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Inheritance of resistance to maize lethal necrosis in tropical maize inbred lines
No full textMaize (Zea mays L.) production in sub-Saharan Africa can be improved by using hybrids with genetic resistance to maize lethal necrosis (MLN). This study aimed to assess the general (GCA) and specific combining ability (SCA), reciprocal effects, and quantitative genetic basis of MLN resistance and agronomic traits in tropical maize inbred lines. A total of 182 hybrids from a 14-parent diallel, along with their parents, were evaluated under artificial MLN inoculation and rainfed conditions for 3 years in Kenya. Disease ratings at four time points, grain yield (GY), and other agronomic traits were analyzed using Griffing’s Method 3 and Hayman’s diallel models. Significant (P < 0.001) GCA and SCA mean squares were observed for all traits under disease conditions and most traits under rainfed conditions, highlighting the importance of both additive and non-additive genetic effects. However, additive gene action predominated for all traits. Narrow-sense heritability estimates for MLN resistance (h2 = 0.52–0.56) indicated a strong additive genetic component. Reciprocal effects were not significant for MLN resistance, suggesting minimal maternal or cytoplasmic inheritance. Four inbred lines showed significant negative GCA effects for MLN resistance and positive GCA effects for GY under artificial MLN inoculation. Inbred lines CKL181281 and CKL182037 (GCA effects for MLN4 = -0.45 and -0.24, respectively) contained the most recessive alleles for MLN resistance. The minimum number of groups of genes involved in MLN resistance was estimated to be three. Breeding strategies that emphasize GCA could effectively be used to improve MLN resistance in this germplasm
Genome-wide association mapping and genomic prediction analyses reveal the genetic architecture of grain yield and agronomic traits under drought and optimum conditions in maize
No full textBackground: Drought is a major abiotic stress in sub-Saharan Africa, impacting maize growth and development leading to severe yield loss. Drought tolerance is a complex trait regulated by multiple genes, making direct grain yield selection ineffective. To dissect the genetic architecture of grain yield and flowering traits under drought stress, a genome-wide association study (GWAS) was conducted on a panel of 236 maize lines testcrossed and evaluated under managed drought and optimal growing conditions in multiple environments using seven multi-locus GWAS models (mrMLM, FASTmrMLM, FASTmrEMMA, pLARmEB, pKWmEB, ISIS EM-BLASSO, and FARMCPU) from mrMLM and GAPIT R packages. Genomic prediction with RR-BLUP model was applied on BLUEs across locations under optimum and drought conditions. Results: A total of 172 stable and reliable quantitative trait nucleotides (QTNs) were identified, of which 77 are associated with GY, AD, SD, ASI, PH, EH, EPO and EPP under drought and 95 are linked to GY, AD, SD, ASI, PH, EH, EPO and EPP under optimal conditions. Among these QTNs, 17 QTNs explained over 10% of the phenotypic variation (R2 >= 10%). Furthermore, 43 candidate genes were discovered and annotated. Two major candidate genes, Zm00001eb041070 closely associated with grain yield near peak QTN, qGY_DS1.1 (S1_216149215) and Zm00001eb364110 closely related to anthesis-silking interval near peak QTN, qASI_DS8.2 (S8_167256316) were identified, encoding AP2-EREBP transcription factor 60 and TCP-transcription factor 20, respectively under drought stress. Haplo-pheno analysis identified superior haplotypes for qGY_DS1.1 (S1_216149215) associated with the higher grain yield under drought stress. Genomic prediction revealed moderate to high prediction accuracies under optimum and drought conditions. Conclusion: The lines carrying superior haplotypes can be used as potential donors in improving grain yield under drought stress. Integration of genomic selection with GWAS results leads not only to an increase in the prediction accuracy but also to validate the function of the identified candidate genes as well increase in the accumulation of favorable alleles with minor and major effects in elite breeding lines. This study provides valuable insight into the genetic architecture of grain yield and secondary traits under drought stress
Identification of quantitative trait nucleotides for grain quality in bread wheat under heat stress
No full textHeat stress is a critical factor affecting global wheat production and productivity. In this study, out of 500 studied germplasm lines, a diverse panel of 126 wheat genotypes grown under twelve distinct environmental conditions was analyzed. Using 35 K single-nucleotide polymorphism (SNP) genotyping assays and trait data on five biochemical parameters, including grain protein content (GPC), grain amylose content (GAC), grain total soluble sugars (TSS), grain iron (Fe), and zinc (Zn) content, six multi-locus GWAS (ML-GWAS) models were employed for association analysis. This revealed 67 stable quantitative trait nucleotides (QTNs) linked to grain quality parameters, explaining phenotypic variations ranging from 3 to 44.5% under heat stress conditions. By considering the results in consensus to at least three GWAS models and three locations, the final QTNs were reduced to 16, with 12 being novel findings. Notably, two novel markers, AX-94461119 (chromosome 2A) and AX-95220192 (chromosome 7D), associated with grain Fe and Zn, respectively, were validated through Kompetitive Allele Specific Polymerase Chain Reaction (KASP) approach. Candidate genes, including the P-loop-containing nucleoside triphosphate hydrolases (NTPases), Bowman-Birk type proteinase inhibitors (BBI), and the NPSN13 protein, were identified within associated genomic regions. These genes could serve as potential targets for enhancing quality traits and heat tolerance in future wheat improvement programs
Priority actions for Fusarium head blight resistance in durum wheat: Insights from the wheat initiative
No full textFusarium head blight (FHB), mainly caused by Fusarium graminearum and Fusarium culmorum, is a major wheat disease. Significant efforts have been made to improve resistance to FHB in bread wheat (Triticum aestivum), but more work is needed for durum wheat (Triticum turgidum spp. durum). Bread wheat has ample genetic variation for resistance breeding, which can be readily exploited, while durum wheat is characterized by higher disease susceptibility and fewer valuable resistance sources. The Wheat Initiative - Expert Working Group on Durum Wheat Genomics and Breeding has promoted a scientific discussion to define the key actions that should be prioritized for achieving resistance in durum wheat comparable to that found in bread wheat. Here, a detailed state of the art and novel tools to improve FHB resistance in durum are presented, together with a perspective on the next steps forward. A meta-analysis grouping all quantitative trait loci (QTL) associated with FHB resistance in both bread and durum wheat has been conducted to identify hotspot regions that do not overlap with Rht alleles, which are known to negatively correlate with FHB resistance. A detailed list of QTL related to FHB resistance and deoxynivalenol contamination and durum lines carrying different sources of FHB resistance are provided as a strategic resource. QTL, closely linked markers and durum wheat lines carrying the useful alleles, can be selected to design an effective breeding program. Finally, we highlight the priority actions that should be implemented to achieve satisfactory resistance to FHB in durum wheat
Opportunities to narrow potato yield gaps and increase resource use efficiency in West Java, Indonesia
No full textConsumer demand for potato in Indonesia increases while production stagnates. Government policy recognised this discrepancy and prioritised efforts to increase potato yields through farmer support programs with moderate effects to date. This study aimed to decompose potato yield gaps and identify agronomic yield constraints in West Java. Actual yield and management practices of 178 farm registrations over five consecutive growing seasons were analysed with stochastic frontier analysis. The potential yield (Yp) for each registration was simulated with the LINTUL-POTATO-DSS crop model. The overall yield gap was decomposed into its efficiency, resource and technology components. The potato yield gap was 21.5 t ha−1, corresponding to 54% of Yp. The efficiency and technology yield gaps were both ca. 10 t ha−1, corresponding to 26% of Yp, and the resource yield gap was negligible. All fields received sufficient inputs for potential production, but most inputs were used inefficiently. An early first fungicide spray after emergence and frequently spraying to control late blight increased yields significantly. The seed generation planted was critical to potato yield gaps as yield decreased significantly with older generations. Some high-yielding fields, however, were also planted with older seed generations, so other production factors contributed to the yield gap as well. Improving potato yield and reducing current yield gaps in West Java will require well-performed late blight control, the use of high-quality seed and improved management practices, which include reduced input rates.1137–115
State of digitalization of seed companies and quality declared seed producers in Tanzania
No full textDigital transformation holds vast potential for advancing sustainable agriculture in the Global South, yet significant gaps remain in sectors such as Tanzania’s seed industry, which plays a critical role in agricultural productivity and food security. This study examines the current level of digital adoption among Tanzanian seed companies and Quality Declared Seed (QDS) producers, focusing on three value chains: common beans, sorghum, and groundnuts. Using survey data from 148 QDS producers and all registered 30 seed companies, collected by the Tanzania Official Seed Certification Institute (TOSCI), we assess the current state of digital use by these entities and how digital technologies can contribute to improved market access, customer engagement, and operational efficiencies. Our analysis highlights the uneven engagement between seed companies and QDS producers, value chain disparities, and persistent barriers such as limited device access, low digital literacy, and restricted awareness of digital tools. Understanding these differences in digital engagement is essential for developing effective strategies that can bridge the digital divide and create inclusive digital transformation pathways for all actors in Tanzania’s seed sector.23 page
Chapter 30. What do we know about the future of maize value chains in a changing climate and agrifood system?
No full textPopulation growth, changing diets, and a rapidly growing feed sector are contributing to a sharp increase in global maize demand, which is expected to double by 2050 relative to 2010. Average global maize yield is projected to decrease by 11 percent under a global warming scenario of 2°C (2060–2084) relative to the 1986–2005 period (in the absence of technological change, adaptation, or market adjustments). The feed demand for maize is expected to grow faster in the coming few decades, largely driven by rapid economic growth and diet shifts in highly populated regions in Asia, the Middle East, and Latin America. Meeting the growing demand for maize will require dramatic increases in production, marketing, use, and resilience of maize-based farming systems. While the supply of maize over the coming decades will be constrained by climate change and limited availability of land and water, technological and policy innovations will bring new opportunities. The combined challenges of increasing food demand, persistent poverty and malnutrition, natural resource depletion, and climate change will require the world to double the productivity and boost the sustainability and resilience of maize-based farming systems within planetary boundaries.117-18
Drought and consumption impacts of climate-smart-agricultural practices adoption in drought prone area of Eastern Hararghe, Ethiopia
No full textAnnual consumption expenditure of the households is seriously affected by climate shocks in the country where the major livelihood of the community depends on rain-based agriculture. Multinomial endogenous switching regression (MESR) model was applied to analyze factors affecting adoption of climate smart agricultural practices and impact of adoption on consumption expenditure in Eastern Hararghe, Ethiopia. Irrigation, crop diversification and integrated soil fertility management were widely practiced in the study area. From East Hararghe zone four districts were randomly selected. The primary data was collected from 430 sample respondents during 2023 year. Using the rainfall data of 33 years, drought was analyzed by using standard precipitation index (SPI). The model result revealed that education of the family head, family size, livestock, market information, drought experience, climate information and drought significantly influenced the adoption of climate smart agricultural practice (CSAPr). The result showed that, the highest consumption expenditure was obtained when farmers adopted combination of crop diversification and irrigation practices (F0D1I1) which is 12610.9ETB. The adopters also obtained 11274ETB when they adopted integrated soil fertility and crop diversification (F1D1I0). All adopters obtained higher consumption expenditure per adult as compared to the non-adopters (F0D0I0) which is 9434.5ETB. It also showed that, out of total consumption increased by adoption of CSAPr, 72.4 percent of incensement was obtained by adopting practices combination whereas 27.6 percent was by single practices. So, it is very important to advance farmers’ information on drought and adoption strategy. The policymakers ought to develop and encourage farmers’ asset building plan, adult education, market linkage facilities and extension service and weather information delivery system to enhance adoption of CSAPr practices to combat the current and future drought. Therefore, the study recommends that policies should promote joint adoption of climate smart practices in drought prone area to increase climate change mitigation and consumption expenditure
Accelerating Varietal Turnover Through Digital Multi-Stakeholder Platforms (MSPs) in Tanzania
No full textVarietal turnover (VTO) - the timely replacement of old seed varieties with newer, improved ones - remains a challenge for Tanzania’s agricultural productivity, especially for openpollinated crops such as common beans, groundnuts, and sorghum. Despite clear benefits of improved varieties, including yield gains of more than 50%, better disease resistance, and higher income potential, adoption rates remain low. Tanzania’s predominantly informal seed system, where over 97% of planting material is sourced from farmer-saved seeds or grain markets, contributes to this slow uptake, with the average age of bean varieties on the market reaching 20 years in 2020. The Accelerated Varietal Turnover of Open-Pollinated Crops (ACCELERATE) project, led by the Alliance of Bioversity International and CIAT/PABRA in collaboration with CIMMYT, TARI, and TOSCI, and funded by the Gates Foundation, aims to tackle these systemic barriers.10 page