which affect grain dimensions, form and density.     

Environmental correlations among grain yield and other important traits of wheat in drylands

Summary Environmental correlation coefficients were computed among all pairs of five traits, namely grain yield, heading date, number of tillers per m², plant height and 1000-grain weight (grain size) using 30 Triticum durum and 30 Triticum aestivum varieties grown in 18 environments. Grain yield was significantly correlated with the other four traits in almost all of the varieties. The mean correlation coefficient over all varieties ranged from 0.58 to –0.83 for durum wheat and 0.66 to 0.88 for aestivum wheat. The correlation coefficients between heading date and the other traits were also significant, ranging from –0.45 to –0.79 in durum wheat and –0.61 to –0.85 in aestivum wheat. The correlation coefficient between number of tillers with plant height and 1000-grain weight were the smallest, 0.19–0.32 in durum wheat and 0.39–0.60 in aestivum wheat. It was concluded that agronomic practices favouring early and good stand establishment in the dry regions will favour the yield components and important adaptive traits, which contribute towards larger yields. Significant differences were found among genotypes in the environmental correlation coefficients and the associated changes in one trait as a result of changes in other traits.     

Selection environment and environmental sensitivity in barley

Summary Groups of 10 barley genotypes were selected for high grain yield under either high yielding (two groups) or low yielding conditions (two groups). The genotypes had a similar average grain yield across a wide range of yielding conditions, but differed in their linear response over environments (environmental sensitivity). The genotypes selected for high grain yield under low yielding conditions were less sensitive to changing environments than genotypes selected for high grain yield under high yielding conditions. The higher stability of genotypes selected under low yielding conditions was shown by both the linear regression analysis and the comparison of coefficients of variation. The use of a safety-first index showed that the probability of a crop failure of genotypes selected for high grain yield under high yielding conditions was between 1.8 and 2.7 times higher than for genotypes selected for high grain yield under low yielding conditions. The development of new cultivars for areas where a large proportion of the crop is grown by subsistence farmers should therefore be based on selection under low yielding conditions.