Line x testers analysis of tropical maize inbred lines under heat stress for grain yield and secondary traits

The combining ability and mode of gene action in tropical maize germplasm is not extensively studied. In the present study, a line x tester analysis involving 290 test-cross hybrids developed by crossing 145 tropical maize inbred lines with two testers and four standard checks was conducted for grain yield and other agronomic traits under heat stress during summer 2013 at B gudi agriculture research station. The main objective of the investigation was to study mode of gene action governing the traits under heat stress along with identification of superior inbred lines based on combining ability to develop heat tolerant hybrids. Analysis of variance showed that mean squares for genotypes was highly significant for grain yield, days to anthesis and silking, anthesis silk interval, plant height and ear height under heat stress. The combining analysis for lines (GCA), tester (GCA) and line x tester (SCA) showed significant difference (P < 0.01) for all the traits under study except ASI for LXT interaction. This indicates that both additive and non additive gene action control the expression of these traits under heat stress. The low GCA variance to SCA variance ratio for all the traits showed preponderance of non-additive gene action in the inheritance of the traits. Among 145 inbred lines used for study, the inbreds L78, L73, and L37 showed good general combining ability for grain yield. The crosses L118 x L2 and L143 x L1 were having good specific combiners ability for grain yield under heat stress. These inbreds can be used in breeding program for development of heat tolerant hybrids through exploitation of dominant gene action

Cancer Patterns in Karachi Division (1998-1999)

Objective: A minimal cancer incidence data for Karachi, the largest city of Pakistan, is being presented here, for the years 1998-1999. The city has a population of 9,802,134; males 5,261,712 (52.6%) and females 4,540,422 (47.4%); census 19981. Methodology: A predominantly mixed (passive and active) registration system has evolved in Karachi, the data sources being the hospitals within the Karachi Division. The reported/retrieved cancer data sets at the Karachi Cancer Registry are checked, coded, computerised in an analytical format and analysed. Results: The incident cancer cases registered in Karachi, during the 2-year period, 1st January 1998 to 31st December 1999 were analysed. The age-standardised incidence rate (ASR) of cancer, all sites was 132.4/100,000 for the males. Cancer of the lung 10.8%; ASR 17.3 was the most frequently recorded malignancy, followed by oral cavity 10.5%; ASR 13.2 and larynx 5.0%; ASR 7.4. The age-standardised incidence rate (ASR) of cancer, all sites was 133.0/100,000 in the females. Cancer of the breast, 32.0%; ASR 40.7 was the most frequently recorded malignancy, followed by oral cavity 8.1%; ASR 11.7 and gall bladder 3.6%; ASR 5.5. Conclusion: The present data has been calculated with an estimated 15-20% probable under ascertainment. Tobacco-associated cancers in Karachi were responsible for 38.3% of the tumours diagnosed amongst the males. Two principal cancers, breast and oral cavity were responsible for 40.1% of the cancers in females. A rare finding was the high incidence of gall bladder cancer in the females. At present it is difficult to determine whether this indicates a genuine high risk or a selection bias. A continuous process of cancer registration to study the trends in the incidence and an adequate cancer control program are possible and essential for Pakistan and can be based on the pattern being practiced in Karachi

Time trends in the incidence of cancer cervix in Karachi South, 1995-2002

Introduction:The objective of the study was to determine the trends of cancer cervix in Karachi South during an eight (1995-2002) year period. Methododology: Cancer cervix cases recorded at Karachi Cancer Registry during 1st January 1995 to 31st December 2002 were analyzed. Trends were studied by analyzing the age standardized incidence rates (ASR)s in 2 time periods, 1995-97 and 1998-2002. Results: Cancer cervix ranked sixth in the 1995-97 period the age standardized incidence rate (ASR) world and crude incidence rate (CIR) per 100,000 were 6.81 and 3.22. It reached the fifth ranking in the 1998-2002 period with an ASR and CIR of 7.5 and 4.0 per 100,000. Thus between 1995 and 2002, the incidence of cervical cancer registered an approximate 10% increase. The mean age of the cancer cases was 53.3 years (SD 11.6, 95% CI 50.58, 55.96, range 32-85 years) and 50.7 years (SD 11.7, 95% CI 48.8, 52.5, range 51 years) in period 1 and 2 respectively. The morphological components of squamous cell carcinoma and adenocarcinoma remained stable during this period, though a marginally higher component and increasing incidence of adenocarcinoma was observed throughout. A negligible down staging was observed in the 1998-2002 period. Localized malignancy was observed in 30.8% in period 2 as compared to 25.7% in period 1 and the component of carcinoma in situ increased from 0% percent in period 1 to 1.3% in the second period. Despite this two thirds of the cases still presented with a regional or distant spread of disease. Conclusion: Pakistan at present falls into a low risk cancer cervix region. The cause of concern is the steadily increasing incidence especially in the younger birth cohorts, the advanced disease at presentation, insignificant in-situ cancers and no preventive intervention or awareness practices in place

Genetic gains in tropical maize hybrids across moisture regimes with multi-trait-based index selection

Unpredictable weather vagaries in the Asian tropics often increase the risk of a series of abiotic stresses in maize-growing areas, hindering the efforts to reach the projected demands. Breeding climate-resilient maize hybrids with a cross-tolerance to drought and waterlogging is necessary yet challenging because of the presence of genotype-by-environment interaction (GEI) and the lack of an efficient multi-trait-based selection technique. The present study aimed at estimating the variance components, genetic parameters, inter-trait relations, and expected selection gains (SGs) across the soil moisture regimes through genotype selection obtained based on the novel multi-trait genotype–ideotype distance index (MGIDI) for a set of 75 tropical pre-released maize hybrids. Twelve traits including grain yield and other secondary characteristics for experimental maize hybrids were studied at two locations. Positive and negative SGs were estimated across moisture regimes, including drought, waterlogging, and optimal moisture conditions. Hybrid, moisture condition, and hybrid-by-moisture condition interaction effects were significant (p ≤ 0.001) for most of the traits studied. Eleven genotypes were selected in each moisture condition through MGIDI by assuming 15% selection intensity where two hybrids, viz., ZH161289 and ZH161303, were found to be common across all the moisture regimes, indicating their moisture stress resilience, a unique potential for broader adaptation in rainfed stress-vulnerable ecologies. The selected hybrids showed desired genetic gains such as positive gains for grain yield (almost 11% in optimal and drought; 22% in waterlogging) and negative gains in flowering traits. The view on strengths and weaknesses as depicted by the MGIDI assists the breeders to develop maize hybrids with desired traits, such as grain yield and other yield contributors under specific stress conditions. The MGIDI would be a robust and easy-to-handle multi-trait selection process under various test environments with minimal multicollinearity issues. It was found to be a powerful tool in developing better selection strategies and optimizing the breeding scheme, thus contributing to the development of climate-resilient maize hybrids

Genomic-regions associated with cold stress tolerance in Asia-adapted tropical maize germplasm

Maize is gaining impetus in non-traditional and non-conventional seasons such as off-season, primarily due to higher demand and economic returns. Maize varieties directed for growing in the winter season of South Asia must have cold resilience as an important trait due to the low prevailing temperatures and frequent cold snaps observed during this season in most parts of the lowland tropics of Asia. The current study involved screening of a panel of advanced tropically adapted maize lines to cold stress during vegetative and flowering stage under field conditions. A suite of significant genomic loci (28) associated with grain yield along and agronomic traits such as flowering (15) and plant height (6) under cold stress environments. The haplotype regression revealed 6 significant haplotype blocks for grain yield under cold stress across the test environments. Haplotype blocks particularly on chromosomes 5 (bin5.07), 6 (bin6.02), and 9 (9.03) co-located to regions/bins that have been identified to contain candidate genes involved in membrane transport system that would provide essential tolerance to the plant. The regions on chromosome 1 (bin1.04), 2 (bin 2.07), 3 (bin 3.05–3.06), 5 (bin5.03), 8 (bin8.05–8.06) also harboured significant SNPs for the other agronomic traits. In addition, the study also looked at the plausibility of identifying tropically adapted maize lines from the working germplasm with cold resilience across growth stages and identified four lines that could be used as breeding starts in the tropical maize breeding pipelines

Heat-tolerant maize for rainfed hot, dry environments in the lowland tropics: from breeding to improved seed delivery

Climate change-induced heat stress combines two challenges: high day- and nighttime temperatures, and physiological water deficit due to demand-side drought caused by increase in vapor-pressure deficit. It is one of the major factors in low productivity of maize in rainfed stress-prone environments in South Asia, affecting a large population of smallholder farmers who depend on maize for their sustenance and livelihoods. The International Maize and Wheat Improvement Center (CIMMYT) maize program in Asia, in partnership with public-sector maize research institutes and private-sector seed companies in South Asian countries, is implementing an intensive initiative for developing and deploying heat-tolerant maize that combines high yield potential with resilience to heat and drought stresses. With the integration of novel breeding tools and methods, including genomics-assisted breeding, doubled haploidy, field-based precision phenotyping, and trait-based selection, new maize germplasm with increased tolerance to heat stress is being developed for the South Asian tropics. Over a decade of concerted effort has resulted in the successful development and release of 20 high-yielding heat-tolerant maize hybrids in CIMMYT genetic backgrounds. Via public–private partnerships, eight hybrids are presently being deployed on over 50,000 ha in South Asian countries, including Bangladesh, Bhutan, India, Nepal, and Pakistan

Genetic trends in CIMMYT’s tropical maize breeding pipelines

Fostering a culture of continuous improvement through regular monitoring of genetic trends in breeding pipelines is essential to improve efficiency and increase accountability. This is the first global study to estimate genetic trends across the International Maize and Wheat Improvement Center (CIMMYT) tropical maize breeding pipelines in eastern and southern Africa (ESA), South Asia, and Latin America over the past decade. Data from a total of 4152 advanced breeding trials and 34,813 entries, conducted at 1331 locations in 28 countries globally, were used for this study. Genetic trends for grain yield reached up to 138 kg ha−1 yr−1 in ESA, 118 kg ha−1 yr−1 South Asia and 143 kg ha−1 yr−1 in Latin America. Genetic trend was, in part, related to the extent of deployment of new breeding tools in each pipeline, strength of an extensive phenotyping network, and funding stability. Over the past decade, CIMMYT’s breeding pipelines have significantly evolved, incorporating new tools/technologies to increase selection accuracy and intensity, while reducing cycle time. The first pipeline, Eastern Africa Product Profile 1a (EA-PP1a), to implement marker-assisted forward-breeding for resistance to key diseases, coupled with rapid-cycle genomic selection for drought, recorded a genetic trend of 2.46% per year highlighting the potential for deploying new tools/technologies to increase genetic gain

Epidemiology of soft tissue sarcomas in Karachi South, Pakistan (1995-7).

Introduction:The present study was conducted with the objective of examining epidemiological characteristics of soft tissue sarcomas (STSs) in Karachi. Patients and Methods: Epidemiological data of 96 (63 male and 33 female) incident STS cases registered at Karachi Cancer Registry (KCR) for Karachi South (KS), from 1st January 1995 to 31st December 1997, were reviewed. Results: The age standardized rate (ASR) world per 100,000 were 3.3 (2.9%) and 2.1 (1.6%) in males and females, respectively, with mean ages of of 41.4 years (95% CI 35.77-46.97) and 40.2 years (95% CI 31.27-49.03). The age-specific curves showed a gradual increase in risk from the first until the eighth decade in both genders, with the highest peak at 75+ in females and 70-74 years in males. In males, 8 (12.7%) STS cases were diagnosed in the pediatric age group (0-14), 12 (19.1%) in adolescents and young adults (15-24 years), 19 (30.1%) in adults 25-49 years of age and 24 (38.1%) in the 50 years+ age group. In females the respective frequencies were 11%, 26%, 30% and 33%. The most common histological tumor was rhabdomyosarcoma, though the occurrence of the histological subtypes was age-dependent. Rhabdomyosarcomas and Ewing\u27s sarcomas were more frequent in children and adolescents whereas fibrosarcomas, leiomyosarcomas, liposarcomas, malignant fibrous histiocytomas (MFHs) and schwannomas were encountered in the elderly. Conclusion: Karachi falls into a high risk region for STS, observed in a relatively younger population, with a male predominance, high frequency of rhabdomyosarcoma and advanced stage at diagnosis. Information on grading and staging remain incomplete for most cases, which negatively affect disease management and survival

Willingness to Pay (WTP) for Heat-Tolerant Maize Hybrids in the Mid-Western Terai Region of Nepal

High atmospheric temperatures can reduce maize production in different parts of Asia. Heat stress is the major driving force behind the need for varietal development that confers a heat tolerance trait (drought + heat tolerant) to maize hybrids. CIMMYT has developed heat-tolerant maize hybrids and deployed them in the market in collaboration with NARS partners. This study was conducted to estimate farmers’ willingness to pay for heat-tolerant maize hybrids in the Terai region of Nepal. A socioeconomic survey of 404 randomly selected maize-growing households was conducted to estimate farmers’ willingness to pay using the contingent valuation method. Given the economic importance of heat-tolerant maize hybrids in maize cultivation, the survey showed that the average WTP for heat-tolerant maize hybrids was 71% more than that for the current varieties in the market, including overall seed sources and subsidized seed. Without a subsidy, the farmers’ WTP price was at a 19% premium compared to the average price paid for conventional hybrids. Factors such as education, owning land, the interaction of hybrid adopters and owning land, soil depth, the number of goats/sheep, and the semi-pucca homes of households influenced the WTP for heat-tolerant maize hybrids. Heterogeneous demand was observed with respect to years of hybrid maize cultivation, farmers’ association with the network group, and the gender of the head of the household. In the context of climate change and global warming scenarios, Nepal’s agriculture policy should prioritize increasing domestic seed production and the distribution of heat-tolerant maize hybrids through a public–private partnership model

Rising incidence of gastric malignancies in Karachi, 1995- 2002.

Introduction:South Asia is an enigma for gastric cancer, a low risk region with a contradictory high prevalence for Helicobacter pylori. Patients and Methods: To examine the demographics, pathology and trends of gastric cancer in Pakistan, epidemiological data of 335 gastric malignancies, registered at Karachi Cancer Registry (KCR) for Karachi South (KS), during 1st January 1995 to 31st December 2002 were reviewed. Trends were studied by categorizing the cases into two time periods \u271995-7\u27 and \u271998-2002\u27. Results: Ninety six cases of gastric cancers were registered in the 1995-7 period, 61 in males and 35 in females. In males, the ASR (world), and crude incidence rate (CIR) per 100,000 were 3.9 and 2.3 respectively. In females, the values were 3.0 and 1.5. In the 1998-02 period 239 cases of gastric cancer were registered, 156 cases in males and 83 in females. The ASR and CIR per 100,000 were 6.0 and 3.4 in males and 3.6 and 2.1 in females. An 18% increase was observed in males and 14% in females during the seven year study period. The male to female ratio was 2:1.The mean age of male Patients was 51.9 years (95% CI 45.8, 58.1, SD -/+17.9) in 1995-7 and 53.7 years (95% CI 51.6, 55.9, SD -/+14.0) in 1998-02. In females the mean age for the two periods was 48.8 years (95% CI 42.5, 55.0, SD -/+ 18.2) and 48.4 years (95% CI 45.4, 51.5, SD -/+13.9) respectively. Age-specific curves showed a gradual increase in risk from the second until the seventh decade. The majority of the cases presented as poorly or moderately differentiated distal (non-cardia) cancers with a regional spread. Conclusion: Gastric cancers in Karachi fall into the prototype of a low risk developing country pattern. The incidence is increasing, most marked in males above 40 years of age. Larger pathology-based studies are required to comment on the precise morphological sub-types of gastric adenocarcinoma. Etiological studies focused on different strains of H. pylori are required to address the gastric cancer enigma, whilst examining possible protective environmental or genetic factors