Wheat is an important cereal crop and staple food in Pakistan. Most of the wheat is cultivated late after cotton, rice and sugarcane. Introduction of long duration Bt cotton varieties further pushed its sowing to late December or even early January. Late sowing of wheat crop results in yield loss in the Punjab province. A study has been conducted in experimental fields of Wheat Research Institute, AARI, Faisalabad, Pakistan to find out the possible reasons of low grain yields in late sown crop. Twelve experimental wheat lines were planted on seven sowing dates starting from 1st November to 30th December with ten days interval. The experimental design was a factorial combination of seven sowing dates as main plots and twelve varieties/ genotypes as subplots in a split-plot design with three replications. Effect of temperature on several crop growth stages was studied. Mean minimum temperature during the month of December, 2016 and January, 2017 remained below 5?C and mean maximum was more than 30?C during March 2017. Weather conditions experienced by the crop at each developmental stage were compared with the optimum conditions required on that specific stage in each sowing date. It was revealed that in late sown crop, different phonological/growth stages of the crop and yield components and grain yield were affected negatively. It was concluded from the study that the late sown crop suffered from two types of temperature stresses. The late sown crop faced low temperature stress at starting phase which result in delayed germination and low tillering. At caryopsis formation and grain filling the same crop face high temperature stress causing reduced grain formation and shriveled grains due to enforced maturity. Sowing of wheat at proper time i.e., by the end of November was recommended to fetch maximum yields.
Primary Author: Subhani, Wheat Research Institute, Faisalabad, Pakistan
Keywords: yield, Pakistan
This paper offers projections of potential effects of climate change on rusts of wheat and how we should factor in a changing climate when planning for the future management of these diseases. Even though the rusts of wheat have been extensively studied internationally, there is a paucity of information on the likely effects of a changing climate on the rusts and hence on wheat production. Due to the lack of published empirical research we relied on the few published studies of other plant diseases, our own unpublished work and relevant information from the vast literature on rusts of wheat to prepare this overview. Potential risks from a changing climate were divided into three major groups: increased loss from wheat rusts, new rust races evolving faster and the reduced effectiveness of rust resistances. Increased biomass of wheat crops grown in the presence of elevated CO2 concentrations and higher temperatures will increase the leaf area available for attack by the pathogen. This combined with increased speed of the pathogen’s life cycle, may increase the rate of epidemic development in many environments. Likewise, should the effects of climate change result in more conducive conditions for rust development there will also be a corresponding increase in the rate of evolution of new and presumably virulent races. The effectiveness of some rust resistance genes are influenced by temperature, crop development stage and even nitrogen status of the host. It is likely that direct and indirect changes on the host from climate change may influence the effectiveness of some of these resistance genes. Currently the likely effects of climate change on the effectiveness of disease resistance is not known and since disease resistance breeding is a long term strategy it is important to determine if any of the important genes may become less effective due to climate change. Studies must be made to acquire new information on the rust disease triangle to increase the adaptive capacity of wheat under climate change. BGRI leadership is needed to broker research on rust evolution and the durability of resistance under climate change.
Primary Author: Sukumar Chakraborty, CSIRO Plant Industry, Australia
Kazakhstan is among the ten largest grain exporters in the world. Winter wheat in Kazakhstan is mainly cultivated in the southern and south-eastern regions on an area of 1.5-2 million hectares, including 140-170 thousand hectares - in irrigated lands. Annual losses of wheat yield from diseases can reach up to 30-40% or more. For Kazakhstan, the most dangerous diseases of winter wheat are stripe rust and leaf rust. Work is under way in Kazakhstan to find new donors for resistance to leaf rust and stripe rust and the use of these donors in breeding. The aim of this research was to expand genetic diversity through crosses and development of lines obtained by the method of remote hybridization, as well as selection of new sources of resistance of bread wheat to leaf rust and stripe rust in southeast Kazakhstan. The subject of the research were 49 hexaploidsynthtic lines of Kyoto University (Japan) and CIMMYT and commercial varieties of winter wheat in the Almaty region. We screened synthetic hexaploid wheat for resistance to diseases. A collection of hexaploid synthetic wheat lines resistant to the diseases and adapted to various conditions of the Almaty region has been established. The character of inheritance of resistance to diseases in crosses of synthetic wheat with local cultivars based on comparison of the first generation and parents was studied. Evaluation of phenotypes inheritance of resistance in hybrids in the generation of F2, showed that 9crosses of synthetic wheat(LANGDON/IG 48042//ZHETISU, LANGDON/IG 48042//FARABI, LANGDON/KU-20-8//AJARLY, LANGDON/KU-2075//AJARLY, LANGDON/KU-2097// ZHETISU, LANGDON/KU-2075//FARABI, LANGDON/KU-2100//STEKLOV, LANGDON/KU-2144//NAZ, LANGDON/KU-2076//NAZ)possess the dominant resistance genes to leaf rust.Seven lines(LANGDON/ KU-2075/AJARLY, LANGDON/KU-2075/FARABI, LANGDON/KU-2092/FARABI, LANGDON/KU-2100/NAZ, LANGDON/KU-2097/STEKLOVINDAYA, LANGDON/KU-2097/ZHETISU, LANGDON/KU-2097/ AJARLY) possess from one to several dominant resistance genes to stripe rust.
Primary Author: Suleimanova, Kazakh National Agrarian University
Wheat stripe rust is an important air borne disease caused by Puccinia striiformis f. sp. tritici, and seriously threatens the safety of wheat production. Breeding and utilization of resistant varieties is the most economical, safe and effective measure to control wheat stripe rust. Sifangmai is a landrace from the state of Guangxi, China, and maintains good resistance to the current epidemic species CYR34, CYR33, CYR32 and CYR29 in China. Sifangmai was crossed with Taichung 29 to obtain F1, F2 and F2:3 to analyze its character of inheritance. In the adult stage, the cross of Sifangmai /Taichung 29 was inoculated by CYR32. The genetic analysis showed that the resistance of Sifangmai to CYR32 was controlled by a dominant gene, named as YrSF. A mapping population of F2 was genotyped with simple sequence repeat (SSR) markers. SSR loci Xgpw8015, Xgpw4098, Xwmc73, Xgpw8092, Xgpw7309 and Xbarc89 on 5B chromosome showed polymorphic between Taichung 29, Sifangmai, and resistant and susceptible pools, indicating that the resistant gene in Sifangmai was located on the 5B chromosome. The linkage map of these SSR markers was constructed and the nearest SSR to the gene is Xgpw8015. A set of Chinese Spring nulli-tetrasomic lines was used to confirm YrSF on chromosome 5B. YrSF is different from known genes in chromosome 5B. Xgpw8015 can be used as a marker for detection of YrSF.
Primary Author: Sun, Institute of Plant Protection, Chinese Academy of Agricultural Sciences
Pgt race TKTTF, virulent for the SrTmp gene present in Ethiopian cv. Digalu and first detected in 2012, caused significant yield losses in Digalu during the 2013 and 2014 seasons. No suitable replacement varieties with significant seed volume were available, and alternate solutions were sought. EIAR, with the support of the DRRW project through CIMMYT-Ethiopia, introduced 5 tonnes of adult plant, rust resistant wheat cv. Kingbird from Kenya. Kingbird was evaluated for agronomic performance at seven locations vs. three checks in 2014, and was also evaluated for stem rust reaction in single-race nurseries (TKTTF, TTKSK, TRTTF and JRCQC). With support from USAID/CIMMYT, seed was concurrently multiplied on 37 ha producing 80 tonnes of seed that was distributed to farmers in 2015. Mean grain yield over locations was 2.76 t ha-1. Mean performance of Kingbird was 3.00 t ha-1 compared to 2.79 t ha-1 for Ogolcho, 2.83 t ha-1 for Biqa and 2.42 t ha-1 for Kakaba. Thus Kingbird gave yield advantages of 5 to 22% over the check varieties. Stem rust severities on Kingbird in the single race nurseries ranged from Tr to 15% and reactions ranged from TMR to SMS. The check varieties rated up to 45% severity with S type reactions. Thus Kingbird was superior in terms of yield potential and stem rust resistance as measured in these trials vs. the check varieties. Stem rust resistance of Kingbird is based on Sr2 and Sr57 and is hypothesized to have at least three additional APR loci. Seedling reactions of Kingbird to races TKTTF and Ug99 are characterized as susceptible. Sr57 is pleiotropic and confers partial resistance to all three rusts, powdery mildew, spot blotch, and BYDV. Based on early maturity, yield performance, and stem rust resistance, Kingbird is recommended for low- to mid-altitude wheat-growing areas of Ethiopia.
Primary Author: Tadesse, Kulumsa Agricutural Research Center, Ethiopian Institute of Agricultural Research, Ethiopia
Keywords: Ethiopia, epidemics, kingbird
Durum wheat landraces have constituted the main source of Moroccan wheat production until the first half of the last century. This local germplasm is still cultivated in less favorable environments particularly in mountains and sub-Saharan regions. In recent decades of the late 20th and early 21th centuries, the genetic improvement had led to the release of new durum wheat cultivars highly uniform and more productive. The present paper investigates the evolution of genetic variability in terms of productivity and quality related traits using an historical series of Moroccan durum wheat genotypes grouped according to their period of release into "Landraces/ Old cultivars," "Intermediate cultivars," and "Modern cultivars". A significant improvement was achieved in durum wheat Morroccan productivity. Modern cultivars exceed their predecessors in terms of productivity related traits. The genetic gain was clearly associated with a reduction in plant cycle and plant height lowering the straw yield which resulted in an increase of grain yield estimated to 15.42Kg/ha/year. However, results revealed a reduction in terms of almost all quality related traits; -0.12% per year for protein content, -0.30 % per year for gluten strength, -0.31% per year for yellow pigment content, and -0.19% per year for vitreousness. The results underline the important variability in grain quality attributes among landraces genotypes. This local germplasm may be used as sources of quality-improving attributes in durum wheat breeding program to develop new varieties combining both high productivity and grain quality.
Primary Author: Taghouti, INRA
Rust diseases are considered the main stress factors that limit wheat productivity in the Azerbaijan. The studies on the impact of rust diseases on physiological processes at reproductive vegetation period is of very importance with view of evaluating size of yield and quality of the studied genotypes. For this purpose the studies focused on bread wheat genotypes (Triticum aestivum L.), which differ sharply by architectonics, biological peculiarities and resistance to rust diseases. Comparative evaluation of the studied genotypes by physiological and quality parameters has been undertaken in two options: over plants infected with diseases in natural background, and over healthy plants (fungicide sprayed plants). Area of photosynthesis apparatus of leaf story (18,3-50,2 sm2) of the studied wheat genotypes changes in wide interval. Infestation level of leaves with yellow rust (Puccinia striiformis West.) in wheat genotypes grown in natural infection background fluctuates between 5MS-40S in ontogenesis, but between 10MS-90S with brown rust (Puccinia recondita Desm.).
High level of infection with rust diseases leads to reduced size of leaf assimilation area and defoliation. Reduction of these dimensions makes up 10-90% in lower story leaves of genotypes infected with rust diseases, but 20-30% in upper story leaves. Genotypes with large and bending leaves subject to this disease more frequently. Value of photosynthesis intensity in ontogenesis at upper story leaves of the genotypes infected with rust diseases at natural background fluctuates between 6-18 ?mol CO2 .m-2.s-1 depending on level of infection, but in healthy plants between 16-29 ?molCO2 .m-2.s-1. Negative impact of these diseases on normal course of plant physiological process ultimately causes is reflected in yield and quality parameters.
Primary Author: Talai, Research Institute of Crop Husbandry, Azerbaijan
Keywords: bread wheat
Rust diseases in wheat are the major threat to wheat production and yield gains. The breakdown in resistance of certain major genes and new emerging aggressive races of rusts are causing serious concerns in all main wheat growing areas of the world. Therefore, it is the need of the hour to search for new sources of resistance genes or QTL's for effective utilization in future breeding programs. In total 100 wheat genotypes were evaluated for seedling and adult-plant resistance to stem rust races TKTTF and TTKSK at Tel Hadya-Syria, and Njoro-Kenya, and Kelardasht-Iran. Evaluation to Yr27 virulent stripe rust race was carried out at Tel Hadya and Terbol-Lebanon research stations. In this study we used genome wide association studies (GWAS) to identify markers or QTLs linked to stem rust and stripe rust races using Diversity Arrays Technology (DArT?) in selected 35 Iranian wheat genotypes. The association of markers and phenotypes was carried out using a unified mixed-model approach (MLM) as implemented in the genome association and prediction integrated tool (GAPIT). Out of 3,072 markers, 986 were polymorphic and used for marker trait associations. A total of 44 DArT markers were identified to be significantly (p<=0.01) associated with studied traits in 16 genomic regions 1A, 1B, 2A, 4A, 6A, 7A, 1B.1R, 2B, 3B, 4B, 5B, 5B.7B, 6B, 7D and an unknown region. Among associated markers, 34 were linked to stem and nine to stripe rust. They were found on 16 genomic regions on chromosome arms 1A, 1B, 2A, 4A, 6A, 7A, 1B.1R, 2B, 3B, 4B, 5B, 5B.7B, 6B, 7D and an unknown region. Associated markers explained phenotypic variation ranging from 21 to 65%. In addition to validation of previously identified genes, this study revealed new QTL's linked to stem and stripe rust which will assist breeders to develop new resistant varieties.
Primary Author: Tehseen, Department of Field Crops, Ege University, Izmir, Turkey
Keywords: stem rust, stripe rust
The "Stubbs Collection", began in 1956 by the late Dutch plant pathologist R.W. Stubbs, refers to a unique historic collection of urediniospore samples of Puccinia striiformis that had been stored in liquid nitrogen for decades. Since 2010 the collection has been maintained by the Global Rust Reference Center (GRRC) in Denmark. Part of the collection is now being in a study of past pathogen diversity. A subset of samples collected between 1958 and 1991 from 35 countries was investigated to assess recovery rate, race identity, and previously undetected virulences. A new method for recovery using an airbrush sprayer and NovecTM 7100 fluid as dispersal agent in inoculating host plants was highly successful, resulting in a 96% recovery from 231 isolates. Phenotyping on the World and European differential host sets and additional wheat genotypes revealed 181 apparently uniform isolates, of which race identities were confirmed for 102. Race identities were updated for additional isolates based on improved resolution due to updated and more informative differential lines. Additional virulences corresponding to Yr17, Yr25, and Yr27 were added, as these were not assayed earlier. The past population structure was investigated by genotyping 212 isolates using 19 multilocus microsatellites. Seven distinct populations were detected, including clonal populations and recombinant populations. These results were compared with recent studies and demonstrated an overall consistent population subdivision at the global scale with clear migration events between populations. The outcome of the study facilitates conclusions about long-term temporal dynamics and overall migration patterns within and among world-wide populations of Pst.
Primary Author: Thach, Department of Agroecology, Aarhus University, Denmark
Keywords: stripe rust, pathogen diversity
Stripe rust and leaf rust have been major constraints to wheat production in Nepal since the 1960s. Several rust epidemics causing hardship for Nepalese wheat growers were due to race changes. Breeding for rust resistance was initiated with establishment of the National Wheat Research Program in 1972, but concerted searches for durable resistance came later with the introduction of wheat genetic resources from CIMMYT, Mexico. The early wheat varieties Nepal 297, Siddhartha, Vinayak, BL1473, BL 1022 and Annapurna series with leaf rust and stripe rust resistance genes Lr13, Lr23, Lr26 and Yr9, and Yr27 in the 1970s and 1980s succumbed to new races within a few years of release. However, Bhrikuti (CMT/COC75/3/PLO/FURY/ANA) with both major and minor gene combinations (Lr10, Lr14a, Lr26/Yr9/Sr31+ and Lr34/Yr18) and released in 1994 was unaffected by Yr9 virulence in 1997 and Yr27 virulence in 2004. This variety with >20 years of leaf rust and stripe rust protection continues to be the most popular wheat variety in Nepal. Three other varieties, Gautam (Siddhartha/Ning8319//Nepal 297) released in 2004, WK 1204 (SW89-3064/Star) released in 2007, and Pasang Lhamu (PGO/SERI) released in 1997 with Lr16, Lr26/Yr9/Sr31, Lr34/Yr18, Lr46/Yr29, Yr7, and Sr2 also remain resistant. The Ug99 resistant varieties Vijay (NL748/NL837), Danphe(KIRITATI//2*PBW65/2*SERI.1B) and Tilottama (Francolin#1 = Waxwing*2/Vivitsi) also possesses APR to the three rusts. Nepalese wheat researchers work closely with the CIMMYT Global Wheat Program and DRRW/BGRI to utilize knowledge and APR germplasm. Strong networks for participatory varietal selection involving women farmers in both the hills and terai help in faster adoption and in establishing varietal diversity. In summary, Nepalese wheat breeders have successfully used APR in protecting wheat crops.
Primary Author: Thapa, Agriculture Botany Division, Nepal Agricultural Research Council (NARC), Nepal
Keywords: Nepal, resistance, major genes, minor genes