Posts Tagged ‘drought’

Exploiting genetic diversity from landraces in wheat breeding for adaptation to climate change

Posted by gabrielamartinez on , in Journal Articles

56898Authors: Lopes, M.S., El-Basyoni, I., Baenziger, P.S., Sukhwinder-Singh, Royo, C., Ozbek, K., Aktas, H., Ozer, E., Ozdemir, F., Manickavelu, A., Ban, T., Vikram, P.

Published in: Journal of Experimental Botany, In press.


 

Climate change has generated unpredictability in the timing and amount of rain, as well as extreme heat and cold spells that have affected grain yields worldwide and threaten food security. Sources of specific adaptation related to drought and heat, as well as associated breeding of genetic traits, will contribute to maintaining grain yields in dry and warm years. Increased crop photosynthesis and biomass have been achieved particularly through disease resistance and healthy leaves. Similarly, sources of drought and heat adaptation through extended photosynthesis and increased biomass would also greatly benefit crop improvement. Wheat landraces have been cultivated for thousands of years under the most extreme environmental conditions. They have also been cultivated in lower input farming systems for which adaptation traits, particularly those that increase the duration of photosynthesis, have been conserved. Landraces are a valuable source of genetic diversity and specific adaptation to local environmental conditions according to their place of origin. Evidence supports the hypothesis that landraces can provide sources of increased biomass and thousand kernel weight, both important traits for adaptation to tolerate drought and heat. Evaluation of wheat landraces stored in gene banks with highly beneficial untapped diversity and sources of stress adaptation, once characterized, should also be used for wheat improvement. Unified development of databases and promotion of data sharing among physiologists, pathologists, wheat quality scientists, national programmes, and breeders will greatly benefit wheat improvement for adaptation to climate change worldwide.

Quantifying production losses due to drought and submergence of rainfed rice at the household level using remotely sensed MODIS data

Posted by Carelia Juarez on , in Journal Articles

Published in Agricultural Systems, 2014.

Mottaleb, K.A.; Gumma, M.K.; Mishra, A.K.; Mohanty, S.

Combining remotely sensed Moderate Resolution Imaging Spectroradiometer (MODIS) data with Bangladesh Household Income and Expenditure Survey (HIES) data, this study estimates losses in rainfed rice production at the household level. In particular, we estimated the rice areas affected by drought and submergence from remotely sensed MODIS data and rice production from Household Income and Expenditure Survey (HIES) data for 2000, 2005 and 2010. Applying two limit Tobit estimation method, this study demonstrated that both drought and submergence significantly affected rice production. Findings reveal that on average, a one percent increase in drought affected area at district level reduces Aman season rice production by approximately 1382 kilograms per household on average, annually. Similarly, a one percent increase in drought area reduces rainfed Aus season rice production by approximately 693 kilograms per household, on average, annually. Based on the findings the paper suggests disseminating and developing drought and submergence tolerant rice and also short duration rice varieties to minimize loss caused by drought and submergence in Aus and Aman rice seasons.

Parental genome contribution in maize DH lines derived from six backcross populations using genotyping by sequencing

Posted by Carelia Juarez on , in Journal Articles

Published in Euphytica, 2014

Ogugo, V.Fentaye Kassa SemagnBeyene, Y.Runo, S.Olsen, M.Warburton, M.L.

Molecular characterization of doubled haploid (DH) maize lines and estimation of parental genome contribution (PGC) may be useful for choosing pairs of DH lines for hybrid make up and new pedigree starts. Six BC1-derived DH populations created by crossing two donor with three recurrent parents were genotyped with 97,190 polymorphic markers with the objectives of: (i) understanding genetic purity, genetic distance and relationship among 417 maize DH lines; (ii) estimating PGC of the DH lines derived from different genetic backgrounds; and (iii) understanding the correlation between donor parent introgression and testcross performance for grain yield and anthesis-silking interval (ASI) under managed drought and optimum environments. The DH lines were 97 % genetically pure, with <2 % heterogeneity; only two DH lines showed heterogeneity >5 %, which is likely to be due to errors during seed multiplication or maintenance. Genetic distance between pairwise comparisons of the 417 DH lines ranged from 0.055 to 0.457; only 0.01 % showed a genetic distance <0.100, indicating large genetic differences among the DH lines. Both populations 1 and 6 showed significantly lower (p < 0.001) donor introgression than the other four populations. Donor parent contribution was significantly (p < 0.001) higher in the CML444 genetic background than CML395 and CML488. The average donor and recurrent PGC across all 417 DH lines was 31.7 and 64.3 %, respectively. Donor genome introgression was higher than expected in 82 % of the DH lines in the BC1 generation, possibly due to artificial selection during the DH process, during the development of F1 or BC1 seed, or during initial agronomic evaluation of the DH lines. Donor parent introgression up to 32 % showed significant positive correlation with grain yield under drought (r = 0.312, p < 0.001) and optimum (r = 0.142, p < 0.050) environments but negative correlation with ASI under drought (r = −0.276, p < 0.001). Additional multi-environment phenotype data under managed drought are needed to confirm the correlations reported in this study and to map the specific genomic regions associated with such correlations.

Managing vulnerability to drought and enhancing livelihood resilience in sub-Saharan Africa: Technological, institutional and policy options

Posted by Carelia Juarez on , in Journal Articles

Published in Weather and Climate Extremes 3 : 67-79, 2014

Shiferaw, B.Kindie Tesfaye FantayeBerresaw Menale KassieAbate, T.Prasanna, B.M.Menkir, A. 

Agriculture and the economies of Sub-Saharan Africa (SSA) are highly sensitive to climatic variability. Drought, in particular, represents one of the most important natural factors contributing to malnutrition and famine in many parts of the region. The overall impact of drought on a given country/region and its ability to recover from the resulting social, economic and environmental impacts depends on several factors. The economic, social and environmental impacts of drought are huge in SSA and the national costs and losses incurred threaten to undermine the wider economic and development gains made in the last few decades in the region. There is an urgent need to reduce the vulnerability of countries to climate variability and to the threats posed by climate change. This paper attempts to highlight the challenges of drought in SSA and reviews the current drought risk management strategies, especially the promising technological and policy options for managing drought risks to protect livelihoods and reduce vulnerability. The review suggests the possibilities of several ex ante and ex post drought management strategies in SSA although their effectiveness depends on agro-climatic and socio-economic conditions. Existing technological, policy and institutional risk management measures need to be strengthened and integrated to manage drought ex ante and to minimize the ex post negative effects for vulnerable households and regions. A proactive approach that combines promising technological, institutional and policy solutions to manage the risks within vulnerable communities implemented by institutions operating at different levels (community, sub-national, and national) is considered to be the way forward for managing drought and climate variability.

Managing vulnerability to drought and enhancing livelihood resilience in sub-Saharan Africa: Technological, institutional and policy options

Posted by Carelia Juarez on , in Journal Articles

Published in Weather and Climate Extremes 67-79, 2014

 Shiferaw, B.Kindie Tesfaye FantayeBerresaw Menale KassieAbate, T.Prasanna, B.M.Menkir, A. 

Agriculture and the economies of Sub-Saharan Africa (SSA) are highly sensitive to climatic variability. Drought, in particular, represents one of the most important natural factors contributing to malnutrition and famine in many parts of the region. The overall impact of drought on a given country/region and its ability to recover from the resulting social, economic and environmental impacts depends on several factors. The economic, social and environmental impacts of drought are huge in SSA and the national costs and losses incurred threaten to undermine the wider economic and development gains made in the last few decades in the region. There is an urgent need to reduce the vulnerability of countries to climate variability and to the threats posed by climate change. This paper attempts to highlight the challenges of drought in SSA and reviews the current drought risk management strategies, especially the promising technological and policy options for managing drought risks to protect livelihoods and reduce vulnerability. The review suggests the possibilities of several ex ante and ex post drought management strategies in SSA although their effectiveness depends on agro-climatic and socio-economic conditions. Existing technological, policy and institutional risk management measures need to be strengthened and integrated to manage drought ex ante and to minimize the ex post negative effects for vulnerable households and regions. A proactive approach that combines promising technological, institutional and policy solutions to manage the risks within vulnerable communities implemented by institutions operating at different levels (community, sub-national, and national) is considered to be the way forward for managing drought and climate variability.

Phenotyping for Abiotic Stress Tolerance in Maize

Posted by Carelia Juarez on , in Journal Articles

Published in Journal of Integrative Plant Biology  54 (4): 138-149, 2012

Benhilda Masuka, Jose Luis Araus, Biswanath Das, Kai Sonder, Jill E. Cairns

The ability to quickly develop germplasm having tolerance to several complex polygenic inherited abiotic and biotic stresses combined is critical to the resilience of cropping systems in the face of climate change. Molecular breeding offers the tools to accelerate cereal breeding; however, suitable phenotyping protocols are essential to ensure that the much-anticipated benefits of molecular breeding can be realized. To facilitate the full potential of molecular tools, greater emphasis needs to be given to reducing the within-experimental site variability, application of stress and characterization of the environment and appropriate phenotyping tools. Yield is a function of many processes throughout the plant cycle, and thus integrative traits that encompass crop performance over time or organization level (i.e. canopy level) will provide a better alternative to instantaneous measurements which provide only a snapshot of a given plant process. Many new phenotyping tools based on remote sensing are now available including non-destructive measurements of growth-related parameters based on spectral reflectance and infrared thermometry to estimate plant water status. Here we describe key field phenotyping protocols for maize with emphasis on tolerance to drought and low nitrogen.

 

Combining ability, heterosis and genetic diversity in tropical maize (Zea mays L.) under stress and non-stress conditions

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Published in Euphytica  180(2): 143-162, 2011

Combining ability, heterosis and genetic diversity in tropical maize (Zea mays L.) under stress and non-stress conditions

 Dan Makumbi, Javier F. Betrán, Marianne Bänziger and Jean-Marcel Ribaut

 Drought and low soil fertility are considered the most important abiotic stresses limiting maize production in sub-Saharan Africa. Knowledge of the combining ability and diversity of inbred lines with tolerance to the two stresses and for those used as testers would be beneficial in setting breeding strategies for stress and nonstress environments. We used 15 tropical maize inbred lines to (i) evaluate the combining ability for grain yield (GY), (ii) assess the genetic diversity of this set of inbred lines using RFLP, SSR, and AFLP markers, (iii) estimate heterosis and assess the relationship between F1 hybrid performance, genetic diversity and heterosis, and (iv) assess genotype × environment interaction of inbred lines and their hybrids. The F1 diallel hybrids and parental inbreds were evaluated under drought stress, low N stress, and well-watered conditions at six locations in three countries. General combining ability (GCA) effects were highly significant (P < 0.01) for GY across stresses and well-watered environments. Inbred lines CML258, CML339, CML341, and CML343 had the best GCA effects for GY across environments. Additive genetic effects were more important for GY under drought stress and well-watered conditions but not under low N stress, suggesting different gene action in control of GY. Clustering based on genetic distance (GD) calculated using combined marker data grouped lines according to pedigree. Positive correlation was found between midparent heterosis (MPH) and specific combining ability (SCA), GD and GY. Hybrid breeding program targeting stress environments would benefit from the accumulation of favorable alleles for drought tolerance in both parental lines.

The relative importance of drought and other water-related constraints for major food crops in South Asian farming systems

Posted by on , in Journal Articles

Published in Food Security 3(1):19-33

The relative importance of drought and other water-related constraints for major food crops in South Asian farming systems.

Xiaoyun Li; Waddington, S.R.; Dixon, J.; Joshi, A.K.; Vicente, M.C. de

Variation in water availability is a major source of risk for agricultural productivity and food security in South Asia. Three hundred and thirty expert informants were surveyed during 2008-09 to determine the relative importance of drought and water-related constraints compared with other constraints limiting the production of four major food crops (wheat, rice, sorghum, chickpea) in five broad-based South Asian farming systems. Respondents considered drought an important constraint to crop yield in those farming systems that are predominantly rainfed, but associated it with low yield losses (well below 10% of all reported losses) for crops in farming systems with well-developed irrigation. In these systems, other water-related constraints (including difficult access to sufficient irrigation water, the high cost of irrigation, poor water management, waterlogging and flooding of low-lying fields) were more important. While confirming the importance of drought and water constraints for major food crops and farming systems in South Asia, this study also indicated they may contribute to no more than 20?30% of current yield gaps. Other types of constraint, particularly soil infertility and the poor management of fertilizer and weeds for the cereals, and pests and diseases for chickpea, contributed most yield losses in the systems. Respondents proposed a wide range of interventions to address these constraints. Continued investments in crop-based genetic solutions to alleviate drought may be justified for food crops grown in those South Asian farming systems that are predominantly rainfed. However, to provide the substantial production, sustainability and food security benefits that the region will need in coming decades, the study proposed that these be complemented by other water interventions, and by improvements to soil fertility for the cereals and plant protection with chickpea.

Dual Alpha13C/Delta18O response to water and nitrogen availability and its relationship with yield in field-grown durum wheat.

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Published in Plant Cell and Environment 34(3): 418-433, 2011

Dual Alpha13C/Delta18O response to water and nitrogen availability and its relationship with yield in field-grown durum wheat

Cabrera-Bosquet L.; Albrizio, R.; Nogues, S.; Araus, J.L.

The combined use of stable carbon and oxygen isotopes in plant matter is a tool of growing interest in cereal crop management and breeding, owing to its relevance for assessing the photosynthetic and transpirative performance under different growing conditions including water and N regimes. However, this method has not been applied to wheat grown under real field conditions. Here, plant growth, grain yield (GY) and the associated agronomic components, carbon isotope discrimination (Δ13C) plus oxygen isotope composition (δ18O) as well as leaf and canopy gas exchange were measured in field-grown wheat subjected to different water and N availabilities. Water limitation was the main factor affecting yield, leaf and canopy gas exchange and Δ13C and δ18O, whereas N had a smaller effect on such traits. The combination of Δ13C and δ18O gave a clear advantage compared with gas exchange measurements, as it provides information on the instantaneous and the long-term plant photosynthetic and transpirative performance and are less labour intensive than gas exchange measurements. In addition, the combination of plant Δ13C and δ18O predicted differences in GY and related agronomical parameters, providing agronomists and breeders with integrative traits for selecting crop management practices and/or genotypes with better performance under water-limiting and N-limiting conditions.

Stem solidness and its relationship to water-soluble carbohydrates: association with wheat yield under water deficit

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Published in Functional Plant Biology 37, 166–174, 2010

Stem solidness and its relationship to water-soluble carbohydrates: association with wheat yield under water deficit

Saint Pierre C., Trethowan R., Reynolds M.

A study of 36 wheat (Triticum aestivum L.) genotypes with different levels of stem solidness was conducted to assess the heritability and relationship among stem morphological properties, stem water-soluble carbohydrates (WSC) storage capacity and grain yield. The total amount of pith-fill in the upper stem internode (VOL) was highly correlated with the total content of WSC per stem under both water deficit (DEF) (r = 0.56) and well irrigated conditions (IRR) (r = 0.49). A positive correlation was also found between VOL and grain yield under DEF (r = 0.49), which was explained by the positive contribution of WSC to grain yield. A closer association of grain yield and morphological traits was identified under DEF than under IRR. The closer associations found among estimations of %WSC and WSC-area and grain yield under DEF indicate that these variables may be adaptive rather than constitutive traits. High heritability values (0.77–0.84) observed for stem morphological traits reinforce their potential use in breeding for high WSC and ultimately, higher grain yield under water-limited environments. Stem length, diameter and solidness could be combined in an ideal plant ideotype to maximise WSC reserves as a strategy to improve yield under water-limited conditions.