Wheat Breeding Research Research Articles

Ekmeklik Buğday (Triticum aestivum L.) Çeşitlerinde Yağışlı Koşullarda Verim ve Kalite Parametrelerine Genotip Çevre Etkisi ve Stabilite

The significant genotype by environment interaction is a major matter for wheat breeding research. The study was carried out for seven growing season (between 2010-2011 and 2016-2017) in the Edirne location in the Trakya region, Türkiye. Each year was considered as a single environment. In the study, a regional yield trial of 25 genotypes, 5 of which were standard cultivars were evaluated across seven environments. The experiments were arranged in a randomized complete block design (RCBD) with four replications. The characters such as yield, days to heading, plant height, thousand kernel weight, hectoliter weight, protein ratio, wet gluten content, gluten index, grain hardness and sedimentation value were investigated in the study. The result of the variance analysis (ANOVA) demonstrated considerable differences (p

Revealing Genetic Diversity and Population Structure in Türkiye’s Wheat Germplasm Using iPBS-Retrotransposon Markers

Investigating the genetic diversity and population structure of wheat germplasm is crucial for understanding the underlying variability essential for breeding programs and germplasm preservation. This research aims to contribute novel insights with respect to the genetic makeup and relationships among these wheat genotypes, shedding light on the diversity present within the Turkish wheat germplasm. In this study, iPBS-retrotransposon markers were employed to analyze 58 wheat genotypes, encompassing 54 landraces and 4 cultivars sourced from Türkiye. These markers serve as genetic indicators that can be used to evaluate genetic variation, build genealogical trees, and comprehend evolutionary connections. The PCR products were visualized on agarose gel, and bands were scored as present/absent. The ten iPBS primers collectively yielded an average of 16.3 alleles, generating a total of 163 polymorphic bands. The number of alleles produced by individual markers ranged from 4 (iPBS-2386) to 29 (iPBS-2219). The genetic parameters were calculated using the popgen and powermarker programs. The genetic relationships and population structures were assessed using the ntsys and structure programs. Polymorphism information content (PIC) per marker varied from 0.13 (iPBS-2390) to 0.29 (iPBS-2386), with an average value of 0.22. Shannon’s information index (I) was calculated as 1.48, while the number of effective alleles (Ne) and Nei’s genetic diversity (H) were determined to be 0.26 and 0.31, respectively. Genotype numbers 3 (Triticum dicoccum) and 10 (Triticum monococcum) exhibited the maximum genetic distance of 0.1292, signifying the highest genetic disparity. Population structure analysis revealed the segregation of genotypes into three distinct subpopulations. Notably, a substantial portion of genotypes clustered within populations correlated with the wheat species. This population structure result was consistent with the categorization of genotypes based on wheat species. The comprehensive assessment revealed noteworthy insights with respect to allele distribution, polymorphism content, and population differentiation, offering valuable implications for wheat breeding strategies and germplasm conservation efforts. In addition, the iPBS markers and wheat genotypes employed in this study hold significant potential for applications in wheat breeding research and germplasm preservation.

Genome-wide identification of microsatellites for mapping, genetic diversity and cross-transferability in wheat (Triticum spp)

Wheat (Triticum aestivum L.) is a crucial global staple crop, and is consistently being improved to enhance yield, disease resistance, and quality traits. However, the development of molecular markers is a challenging task due to its hexaploid genome. Molecular marker system such as simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) are helpful for breeding, but SNP has limitations due to its development cost and its conversion to breeder markers. The study proposed an in-silico approach, by utilizing the low-cost transcriptome sequencing of two parental lines, ‘TAC 75′ and ‘WH 1105′, to identify polymorphic SSRs for mapping in a recombinant inbred line (RIL) population. This study introduces a new approach to bridge wheat genetics intricacies and next-generation sequencing potential. It presents a comprehensive genome-wide SSR distribution using IWGSC CS RefSeq v2.1 genome assembly and to identify 189 polymorphic loci through in-silico strategy. Of these, 54.76% showed polymorphism between parents, surpassing the traditional low polymorphic success rate. A RIL population screening validated these markers, demonstrating the fitness of identified markers through chi-square tests. The designed SSRs were also validated for genetic diversity analysis in a subset of 37 Indian wheat genotypes and cross-transferability in the wild/relative wheat species. In diversity analysis, a subset of 38 markers revealed 95 alleles (2.5 allele/locus), indicating substantial genetic variation. Population structure analysis unveiled three distinct groups, supported by phylogenetic and PCoA analyses. Further the polymorphic SSRs were also analyzed for SSR-gene association using gene ontology analysis. By utilizing the developing seed transcriptome data within parental lines, the study has enhanced the polymorphic SSR identification precision and facilitated in the RIL population. The undertaken study pioneers the use of transcriptome sequencing and genetic mapping to overcome challenges posed by the intricate wheat genome. This approach offers a cost-effective, less labour-intensive alternative to conventional methods, providing a platform for advancing wheat breeding research.

An Intelligent Analysis Method for 3D Wheat Grain and Ventral Sulcus Traits Based on Structured Light Imaging.

The wheat grain three-dimensional (3D) phenotypic characters are of great significance for final yield and variety breeding, and the ventral sulcus traits are the important factors to the wheat flour yield. The wheat grain trait measurements are necessary; however, the traditional measurement method is still manual, which is inefficient, subjective, and labor intensive; moreover, the ventral sulcus traits can only be obtained by destructive measurement. In this paper, an intelligent analysis method based on the structured light imaging has been proposed to extract the 3D wheat grain phenotypes and ventral sulcus traits. First, the 3D point cloud data of wheat grain were obtained by the structured light scanner, and then, the specified point cloud processing algorithms including single grain segmentation and ventral sulcus location have been designed; finally, 28 wheat grain 3D phenotypic characters and 4 ventral sulcus traits have been extracted. To evaluate the best experimental conditions, three-level orthogonal experiments, which include rotation angle, scanning angle, and stage color factors, were carried out on 125 grains of 5 wheat varieties, and the results demonstrated that optimum conditions of rotation angle, scanning angle, and stage color were 30°, 37°, black color individually. Additionally, the results also proved that the mean absolute percentage errors (MAPEs) of wheat grain length, width, thickness, and ventral sulcus depth were 1.83, 1.86, 2.19, and 4.81%. Moreover, the 500 wheat grains of five varieties were used to construct and validate the wheat grain weight model by 32 phenotypic traits, and the cross-validation results showed that the R2 of the models ranged from 0.77 to 0.83. Finally, the wheat grain phenotype extraction and grain weight prediction were integrated into the specialized software. Therefore, this method was demonstrated to be an efficient and effective way for wheat breeding research.

English

The objectives of this study were to evaluate released Ethiopian bread wheat varieties for yield stability using the GGE biplot method and identify well adapted and high-yielding genotypes for the highland environments of South-western Ethiopia. Twenty five varieties were evaluated in a randomized complete block design with three replications at Dedo and Gomma during the main cropping season of 2016 and at Dedo, Bedelle, Gomma and Manna during the main cropping season of 2017, generating a total of six environments in location-by-year combinations. Combined analyses of variance for grain yield indicated highly significant (p<0.001) mean squares due to environments, genotypes and genotype-by-environment interaction. Yield data were also analyzed using the GGE (that is, G, genotype + GEI, genotype-by-environment interaction) biplot method. Environment explained 73.2% of the total sum of squares, and genotype and genotype X environment interaction explained 7.16 and 15.8%, correspondingly. The first 2 principal components (PC1 and PC2) were used to create a 2-dimensional GGE biplot and explained 63.88 and 15.71% of GGE sum of squares, respectively. The GGE biplot identified two wheat growing mega-environments. The first mega environment consisted of environments E1 (Gomma-2016), E2 (Dedo-2016), E3 (Bedele-2017), E4 (Manna-2017) and E5 (Gomma-2017) with G6 (Ogolcho) as a vertex genotype. The second mega environment consisted of E6 (Dedo-2017) with G8(Hulluka) as its vertex genotype. Genotypes (G10) Mekelle-4, (G7) Hoggana, (G16) Danda’a and (G14) Ga’ambo did not fit in any of the mega-environments. Genotypes (G5) Hidasse, (G15) Kakaba, (G21) Sofumar, (G11) Shorima, (G20) Tay, (G14) Ga'ambo, (G17) Gassay and (G4) Millan were found to be the most stable genotypes with mean grain yield exceeding the grand mean. Genotypes (G14) Ga'ambo and (G20) Tay were found to be benchmarks/ideal genotypes and could be used as checks to evaluate the performance of other genotypes and also can be recommended for wider cultivation in the highland environments of South-western Ethiopia. However, bread wheat breeding research should be started to identify higher yielding genotypes for these environments with testing sites established at Bedelle and Dedo to address the two mega environments. Key words: GGE biplot, GXE interaction, Ideal genotypes/environments, mega-environments.

Genetic Analysis of Fusarium Head Blight Resistance in CIMMYT Bread Wheat Line C615 Using Traditional and Conditional QTL Mapping.

Fusarium head blight (FHB) is a destructive wheat disease present throughout the world, and host resistance is an effective and economical strategy used to control FHB. Lack of adequate resistance resource is still a main bottleneck for FHB genetics and wheat breeding research. The synthetic-derived bread wheat line C615, which does not carry the Fhb1 gene, is a promising source of FHB resistance for breeding. A population of 198 recombinant inbred lines (RILs) produced by crossing C615 with the susceptible cultivar Yangmai 13 was evaluated for FHB response using point and spray inoculations. As the disease phenotype is frequently complicated by other agronomic traits, we used both traditional and multivariate conditional QTL mapping approaches to investigate the genetic relationships (at the individual QTL level) between FHB resistance and plant height (PH), spike compactness (SC), and days to flowering (FD). A linkage map was constructed from 3,901 polymorphic SNP markers, which covered 2,549.2 cM. Traditional and conditional QTL mapping analyses found 13 and 22 QTL for FHB, respectively; 10 were identified by both methods. Among these 10, three QTL from C615 were detected in multiple years; these QTL were located on chromosomes 2AL, 2DS, and 2DL. Conditional QTL mapping analysis indicated that, at the QTL level, SC strongly influenced FHB in point inoculation; whereas PH and SC contributed more to FHB than did FD in spray inoculation. The three stable QTL (QFhbs-jaas.2AL, QFhbp-jaas.2DS, and QFhbp-jaas.2DL) for FHB were partly affected by or were independent of the three agronomic traits. The QTL detected in this study improve our understanding of the genetic relationships between FHB response and related traits at the QTL level and provide useful information for marker-assisted selection for the improvement of FHB resistance in breeding.

Acceptance and competitiveness of new improved wheat varieties by smallholder farmers

ABSTRACTWe conducted this research because earlier research revealed that Pakistani farmers were growing 8–10-year-old wheat (Triticum aestivum L.) varieties and hence not benefitting from the recent advances in wheat breeding. Participatory varietal selection (PVS) trials were conducted to have farmers validate and include newly released wheat varieties into seed-production stream to speed up replacement of old and obsolete wheat varieties by farmer-preferred new high-yielding varieties. Fourteen new varieties recommended for irrigated and eight for rainfed environments were evaluated in this research involving smallholder farmers in food-deficit districts of Pakistan. Collaborating farmers preferred 10 varieties from the PVS trials, eight of which were germplasm from the International Maize and Wheat Improvement Center (CIMMYT) that yielded on average 5–17% more grain than local checks. Local checks used in the PVS trials in Sindh and Khyber Pakhtunkhwa were old improved varieties. Greater yield advantage from new varieties over local checks was reported from rainfed environments and areas where old local checks were used. The PVS research showed the possibility of ensuring food security of smallholder farmers as new high-yielding varieties gave an additional 0.3 –0.5 tons of grain per ha, sufficient to feed two to three persons per year. Research also revealed that innovative farmers in rainfed regions grew wheat varieties recommended for irrigated regions to identify high-yielding wheat varieties with stable performance. Feedback by farmers to wheat breeding research system was to develop even higher yielding new wheat varieties with diseases resistance to replace old and obsolete varieties to boost food security.

Overview of the Wheat Genetic Transformation and Breeding Status in China.

In the past two decades, Chinese scientists have achieved significant progress on three aspects of wheat genetic transformation. First, the wheat transformation platform has been established and optimized to improve the transformation efficiency, shorten the time required from starting of transformation procedure to the fertile transgenic wheat plants obtained as well as to overcome the problem of genotype-dependent for wheat genetic transformation in wide range of wheat elite varieties. Second, with the help of many emerging techniques such as CRISPR/cas9 function of over 100 wheat genes has been investigated. Finally, modern technology has been combined with the traditional breeding technique such as crossing to accelerate the application of wheat transformation. Overall, the wheat end-use quality and the characteristics of wheat stress tolerance have been improved by wheat genetic engineering technique. So far, wheat transgenic lines integrated with quality-improved genes and stress tolerant genes have been on the way of Production Test stage in the field. The debates and the future studies on wheat transformation have been discussed, and the brief summary of Chinese wheat breeding research history has also been provided in this review.

Quality-oriented technical change in Japanese wheat breeding

The article presents a productivity analysis of Japanese wheat breeding research. We first estimate a hedonic function to determine the marginal implicit values of Japanese wheat characteristics and find that protein contributes substantially to millers’ price offers to farmers. Induced innovation theory implies breeders thus should be responding to new protein-oriented price policies by developing high-protein wheat varieties. We test this hypothesis by estimating a distance function relating breeding resources – including what we call gene-recharge rates – to the yield and protein characteristics of discovered varieties. New varieties indeed have been protein-favoring and yield-disfavoring, suggesting government research programs have been market-oriented.

Impacts of international wheat breeding research in the developing world, 1988-2002

The third in a series of global studies, this report (covering 1988-2002) documents the adoption and diffusion of modern wheat varieties in the developing world and assesses the benefi ts generated by international wheat breeding efforts. It updates the fi ndings and confi rms the three major conclusions of the two earlier studies, and extends the coverage to include many countries in Eastern Europe and the former Soviet Union. In the postGreen Revolution era, CIMMYT’s improved germplasm continues to be used extensively by breeding programs in developing countries, and public investment in international wheat breeding research continues to generate high rates of return. Measured in terms of varietal releases, wheat breeding programs in developing countries continue to be very productive. Between 1988 and 2002, public national research organizations and private seed companies in the developing world released nearly 1,700 wheat varieties. The international wheat breeding system continues to be dominated by public breeding programs, but private companies also engage in wheat breeding in a number of developing countries. More than 75% of protected cultivars (those with plant breeding rights) in South America have CIMMYT ancestry. Of the area planted to wheat in the surveyed countries, 64% was sown to varieties containing CIMMYT-related germplasm, and 24% of varieties in those countries were derived from CIMMYT crosses. A simple economic surplus model was used to estimate the value of additional grain production attributable to the adoption of modern wheat varieties in developing countries. Depending on the stringency of the method used, the value of additional grain ranges from US$ 2.0 to 6.1 billion per year (2002 dollars). The extensive use of CIMMYT germplasm by public and private breeding programs, combined with the widespread adoption of CIMMYT-derived varieties, generates signifi cant benefi ts. Using the most conservative rule for attributing credit to CIMMYT (CIMMYT cross), the annual benefi ts associated with the use of CIMMYT-derived germplasm range from US$ 0.5 to 1.5 billion (2002 dollars), a huge return on CIMMYT’s annual investment (US$ 9-11 million in 2002 dollars) in wheat improvement research.

Is research on marginal lands catching up? The case of unfavourable wheat growing environments⋆

AbstractIt is widely believed that the Green Revolution had very little effect in unfavourable or marginal environments. Many researchers have been concerned about the slow progress of technical change in marginal environments and the level of research resources allocated to these areas. This paper provides empirical evidence that there has been significant growth in wheat yield potential in marginal environments, especially during the post‐Green Revolution. International yield trial data, covering all major wheat growing environments from 1964 to 1999, were used in estimating the growth in wheat yield potential and changes in yield variability. The global database on wheat varietal adoption and yield gains based on estimated wheat yield growth rates were used to determine production increases due to wheat breeding research. Results show greater progress in shifting the wheat yield frontier in marginal areas, particularly in drought and high temperature environments. Furthermore, yield variability in marginal environments has notably declined, while it has increased slightly in favourable environments. While initial gains came from crossover of varieties from favourable environments, targeted breeding efforts have contributed significantly to more recent productivity growth in marginal environments. Increased production from marginal environments accounted for around 25% of the total wheat production increase in 1997. These findings show greater progress in wheat research and the huge potential of improving wheat productivity in unfavourable environments.

Is research on marginal lands catching up?: The case of unfavourable wheat growing environments

It is widely believed that the Green Revolution had very little effect in unfavourable or marginal environments. Many researchers have been concerned about the slow progress of technical change in marginal environments and the level of research resources allocated to these areas. This paper provides empirical evidence that there has been significant growth in wheat yield potential in marginal environments, especially during the post-Green Revolution. International yield trial data, covering all major wheat growing environments from 1964 to 1999, were used in estimating the growth in wheat yield potential and changes in yield variability. The global database on wheat varietal adoption and yield gains based on estimated wheat yield growth rates were used to determine production increases due to wheat breeding research. Results show greater progress in shifting the wheat yield frontier in marginal areas, particularly in drought and high temperature environments. Furthermore, yield variability in marginal environments has notably declined, while it has increased slightly in favourable environments. While initial gains came from crossover of varieties from favourable environments, targeted breeding efforts have contributed significantly to more recent productivity growth in marginal environments. Increased production from marginal environments accounted for around 25% of the total wheat production increase in 1997. These findings show greater progress in wheat research and the huge potential of improving wheat productivity in unfavourable environments.

Adoption of maize and wheat technologies in Eastern Africa: A synthesis of the findings of 22 case studies

This paper synthesizes the findings of 22 micro-level studies on technology adoption carried out by the International Maize and Wheat Improvement Center (CIMMYT) with national agricultural research systems in Ethiopia, Kenya, Tanzania, and Uganda from 1996-1999. The authors found that technology adoption is taking place across Eastern Africa but considerable scope remains to improve the productivity of smallholder agriculture in higher potential regions with high levels of adoption. Extension was the variable most highly correlated with technology adoption, and extension services continue to play an important role in disseminating information on new varieties and how to manage them. Despite the usefulness of the micro-study results, especially for priority setting and impact assessment, future adoption studies can be improved by standardizing definitions across studies and using sampling techniques that allow results to be generalized across wider areas. Finally, the paper suggests that maize and wheat breeding research should be made more relevant to the preferences and circumstances of farmers, that the link between research and extension should be strengthened and include the private sector and non-governmental organizations, that policies should support the development and expansion of efficient markets for inputs and outputs, and that rural credit systems should be strengthened.

Linking technical change to research effort: an examination of aggregation and spillovers effects

AbstractWe used a disaggregate approach to examine investment efficiency of wheat breeding research in India. India's total research effort comprizes 20 research programs spread across 50 experiment stations. A technology spillover matrix was constructed for both potential and actual spillovers. Spillovers and free‐riding were dominant characteristics of technical change during the period studied. Although the aggregate rate of return to wheat improvement research in India was estimated to be 55%, eight programs were found to have earned a negative rate of return when spillins were taken into account. Research output is concentrated on a few strong programs. The two strongest programs generated 75% of all the technical change benefits, even though they claimed just 22% of research resources. These two programs include a significant degree of overlap, while on the other hand many farmers were not reached by any of the programs – 56 and 78% of rainfed and durum area, respectively, in 1990 was still sown with pre‐1976 varieties.

International wheat breeding research in Eastern and Southern Africa, 1966-97

This paper describes and analyzes some of the impacts of wheat improvement research in seven countries in the Eastern and Southern regions of Africa. The countries—South Africa, Ethiopia, Sudan, Kenya, Zimbabwe, Tanzania, and Zambia—produce nearly 99% of all the wheat grown in the region and 97% of all wheat grown in sub-Saharan Africa. The first section of the paper is a brief review of wheat production in the region, concentrating on production levels and growing environments. The second section analyzes the wheat improvement research effort. The third section looks at the pattern of release of wheat varieties over time, as well as the use of wheat germplasm from CIMMYT. The fourth section presents data about varieties that are currently grown in farmers' fields. The fifth section considers some of the organizational issues involved in making wheat breeding research more efficient. The paper concludes that many of the wheat improvement research programs in Eastern and Southern Africa have been successful. However, the small amount of wheat produced in many countries raises the question of whether the same results could have been obtained at lower cost through greater efficiencies in research organization and even greater reliance on research spill-ins.

The economics of wheat research in developing countries: The one hundred million dollar puzzle

Currently, 1,150 scientists are carrying out wheat improvement research in developing countries with an annual budget of around $100 million. Because of the recent reduction in agricultural research budgets, this study marshalls evidence from 71 wheat research programs in 35 developing countries to address the following puzzle: what is the optimal size, type and location of wheat research programs in the developing world? The analysis reveals that if research spillins are taken into consideration, almost half of the wheat improvement programs in developing countries are inefficient. The efficiency of wheat research in many National Agricultural Research Systems can be increased by reducing the size of research programs, consolidating state and federal research programs, and shifting from wheat-breeding research to capturing spillins from other countries and from the International Maize and Wheat Improvement Center (CIMMYT).

Returns to wheat breeding research in Nepal

AbstractReturns to investment in wheat breeding research in Nepal were estimated for two periods: (1) the Green Revolution period (1960–1990), when modern semidwarf wheat varieties first appeared and spread throughout the country, and (2) the post‐Green Revolution period (after 1990), when first‐generation modern varieties will be replaced by newer materials. Major benefits of the Nepalese wheat breeding program have included maintenance of disease resistance and faster dissemination of exotic germplasm. Attractive rates of return to investment in wheat breeding have been due in part to Nepal's ability to capture spillover benefits from neighboring countries and from international agricultural research centers.

Returns to wheat breeding research in Nepal

Returns to investment in wheat breeding research in Nepal were estimated for two periods: (1) the Green Revolution period (1960–1990), when modern semidwarf wheat varieties first appeared and spread throughout the country, and (2) the post-Green Revolution period (after 1990), when first-generation modern varieties will be replaced by newer materials. Major benefits of the Nepalese wheat breeding program have included maintenance of disease resistance and faster dissemination of exotic germplasm. Attractive rates of return to investment in wheat breeding have been due in part to Nepal's ability to capture spillover benefits from neighboring countries and from international agricultural research centers.

Technical Change and Returns to Wheat Breeding Research in Pakistan's Punjab in the Post-Green Revolution Period

Rates of yield gain and returns to investtnent in wheat breeding research are estimated for Pakistan's Punjab for the period since the introduction of semidwarf varieties. Analysis of two comprehensive data sets indicates that wheat breeders have maintained a rate of yield gain in newer releases of semidwarf varieties of about 1 percent per year. Improved disease resistance of newer varieties may have also prevented a yield decline of the order of 0.25 percent per year. Yield gains on farms may be less (0.6 percent per year) because of slow diffusion of new varieties. Given costs of wheat research, returps to investment in wheat breeding have been above 20 percent and are over 15 percent even if all research costs at the national and international level are included. However, more rapid diffusion of new varieties in the Punjab could considerably increase returns to wheat research.

Experiments with Semidwarf Wheats in Kansas

Kansas wheat breeding research since 1949 has indicated that twogene semidwarf wheats are not well adapted to Kansas conditions, primarily because of severe lodging. One-gene semidwarfs may be useful, but they often have lower test weight, lighter kernel weight, and lodge more than hard red winter wheat cultivars used as parents. O*er characteristics such as disease resistance, maturity, and quality can be successfully bred into the semidwarf types. IXtroduction The productiveness of semidwarf cultivars of wheat has stimulated much interest in their development throughout the world. Highest farm yields recorded have been from new semidwarf wheats grown under irrigation and heavily fertilized. (State of Washington, 170 bushels per acre in 1964 and 209 bushels in 1965, Reitz, 1968.) Short type wheats were Srst grown commercially in Japan and Italy. Short cultivars were introduced from Japan into the United States in the late 1940's by S. C. Salmon; and the first published report in the United States was by RTogel et v1., (1956). Other reports and reviews are available, i.e., McNeal et dl., (1960); Vogel et v1., (1963); Porter et d1., (1964); Johnson et v1., (1966); Briggle and Vogel, (1968); Reitz, (1968); and Reitz and Salmon, (1968) . World wide use of short types has been advanced through the research project of Rockefeller Foundation in Mexico (Borlaug, 1968). A breeding program to develop semidwarf cultivars was initiated in Kansas in 1949, using Norin 10, PI 156641, and Norin 66, PI 155276; later other sources of short germplasm were crossed with adapted cultivars. To date no satisfactory types have been selected in Kansas. The major diiculty has been lodging of the short types under either stress conditions or high fertilization and moisture. This response does not agree with results in the Pacific Northwest or with semidwarf spring wheat cultivars developed in Mexico. Experiments with Semidwarf Wheats in Kansasl This content downloaded from 207.46.13.189 on Thu, 04 Aug 2016 04:13:42 UTC All use subject to http://about.jstor.org/terms 148 Transactions of the Kansas Acvdemy of Scienre Reasons for the inconsistent results in Kansas are not known but, generally, one-gene semidwarfs and especially two-gene semidwarfs have lighter kernels and lower test weight (Reddi et al., 1969 and Malott, 1970), than standard height segregates from a cross. They also tend to lodge more under certain environmental conditions. This lodging is characterized by straw breakage at the top node at or just before . . . comblne-rlpe. A few of the many crosses and their progenies studied in Kansas since 1949 are presented here. Materials and Methods One of the original crosses was Norin 10/Pawnee. Backcrosses were made to Pawnee) an adapted cultivar, with intense selection for agronomic traits between backcrosses. Selections of the cross Norin 10/5*Pawnee, which are theoretically 15/16 Pawnee, and selections from the cross NorIn 10/3tPawnee//2*Kaw, which are 3/4 Kaw, were studied. Designation of pedigrees follows the system of Purdy et 1. (1968). More than 1100 F3 plant progenies were studied in 1966 and 1967 (Reddi et dl., 1969) and 36 in 1968 and 1969 (Malott) 1970). Only four were studied in 1970. Other material reported here involves crosses of Triumph, Parker, Bison, BlueJacket, Ottawa, and Ponca with Norin 107 Norin 16, and Seu Seun. Scout and Triumph 64 were additional standard cultivars tested. Yield, test 7eight and kernel weight were obtained from regular nursery trials. Harvested plot size was 16 or 19 2 square feet, each replicated four times in a randomized complete block design. Data were obtained from Hutchinson and Manhattan during 1967-70, and from Garden City and Hays in 1968. About 50 pounds of P205 was applied per acre to the soil at Hutchinson and Manhattan. In 1968, 1969, and 1970 about 10 pounds of nitrogen was applied per acre the previous fall at Manhattan. In 1968 and 1970, both Manhattan and Hutchinson, about 100 pounds of nitrogen was applied in the spring on half of each plot. The test was irrigated and 50 pounds of nitrogen added at Garden City in 1968. The test at Hays was fertilized with a fall application of 30 pounds of N. Results Segregation for height indicated two probable main genetic factors for height with Norin 10 crosses (Reddi et 41., 1969). This agrees with the findings of Allan and Vogel (1963). The two-gene semidwarf lines were easily identified as were one-gene semidwarfs in most cases. There are two theoretically different one-gene semidwarf genotypes but all appeared the same. Allan (1971) has developed tester stocks to identify This content downloaded from 207.46.13.189 on Thu, 04 Aug 2016 04:13:42 UTC All use subject to http://about.jstor.org/terms Experi11tents with Semiduarf Wheats in Kansas 149 the two different one-gene dwarfs. Fig. 1 illustrates two-gene, one-gene, and standard heights expressed at Hutchinson in 1969.