A Review of Rain-Fed Wheat Production Constraints in Zambia

Tembo, Batiseba

doi:10.32861/jac.59.158.161

Cited by 7 publications

(7 citation statements)

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“…After correcting those conditions, the specificity of the MoT3 was reconfirmed using the same strains (Yasuhara-Bell et al 2019). Moreover, the loss of the MoT3 allele may be possible due to hybridization events through inter-lineages recombination, which may explain the small failure rate, according to the authors (Pieck et al 2017;Yasuhara-Bell et al 2018a, 2019.…”

Section: Discussionmentioning

confidence: 99%

“…Even being one of Bangladesh's neighbor countries and having conductive weather conditions to wheat blast occurrence, no formal scientific reports confirmed the wheat blast introduction in India (Islam et al 2020, Singh et al 2021. More recently, the wheat blast pathogen arrived in Africa: Zambia (Tembo 2019;Tembo et al 2020) (Figure 1). (Viedma 2005;Pieck et al 2017), Uruguay (Saharan et al 2016;Yasuhara-Bell et al 2018b), Argentina (Perelló et al 2015), United States (Farman et al 2017), Bangladesh (Islam et al 2016), and Zambia (Tembo et al 2020(Tembo et al , 2021Croll 2021).…”

Section: Geographical Distribution Of Wheat Blastmentioning

confidence: 99%

“…This is evident based on the increase in the yearly number of original articles and reviews published after the major epidemics reported in the Cerrado, Brazil, and disease's introduction into both Asia and Africa (Figure 2A). (Rajiv 2017;Sadat and Choi 2017;Cruz and Valent 2017;Mottaleb et al 2018Mottaleb et al , 2019Ceresini et al 2018Ceresini et al , 2019Islam et al , 2020Kamoun et al 2019;Tembo 2019;Yesmin et al 2020;Mbinda and Masaki 2021, Singh et al 2021, Tosa 2021. While some aspects have been given more attention, such as the taxonomy and population genetics (Couch and Kohn 2002;Tanaka et al 2009;Luo and Zhang 2013;Maciel et al 2014;Murata et al 2014;Klaubauf et al 2014;Gladieux et al 2015Gladieux et al , 2018Castroagudín et al 2016;Valent et al 2019), chemical control (Kim et al 2003;Cruz et al 2011Cruz et al , 2019Pagani et al 2014;Rocha et al 2014;Castroagudín et al 2015;Oliveira et al 2015;Dorigan et al 2019;D'Ávila et al 2021;Ascari et al 2021) and host genetic resistance (Cruz et al 2016b;Anh et al 2018;Rocha et al 2019;…”

Section: Economical and Scientific Importancementioning

confidence: 99%

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Taxonomic and pathogenic diversity of the blast pathogen populations infecting wheat and grasses in Minas Gerais

Ascari¹,

Ponte²

2021

Preprint

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The blast disease of Poaceae is caused by a large species complex, among which P. oryzae is composed of several host-specialized lineages. The Pyricularia oryzae Triticum pathotype (PoT) causes the blast disease in wheat, but is also capable of infecting other grasses, which may serve as an inoculum reservoir for epidemics in wheat. In Brazil, severe wheat blast epidemics are most common in the Cerrado region. The dominant hypothesis is that signal grass (Urochloa sp.) and other gramineous plants harbor the wheat blast pathogen, thus serving as a major reservoir of inoculum for epidemics in wheat. A two-year survey of the Pyricularia blast pathogens was conducted in both wheat and non-wheat areas as well as prior (February) and during (May) the wheat growing season in Minas Gerais. A total of 1,368 plant samples representative of 31 Poaceae species, including wheat, were collected and inspected for the presence of blast symptoms. During the isolations, 932 isolates were obtained, being one fourth obtained from gramineous plants. A subset of 572 isolates was selected for identification at the species level based on portions of the CH7-BAC9 gene sequences. Most of the isolates (n = 494) were P. oryzae, within which 68% were PoT and 32% non-PoT based on two PCR assays targeting (MoT3 and C17 PCR assays). The PoT lineage was found predominantly (97%) in wheat and rarely in the other hosts, even nearby wheat fields (2.1%), as well as at longer distances from wheat regions (0.1%). The blast pathogen population isolated from signal grass grouped in different clades from PoT, and therefore referred to Urochloa lineage (PoU). A series of cross-inoculation greenhouse experiments was conducted using wheat (cv. BRS Guamirim and BR 18-Terena) and signal grass (cv. Marandu) as host and 14 PoT and six PoU isolates as pathogen factor. In the first leaf-inoculation experiment, results showed a significant interaction between host and pathogen; PoT was strongly/weakly aggressive towards wheat/signal grass and PoU was strongly/weakly aggressive towards signal grass/wheat. In inoculated wheat heads, PoT was more aggressive (>91% infected spikelets) than PoU (52% infected spikelets). In a third experiment, four signal grass cultivars (Marandu, Basilisk, Piatã, and Xaraés) were inoculated with the same set of 20 isolates. Similarly, signal grass cultivars were generally more susceptible to PoU than PoT. Severity induced by PoU was twice (7.7% severity) as high as PoT (3.8%) and so was the number of conidia/leaf produced by PoU (47,500) and PoT (23,200). Two groups of signal grass cultivars were formed, the most susceptible composed of Marandu and Basilisk and the least susceptible composed of Piatã and Xaraés. Results of our study confirm the host-specialization and the shaping of the blast populations according to the host. We further suggest that grasses in general, especially signal grass, may not play a major role as an inoculum reservoir for PoT, as it harbors mainly the PoU population. However, due to the large extent of pasture-growing regions and cross-infection ability in wheat, signal grass may harbor amounts of PoT inoculum that are sufficient for initiating leaf and head blast epidemics in wheat blast in Minas Gerais state.

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Section: Discussionmentioning

confidence: 99%

Section: Geographical Distribution Of Wheat Blastmentioning

confidence: 99%

Section: Economical and Scientific Importancementioning

confidence: 99%

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Taxonomic and pathogenic diversity of the blast pathogen populations infecting wheat and grasses in Minas Gerais

Ascari¹,

Ponte²

2021

Preprint

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“…There are current efforts by the Zambia Agriculture Research Institute (ZARI) to promote rain-fed growing of wheat among smallholder farmers in Zambia. The positive impact of such efforts in Zambia will be reduced by the emergency of wheat blast disease coupled with other fungal diseases that have been reported in Zambia [16]. It is therefore important that measures to limit damage to wheat crops be instituted and collaborative research efforts started to prevent spread of the disease to new areas.…”

Section: Discussionmentioning

confidence: 99%

Detection and characterization of fungus (Magnaporthe oryzae pathotype Triticum) causing wheat blast disease on rain-fed grown wheat (Triticum aestivum L.) in Zambia

et al. 2020

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Wheat blast caused by Magnaporthe oryzae pathotype Triticum (MoT) is a threat to wheat production especially in the warmer-humid environments. In Zambia, wheat blast symptoms were observed for the first time on wheat (Triticum aestivum L.) grown in experimental plots and five farmers' fields in Mpika district of Muchinga Province during the 2017-18 rainy season. Infected plants showed the typical wheat blast symptoms with the spike becoming partially or completely bleached with the blackening of the rachis in a short span of time. Incidence of blast symptoms on nearly all wheat heads was high and ranged from 50 to 100%. Examination of diseased plant leaves showed the presence of elliptical, grayish to tan necrotic lesions with dark borders on the leaf often mixed with other foliar diseases. A study was conducted to isolate and identify the causal pathogen(s) using classical and molecular methods and determine the pathogenicity of the detected disease causal agent. Morphobiometrical determination of causal pathogen revealed conidia with characteristic pear shaped 2-septate hyaline spores associated with M. oryzae species. Preliminary polymerase chain reaction screening of six isolates obtained from wheat blast infected samples with diagnostic primers (MoT3F/R) was conducted at ZARI, Zambia, and subsequent analysis of two isolates with MoT3F/R and C17F/R was performed at USDA-ARS, USA. Both experiments confirmed that MoT is the causal agent of wheat blast in Zambia. Further, pathogenicity tests performed with pure culture isolates from samples WS4 and WS5 produced typical blast symptoms on all the six inoculated wheat genotypes. Results of this study indicate that MoT is causing wheat blast in rain-fed wheat grown in Zambia, thus making it the first report of MoT in Zambia and Africa. This inter-continental movement of the pathogen (disease) has serious implication for wheat production and trade that needs to be urgently addressed.

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“…Rain-fed wheat yields are not only low, they also fluctuate considerably. Their fluctuation can be attributed to different stresses, such as heat, drought, rainfall, soils, and diseases, and/or lack of improved and adaptable varieties (Tembo, 2019). Yan and Kang (2003) reported that the performance of a genotype in an environment is a function of genotype, environment, and genotype by environment interaction (GEI).…”

Section: Introductionmentioning

confidence: 99%

Genotype by environment interaction analysis of wheat (Triticum aestivum L.) grain yield under rain-fed conditions in Zambia

Tembo¹

2021

SABRAOJBG

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Understanding genotype by environment interaction (GEI) is important for crop improvement because it aids in the recommendation of cultivars and the identification of appropriate production environments. The objective of this study was to determine the magnitude of GEI for the grain yield of wheat grown under rain-fed conditions in Zambia by using the additive main effects and multiplicative interaction (AMMI) model. The study was conducted in 2015/16 at Mutanda Research Station, Mt. Makulu Research Station and Golden Valley Agricultural Research Trust (GART) in Chibombo. During2016/17, the experiment was performed at Mpongwe, Mt. Makulu Research Station and GART Chibombo, Zambia. Fifty-five rain-fed wheat genotypes were evaluated for grain yield in a 5 × 11 alpha lattice design with two replications. Results revealed the presence of significant variation in yield across genotypes, environments, and GEI indicating the differential performance of genotypes across environments. The variance due to the effect of environments was higher than the variances due to genotypes and GEI. The variances ascribed to environments, genotypes, and GEI accounted for 45.79%, 12.96%, and 22.56% of the total variation, respectively. These results indicated that in rain-fed wheat genotypes under study, grain yield was more controlled by the environment than by genetics. AMMI biplot analysis demonstrated that E2 was the main contributor to the GEI given that it was located farthest from the origin. Furthermore, E2 was unstable yet recorded the highest yield. Genotype G47 contributed highly to the GEI sum of squares considering that it was also located far from the origin. Genotypes G12 and G18 were relatively stable because they were situated close to the origin. Their position indicated that they had minimal interaction with the environment. Genotype 47 was the highest-yielding genotype but was unstable, whereas G34 was the lowest-yielding genotype and was unstable.

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A Review of Rain-Fed Wheat Production Constraints in Zambia

Cited by 7 publications

References 0 publications

Taxonomic and pathogenic diversity of the blast pathogen populations infecting wheat and grasses in Minas Gerais

Taxonomic and pathogenic diversity of the blast pathogen populations infecting wheat and grasses in Minas Gerais

Detection and characterization of fungus (Magnaporthe oryzae pathotype Triticum) causing wheat blast disease on rain-fed grown wheat (Triticum aestivum L.) in Zambia

Genotype by environment interaction analysis of wheat (Triticum aestivum L.) grain yield under rain-fed conditions in Zambia

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