CIMMYT International

El Barrancón del Tío Blas (El Barrancón), Mexico

CIMMYT International

El Barrancón del Tío Blas (El Barrancón), Mexico
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Obanor F.,CSIRO | Erginbas-Orakci G.,Eskiehir Osmangazi University | Tunali B.,Ondokuz Mayis University | Nicol J.M.,CIMMYT International | Chakraborty S.,CSIRO
Fungal Biology | Year: 2010

Fusarium culmorum is a major pathogen of wheat and barley causing head blight and crown rot in cooler temperate climates of Australia, Europe, West Asia and North Africa. To better understand its evolutionary history we partially sequenced single copy nuclear genes encoding translation elongation factor 1-α (TEF), reductase (RED) and phosphate permease (PHO) in 100 F. culmorum isolates with 11 isolates of Fusarium crookwellense, Fusarium graminearum and Fusarium pseudograminearum. Phylogenetic analysis of multilocus sequence (MLS) data using Bayesian inference and maximum parsimony analysis showed that F. culmorum from wheat is a single phylogenetic species with no significant linkage disequilibrium and little or no lineage development along geographic origin. Both MLS and TEF and RED gene sequence analysis separated the four Fusarium species used and delineated three to four groups within the F. culmorum clade. But the PHO gene could not completely resolve isolates into their respective species. Fixation index and gene flow suggest significant genetic exchange between the isolates from distant geographic regions. A lack of strong lineage structure despite the geographic separation of the three collections indicates a frequently recombining species and/or widespread distribution of genotypes due to international trade, tourism and long-range dispersal of macroconidia. Moreover, the two mating type genes were present in equal proportion among the F. culmorum collection used in this study, leaving open the possibility of sexual reproduction. © 2010 The British Mycological Society.

Tunali B.,Ondokuz Mayis University | Obanor F.,CSIRO | Erginbas G.,Eskiehir Osmangazi University | Westecott R.A.,Ondokuz Mayis University | And 2 more authors.
FEMS Microbiology Ecology | Year: 2012

Crown rot and head blight of wheat are caused by the same Fusarium species. To better understand their biology, this study has compared 30 isolates of the three dominant species using 13 pathogenic and saprophytic fitness measures including aggressiveness for the two diseases, saprophytic growth and fecundity and deoxynivalenol (DON) production from saprophytic colonization of grain and straw. Pathogenic fitness was generally linked to DON production in infected tissue. The superior crown rot fitness of Fusarium pseudograminearum was linked to high DON production in the stem base tissue, while Fusarium culmorum and Fusarium graminearum had superior head blight fitness with high DON production in grains. Within each species, some isolates had similar aggressiveness for both diseases but differed in DON production in infected tissue to indicate that more than one mechanism controlled aggressiveness. All three species produced more DON when infecting living host tissue compared with saprophytic colonization of grain or straw, but there were significant links between these saprophytic fitness components and aggressiveness. As necrotrophic pathogens spend a part of their life cycle on dead organic matter, saprophytic fitness is an important component of their overall fitness. Any management strategy must target weaknesses in both pathogenic fitness and saprophytic fitness. © 2012 Federation of European Microbiological Societies.

Zou C.Q.,Key Laboratory of Plant Soil Interaction | Zhang Y.Q.,Key Laboratory of Plant Soil Interaction | Rashid A.,Pakistan Academy of science | Ram H.,Punjab Agricultural University | And 16 more authors.
Plant and Soil | Year: 2012

Aim: Zinc (Zn) fertilization is an effective agronomic tool for Zn biofortification of wheat for overcoming human Zn deficiency. But it still needs to be evaluated across locations with different management practices and wheat cultivars, since grain Zn concentrations may be significantly affected by locations, cultivars and management. Materials: Field experiments were conducted over 3 years with the following four Zn treatments: nil Zn, soil Zn application, foliar Zn application and soil + foliar Zn application to explore the impact of Zn fertilization in Zn biofortification of wheat. The experiments were conducted at a total of 23 experimental site-years in China, India, Kazakhstan, Mexico, Pakistan, Turkey and Zambia. Results: The results showed that foliar Zn application alone or in combination with soil application, significantly increased grain Zn concentrations from 27 mg kg-1 at nil Zn to 48 and 49 mg kg-1 across all of 23 site-years, resulting in increases in grain Zn by 84 % and 90 %, respectively. Overall, soil Zn deficiency was not a growth limiting factor on the experimental sites. A significant grain yield increase in response to soil Zn fertilization was found only in Pakistan. When all locations and cropping years are combined, soil Zn fertilization resulted in about 5 % increase in grain yield. Foliar Zn application did not cause any adverse effect on grain yield, even slightly improved the yield. Across the 23 site-years, soil Zn application had a small effect on Zn concentration of leaves collected before foliar Zn application, and increased grain Zn concentration only by 12 %. The correlation between grain yield and the effectiveness of foliar Zn application on grain Zn was condition dependent, and was positive and significant at certain conditions. Conclusion: Foliar Zn application resulted in successful biofortification of wheat grain with Zn without causing yield loss. This effect of Zn fertilization occurred irrespective of the soil and environmental conditions, management practices applied and cultivars used in 23 site-years. Foliar Zn fertilizer approach can be locally adopted for increasing dietary Zn intake and fighting human Zn deficiency in rural areas. © 2012 Springer Science+Business Media B.V.

Rosyara U.,Institute of Agriculture and Animal Science | Rosyara U.,South Dakota State University | Subedi S.,Institute of Agriculture and Animal Science | Duveiller E.,CIMMYT International | Sharma,ICARDA
Journal of Phytopathology | Year: 2010

Terminal heat and spot blotch caused by Cochliobolus sativus are important stresses causing significant wheat (Triticum aestivum L.) yield losses in the south Asian plains. Recent studies have shown that chlorophyll-related traits are correlated with heat stress and spot blotch resistance in wheat. This study was conducted to evaluate leaf photochemical efficiency and leaf greenness (measured as SPAD value) for combined selection of spot blotch and terminal heat stress. The efficiency of photosystem II was measured as ratio of variable to maximal chlorophyll fluorescence, Fv/Fm, using chlorophyll fluorometer build on pulse modulation principle. The study was conducted in three spring wheat populations derived by crossing spot blotch-resistant wheat genotypes 'Milan/Shanghai#7', 'Chirya.3' and 'NL971' with a susceptible cultivar 'BL 1473'. The F3 and F4 generations were grown under natural epiphytotics of spot blotch either in optimal or in terminal heat stress conditions at Rampur, Nepal. The heritability (h2) of Fv/Fm, SPAD measurements and their genetic correlation with 1000-kernel weight (TKW) and area under disease progress curve (AUDPC) were estimated. The h2 estimates for Fv/Fm and SPAD measurements were moderate to high. In addition, AUDPC and TKW showed low to high genetic correlation with these traits. These findings suggest that Fv/Fm and SPAD measurements could be used as complementary traits in selecting for spot blotch resistance and heat tolerance in wheat. © 2010 Blackwell Verlag GmbH.

Devkota K.P.,CIMMYT International | Manschadi A.,University of Natural Resources and Life Sciences, Vienna | Lamers J.P.A.,University of Bonn | Devkota M.,Post Doctoral Fellow | Vlek P.L.G.,University of Bonn
European Journal of Agronomy | Year: 2013

Increasing water shortage and low water productivity in the irrigated drylands of Central Asia are compelling farmers to develop and adopt resource conservation technologies. Nitrogen (N) is the key nutrient for crop production in rice-wheat cropping systems in this region. Nitrogen dynamics of dry seeded rice-(aerobic, anaerobic) planted in rotation with wheat (well drained, aerobic) can differ greatly from those of conventional rice cultivation. Soil mineral N dynamics in flood irrigated rice has extensively been studied and understood, however, the impact of establishment method and residue levels on this dynamics remains unknown. Experiments on resource conservation technologies were conducted between 2008 and 2009 to assess the impact of two establishment methods (beds and flats) in combination with three (R0, R50 and R100) residue levels and two irrigation modes (alternate wet and dry (AWD) irrigation (all zero till), and a continuously flooded conventional tillage (dry tillage)) with water seeded rice (WSR) on the mineral N dynamics under dry seeded rice (DSR)-surface seeded wheat systems. N balance from the top 80cm soil layers indicated that 32-70% (122-236kgha-1) mineral N was unaccounted (lost) during rice cropping. The amount of unaccounted mineral N was affected by the irrigation method. Residue retention increased (p<0.001) the unaccounted mineral N content by 38%. With AWD irrigation, the N loss was not different among dry seeded rice in flat (DSRF), dry seeded rice in bed (DSRB), and conventional tillage WSR. Under different irrigation, establishment methods and residue levels, unaccounted mineral N was mainly affected by plant N uptake and soil mineral N content. Major amounts (43-58%) of unaccounted mineral N from DSR field occurred between seeding and panicle initiation (PI). During the entire rice and wheat growing seasons, NH4N consistently remained at very high levels, while, NO3N remained at very low levels in all treatments. In rice, the irrigation method affected NH4N content. Effect of residue retention and establishment methods were not significant on NH4N and NO3N dynamics in both crops and years. Further evidence of the continuously fluctuating water filled pore spaces (WFPS) of 64% and the microbial aerobic activity of 93% at the top 10cm soil surface during rice growing season indicates soil in the DSR treatments was under frequent aerobic-anaerobic transformation, a conditions very conducive for higher amounts of N loss. In DSR treatments, the losses appeared to be caused by a combination of denitrification, leaching and N immobilization. When intending to use a DSR management strategies need to be developed for appropriate N management, irrigation scheduling, and residue use to increase mineral N availability and uptake before this practices can be recommended. © 2013 Elsevier B.V.

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