The migration of Ug99 variants of Puccinia graminis f. sp. tritici is of concern to global wheat production (1). Seven races have been characterized in the Ug99 lineage (3), three of which occur in South Africa (4). During surveys of wheat fields for Ug99 in Zimbabwe and Mozambique in August and September 2010, high stem rust severities were found at Chiredzi, Chisumbanje, and Birchenough in Zimbabwe and at Rotanda in Mozambique. Stem rust was widespread in the lowlands (<800 m above sea level) of Zimbabwe and trace amounts were present in the mid-altitude areas. In Mozambique, stem rust was only observed at Rotanda (sample Moz1001). Collections from Chiredzi (samples Zim1004 and Zim1005), Chisumbanje (Zim1006), and Birchenough (Zim1009 and Zim1010) yielded viable urediniospores for infection studies. According to race analysis conducted on seedlings of the North American stem rust differential set (2) in a greenhouse at 18 to 25°C, Zim1005 and Zim1006 were typed as PTKST and Zim1004 and Zim1009 as TTKSF. Both TTKSF and PTKST were detected in the Zim1010 sample. Race analysis experiments were conducted three times. Urediniospores of isolate Moz1001 were not viable in infection studies, but yielded fungal DNA for simple sequence repeat (SSR) analysis. Using eight selected SSR primer combinations (4), all six isolates clustered within the Ug99 lineage. Isolates Zim1005, Zim1006, Zim1009, Zim1010, and Moz1001 and the stem rust control races TTKSF, TTKSK, and PTKST grouped into two main clusters, with Zim1009 and Zim1010 clustering together and sharing 88% similarity with the rest of the isolates. Zim1005 and Zim1006 were identical to TTKSF and TTKSK, respectively. Zim1004 shared 96% genetic similarity with the TTKSP control, with these two sharing 74% genetic similarity with the remaining isolates. The SSR data correlated with the infection data, except for Zim1004, which was typed as TTKSF but clustered close to TTKSP. Wheat cvs. SC Nduna, SC Shine, SC Stallion, SC Smart, Kana, Insiza, and Dande are predominant in Zimbabwe. Cv. SC Stallion and other unidentified cultivars were susceptible to P. graminis f. sp. tritici in the field in Zimbabwe. In Mozambique, the tall, local cv. Sitsonko was susceptible to P. graminis f. sp. tritici but no infections were observed on SC Nduna or SC Shine. The similarity in P. graminis f. sp. tritici races in Zimbabwe, South Africa, and Mozambique suggests that inoculum is exchanged within the region and explains the detection of race PTKST in South Africa in 2009. Trajectory models showed winds originating at Birchenough in October 2009, where stem rust was observed, passing directly over KwaZulu-Natal, South Africa within 48 to 72 h. Race PTKST was confirmed from collections in KwaZulu-Natal in November 2009 (4). The confirmation of Sr31 virulence in race PTKST in Zimbabwe is important because it provides new geographical records for an Ug99-related race and puts Southern African cultivars with 1B.1R resistance at risk. References: (1) D. Hodson. Euphytica 179:93, 2011. (2) Y. Jin et al. Plant Dis. 92:923, 2008. (3) R. F. Park et al. Euphytica 179:109, 2011. (4) B. Visser et al. Euphytica 179:119, 2011.
Classification of sorghum [Sorghum bicolor (L) Moench] breeding material based on multiple crucial characters is important towards the possible formation of homogeneous groups of genotypes and groups that can be exploited in the identification of parents for use in a breeding program. The objective was to determine the morphological characters that distinguish desirable breeding material and group the genotypes of sorghum according to similarity. Principal component analysis (PCA) and cluster analysis were used to establish the relationships among germplasm and the Shannon Diversity index was used to quantify the level of diversity. The experiment involving 26 sorghum genotypes was conducted at Sussundenga Research Station across two seasons and laid out in a 13 × 2 alpha lattice design with four replications. Cluster analysis grouped genotypes into four clusters based on 15 evaluated traits. Five principal components cumulatively accounting for 58.5% of the total variation were estimated from the PCA analysis. The results showed that genotypes 150B, IS 14257R, LARSVYT 46B, TX 631B, TX 630B and 8601B were the early maturity while for late maturity genotypes were MA 6B, A 6352R, ICSA 19B and MZ 30R. The genotypes IS 7179R, SPL 9B, A 6353R, SPL 38B, SDS 6013R and MZ 2R showed a potential for grain yield improvement. Other genotypes presented potential for drought tolerance and birds attack. The multivariate analyses clearly showed the grouping of the genotypes according to the characters outlined in the study. These results have implications in selecting parents for use in sorghum breeding program.
Em Moçambique, a província de Manica é referência na ocorrência e exploração de ouro aluvionar. Este mineral é atualmente explorado na escala industrial e artesanal. A extração deste mineral consiste na remoção de sedimentos ricos e pobres em mineral de ouro e posterior concentração ou separação do mineral de ouro com sedimentos ou outros minerais. Os sedimentos assim como os rejeitos do processamento são descartados na superfície, recobrindo os solos superficiais ricos em minerais e nutrientes alterando as características naturais deste, deixando-os inférteis para a prática de agrícola. Assim, objetivou-se com este trabalho avaliar os parâmetros químicos dos solos nas áreas de atividade garimpo em relação a fertilidade para a produção agrícola, designadamente pH, Hg, Zn, NPK, MO e CTC. O estudo foi realizado em Moçambique, província de Manica, distrito de Manica, nas localidades de Cacárue, Mucurumadze e Penhalonga, onde foram coletadas amostras de solos em dez pontos, escolhidos de forma aleatória 10 pontos de amostragens de solos, nas camadas de 0-20 cm e 20-40 cm. Verificou-se que o pH variou e os teores de N, P e K foram baixos. Estes resultados da análise laboratoriais dos solos mostraram que algumas das áreas podem ser reaproveitadas para agricultura, mas para culturas específicas após o tratamento dos solos. A atividade de garimpo nestas localidades compromete a qualidade dos solos, no concernente aos padrões exigidos para a prática de agricultura.
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