International Crops Research Institute for the Semi-Arid Tropics
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Variation in nitrogen partitioning and reproductive stage nitrogen remobilization determines nitrogen grain production efficiency (NUEg) in diverse rice genotypes under varying nitrogen supply
Get PDFNitrogen (N) is an important macronutrient needed for grain yield, grain N and grain protein content in rice. Grain yield and quality are significantly determined by N availability. In this study, to understand the mechanisms associated with reproductive stage N remobilization and N partitioning to grain 2 years of field experiments were conducted with 30 diverse rice genotypes during 2019-Kharif and 2020-Kharif seasons. The experiments were conducted with two different N treatments; N deficient (N0-no external N application, available soil N; 2019-234.15 kgha-1, 2020-225.79 kgha-1) and N sufficient (N120-120 kgha-1 external N application, available soil N; 2019-363.77 kgha-1, 2020-367.95 kgha-1). N application increased the NDVI value, biomass accumulation, grain yield, harvest index and grain N accumulation. Post-anthesis N uptake and N remobilization from vegetative tissues to grain are critical for grain yield and N harvest index. Rice genotypes, Kalinga-1, BAM-4234, IR-8384-B-B102-3, Sahbhagi Dhan, BVD-109 and Nerica-L-42 showed a higher rate of N remobilization under N sufficient conditions. But, under N deficiency, rice genotypes-83929-B-B-291-3-1-1, BVD-109, IR-8384-B-B102-3 and BAM-4234 performed well showing higher N remobilization efficiency. The total amount of N remobilization was recorded to be high in the N120 treatment. The harvest index was higher in N120 during both the cropping seasons. RANBIR BASMATI, BAM-832, APO, BAM-247, IR-64, Vandana, and Nerica-L-44 were more efficient in N grain production efficiency under N deficient conditions. From this study, it is evident that higher grain N accumulation is not always associated with higher yield. IR-83929-B-B-291-3-1-1, Kalinga-1, APO, Pusa Basmati-1, and Nerica-L-44 performed well for different N use efficiency component traits under both N deficient (N0) and N sufficient (N120) conditions. Identifying genotypes/donors for N use efficiency-component traits is crucial in improving the fertilizer N recovery rate and site specific N management
Effects of urbanisation on urban residents’ perception of vegetable production in Yaoundé, Cameroon
No full textIn the context of rapid and unplanned urbanisation in many Sub-Saharan African cities, the social and political context of urban and peri-urban vegetable production is becoming unfriendly despite its multifunctionality in achieving human development. This paper aims at measuring the effects of urbanisation on urban residents’ perception of vegetable production in urban and peri-urban areas of Yaoundé, Cameroon. Data from a survey conducted by the World Vegetable Centre among urban residents living within and around vegetable production areas was employed for the study. The results show that urban residents agree with vegetable production in their vicinity, but depending on the extent of urbanisation, the magnitude of their positive perception varies significantly from one production area to another. More specifically, while proximity to the city centre increases the likelihood of urban residents’ ability to agree with local vegetable production, the density of the population decreases this positive perception instead
SSR and SNP Marker-Based Investigation of Indian Rice Landraces in Relation to Their Genetic Diversity, Population Structure, and Geographical Isolation
Get PDFIndia is blessed with an abundance of diverse rice landraces in its traditional cultivated areas. Two marker systems (simple sequence repeats (SSR) and single nucleotide polymorphism (SNP)) were used to study a set of 298 rice landrace accessions collected from six different regions of India (Andaman and Nicobar Islands, Chhattisgarh, Jharkhand, Uttar Pradesh, Uttarakhand, and West Bengal). Thirty hyper-variable simple sequence repeats (HvSSRs) and 32,782 single nucleotide polymorphisms (SNPs) were used in inferring genetic structure and geographical isolation. Rice landraces from Uttar Pradesh were the most diverse, with a gene diversity value of 0.42 and 0.49 with SSR and SNP markers, respectively. Neighbor-joining trees classified the rice landraces into two major groups with SSR and SNP markers, and complete geographical isolation was observed with SSR markers. Fast STRUCTURE analysis revealed four populations for SSR markers and three populations for SNP markers. The population structure with SSR markers showed that few individuals from Uttarakhand and Andaman and Nicobar Islands were grouped in small clusters. Population structure analysis with SNP markers showed not very distinct region-wise clustering among the rice landraces. Discriminant analysis of principal components (DAPC) and minimum spanning network (MSN) using SSR markers showed region-wise grouping of landraces with some intermixing, but DAPC and MSN with SNP markers showed very clear region-wise clustering. Genetic differentiation of rice landraces between the regions was significant with both SSR (Fst 0.094–0.487) and SNP markers (Fst 0.047–0.285). A Mantel test revealed a positive correlation between the genetic and geographic distance of rice landraces. The present study concludes that rice landraces investigated in this study were very diverse, and unlinked SSR markers show better geographical isolation than a large set of SNP markers
The conservation of gene models can support genome annotation
Get PDFMany genome annotations include false-positive gene models, leading to errors in phylogenetic and comparative studies. Here, we propose a method to support gene model prediction based on evolutionary conservation and use it to identify potentially erroneous annotations. Using this method, we developed a set of 15,345 representative gene models from 12 legume assemblies that can be used to support genome annotations for other legumes
Aflatoxin Contamination, Exposure among Rural Smallholder Farming Tanzanian Mothers and Associations with Growth among Their Children
No full textRecently, aflatoxin exposure especially through maize and groundnuts has been associated with growth impairment in children. Infants and children are considered to be more susceptible to toxins because of their lower body weight, higher metabolic rate, and lower ability to detoxify.
On the other hand, for women of reproductive age, aflatoxin exposure may not only affect their health but also that of their foetus in the case of pregnancy. This study focused on investigating AFB1 contamination in maize and groundnut from respondent households, exposure among women of reproductive age and associations of aflatoxin contamination with growth retardation among children in Mtwara region, Tanzania. The highest maximum AFB1 contamination levels from all samples obtained were in maize grain (2351.5 μg/kg). From a total of 217 maize samples collected, aflatoxins were above European Union (EU) and East African Community (EAC) tolerable limits
in 76.0% and 64.5% of all samples. Specifically, maize grain had the highest proportion of samples contaminated above tolerable limits (80.3% and 71.1% for EU and EAC limits). Groundnut had 54.0% and 37.9% of samples above EU and EAC maximum tolerable limits. The lowest proportion of contaminated samples on the other hand was for bambara nut (37.5% and 29.2% for EU and EAC limits, respectively). Aflatoxin exposure in our surveyed population was much higher than previous observations made in Tanzania and also higher than those observed in Western countries such as Australia and the USA. Among children, AFB1 concentration was associated with lower weight for height z scores and weight for age z scores in the univariate model (p < 0.05). In summary, these results indicate the seriousness of aflatoxin contamination in foods commonly consumed in the
vulnerable population assessed. Strategies both from the health, trade, and nutrition sectors should therefore be designed and implemented to address aflatoxin and mycotoxin contamination in diets
AN ENABLING ENVIRONMENT FOR THE NATIONAL FLOUR BLENDING POLICY: A FOOD SYSTEMS ANALYSIS
No full textA national flour blending policy is about to be implemented in Kenya. This requires maize flour (the country’s main staple) to be blended with at least 10 percent of either one or a composite of traditional crops, such as sorghum and millet.1 The blending ratio is expected to increase gradually, with the goal of ultimately reaching 30 percent. The policy envisages achieving several goals. The first is to improve the nutritional quality of maize flour: sorghum and millet (and other candidate blending crops) have micronutrient characteristics that are absent in maize. The second is to promote more climate-tolerant crops and technologies: sorghum and millet can be grown in less favorable arid and semiarid lands (ASALs), in the very conditions that many farmers face in Kenya. This is particularly important given that maize is more susceptible than other staple crops to climate change. The third is to reduce the country’s overreliance on imported maize and concerns about its food sovereignty
Characterization of finger millet global germplasm diversity panel for grain nutrients content for utilization in biofortification breeding
Get PDFFinger millet (Eleusine coracana L.) is a versatile dryland crop known for its high calcium (Ca) content. Estimating the variability for grain nutrients in diverse germplasm is important for developing biofortified cultivars. A finger millet diversity panel consisting of 310 accessions and four controls was evaluated in two rainy seasons at International Crops Research Institute for the Semi-Arid Tropics, Hyderabad, India, to assess variability for grain nutrient content and its association with agronomic traits and identify promising accessions. Inductively coupled plasma optical emission electrometry was used to analyze grain nutrients content, and the protein content was estimated from the total nitrogen content of the finger millet grains using the sulfuric acid–selenium digestion method. Highly significant variability was found for all the grain nutrients and was significantly influenced by the genotype, environment, and their interactions. Grain nutrients showed a significant relationship between the 2 years (R2 = 0.06 for phosphorus to 0.60 for Ca, p ≥ 0.001). A nonsignificant correlation between grain yield and Ca was noticed among accessions within landraces, breeding lines, and accessions from Asia, while this correlation was significantly negative among accessions from Africa and in the entire set. The estimated percent daily values indicated that the consumption of 100 g of finger millet grains could potentially contribute to the recommended dietary allowance of up to 49% Ca, 52% magnesium, 23% protein, 23% iron, and 26% zinc. This study provides valuable insights into the variability in the finger millet germplasm, and identified grain nutrient dense accessions, that could be used in finger millet improvement to develop the biofortified cultivars
Bacterial Biofilters for Arsenic Removal
No full textArsenic (As) contamination is one of major causes of health threats in various regions of the world. The primary source for arsenic pollution is through groundwater contaminated by natural sources of arsenic found in the earth’s crust. Additionally, they enter the ecosystem via various anthropogenic activities such as mining, smelting and agricultural products comprising arsenic salts. Some medicinal agents have also been found to contain arsenic as a major component for the treatment of diseases. Small concentrations of arsenic have the potential to cause long term toxic effects such as arsenicosis. The reduced form of As(V) (arsenate) is As(III) (arsenite) which is relatively more toxic. Further, the inorganic form is more toxic than the organic arsenic species. Numerous phototrophic anaerobic bacterial species are known to possess mechanism which transforms As (III) to As(V). Many of the bacterial species have also evolved mechanisms to use As for internal metabolic purposes such as arsenotrophy which is the reduction of As(V) or oxidation of As (III). Additionally, microorganisms also possess tolerance systems which detoxify As(III) into its reduced form As(V) via certain factors. Numerous such bacterial species have been identified and isolated from arsenic contaminated environments and the various mechanisms associated with arsenic removal have been explored. As(III) oxidizing bacteria have shown promising results in the reduction of arsenic in groundwater which is the main source of arsenic contamination. Modern technologies would further aid in defining the direct or indirect roles of such bacterial species in the treatment of arsenic contamination and its associated bioremoval
Genetic Diversity for Grain Nutrients Content in Finger Millet (Eleusine Coracana (L.) Gaertn.) Germplasm
No full textKnowledge of existing genetic variability is essential for initiating a successful plant breeding program. This chapter reviews nutrient diversity studies conducted on finger millet germplasm globally. In all the studies, very high variability was observed in all the quality traits determined. Most of the nutrients were positively correlated with each other, implying that they can simultaneously be improved. Grain color and glume covering were associated with nutrient content, with darker grains having higher compared to white-colored and enclosed grains having higher nutrient content than intermediate covered having higher content. These two can be used as morphological markers. Local cultivars and varieties released in the East and South Asia (ESA) region had significantly lower levels of the main essential nutrients (Ca, Fe, and Zn) found in finger millet, most likely as a result of farmers selecting for varieties with brown-colored grain. Country of origin was highly significant for all the nutrients, with accessions from eastern and southern Africa having significantly lower nutrient contents. Grain color was associated with nutrient content with darker grains having higher compared to white colored. All nutrients were positively correlated (P < 0.001) with each other. Grain yield was not significantly correlated with any nutrient content. The substantial variability for the grain nutrients observed in the finger millet core collection and local germplasm indicates the possibility for the selection of nutrient-rich accessions for use in the breeding program
Field and agroinoculation screening of national collection of urd bean (Vigna mungo) germplasm accessions for new sources of mung bean yellow mosaic virus (MYMV) resistance
No full textYellow mosaic disease (YMD) is a major problem in Urd bean (Vigna mungo L.) in India, which causes huge yield losses. Breeding for wide spectrum and durable Mungbean yellow mosaic virus (MYMV) resistance and cultivating resistant cultivars is the most appropriate and effective approach. However, the task has become challenging with the report of at least two species of the virus, viz., Mungbean yellow mosaic virus (MYMV) and Mungbean yellow mosaic India virus (MYMIV) and their recombinants; the existence of various isolates of these species with varied virulence and rapid mutations noted in the virus as well as in the whitefly vector population. Thus the present study was carried out to identify and characterize novel and diverse sources of YMV resistance and develop linked molecular markers for breeding durable and broadspectrum resistant urdbean cultivars against YMV. Towards this goal, we have screened 998 accessions of urdbean national collection of germplasm against YMD Hyderabad isolate both in a field under the natural level of disease incidence and through agro inoculation in the laboratory using viruliferous clones of the same isolate. Ten highly resistant accessions identified through repeated testing have been characterized in terms of reported linked markers. We attempted to see diversity among the ten resistant accessions reported here using earlier reported resistance-linked SCAR marker YMV1 and SSR CEDG180 marker. SCAR marker YMV1 did not amplify with any of the 10 accessions. But with CEDG180, results suggested that 10 accessions shortlisted through field and laboratory tests do not carry PU31 allele and this shows that it may be likely to carry novel gene(s). Further studies are needed to genetically characterize these new sources