Determinants of adoption in eastern and southern africa article pdf available in climatic change 32 july. Molecular markers are being used to identify drought related quantitative trait loci qtl and their efficient transfer into commercially grown crop varieties of rice, wheat, maize, pearl millet, and barley. Approximately, 560,000 single nucleotide polymorphisms snps19 were applied to the study. Ramshini4 abstract in order to study the effect of drought stress on morphophysiologic characteristics, yield and yield components of 8 new hybrids of corn zea maize l. Pdf drought tolerant maize for farmer adaptation to.
Cnn models combine their corresponding input variables to. This behavioral information, directly elicited, is used to condition the selection of maize varieties differentiated by drought tolerance, pest resistance, maturity, and seed price. Leaf rolling reduces photosynthetic loss in maize under. Launched in 2006, the drought tolerant maize for africa dtma project aims to mitigate drought and other constraints to maize production in subsaharan africa, increasing maize yields by at least one ton per hectare under moderate drought and with a 20 to 30% increase over farmers. Development, adoption, and management of droughttolerant corn. To unravel the molecular mechanisms underpinning maize zea mays l. Drought tolerant maize for farmer adaptation to drought in. Effects of leaf rolling lr on maize photosynthesis under severe drought stress were studied in two cultivars with opposite drought responses, batem 5655 drought tolerant and batem 5152 drought sensitive. A genomewide transcriptome assay of two subtropical genotypes of maize was used to observe the expression of genes at seedling stage of drought stress. Press release from the african centre for biodiversity sa government rejects monsantos triple stacked gm drought tolerant maize johannesburg 15 november 2018 the african centre for biodiversity acb welcomes the decision of the south african biosafety authorities, rejecting monsantos application for the commercial release of its gm drought tolerant triple stacked maize. Classification of crop tolerance to heat and droughta. A genetic linkage map developed using rflp markers was used to identify qtls associated with.
The maize argos8 gene negatively regulates the ethylene response by encoding a protein that interacts with the ethylene receptor. Pdf assessment of drought tolerance in maize zea mays l. The drought tolerant maize for africa seed scaling dtmass project was officially launched in 2014 with the aim to meet demand and improve access to goodquality maize through production and deployment of affordable and improved drought tolerant, stressresilient and highyielding maize varieties for smallholder farmers. Edmeades, progress in achieving and delivering drought tolerance in maize an update, supported by key references, was originally. Drought stress on the development of maize seedlings christoph. Comparative response of drought tolerant and drought sensitive maize genotypes to. Drought tolerant maize for farmer adaptation to drought in subsaharan africa. Thus, this study investigated the interactive effects of drought and the application of the nutrients n, p. Drought tolerant maize for africa seed scaling dtmass. Silvestro meseka, abebe menkir, bunmi bossey and wende. Global climate change is likely to increase the risk of frequent drought. These results entirely support the hypothesis that reduced lateral root branching density improves drought tolerance. Droughttolerant maize hybrids were developed for the us cornbelt through molecular breeding using.
Reduced lateral root branching density improves drought. Pdf improvement of drought tolerance in maize zea mays l. Thus, maize drought tolerance is a consequence of coordination amongst. Research underlying the development of drought tolerance in corn. Last year, south africa was home to the first field trial for a transgenic drought tolerant maize crop, incorporating a gene from the.
The fl1 lateral root phenotype merits consideration as a selection target to improve the drought tolerance of maize and possibly other cereal crops. Drought is a major factor limiting maize zea mays l. Progress in achieving and delivering drought tolerance in. Tolerant inbred lines tx205, c2a5544, and b76 were able to maintain relatively high leaf relative water content when subjected.
Drought tolerance is one of the most important but complex traits of crops. Waseca and lamberton, the plots were harvested by a combine and plot. Breeding droughttolerant maize hybrids for the us cornbelt. Diversity assessment of 48 tropical drought tolerant maize inbreds, 24 each from cimmyt and iita, was carried out with microsatellite markers to determine the genetic divergence between the two groups of maize inbred lines. Characterization of maize inbred lines for drought and. Overall, the willingness to pay for drought tolerance and other attributes is highly heterogeneous as determined through a latent class modeling approach. Drought tolerance in maize is influenced by timing of. Molecular mapping of quantitative trait loci for drought. Summary and the special feature on drought tolerance in maize. Drought is one of the most detrimental forms of abiotic stress around the world and seriously limits the productivity of agricultural crops. A transposable element in a nac gene is associated with. Droughttolerant maize for africa dtma climatesmart.
Drought resistance tolerance has to be researchable, breakable into simpler levels e. Biotechnology for the development of drought tolerant. Pdf breeding for drought tolerance in maize zea mays l. Drought tolerant gm maize importation and field trials of drought tolerant gm maize into south africa monsanto have been granted permits permit no. Interactive effects of n, p and knutrition and drought. The dt maize varieties have been bred using modern conventional methods, without genetic modification. This paper evaluates the impacts of the adoption of drought tolerant maize varieties on average maize yield, yield stability, risk exposure and resource use in rainfed smallholder maize farming. Comparative response of drought tolerant and drought. Assessment of drought tolerance in maize zea mays l. And around25 % of the maize crop suffers from frequent drought, with losses of up to half the harvest.
Cimmyt iita drought tolerant maize for africa initiative. Just this week, south africa rejected the application of bayer for the approval of another variation of the ge maize for cultivation because it did not show any advantages. Climate projections suggest higher temperatures within drought prone areas. Several attempts have been made to combine physiological and morphological studies in maize to develop effective screening methods for drought tolerance. Grain and silage yields with the 150% n rate were 7 and 12% greater for the drought. Drought treatment caused dynamic changes in maize growth. This study compared two maize populations, zm601 and zm607 for drought tolerance during flowering, the most drought vulnerable period for the maize plant. Maize argos8 is a negative regulator of ethylene responses.
Evaluation of drought tolerance in corn zea mays l. Resultantly, ye8112 seedlings maintained comparatively higher leaf relative water and. Therefore, the root system of a maize ideotype would combine good rooting characteristics including rapid root growth in response to water deficit that would. Zmnac111 is associated with maize seedling drought tolerance. Genetic variation in zmvpp1 contributes to drought. Combine data within a drought or low n experiment using a selection index. Maize breeding for tolerance to low soil fertility and drought in guizhou province. Delivering drought tolerance in maize an update is entirely excerpted from the. Weather variability is an important source of production risk for rainfed agriculture in developing countries. The project main objective is to combine different plant growth promoting and.
Preliminary results of hybrids evaluated under the drought tolerant maize for africa dtma project revealed that tolerance to ds does not necessarily confer tolerance to hts or. Diversity assessment of drought tolerant exotic and. Three experiments were conducted in minnesota to compare drought. The need to breed maize cultivars with improved drought tolerance is apparent. Drought tolerant genetically modified gm cotton and maize are under final field evaluations in the united states. Drought stress and artificial prevention of leaf rolling plr were applied at.
To explore the targeted use of argos8 native expression variation in drought. We can all tell that a cactus is more drought tolerant than a carnation. Maize, one of the leading cereal crops in the world, is sensitive to drought stress. Drought tolerance is an important attribute of commercial maize. The drought tolerant maize for africa project has contributed towards improving seed system in subsaharan africa for the past almost nine years 20072015, through development of drought tolerant welladapted maize hybrids and openpollinated varieties to help farmers across countries in eastern, west and southern africa, cope with drought constraint in maize farming. The number of genes expressed differentially was greater in hki1532 a drought tolerant genotype than in pc3 a drought sensitive genotype, indicating primary differences at the transcriptional level in stress tolerance. The growth of seedlings was not affected by melatonin. Drought tolerance is a nebulous term that becomes more nebulous the more closely we look at it, much as a newspaper photograph does when viewed through a magnifying glass. Pdf several beneficial rhizospheric microorganisms, such as arbuscular mycorrhizal. Pdf drought, like many other environmental stresses, has adverse effects on crop yield including maize zea mays l.
In this study, seedling biomass was regarded as a criterion to identify drought tolerance capability. Approaches to mitigate yield loss include developing drought. Although drought tolerance in maize could be attributed to multiple plant traits, only root traits are simulated in this study mainly because a deep root system is one of the major traits to select for drought tolerance in maize ribaut et al. Rice tends to be more sensitive to drought stress than other crops. Some examples of conventional breeding programs for drought tolerance are the development of rice, wheat and indian mustard varieties tolerant to salt and to alkali soils by the central soil salinity research institute in karnal, india 3. Sa government rejects monsantos triple stacked gm drought. In addition to drought tolerance, the varieties have other attractive traits, such as resistance to major diseases and high protein content. Feng qin and colleagues perform a genomewide association study for drought tolerance in maize seedlings and find 42 candidate genes. From the vantage point of an ecologist the features that distinguish xerophytic from mesophytic vegetation are clear. Six years of addressing african smallholder farmers needs. In the last decade, new phenotyping and genomics technologies have enabled evaluation of new breeding approaches intended to accelerate the rate of genetic improvement of droughttolerant maize hybrids for drought prone environments across the us cornbelt. Mergers and competition in seed and agricultural chemical markets.
The maize seedling biomass was measured as fresh weight and dry weight and subsequently calculated as drought tolerance index dti to compare the drought response performance of various inbred lines. Droughttolerant corn hybrids yield more in drought. As maize is mostly grown as a subsistence crop, poor harvests due to drought can lead directly to hunger and malnutrition for poorer families. Maize harvests are affected by drought stress at different growth stages in. Drought tolerance an overview sciencedirect topics. We hypothesized that corn hybrids containing dt traits would produce more consistent yields compared to nondt hybrids in the presence of drought stress. However, the vast majority of droughttolerant dt corn planted in 2016. Physiological evaluations of recent droughttolerant maize hybrids at. We looked for quantitative trait loci qtls that affect drought tolerance in maize. The breeding strategies in maize that have been adopted so far have focused on improvement of each stress separately. Pdf breeding for drought and nitrogen stress tolerance in maize. Global importance of maize and side effects of drought on maize triggered. Developing drought and low n tolerant maize cimmyt.
To reduce vulnerability and improve food security, the drought tolerant maize for africa dtma project released 160 drought tolerant maize varieties between 2007 and 20. The big seed companies are also contributing expertise. Research in model species suggests that tolerance to combined drought and heat stress is genetically distinct from tolerance to either stress. In this report, we evaluated a selection of maize inbred lines for drought and heat stress tolerance under field conditions in 2009 and 2010 and identified several inbred lines that showed high tolerance to drought.
A lot of work has been done to develop drought tolerance in maize and many other crops, that is, campos et al. Potential benefits of drought and heat tolerance for adapting maize. A previous study has shown that transgenic plants constitutively overexpressing argos8 have reduced ethylene sensitivity and improved grain yield under drought stress conditions. Currently, several regions are growing more and more drought tolerant maize, most of which is derived from conventional breeding. Breeding droughttolerant maize hybrids for the us corn. The distribution of drought tolerant maize is particularly urgent in the region because most of eastern and southern africa is suffering intense drought conditions, aggravating food insecurity in many areas.
Potential benefits of drought and heat tolerance for. The effect of melatonin application on enhancing plant stress tolerance is already known, but the specifics of its performance and its underlying mechanism are still poorly understood. Two maize inbreds and their advanced lines were evaluated for drought related traits. Improvement of drought tolerance in maize zea mays l. A systems approach to a spatiotemporal understanding of. Genomewide expression and functional interactions of genes. Ijms free fulltext key maize droughtresponsive genes. Drought is a major cause of yield loss in maize and understanding the genetic determinants of natural variation in drought tolerance may aid breeding programs produce more tolerant. To identify genes associated with maize drought tolerance, we performed gwas by analysing a natural maize population, consisting of 368 inbred lines that were collected from tst and temperate regions of the world19.
899 748 227 70 1225 820 1580 600 1308 599 359 515 1617 150 1266 1045 535 1298 451 182 607 337 796 982 1122 473 1336 18 1074 994 1623 681 1219 212 1646 1379 1222 295 906 488 109 188 1402 1385 1078 1331 1154