Genomic Prediction of Grain Yield and Drought-Adaptation Capacity in Sorghum Is Enhanced by Multi-Trait Analysis
Velazco, Julio G. ; Jordan, David R. ; Mace, Emma S. ; Hunt, Colleen H. ; Malosetti, Marcos ; Eeuwijk, Fred A. van - \ 2019
Frontiers in Plant Science 10 (2019). - ISSN 1664-462X
auxiliary trait - blended kinship matrix - BLUP - genomic prediction - grain yield - multi-trait analysis - sorghum - stay-green
Grain yield and stay-green drought adaptation trait are important targets of selection in grain sorghum breeding for broad adaptation to a range of environments. Genomic prediction for these traits may be enhanced by joint multi-trait analysis. The objectives of this study were to assess the capacity of multi-trait models to improve genomic prediction of parental breeding values for grain yield and stay-green in sorghum by using information from correlated auxiliary traits, and to determine the combinations of traits that optimize predictive results in specific scenarios. The dataset included phenotypic performance of 2645 testcross hybrids across 26 environments as well as genomic and pedigree information on their female parental lines. The traits considered were grain yield (GY), stay-green (SG), plant height (PH), and flowering time (FT). We evaluated the improvement in predictive performance of multi-trait G-BLUP models relative to single-trait G-BLUP. The use of a blended kinship matrix exploiting pedigree and genomic information was also explored to optimize multi-trait predictions. Predictive ability for GY increased up to 16% when PH information on the training population was exploited through multi-trait genomic analysis. For SG prediction, full advantage from multi-trait G-BLUP was obtained only when GY information was also available on the predicted lines per se, with predictive ability improvements of up to 19%. Predictive ability, unbiasedness and accuracy of predictions from conventional multi-trait G-BLUP were further optimized by using a combined pedigree-genomic relationship matrix. Results of this study suggest that multi-trait genomic evaluation combining routinely measured traits may be used to improve prediction of crop productivity and drought adaptability in grain sorghum.
AgMIP's Global Gridded Crop Model Intercomparison (GGCMI) phase 1 output data set: CGMS-WOFOST sorghum
Hoek, Steven ; Wit, Allard de - \ 2018
Wageningen University and Research
AgMIP - GGCMI - crop model - historical simulations - global - sorghum - CGMS-WOFOST
This is model output from CGMS-WOFOST for sorghum as part of AgMIP's Global Gridded Crop Model Intercomparison (GGCMI) phase 1 output data set. The data have been generated following the modeling protocol of Elliott et al. (2015) and has been used to evaluate the models (Müller et al., 2017). A data description paper has been published in Scientific Data (Müller et al. 2019).
A higher proportion of Iron-Rich leafy vegatables in a typical burkinabe maize meal does not increase the amount of iron absorbed in young women
Cercamondi, C.I. ; Icard-Verniere, C. ; Egli, I. ; Vernay, M. ; Hama, F. ; Brouwer, I.D. - \ 2014
The Journal of Nutrition 144 (2014)9. - ISSN 0022-3166 - p. 1394 - 1400.
phenolic-compounds - stable-isotope - pearl-millet - fortification iron - ascorbic-acid - phytic acid - in-field - absorption - foods - sorghum
Food-to-food fortification can be a promising approach to improve the low dietary iron intake and bioavailability from monotonous diets based on a small number of staple plant foods. In Burkina Faso, the common diet consists of a thick, cereal-based paste consumed with sauces composed of mainly green leaves, such as amaranth and jute leaves. Increasing the quantity of leaves in the sauces substantially increases their iron concentration. To evaluate whether increasing the quantity of leaves in sauces would provide additional bioavailable iron, an iron absorption study in 18 young women was conducted in Zurich, Switzerland. Burkinabe composite test meals consisting of the maize paste tô accompanied by an iron-improved amaranth sauce, an iron-improved jute sauce, or a traditional amaranth sauce were provided as multiple meals twice a day for 2 consecutive days. Iron absorption was measured as erythrocyte incorporation of stable iron isotopes. Mean fractional iron absorption from maize paste consumed with an iron-improved amaranth sauce (4.9%) did not differ from the same meal consumed with an iron-improved jute sauce (4.9%; P = 0.9), resulting in a similar quantity of total iron absorbed (679 vs. 578 µg; P = 0.3). Mean fractional iron absorption from maize paste accompanied by a traditional amaranth sauce (7.4%) was significantly higher than that from the other 2 meal types (P <0.05), but the quantity of total iron absorbed was similar (591 µg; P = 0.4 and 0.7, respectively). A food-to-food fortification approach based on an increase in leafy vegetables does not provide additional bioavailable iron, presumably due to the high phenolic compound concentration of the leaves tested. Alternative measures, such as adding iron absorption enhancers to the sauces, need to be investigated to improve iron nutrition from Burkinabe maize meals.
Effect of phosphate-based seed priming on strigolactone production and Striga hermonthica infection in cereals
Jamil, M. ; Charnikhova, T. ; Verstappen, F.W.A. ; Ali, Z. ; Wainwright, H. ; Bouwmeester, H.J. - \ 2014
Weed Research 54 (2014)3. - ISSN 0043-1737 - p. 307 - 313.
arbuscular mycorrhizal fungi - phosphorus deficiency - root parasites - sorghum - plants - management - exudation - promotes - africa - growth
Strigolactones, plant-secreted underground signalling molecules, play an important role in agricultural ecosystems, because they mediate the interaction of crops with symbiotic AM fungi and parasitic weeds like Striga hermonthica. Cereal host plants secret these signalling molecules particularly under nutrient-deficient conditions and especially when phosphate (P) is limiting. The objective of the present study was to see the potential of P seed priming for S. hermonthica management in cereals in relation to strigolactone production. It has been demonstrated that P fertiliser application down-regulates the production of these signalling molecules in the rhizosphere, which results in lower S. hermonthica infection of cereals. The laboratory study showed maximum production of strigolactones from dry and water-soaked seeds, while seed soaking in P solution reduced their production. Similarly, maximum S. hermonthica infection was observed under control treatments with dry sowing or water soaking, while P seed soaking decreased S. hermonthica germination, emergence and dry biomass in all cereal crops. Our study shows that P seed priming resulted in lower exudation of strigolactones, which induced less S. hermonthica seeds germination and hence may lead to lower S. hermonthica infection. P-based seed priming could prove to be an effective and affordable strategy to reduce S. hermonthica infection in cereals. Further research for practical field application is needed
Evaluation of climate adaptation options for Sudano-Sahelian cropping systems
Traore, B. ; Wijk, M.T. van; Descheemaeker, K.K.E. ; Corbeels, M. ; Rufino, M.C. ; Giller, K.E. - \ 2014
Field Crops Research 156 (2014). - ISSN 0378-4290 - p. 63 - 75.
millet pennisetum-americanum - lowland tropical maize - west-african monsoon - pearl-millet - grain-yield - drought tolerance - plant-population - water-stress - variability - sorghum
In the Sudano-Sahelian region, smallholder agricultural production is dominated by rain-fed production of millet, sorghum and maize for food consumption and of cotton for the market. A major constraint for crop production is the amount of rainfall and its intra and inter-annual variability. We evaluated the effects of planting date on the yield of different varieties of four major crops (maize, millet, sorghum and cotton) over three contrasting growing seasons in 2009–2011 (with 842 mm, 1248 mm and 685 mm of rainfall respectively) with the aim of identifying climate adaptation options in the Sudano-Sahelian region. Three planting dates (early, medium, and late) and three varieties of long, medium, and short duration of each crop were compared. For fertilized cereal crops, maize out yielded millet and sorghum by respectively 57% and 45% across the three seasons. Analysis of 40 years of weather data indicates that this finding holds for the longer time periods than the length of this trial. Late planting resulted in significant yield decreases for maize, sorghum and cotton, but not for millet. However, a short duration variety of millet was better adapted for late planting. When the rainy season starts late, sorghum planting can be delayed from the beginning of June to early July without substantial reductions in grain yield. Cotton yield at early planting was 28% larger than yield at medium planting and late planting gave the lowest yield with all three varieties. For all four crops the largest stover yields were obtained with early planting and the longer planting was delayed, the less stover was produced. There was an interaction between planting date and variety for millet and sorghum, while for maize and cotton the best planting date was more affected by the weather conditions. The findings of this study can support simple adaptation decisions: priority should be given to planting cotton early; maize is the best option if fertilizer is available; planting of maize and sorghum can be delayed by up to a month without strong yield penalties; and millet should be planted last.
Quality of core collections for effective utilisation of genetic resources review, discussion and interpretation
Odong, T.L. ; Jansen, J. ; Eeuwijk, F.A. van; Hintum, T.J.L. van - \ 2013
Theoretical and Applied Genetics 126 (2013)2. - ISSN 0040-5752 - p. 289 - 305.
morphological descriptors - germplasm collection - sampling strategies - diversity - algorithm - establishment - accessions - selection - markers - sorghum
Definition of clear criteria for evaluation of the quality of core collections is a prerequisite for selecting high-quality cores. However, a critical examination of the different methods used in literature, for evaluating the quality of core collections, shows that there are no clear guidelines on the choices of quality evaluation criteria and as a result, inappropriate analyses are sometimes made leading to false conclusions being drawn regarding the quality of core collections and the methods to select such core collections. The choice of criteria for evaluating core collections appears to be based mainly on the fact that those criteria have been used in earlier publications rather than on the actual objectives of the core collection. In this study, we provide insight into different criteria used for evaluating core collections. We also discussed different types of core collections and related each type of core collection to their respective evaluation criteria. Two new criteria based on genetic distance are introduced. The consequences of the different evaluation criteria are illustrated using simulated and experimental data. We strongly recommend the use of the distance-based criteria since they not only allow the simultaneous evaluation of all variables describing the accessions, but they also provide intuitive and interpretable criteria, as compared with the univariate criteria generally used for the evaluation of core collections. Our findings will provide genebank curators and researchers with possibilities to make informed choices when creating, comparing and using core collections
The turbulent life of Sirevirus retrotransposons and the evolution of the maize genome: more than ten thousand elements tell the story
Bousios, A. ; Kourmpetis, Y.I.A. ; Pavlidis, P. ; Minga, E. ; Tsaftaris, A. ; Darzentas, N. - \ 2012
The Plant Journal 69 (2012)3. - ISSN 0960-7412 - p. 475 - 488.
plant transposable elements - ty1/copia retrotransposons - ltr retrotransposons - rice genome - diversity - gene - arabidopsis - sequence - sorghum - rearrangement
Sireviruses are one of the three genera of Copia long terminal repeat (LTR) retrotransposons, exclusive to and highly abundant in plants, and with a unique, among retrotransposons, genome structure. Yet, perhaps due to the few references to the Sirevirus origin of some families, compounded by the difficulty in correctly assigning retrotransposon families into genera, Sireviruses have hardly featured in recent research. As a result, analysis at this key level of classification and details of their colonization and impact on plant genomes are currently lacking. Recently, however, it became possible to accurately assign elements from diverse families to this genus in one step, based on highly conserved sequence motifs. Hence, Sirevirus dynamics in the relatively obese maize genome can now be comprehensively studied. Overall, we identified >10 600 intact and approximately 28 000 degenerate Sirevirus elements from a plethora of families, some brought into the genus for the first time. Sireviruses make up approximately 90% of the Copia population and it is the only genus that has successfully infiltrated the genome, possibly by experiencing intense amplification during the last 600 000 years, while being constantly recycled by host mechanisms. They accumulate in chromosome-distal gene-rich areas, where they insert in between gene islands, mainly in preferred zones within their own genomes. Sirevirus LTRs are heavily methylated, while there is evidence for a palindromic consensus target sequence. This work brings Sireviruses in the spotlight, elucidating their lifestyle and history, and suggesting their crucial role in the current genomic make-up of maize, and possibly other plant hosts
Seasonal nitrogen budgets of mature citrus trees on a sandy entisol
Morgan, K. ; Scholberg, J.M.S. ; Obreza, T. ; Wheaton, T. - \ 2012
Journal of Plant Nutrition 35 (2012)13. - ISSN 0190-4167 - p. 2009 - 2023.
uptake efficiency - leaching losses - soil - irrigation - mineralization - fertilization - management - sorghum - young - corn
Approximately 30% of Florida citrus is grown on well-drained Entisols with low nutrient-holding capacity, which are prone to high nitrogen (N) leaching losses. However, increasing application frequency of N-fertilizer via multiple fertigations does not increase crop yield, whereas in agronomic crops, such an approach typically enhances N uptake efficiency. We assessed seasonal tree N tissue concentration dynamics as affected by N rate for mature fourteen-year-old 'Hamlin' orange (Citrus sinensis L. Osbeck) trees on either Carrizo citrange (C. sinsensis L. Osbeck X Poncirus trifoliata L. Raf.) or Swingle citrumelo (C. paradisi Macf. X P. trifoliata L. Raf.) rootstocks. Nitrogen was applied as ammonium nitrate in six split fertigation applications with N target values of 179 and 269 kg ha(-1)yr(-1). Leaf, twig, and branch bark tissue N concentrations decreased through the spring to minima in May and June. This time period corresponds to a period of high N demand associated with both vegetative and reproductive growth. Tissue N concentrations increased from late spring minimums to fall and winter maximum concentrations. Reduction in branch bark and wood tissue N concentrations may have been due to a redistribution of N to leaf, twig, and fruit tissues in response to low N supply. The majority of the spring N should be supplied prior to May.
Sowing the seeds of social relations: social capital and agricultural diversity in Hararghe Ethiopia
Cavatassi, R. ; Lipper, L. ; Winters, P. - \ 2012
Environment and Development Economics 17 (2012)5. - ISSN 1355-770X - p. 547 - 578.
adoption - sorghum
The paper presents an analysis of the role of two forms of social capital – linking and bonding – on two key farm outcomes: on-farm crop diversity and household wellbeing. Where market transactions are limited, social capital is an important household asset for accessing seed and channelling information. The study is set in a drought-prone region of Ethiopia, with high rates of food insecurity and dependency on agriculture for livelihoods. The region is very rich in crop genetic diversity, particularly for sorghum. The data were collected for a production year that experienced a major drought shock. Results of the analysis indicate that social capital is an important determinant of farm level diversity and wellbeing, with opposing effects related to the two different forms of social capital. This suggests possible trade-offs between the two forms of social capital in terms of food security, production and diversity, which need to be considered in planning interventions.
The tomato genome sequence provides insights into fleshy fruit evolution
Sato, S. ; Tabata, S. ; Hirakawa, H. ; Klein Lankhorst, R.M. ; Jong, H. de; Ham, R.C.H.J. van; Datema, E. ; Smit, S. ; Schijlen, E.G.W.M. ; Haarst, J.C. van; Peters, S.A. ; Henkens, M.H.C. ; Staveren, M.J. van; Mooijman, P.J.W. ; Hesselink, T. ; Belt, J. van de; Szinay, D. ; Bai, Y. ; Visser, R.G.F. - \ 2012
Nature 485 (2012). - ISSN 0028-0836 - p. 635 - 641.
lycopersicon-esculentum - gene - diversification - arabidopsis - patterns - ortholog - history - sorghum - potato
Tomato (Solanum lycopersicum) is a major crop plant and a model system for fruit development. Solanum is one of the largest angiosperm genera1 and includes annual and perennial plants from diverse habitats. Here we present a high-quality genome sequence of domesticated tomato, a draft sequence of its closest wild relative, Solanum pimpinellifolium2, and compare them to each other and to the potato genome (Solanum tuberosum). The two tomato genomes show only 0.6% nucleotide divergence and signs of recent admixture, but show more than 8% divergence from potato, with nine large and several smaller inversions. In contrast to Arabidopsis, but similar to soybean, tomato and potato small RNAs map predominantly to gene-rich chromosomal regions, including gene promoters. The Solanum lineage has experienced two consecutive genome triplications: one that is ancient and shared with rosids, and a more recent one. These triplications set the stage for the neofunctionalization of genes controlling fruit characteristics, such as colour and fleshiness.
Mapping yield variability of sorghum and millet in Mali
Conijn, J.G. ; Hengsdijk, H. ; Rutgers, B. - \ 2012
Wageningen : Plant Research International (Report / Plant Research International 440) - 14
sorghum - pennisetum - gierst - gewasopbrengst - weersgegevens - weer - landgebruik - bodem - simulatiemodellen - mali - sorghum - pennisetum - millets - crop yield - weather data - weather - land use - soil - simulation models - mali
Genetic variation in strigolactone production and tillering in rice and its effect on Striga hermonthica infection
Jamil, M. ; Charnikhova, T. ; Houshyani Hassanzadeh, B. ; Ast, A. van; Bouwmeester, H.J. - \ 2012
Planta 235 (2012)3. - ISSN 0032-0935 - p. 473 - 484.
arbuscular mycorrhizal fungi - parasitic plants - germination stimulants - phosphate deficiency - am fungi - sorghum - arabidopsis - signals - auxin - inhibition
Tillering in cereals is a complex process in the regulation of which also signals from the roots in the form of strigolactones play an important role. The strigolactones are signalling molecules that are secreted into the rhizosphere where they act as germination stimulants for root parasitic plants and hyphal branching factors for arbuscular mycorrhizal fungi. On the other hand, they are also transported from the roots to the shoot where they inhibit tillering or branching. In the present study, the genetic variation in strigolactone production and tillering phenotype was studied in twenty rice varieties collected from all over the world and correlated with S. hermonthica infection. Rice cultivars like IAC 165, IAC 1246, Gangweondo and Kinko produced high amounts of the strigolactones orobanchol, 2'-epi-5-deoxystrigol and three methoxy-5-deoxystrigol isomers and displayed low amounts of tillers. These varieties induced high S. hermonthica germination, attachment, emergence as well as dry biomass. In contrast, rice cultivars such as Super Basmati, TN 1, Anakila and Agee displayed high tillering in combination with low production of the aforementioned strigolactones. These varieties induced only low S. hermonthica germination, attachment, emergence and dry biomass. Statistical analysis across all the varieties confirmed a positive correlation between strigolactone production and S. hermonthica infection and a negative relationship with tillering. These results show that genetic variation in tillering capacity is the result of genetic variation in strigolactone production and hence could be a helpful tool in selecting rice cultivars that are less susceptible to S. hermonthica infection.
The use of ß-xylanase for increasing the efficiency of biocatalytic conversion of crop residues to bioethanol
Juodeikiene, G. ; Basinskiene, L. ; Vidmantiene, D. ; Makaravicius, T. ; Bartkiene, E. ; Schols, H.A. - \ 2011
Catalysis today 167 (2011)1. - ISSN 0920-5861 - p. 113 - 121.
endoxylanase inhibitors - simultaneous saccharification - ethanol-production - cereals - family - rye - arabinoxylans - fermentation - integration - sorghum
Proteinaceous inhibitors of xylanase naturally occur in cereals where they are involved in various roles in the plant defence metabolism. This study focused on the inhibitors of xylanase present in local rye cultivars, and their influence on the efficiency of the fermentation processes during bioethanol production from rye residues in comparison with common wheat. Different origin xylanases from Thermomyces lanuginosus and Trichoderma reesei were the objects of the investigations. Kinetic studies of these xylanases in the presence of proteins with inhibitory activity indicated that Th. lanuginosus was found more sensitive to proteinaceous xylanase inhibitors presented in rye than T. reesei. The highest yield of xylose and arabinose was achieved by adding T. reesei to cell wall substrates, while Th. lanuginosus converted to arabinoxylans only into xylooligosaccharides and monosaccharide were not released. The activity of xylanase in composition with a-amylase and glucoamylase was selected to achieve a higher ethanol yield in the distillate. It improved the quality of bioethanol by increasing the content of ethanol and decreasing the concentrations of propanol, isobutanol, isoamyl and amyl alcohols and the methanol concentration. No significant differences were found between the contents of ethanol from different type of bran
Quantification of the relationship between strigolactones and Striga hermonthica infection in rice under varying levels of nirtrogen and phosphorus
Jamil, M. ; Charnikhova, T. ; Cardoso, C. ; Jamil, T. ; Ueno, K. ; Verstappen, F.W.A. ; Asami, T. ; Bouwmeester, H.J. - \ 2011
Weed Research 51 (2011)4. - ISSN 0043-1737 - p. 373 - 385.
arbuscular mycorrhizal fungi - asiatica l kuntze - germination stimulants - upland rice - seed-germination - parasitic weeds - root parasites - soil fertility - oryza-sativa - sorghum
Strigolactone exudation, as well as Striga hermonthica germination and attachment, was studied under different levels of nitrogen (N) and phosphorus (P) in two cultivars of rice (IAC 165 and TN 1). Exudation of strigolactones by rice was the highest under mineral-deficient conditions, whereas increasing N and P dose reduced the amount of strigolactones in the exudates. Deficiency of P led to the highest strigolactone exudation, when compared with N or NP deficiency. Production of strigolactones differed strongly between the two cultivars. IAC 165 produced about 100-fold higher amounts than TN 1 of 2'-epi-5-deoxystrigol, orobanchol and three new strigolactones. Across all N and P treatments, a positive relationship was found between the amount of strigolactones in the exudates of both cultivars and in vitro S. hermonthica germination. These results show that the positive effect of fertiliser application in S. hermonthica control is, at least partly, because of the suppression of strigolactone production and hence of S. hermonthica germination and subsequent attachment. This warrants further research into practical application. Maintaining suitable N and P nutrient status of soil through fertiliser use might be a promising strategy to reduce damage in cereals by this notorious weed.
Pre-attachment Striga hermonthica resistance of New Rice for Africa (NERICA) cultivars based on low strigolactone production
Jamil, M. ; Rodenburg, J. ; Charnikhova, T. ; Bouwmeester, H.J. - \ 2011
New Phytologist 192 (2011)4. - ISSN 0028-646X - p. 964 - 975.
arbuscular mycorrhizal fungi - germination stimulants - phosphorus deficiency - parasitic weeds - root parasites - upland rice - am fungi - sorghum - asiatica - crops
Striga hermonthica (Striga) is an obligate hemiparasitic weed, causing severe yield losses in cereals, including rice, throughout sub-Saharan Africa. Striga germination depends on strigolactones (germination stimulants) exuded by the host roots. The interspecific New Rice for Africa (NERICA) cultivars offer a potentially interesting gene pool for a screen for low germination-inducing rice cultivars. •Exudates were collected from all NERICA cultivars and their parents (Oryza sativa and Oryza glaberrima) for the analysis of strigolactones. In vitro and in situ Striga germination, attachment and emergence rates were recorded for each cultivar. •NERICA 1 and CG14 produced significantly less strigolactones and showed less Striga infection than the other cultivars. NERICAs 7, 8, 11 and 14 produced the largest amounts of strigolactones and showed the most severe Striga infection. Across all the cultivars and parents, there was a positive relationship between the amount of strigolactones in the exudate and Striga germination, attachment and emergence rates. •This study shows that there is genetic variation in Striga pre-attachment resistance in NERICA rice. Cultivars combining this pre-attachment resistance with post-attachment resistance (already identified) can provide a key component for durable integrated management of this noxious weed in cereal production systems in sub-Saharan Africa.
Gibberella musae (Fusarium musae) sp. nov., a recently discovered species from banana is sister to F. verticillioides
Hove, F. van; Waalwijk, C. ; Logrieco, A. ; Munaut, F. ; Moretti, A. - \ 2011
Mycologia 103 (2011)3. - ISSN 0027-5514 - p. 570 - 585.
fujikuroi mating population - pcr-rflp analysis - section liseola - fumonisin production - prairie grasses - gene-cluster - complex - anamorph - sorghum - differentiation
Several strains of Fusarium isolated from banana were identified previously as F. verticillioides (Sacc.) Nirenberg but described as unable to produce fumonisin. Here we report biochemical and morphological evidence, as well as multilocus phylogenetic analyses based on elongation factor (EF-1a), calmodulin, b-tubulin, and the second largest subunit of RNA polymerase II (RPB2) sequences, indicating that these isolates represent a unique lineage in the Gibberella fujikuroi species complex related to but distinct from F. verticillioides. Together with previous results of molecular studies, as well as with results of metabolite analyses, crossing experiments, pathogenicity tests and morphological characterization, these new data indicate that these strains isolated from banana represent a new species, Gibberella musae Van Hove et al. sp. nov. (anamorph: Fusarium musae Van Hove et al. sp. nov.), which is described herein
Long-term effects of conservation soil management in Saria, Burkina Faso, West Africa
Zacharie, Z. - \ 2011
Wageningen University. Promotor(en): Leo Stroosnijder, co-promotor(en): A. Mando; B. Ouattara. - [S.l.] : S.n. - ISBN 9789085858362 - 142
bodembeheer - grondbewerking gericht op bodemconservering - bodemfauna - bodemeigenschappen - sorghum - rotaties - veldwaterbalans - afrika ten zuiden van de sahara - soil management - conservation tillage - soil fauna - soil properties - sorghum - rotations - field water balance - africa south of sahara
The negative degradation spiral that currently leads to deteriorating soil properties in African drylands is a serious problem that limits food production and threatensthe livelihoods of the people. Nutrient depletion and water and wind erosion are the main factors in soil degradation in Africa. This thesis describes field research conducted from 2006 through 2008 to assess how changes in physical and hydrological soil properties, induced by differences in land management and macro-faunal biodiversity determine water and nitrogen use efficiencies in Burkina Faso. The methodology involved systematic soil sampling of selected treatments (including a fallow control) coupled with macro-fauna identification. Measurements were used to generate information on the effect of the long-term land management practices on soil properties and the different terms of the field water balance. Crop sampling (leaves, stem and grains) allowed determination of plant nutrient uptake and calculation of water and nitrogen use efficiency. Differences in soil properties between treatments were smaller than expected after so many years of applying the same soil management practice. Results indicate that long-term permanent cultivation result in a decrease in the quality of most soil properties when compared with the fallow. We also found that there are clear benefits from inclusion of cowpea in a rotation system due to its N fixation and deeper root system. Regarding soil fauna, long-term application of the same soil management practices resulted in specialization of the food type for the macro-fauna leading to less fauna diversity. Also, more diverse and abundant macro-fauna was discovered under superficially tilled plots compared to tractor plowed plots. The contribution of the soil fauna to aggregate building depends on the amount and type of organic material available to the fauna as well as the soil management regime. In spite of the amount of applied organic amendments used in our trials, the C-stock in the soil has decreased at a rate of 0.25 % per year, perhaps limiting macro-fauna activity. The 3-year average of the green water use efficiency (ratio T/P) was only 14% and the crop yield was also low due to less than optimal crop management. Results further suggest that systematic, rather than strategically timed, N applications (organic and/or mineral) are likely to lead to N losses. Synchronizing N fertilizer application with crop-N demand and accounting for residual Nitrogen will lead to higher N fertilizer use efficiency. Soil management practices, crop selection and fertilizer regime can have positive or negative impacts on water and nutrient use efficiency. Practices with positive impact should be encouraged in order to increase crop productivity and improve food security in Burkina Faso.
Host-plant defence against Striga spp.: reconsidering the role of tolerance
Rodenburg, J. ; Bastiaans, L. - \ 2011
Weed Research 51 (2011)5. - ISSN 0043-1737 - p. 438 - 441.
hermonthica - resistance - cultivars - selection - sorghum - rice
Parasitic weeds of the genus Striga cause high yield losses in cereal crops across Africa. Host-plant defence against Striga spp. can be an effective control strategy. It ideally consists of resistance, to reduce infection, complemented with tolerance, to mitigate the effects of infection. As resistance against Striga spp. can both minimise yield losses and reduce future infestation levels in infested fields, current breeding efforts are mainly directed towards this trait. Because it is nearly impossible to screen for tolerance on highly resistant genetic lines, tolerance is often neglected. Here, we argue reconsidering the role of tolerance, as recent findings regarding the physiological expression of tolerance offer a promising track for identifying the genetic background of tolerance. Identification of quantitative trait loci for tolerance would facilitate the inclusion of this trait in adapted cultivars with high levels of resistance, where its main role would be to function as a safety net in case the genetically highly variable parasite populations overcome host-plant resistance. Because Striga spp. are mainly prevalent in subsistence farming systems, we consider this an important addition and it is for this reason that we make a plea for a more prominent role of tolerance in present-day integrated management of this weed.
Purple witchweed (Striga hermonthica) germination and seedbank depletion under different crops, fallow, and bare soil
Mourik, T.A. van; Stomph, T.J. ; Murdoch, A.J. - \ 2011
Weed Biology and Management 11 (2011)2. - ISSN 1444-6162 - p. 100 - 110.
long-term management - strategy evaluation - population-model - longevity - sorghum - banks - seeds
Seedbank density is an important aspect that determines the amount of damage that the parasitic weed, purple witchweed (Striga hermonthica; hereafter, called “Striga”), causes on its crop hosts. The seedbank depletion of Striga was measured in Mali and Niger during the 2004 rainy season under the host crops, pearl millet and sorghum, the non-host crops, cowpea and sesame, the intercrops of pearl millet or sorghum with cowpea or sesame, and fallow with or without weeding. Two methods were used and compared; namely, a seed bag method and a soil-sampling method. The fate of the seeds was assessed by a seed press test. Seed germination, as determined by the presence of empty seed coats, contributed most to the seedbank depletion of Striga under a variety of crop covers and fallow. The highest seedbank depletion was found under the monocultures of the host crops. The intercrops of the host and non-host crops caused less seedbank depletion, followed by the monocultures of the non-host crops, fallow, and bare soil. The seed bag method and the soil-sampling method yielded similar percentages of seedbank depletion, while the former allowed for distinguishing between the germinated and diseased seeds. The results suggest that, although all the tested crop species can cause the seed germination and seedbank depletion of Striga, management by using host cereal crops causes the highest amount of germination and has the highest potential to deplete the soil seed bank, provided that seed production is prevented
Lignin based controlled release coatings
Mulder, W.J. ; Gosselink, R.J.A. ; Vingerhoeds, M.H. ; Harmsen, P.F.H. ; Eastham, D. - \ 2011
Industrial Crops and Products 34 (2011)1. - ISSN 0926-6690 - p. 915 - 920.
slow-release - kraft lignin - fertilizer - formulations - urea - polymers - sorghum
Urea is a commonly used fertilizer. Due to its high water-solubility, misuse easily leads to excess nitrogen levels in the soil. The aim of this research was to develop an economically feasible and biodegradable slow-release coating for urea. For this purpose, lignin was selected as coating material. From four commercially available lignins, two lignosulfonates (Wafex P and Borresperce), a softwood kraft (Indulin AT) and soda flax lignin (Bioplast), the latter showed the best potential with respect to film forming properties. Bioplast dispersions up to a dry matter content of 50% are processable. However, high losses during processing resulted in thin coating layers on the urea granules. To reduce urea release, hydrophobic compounds and crosslinkers were added to the Bioplast dispersions. Addition of alkenyl succinic anhydride (ASA) significantly decreased the release of urea in water. However, complete release of urea still occurred within one hour, which can be explained by a low reactivity of the selected compounds towards lignin, too low percentages of applied coating or negative effects of the selected compounds on the film forming process. In addition, urea partly dissolves in the aqueous lignin dispersions due to its high water-solubility. This causes incorporation of urea in the lignin layer, which results in coatings with a low water resistance. This was improved by application of an inner coating layer with high dry matter content. In conclusion, lignin shows high potential as coating material. For industrial application, more insight in the film forming properties is desired.