scholarly journals Identification of Resistance Sources to Wheat Stem Rust from Introduced Genotypes in Kenya

2017 ◽  
Vol 9 (2) ◽  
pp. 73
Author(s):  
Molly O. Akello ◽  
Felister Nzuve ◽  
Florence Olubayo ◽  
Godwin Macharia ◽  
James Muthomi
Keyword(s):  
Plant Height ◽  
Stem Rust ◽  
Agronomic Traits ◽  
Negative Relationship ◽  
Kernel Weight ◽  
Sources Of Resistance ◽  
Wheat Stem Rust ◽  
Progress Curve ◽  
Rust Severity ◽  
Infection Types

Stem rust Puccinia graminis Pers. f. sp. tritici of wheat is the most important disease in Kenya. Emergence of race Ug99 and other variants virulent to host resistance genes including Sr31 has rendered 95% of Kenyan cultivars susceptible. This study aimed to identify new sources of resistance to stem rust in a collection of exotic genotypes. Three hundred and sixteen wheat genotypes were screened at the Kenya Agricultural and Livestock Research Organization (KALRO) in Njoro for two seasons in 2015. The host reaction to disease was evaluated based on the modified Cobb scale. The relative Final Rust Severity (rFRS), Average Coefficient of Infection (ACI) and relative Area Under Disease Progress Curve (rAUDPC) were used to characterize the genotypes for stem rust resistance. Agronomic traits were also recorded. Six genotypes namely ALBW-100, ALBW- 204, EPCBW-261, EPCBW-295, PCHP-309 and PCHPBW-310 with significantly low ACI, rAUDPC and rFRS were identified. Thirty five genotypes showed Pseudo-Black Chaff (PBC) phenotype associated with resistant gene Sr2, a source of partial resistance in wheat. The genotypes also showed low disease severity (20-25%) and Moderately Susceptible (MS) – Susceptible (S) infection types in both seasons. Genotypes had significant differences (p ≤ 0.05) on plant height, 1000-kernel weight and number of tillers indicating genetic variation which could be exploited in breeding for resistance to stem rust. The negative relationship between agronomic variables involving plant height, spikelet length and 1000-kernel weight showed harmful effects of stem rust on plant characteristics including yield. The stem rust resistant genotypes with good agronomic traits could be introgressed into adapted Kenyan backgrounds while the genotypes showing presence of PBC could be utilized to develop durable stem rust resistant wheat. Inheritance studies to elucidate the exact genes conferring resistance to stem rust could be conducted for breeders to exploit their genetic variability.

scholarly journals Foliar Fungicides to Control Wheat Stem Rust, Race TTKS (Ug99), in Kenya

Plant Disease ◽  
2009 ◽  
Vol 93 (9) ◽  
pp. 929-932 ◽  
Author(s):  
R. Wanyera ◽  
J. K. Macharia ◽  
S. M. Kilonzo ◽  
J. W. Kamundia
Keyword(s):  
Grain Yield ◽  
Stem Rust ◽  
Untreated Control ◽  
Block Design ◽  
Kernel Weight ◽  
Control Treatment ◽  
Wheat Stem Rust ◽  
Progress Curve ◽  
Rust Severity ◽  
Field Plots

The emergence of a new virulent race of stem rust (Puccinia graminis f. sp. tritici) of wheat (Triticum aestivum), TTKS (Ug99), calls for urgent measures to contain the disease, which is a serious threat to wheat production in Kenya. Nine commercial fungicides were evaluated for control of stem rust in the field in three locations in 2005 and 2006. Ten treatments, including untreated control, were applied on field plots in a randomized complete block design with four replications. Assessment of stem rust severity was done at growth stage (GS) 55 (heading), GS 65 (flowering), and GS 75 (late milk) and expressed in terms of mean rust severity and area under the disease progress curve (AUDPC). In general, fungicide treatment significantly (P ≤ 0.05) reduced rust severity, AUDPC, and losses in grain yield and 1,000-kernel weight for cv. Duma compared with the untreated control. Stem rust was severe in both years across all sites, resulting in significantly less grain yield in the control treatment. The 1,000-kernel weight was significantly less at two locations in 2006. Fungicides azoxystrobin at 200 g/liter + cyproconazole at 80 g/liter (AmistarXtra 280 SC), tebuconazole (Folicur 250 EC), tebuconazole + tridimenol (Silvacur 375 EC), and tebuconazole (Orius 25 EW) were more effective in reducing stem rust across the sites. Fungicides trifloxystrobin + propiconazole (Stratego 250 EC), hexaconazole (Cotaf 5 EC), epoxiconazole + carbendazim (Swing 250 EC), cyproconazole at 80 g/liter + propiconazole at 250 g/liter (Artea 330EC), and epoxiconazole at 125 g/liter + carbendazim at 125 g/liter (Soprano C 250 EC) were inconsistent in the reduction of the disease. The results suggest that fungicides can be used effectively in reducing stem rust severity and increasing yield of susceptible wheat cultivars in stem-rust-prone areas.

scholarly journals Wheat Stem Rust Severity and Physiological Races in North Rift Region of Kenya

2012 ◽  
Vol 6 (2) ◽  
pp. 25-32
Author(s):  
S.G. Ismail ◽  
M.G. Kinyua ◽  
A.M. Kibe ◽  
I.N. Wagara
Keyword(s):  
Stem Rust ◽  
Wheat Stem Rust ◽  
Physiological Races ◽  
Rust Severity

scholarly journals Evaluation of agronomic traits and assessment of genetic variability in some popular wheat genotypes cultivated in Saudi Arabia

2019 ◽  
pp. 847-856 ◽  
Author(s):  
Soleman M. Al-Otayk
Keyword(s):  
Grain Yield ◽  
Durum Wheat ◽  
Plant Height ◽  
Bread Wheat ◽  
Coefficient Of Variation ◽  
Agronomic Traits ◽  
Kernel Weight ◽  
Wheat Genotypes ◽  
Days To Heading ◽  
Days To Maturity

The present study was carried out to evaluate agronomic traits and assessment of genetic variability of some wheat genotypes at Qassim region, Saudi Arabia', during 2010/11 and2011/12 seasons. Fourteen wheat genotypes including five bread wheat and nine durum wheat genotypes were evaluated in randomized complete block design with three replications. The genotypes were evaluated for ten different yield contributing characters viz., days to heading, days to maturity, grain filling period, grain filling rate, plant height, number of spikes m-2, kernels spike-1, 1000-kernel weight, grain yield and straw yield. The combined analysis of variance indicated the presence of significant differences between years for most characters. The genotypes exhibited significant variation for all the characters studied indicating considerable amount of variation among genotypes for each character. Maximum coefficient of variation was observed for number of spikes m-2 (17%), while minimum value was found for days to maturity. Four genotypes produced maximum grain yield and statistically similar, out of them two bread wheat genotypes (AC-3 and SD12) and the other two were durum wheat (AC-5 and BS-1). The genotypes AC-3, AC-5 and BS-1 had higher grain yield and stable in performance across seasons. The estimation of phenotypic coefficient of variation in all the traits studied was greater than those of the genotypic coefficient of variation. High heritability estimates (> 0.5) were observed for days to heading, days to maturity, and plant height, while the other characters recorded low to moderate heritability. The high GA % for plant height and days to heading (day) was accompanied by high heritability estimates, which indicated that heritability is mainly due to genetic variance. Comparatively high expected genetic advances were observed for grain yield components such as number of kernels spike-1 and 1000-kernel weight. Grain yield had the low heritability estimate with a relatively intermediate value for expected genetic advance. The results of principle component analysis (PCA) indicated that the superior durum wheat genotypes for grain yield in the two seasons (AC-5 and BS-1) are clustered in group II (Fig. 2). Also, the superior two bread wheat genotypes (AC-3 and SD12) were in group I. Therefore, it could be future breeding program to develop new high yielding genotypes in bread and durum wheat.

scholarly journals Pathogenic Variability of Wheat Stem Rust Pathogen (Puccinia graminis f. sp. tritici) in Hararghe Highlands, Ethiopia

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Arif Abrahim ◽  
Temam Hussein ◽  
Ayele Badebo
Keyword(s):  
Resistance Genes ◽  
Stem Rust ◽  
Agricultural Research ◽  
Low Frequency ◽  
Puccinia Graminis ◽  
Total Production ◽  
Rust Disease ◽  
Wheat Stem Rust ◽  
Pathogenic Variability ◽  
Infection Types

Wheat is one of the important major crops of Hararghe Highlands. It is third in land coverage and total production after sorghum and maize. However, the wheat stem rust disease is threatening production of wheat in this region. So, this research was conducted with the following objective: to determine the population of Puccinia graminis f. sp. tritici in Hararghe Highlands. A total of 200 fields were surveyed and stem rust samples were collected and transported to Kulumsa Agricultural Research Center for race analysis. Inoculation of differentials carrying resistance genes Sr24 and Sr-Tmp indicated typical low infection types on all isolates. Isolates EH5, EH8, and EH3 from East Hararghe and WH2, WH1, and WH3 from West Hararghe showed high virulence of infection in all differential lines. Ten (10) races were identified by using Puccinia graminis tritici code system: TTGSK, PTJQK, TTSSK, TTKSK, TRSSK, and TTJQK from East Hararghe and TTTSK and TTSQK from West Hararghe zones. Race TTSSK was most frequent (25%) followed by TTKSK (25%) in East Hararghe. Race TTSSK showed 50% frequency of occurrence in West Hararghe zones. The low frequency of occurrences indicated high variability of the races in the survey areas. Therefore, monitoring of populations of pathogens is important for the national and regional research centers. Detection of pathogen virulence evolution and of currently effective resistance genes is necessary and must be applied within a system of resistance gene management.

scholarly journals Detection of Virulence to Wheat Stem Rust Resistance Gene Sr31 in Puccinia graminis. f. sp. tritici in Uganda

Plant Disease ◽  
2000 ◽  
Vol 84 (2) ◽  
pp. 203-203 ◽  
Author(s):  
Z. A. Pretorius ◽  
R. P. Singh ◽  
W. W. Wagoire ◽  
T. S. Payne
Keyword(s):  
South African ◽  
Stem Rust ◽  
Rust Resistance ◽  
The United States ◽  
Chromosome Translocation ◽  
Research Station ◽  
Puccinia Graminis ◽  
Wheat Stem Rust ◽  
Light Mineral ◽  
Infection Types

In much of the world, resistance to stem rust in wheat, caused by Puccinia graminis f. sp. tritici, is based at least in part on the gene Sr31. During February 1999, high levels of stem rust infection were observed on entries in wheat (Triticum aestivum) grown in a nursery at Kalengyere Research Station in Uganda. Because several of the rusted entries were known to carry the 1BL-1RS chromosome translocation containing the Sr31, Lr26, and Yr9 genes for rust resistance, virulence to Sr31 was suspected. Urediniospores, collected in bulk from rusted stems of seven entries containing Sr31, were suspended in light mineral oil and sprayed on primary leaves of 7-day-old seedlings of South African wheat cv. Gamtoos (=Veery #3, pedigree: Kvz/Buho‘S’//Kal/BB). Plants were kept overnight at 19 to 21°C in a dew chamber before placement in a greenhouse at 18 to 25°C. After ≈14 days, urediniospores were collected from large, susceptible-type stem rust pustules and subsequently increased on Gamtoos, which served as a selective host for the new rust culture, designated Pgt-Ug99. Pathogenicity of Pgt-Ug99 was studied in seedling tests of available wheats containing Sr31, as well as other stem rust differential lines. All seedling tests were conducted at least three times in independent inoculations. Isolate Pgt-Ug99 was not virulent to Avocet‘S’/Yr9 (Australian line containing Sr26) or Oom Charl (South African cultivar) but was virulent to the other Sr31 testers: Alondra ‘S’, Bobwhite, Chokka, Clement, Federation/Kavkaz, Gamtoos, Grebe, Kavkaz, Letaba, Line E/Kavkaz, RL6078, and Veery ‘S’. Virulence to Sr31 (infection types [ITs] 3-3 to 3++4) was clearly contrasted by the low reactions (ITs 0; to 1) produced by UVPgt53, a South African pathotype avirulent to Sr31. According to the reactions of the differential lines, Pgt-Ug99 is avirulent to Sr21, -22, -24, -25, -26, -27, -29, -32, -33, -34, -35, -36, -39, -40, -42, and -43, Agi, and Em and virulent to Sr5, -6, -7b, -8a, -8b, -9b, -9e, -9g, -11, -15, -17, -30, -31, and -38. Virulence to the T. ventricosum-derived gene Sr38, which is linked to Lr37 and Yr17 and occurs in cultivars from Australia, the United Kingdom, and the United States, was not known previously (1). Both Pgt-Ug99 and UVPgt53 produced a continuum of ITs (; to 2+3) on Petkus rye (obtained from the USDA-ARS National Small Grains Collection, Aberdeen, ID), the original Sr31 donor source. Pgt-Ug99 did not appear more virulent than UVPgt53 on Petkus. All triticales tested, as well as oat cv. Overberg, were highly resistant to Pgt-Ug99. According to McIntosh et al. (1), Huerta-Espino mentioned a Sr31-virulent culture from Turkey, but this could not be confirmed. Should the Sr31-virulent pathotype migrate out of Uganda, it poses a major threat to wheat production in countries where the leading cultivars have resistance based on this gene. Reference: (1) R. A. McIntosh et al. 1995. Wheat Rusts: An Atlas of Resistance Genes. Kluwer Academic Publishers, Dordrecht, the Netherlands.

Potentiality of some essential oils and algae extract spray treatments on suppressing wheat stem rust severity under field conditions

2021 ◽  
pp. 1-16
Author(s):  
Mokhtar M. Abdel-Kader ◽  
Nadia G. El-Gamal ◽  
Mohamed S. A. Khalil ◽  
Nehal S. El-Mougy ◽  
Abo El-Khair Badawy El-Sayed
Keyword(s):  
Essential Oils ◽  
Stem Rust ◽  
Field Conditions ◽  
Wheat Stem Rust ◽  
Rust Severity

scholarly journals Identification of Resistance to Races of Puccinia graminis f. sp. tritici with Broad Virulence in Triticale (×Triticosecale)

Plant Disease ◽  
2013 ◽  
Vol 97 (4) ◽  
pp. 479-484 ◽  
Author(s):  
P. D. Olivera ◽  
Z. A. Pretorius ◽  
A. Badebo ◽  
Y. Jin
Keyword(s):  
South African ◽  
Stem Rust ◽  
Triticum Turgidum ◽  
Puccinia Graminis ◽  
Wheat Stem Rust ◽  
Cereal Rye ◽  
Infection Types ◽  
Stem Rust Resistance Genes ◽  
Moderately Resistant ◽  
Excellent Source

Triticale (×Triticosecale), an amphiploid of wheat (mainly Triticum turgidum) and cereal rye (Secale cereale), is an excellent source of resistance to wheat stem rust, caused by Puccinia graminis f. sp. tritici. A collection of 567 triticale accessions originating from 21 countries was evaluated at the seedling stage for reaction to races of P. graminis f. sp. tritici with broad virulence, including TTKSK, TRTTF, and TTTTF. A high frequency (78.4%) of accessions was resistant to race TTKSK, with low infection types ranging from 0; to X. A selection of 353 TTKSK-resistant accessions was evaluated for reaction to three South African isolates of P. graminis f. sp. tritici with single and/or combined virulences to stem rust resistance genes SrSatu, Sr27, and SrKw present in triticale. Genes SrSatu, Sr27, and SrKw were postulated to be present in 141 accessions and contributed to TTKSK resistance. The remaining 212 resistant accessions may possess uncharacterized genes or combinations of known genes that could not be determined with these isolates. These accessions were further evaluated for resistance to races TTKST, TPMKC, RKQQC, RCRSC, QTHJC, QCCSM, and MCCFC. Resistance remained effective across the entire set of races in the majority of the accessions (n = 200), suggesting that the resistances are effective against a broad spectrum of virulence. In all, 129 (79.6%) resistant accessions with noncharacterized genes were resistant to moderately resistant in field stem rust nurseries at Debre Zeit (Ethiopia) and St. Paul (Minnesota). Results from evaluating F2 populations derived from resistant–susceptible crosses revealed that resistance to TTKSK in triticale was conferred mostly by single genes with dominant effects.

scholarly journals Sources of Resistance to Stem Rust Race Ug99 in Spring Wheat Germplasm

Plant Disease ◽  
2011 ◽  
Vol 95 (6) ◽  
pp. 762-766 ◽  
Author(s):  
M. N. Rouse ◽  
R. Wanyera ◽  
P. Njau ◽  
Y. Jin
Keyword(s):  
Spring Wheat ◽  
Resistance Genes ◽  
North American ◽  
Stem Rust ◽  
Wheat Breeding ◽  
Field Resistance ◽  
Eastern Africa ◽  
Adult Plant ◽  
Sources Of Resistance ◽  
Wheat Stem Rust

Wheat stem rust (Puccinia graminis f. sp. tritici) race TTKSK (Ug99), with virulence to the majority of the world's wheat (Triticum aestivum) cultivars, has spread from Uganda throughout eastern Africa, Yemen, and Iran. The identification and spread of variants of race TTKSK with virulence to additional stem rust resistance genes has reminded breeders and pathologists of the danger of deploying major resistance genes alone. In order to protect wheat from this rapidly spreading and adapting pathogen, multiple resistance genes are needed, preferably from improved germplasm. Preliminary screening of over 700 spring wheat breeding lines and cultivars developed at least 20 years ago identified 88 accessions with field resistance to Ug99. We included these resistant accessions in the stem rust screening nursery in Njoro, Kenya for two additional seasons. The accessions were also screened with a bulk of North American isolates of P. graminis f. sp. tritici in the field in St. Paul, MN. In order to further characterize the resistance in these accessions, we obtained seedling phenotypes for 10 races of P. graminis f. sp. tritici, including two races from the race TTKSK complex. This phenotyping led to the identification of accessions with either adult-plant or all-stage resistance to race TTKSK, and often North American races of P. graminis f. sp. tritici as well. These Ug99 resistant accessions can be obtained by breeders and introgressed into current breeding germplasm.

scholarly journals Heterosis for Flowering Time and Agronomic Traits among Early Open-pollinated Sweet Corn Cultivars

2002 ◽  
Vol 127 (5) ◽  
pp. 793-797 ◽  
Author(s):  
T.E. Dickert ◽  
W.F. Tracy
Keyword(s):  
Flowering Time ◽  
Plant Height ◽  
Combining Ability ◽  
Sweet Corn ◽  
Agronomic Traits ◽  
Diallel Cross ◽  
Kernel Weight ◽  
Ear Height ◽  
The Difference ◽  
Very High

Heterosis in corn (Zea mays L.) usually results in earlier flowering, larger plants, and increased yield. In extremely early sweet corn the effect of heterosis on flowering time may be reduced or eliminated due to developmental and physiological requirements for vegetative growth before the transition to reproductive phase. The objective of this study was to determine the level of heterosis and the combining ability for flowering time and other agronomic traits in a diallel cross of six very early open-pollinated sweet corn cultivars. The diallel was grown in 1995 and 1996. Hybrids and parents averaged over hybrids differed for silk date, plant height, ear height, 10-ear weight, ear length, and 100-kernel weight but did not differ for row number and ear width. Heterosis for silk date was significant, but the difference between parents and hybrids was very small, 0.5 day. No hybrids were earlier than the earliest parent, and average midparent heterosis was -0.8%. In contrast midparent heterosis was significant and relatively high for 100-kernel weight (10.0%), ear length (12.9%), ear height (8.6%), plant height (9.0%), and 10-ear weight (28.2%). The traits with low heterosis had very high general combining ability/specific combining ability ratios while these ratios were much smaller in traits with high heterosis. Heterosis for many of the traits, including 10-ear weight, was higher than published values. Conversely, heterosis for flowering time was small, compared to other traits in this study and to published values for silk date, indicating that this extremely early germplasm may be at or near the limit for flowering time under the photoperiod and temperatures typical of summer in Madison, Wis. (43.05°N, 89.31°W).

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