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Polyphenol oxidase (PPO) causes undesirable darkening in wheat products such as Asian noodles. The inheritance of PPO activity was investigated in a doubled haploid (DH) population derived from a hybrid between a null PPO genotype VAW08-A17 and Australian wheat variety QALBis. The observed genetic ratio indicated three genes controlling high PPO activity. Quantitative trait loci (QTL) mapping was performed in this DH population using diversity arrays technology (DArT) to genotype the population. Three highly significant QTLs that control PPO activity were identified on chromosomes 2AL, 2BS and 2DL with additive mode of action. Three closely associated DArT markers, wPt-7024, wPt-0094 and wPt-2544, were identified corresponding to these QTLs. Collectively, these loci explained 74% of the observed variation in PPO activity. Identification of DArT markers associated with PPO genes will accelerate the development of null or very low PPO cultivars that exhibit reduced time-dependent darkening of Asian ...

Wheat is the most important food crop in the world. In Bangladesh, wheat consumption increased substantially during the last few decades. Currently, 7.3 million tons of wheat is consumed each year, of which 1.3 million tons are grown locally and the rest is imported. Local wheat production must be increased to meet the growing demand and save hard-earned foreign currency. To achieve this, high-yielding varieties, resistant to diseases and insects, and varieties which are suitable for cultivation under salinity, heat and moisture stress conditions are required. Development of such varieties with traditional breeding methods requires 10 to 12 years. However, with doubled haploid technology, a variety can be developed in just 6 years. Using this technology, completely homozygous breeding lines can be produced in just 1 generation, compared to 6–8 generations required by the traditional methods, and thus variety development time is reduced. The University of Sydney, Plant Breeding Institute, established a highly effective doubled haploid production technology in 2002. This technology has been widely used by Australian plant breeding companies for variety development and to study different genetic traits. Between 2010 and 2019, 16 doubled haploid varieties have been developed, which are being popularly grown by the Australian farmers. Molecular markers and doubled haploids are used in combination by some breeding companies to further reduce breeding time. Undesirable plants can be easily identified and removed from the population using these markers. Wheat breeders of Bangladesh may consider using these technologies for rapid development of new varieties to increase wheat production. This chapter provides important information on doubled haploid research at the University of Sydney that is of relevance to Bangladeshi wheat research and production.

Emmer wheat (Triticum dicoccon Schrank) is a potential source of new genetic diversity for the improvement of hexaploid bread wheat. Emmer wheat was crossed and backcrossed to bread wheat and 480 doubled haploids (DHs) were produced from BC1F1 plants with hexaploid appearance derived from 19 crossses. These DHs were screened under well-watered conditions (E1) in 2013 to identify high-yielding materials with similar phenology. One-hundred and eighty seven DH lines selected on this basis, 4 commercial bread wheat cultivars and 9 bread wheat parents were then evaluated in extensive field experiments under two contrasting moisture regimes in north-western NSW in 2014 and 2015. A significant range in the water-use-efficiency of grain production (WUEGrain) was observed among the emmer derivatives. Of these, 8 hexaploid lines developed from 8 different emmer wheat parents had significantly improved intrinsic water-use-efficiency (WUEintr) and instantaneous water-use-efficiency (WUEi) compared to their bread wheat recurrent parents. Accurate and large scale field-based phenotyping was effective in identifying emmer wheat derived lines with superior performance to their hexaploid bread wheat recurrent parents under moisture stress.

Calculations using a heat balance and a radiative transfer model have been done to study relations among evaporation coefficients and vegetation indices. The evaporation coefficients are the crop coefficient (defined as the ratio of total evaporation and reference crop evaporation) and the transpiration coefficient (defined as the ratio of unstressed transpiration and reference crop evaporation), while the vegetation indices considered in this study are the normalized difference, soil adjusted vegetation index, and transformed soil adjusted vegetation index. The reference crop evaporation has been calculated using the Priestley-Taylor equation. The observed variations of crop (wheat) height, leaf area index, and weather conditions for 30 days at Phoenix (Arizona), together with the reflectances of different types of soil in wet and dry states, are used in the simulation. The total evaporation calculated from the model compared well with lysimeter observations. Variations in soil evaporation can introduce considerable scatter in the relation between the crop coefficient and leaf area index, while this scatter is much less for the relation between transpiration coefficient and leaf area index. The simulation results for 30 days of crop and weather data and reflectances of 19 soil types in wet and dry conditions gave significant linear correlations between the transpiration coefficient and the vegetation indices, the explained variance (r2) being highest for the soil adjusted vegetation index (r2 = 0.88) and lowest for the normalized difference (r2= 0.81). A clump model is used to address the effect of spatial heterogeneity on the relationship between the transpiration coefficient and soil adjusted vegetation index. These simulated relationships between transpiration coefficient and vegetation indices for wheat are discussed in the context of the relationships derived from observations for several crops and grasses. The present analysis provides a theoretical basis for estimating transpiration from remotely sensed data.

A numerical model based on the convective plumes observed in the convecting planetary boundary layer has been developed for material dispersion from both elevated and ground source releases. Mechanistic formulation, rather than parameterization, or statistical behavior of PBL phenomenon, has been used as a basis. This model uses two universal constants, the turbulent entrainment constant, a, and decay constant, A. The model results have physical significance with regard to the observed plume behavior in a convective field. An observed case of diffusion has been simulated. The model results are in reasonable agreement with the observation without introducing any adjustable parameters to improve the fit.

The NGO Service Delivery Program (NSDP), a USAID-funded programme, is the largest NGO programme in Bangladesh. Its strategic flagship activity is the essential services package through which healthcare services are administered by NGOs in Bangladesh. The overall goal of the NSDP is to increase access to essential healthcare services by communities, especially the poor. Recognizing that the poorest in the community often have no access to essential healthcare services due to various barriers, a study was conducted to identify what the real barriers to access by the poor are. This included investigations to further understand the perceptions of the poor of real or imagined barriers to accessing healthcare; ways for healthcare centres to maximize services to the poor; how healthcare providers can maximize service-use; inter-personal communication between healthcare providers and those seeking healthcare among the poor; and ways to improve the capacity of service providers to reach the poorest segment of the community. The study, carried out in two phases, included 24 static and satellite clinics within the catchment areas of eight NGOs under the NSDP in Bangladesh, during June-September 2003. Participatory urban and rural appraisal techniques, focus-group discussions, and in-depth interviews were employed as research methods in the study. The target populations in the study included males and females, service-users and non-users, and special groups, such as fishermen, sex workers, potters, Bedes (river gypsies), and lower-caste people—all combined representing a heterogeneous community. The following four major categories of barriers emerged as roadblocks to accessing quality healthcare for the poor: (a) low income to be able to afford healthcare, (b) lack of awareness of the kind of healthcare services available, (c) deficiencies and inconsistencies in the quality of services, and (d) lack of close proximity to the healthcare facility. Those interviewed perceived their access problems to be: (a) a limited range of NGO services available as they felt what are available do not meet their demands; (b) a high service-charge for the healthcare services they sought; (c) higher prices of drugs at the facility compared to the market place; (d) a belief that the NGO clinics are primarily to serve the rich people, (e) lack of experienced doctors at the centres; and (f) the perception that the facility and its services were more oriented to women and children, but not to males. Others responded that they should be allowed to get treatment with credit and, if needed, payment should be waived for some due to their poverty level. While the results of the study revealed many perceptions of barriers to healthcare services by the poor, the feedback provided by the study indicates how important it is to learn from the poorest segment of society. This will assist healthcare providers and the healthcare system itself to become more sensitized to the needs and problems faced by this segment of the society and to make recommendations to remove barriers and improvement of access. Treatment with credit and waived payment for the poorest were also recommended as affordable alternative private healthcare services for the poor.

Stripe rust resistance was identified in Triticum vavilovii (T. vavilovii Aus22498)-derived Russian wheat aphid (RWA)-resistant germplasm. Inheritance studies indicated monogenic control of resistance. The resistance gene was tentatively designated as Yrvav and was located on chromosome 1B by monosomic analysis. A close association (1.5±0.9% recombination) of Yrvav with a T. vavilovii-derived gliadin allele (Gli-B1vav) placed it in chromosome arm 1BS. Yrvav was allelic with Yr10. Tests with Yr10 avirulent and virulent pathotypes showed that Yrvav and Yr10 possess identical pathogenic specificity. Yrvav and Yr10 showed close genetic associations with alternate alleles at the Xpsp3000 (microsatellite marker), Gli-B1 and Rg1 loci. Based on these observations Yrvav was named as Yr10vav. The close association between Xpsp3000 and Gli-B1 was also confirmed. The Yr10vav-linked Xpsp3000 allele (285 bp) was not present in 65 Australian cultivars, whereas seven Australian wheats lacking Yr10 carried the same Xpsp3000 allele (260 bp) as Yr10 carrying wheat cultivar Moro. Xpsp3000 and/or Gli-B1 could be used in marker-assisted selection for pyramiding Yr10vav or Yr10 with other stripe rust resistance genes. Yr10vav was inherited independently of the T. vavilovii-derived RWA resistance.

Doubled haploid populations of CD87/Katepwa, Cranbrook/Halberd, and Sunco/Tasman were assessed for seedling response to stem rust and stripe rust. The CD87/Katepwa population was also screened as adult plants in the field against stripe rust. The respective parents differed in presence or absence of various stem rust and stripe rust resistance genes. At least 4 resistance loci controlled adult plant resistance to stripe rust in the CD87/Katepwa population, and based on quantitative trait loci mapping results, two of these were contributed by CD87. Pedigree information indicated that these regions correspond to durable adult plant stripe rust resistance genes Yr18 and Yr29. Yr29 was mapped to the distal region of chromosome 1BL. The third gene, contributed by Katepwa, YrKat, was located in chromosome arm 2DS. Sr30 mapped distal to markers abg3 and P36/M61-170 in chromosome arm 5DL. Genes Yr7 and Pbc (completely linked with durable stem rust resistance gene Sr2) showed close associations with markers in chromosome arms 2BL and 3BS, respectively. A distally located genomic region in chromosome 6AS also affected the expression of Pbc. The temperature-sensitive stripe rust resistance gene, YrCK, carried by Sunco showed monogenic inheritance and was located in chromosome arm 2DS. Several markers showed complete association with Triticum timopheevi derived stem rust resistance gene Sr36. Microsatellite markers stm773 and gwm271A were validated on a set of wheat genotypes and were found to be diagnostic for the detection of Sr36. TheSr36-linked Xstm773 allele showed better amplification than the Sr36-linked Xgwm271A allele. These markers could be used for marker assisted identification of Sr36 in breeding populations.