Leaf rolling reduces photosynthetic loss in maize under. 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. And around25 % of the maize crop suffers from frequent drought, with losses of up to half the harvest. This behavioral information, directly elicited, is used to condition the selection of maize varieties differentiated by drought tolerance, pest resistance, maturity, and seed price.
Classification of crop tolerance to heat and droughta. Silvestro meseka, abebe menkir, bunmi bossey and wende. The project main objective is to combine different plant growth promoting and. 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. Combine data within a drought or low n experiment using a selection index. Evaluation of drought tolerance in corn zea mays l. Droughttolerant maize for africa dtma climatesmart. Biotechnology for the development of drought tolerant. Drought tolerance in maize is influenced by timing of. 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. Determinants of adoption in eastern and southern africa article pdf available in climatic change 32 july. Drought stress and artificial prevention of leaf rolling plr were applied at. 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.
Global climate change is likely to increase the risk of frequent drought. 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. 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. Pdf assessment of drought tolerance in maize zea mays l. Drought treatment caused dynamic changes in maize growth. Cimmyt iita drought tolerant maize for africa initiative. From the vantage point of an ecologist the features that distinguish xerophytic from mesophytic vegetation are clear. 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. Global importance of maize and side effects of drought on maize triggered. Droughttolerant maize hybrids were developed for the us cornbelt through molecular breeding using. Reduced lateral root branching density improves drought. We looked for quantitative trait loci qtls that affect drought tolerance in maize. A previous study has shown that transgenic plants constitutively overexpressing argos8 have reduced ethylene sensitivity and improved grain yield under drought stress conditions.
Progress in achieving and delivering drought tolerance in. 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. Thus, this study investigated the interactive effects of drought and the application of the nutrients n, p. Waseca and lamberton, the plots were harvested by a combine and plot. These results entirely support the hypothesis that reduced lateral root branching density improves drought tolerance. Drought tolerance is an important attribute of commercial maize. Improvement of drought tolerance in maize zea mays l. Resultantly, ye8112 seedlings maintained comparatively higher leaf relative water and. 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.
We hypothesized that corn hybrids containing dt traits would produce more consistent yields compared to nondt hybrids in the presence of drought stress. Drought is one of the most detrimental forms of abiotic stress around the world and seriously limits the productivity of agricultural crops. Six years of addressing african smallholder farmers needs. We can all tell that a cactus is more drought tolerant than a carnation. 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. 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. Sa government rejects monsantos triple stacked gm drought. Diversity assessment of drought tolerant exotic and. Potential benefits of drought and heat tolerance for. As maize is mostly grown as a subsistence crop, poor harvests due to drought can lead directly to hunger and malnutrition for poorer families. Cnn models combine their corresponding input variables to. 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. 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. 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.
Pdf breeding for drought tolerance in maize zea mays l. The potential benefit of drought tolerant dt corn zea mays l. A genomewide transcriptome assay of two subtropical genotypes of maize was used to observe the expression of genes at seedling stage of drought stress. 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. Approximately, 560,000 single nucleotide polymorphisms snps19 were applied to the study.
Drought tolerant maize for farmer adaptation to drought in subsaharan africa. In this study, seedling biomass was regarded as a criterion to identify drought tolerance capability. Comparative response of drought tolerant and drought. Maize harvests are affected by drought stress at different growth stages in. 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. Drought resistance tolerance has to be researchable, breakable into simpler levels e. Thus, maize drought tolerance is a consequence of coordination amongst. Approaches to mitigate yield loss include developing drought. A lot of work has been done to develop drought tolerance in maize and many other crops, that is, campos et al.
Two maize inbreds and their advanced lines were evaluated for drought related traits. Ijms free fulltext key maize droughtresponsive genes. Pdf several beneficial rhizospheric microorganisms, such as arbuscular mycorrhizal. Overall, the willingness to pay for drought tolerance and other attributes is highly heterogeneous as determined through a latent class modeling approach. However, the vast majority of droughttolerant dt corn planted in 2016. Zmnac111 is associated with maize seedling drought tolerance. 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. Pdf improvement of drought tolerance in maize zea mays l. This study compared two maize populations, zm601 and zm607 for drought tolerance during flowering, the most drought vulnerable period for the maize plant. Three experiments were conducted in minnesota to compare drought. 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. Droughttolerant corn hybrids yield more in drought. Development, adoption, and management of droughttolerant corn.
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. Drought tolerance an overview sciencedirect topics. 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. Comparative response of drought tolerant and drought sensitive maize genotypes to. In addition to drought tolerance, the varieties have other attractive traits, such as resistance to major diseases and high protein content. The fl1 lateral root phenotype merits consideration as a selection target to improve the drought tolerance of maize and possibly other cereal crops. Maize, one of the leading cereal crops in the world, is sensitive to drought stress.
Genetic variation in zmvpp1 contributes to drought. Drought tolerant genetically modified gm cotton and maize are under final field evaluations in the united states. Weather variability is an important source of production risk for rainfed agriculture in developing countries. Genomewide expression and functional interactions of genes. The growth of seedlings was not affected by melatonin. The maize argos8 gene negatively regulates the ethylene response by encoding a protein that interacts with the ethylene receptor. Therefore, the root system of a maize ideotype would combine good rooting characteristics including rapid root growth in response to water deficit that would. Several attempts have been made to combine physiological and morphological studies in maize to develop effective screening methods for drought tolerance. Mergers and competition in seed and agricultural chemical markets.
Interactive effects of n, p and knutrition and drought. Grain and silage yields with the 150% n rate were 7 and 12% greater for the drought. The breeding strategies in maize that have been adopted so far have focused on improvement of each stress separately. Assessment of drought tolerance in maize zea mays l. Maize breeding for tolerance to low soil fertility and drought in guizhou province. Drought tolerant gm maize importation and field trials of drought tolerant gm maize into south africa monsanto have been granted permits permit no. Drought tolerant maize for farmer adaptation to drought in. Drought is a major factor limiting maize zea mays l. A transposable element in a nac gene is associated with. Breeding droughttolerant maize hybrids for the us cornbelt.
Characterization of maize inbred lines for drought and. Last year, south africa was home to the first field trial for a transgenic drought tolerant maize crop, incorporating a gene from the. Delivering drought tolerance in maize an update is entirely excerpted from the. Maize argos8 is a negative regulator of ethylene responses. Currently, several regions are growing more and more drought tolerant maize, most of which is derived from conventional breeding. Tolerant inbred lines tx205, c2a5544, and b76 were able to maintain relatively high leaf relative water content when subjected. Physiological evaluations of recent droughttolerant maize hybrids at. Breeding droughttolerant maize hybrids for the us corn. A genetic linkage map developed using rflp markers was used to identify qtls associated with. The dt maize varieties have been bred using modern conventional methods, without genetic modification. Drought stress on the development of maize seedlings christoph.
Pdf drought tolerant maize for farmer adaptation to. Potential benefits of drought and heat tolerance for adapting maize. Pdf drought, like many other environmental stresses, has adverse effects on crop yield including maize zea mays l. To explore the targeted use of argos8 native expression variation in drought. Climate projections suggest higher temperatures within drought prone areas. 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. To unravel the molecular mechanisms underpinning maize zea mays l. The big seed companies are also contributing expertise. Feng qin and colleagues perform a genomewide association study for drought tolerance in maize seedlings and find 42 candidate genes. Summary and the special feature on drought tolerance in maize. Developing drought and low n tolerant maize cimmyt.
Within this context, promoting the idea of a drought tolerant maize plant appears very attractive, especially in semiarid regions of africa and more so in the light of the. Research in model species suggests that tolerance to combined drought and heat stress is genetically distinct from tolerance to either stress. The need to breed maize cultivars with improved drought tolerance is apparent. Drought tolerance is one of the most important but complex traits of crops. Molecular mapping of quantitative trait loci for drought. Research underlying the development of drought tolerance in corn. Rice tends to be more sensitive to drought stress than other crops.
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