SELIAN AGRICULTURAL RESEARCH INSTITUTE
P.O. Box 6024, Arusha, Tanzania.
Patchy stunting of wheat and barley in Tanzania.
Catherine A. Kuwite.
Patchy stunting of cereals has been observed on wheat farms of the Hanang Wheat Complex, Tanzania, since the early 1970s and recently also on farms at West Kilimanjaro and Karatu. Estimated yield losses amount to approximately 5-30 %, but could be as high as 40-50 % during drier years on newly broken land. A survey was conducted to determine the incidence of the patchy stunt pathogen (Rhizoctonia solani AG-6) and other pathogenic fungi in the main production areas and in different soil types. Potentially pathogenic fungal species commonly isolated from the roots and crowns of wheat and barley include Bipolaris sorokiniana, Fusarium equiseti, F. nygamai, F. oxysporum, F. solani, Periconia macrospinosa, and Rhizoctonia spp. Roots yielded mainly Fusarium spp., whereas B. sorokiniana was predominantly and almost exclusively isolated from crowns. The incidence of fungi in the various soil types and production areas did not differ significantly. Contrary to crater disease of wheat in South Africa, patchy stunt occurs not only in black montmorillonitic clay soils, but also in clay, clay loam, and sandy clay soils. However, the disease is more pronounced in the predominating black clay soils. Chemical analysis of the different soil types revealed significantly higher levels of Ca, Mg, and Na, and a lower K content in the black soil as compared to the other soil types. Accordingly, in vitro growth of R. solani AG-6 was stimulated by increasing levels of Ca, Mg, and Na, whereas high concentrations of K inhibited the organism. [Work conducted together with K. van Dyk, J.J. du Toit Meiring, and L. Meyer, Department of Microbiology and Plant Pathology, University of Pretoria, Pretoria 0002, South Africa.]
ROTIAN SEED COMPANY, LTD.
P.O. Box 11584, Arusha, Tanzania.
Quality attributes of Tanzanian bread wheat cultivars.
M.A. Shelembi, J.S. Noll, B.B. Chubey, and E.J. Maeda.
Commercial bread wheat cultivars grown in Tanzania in the past were selected and promoted on the merit of high yield potential and resistance to disease. Very little, if any, work was done on the industrial quality of those varieties. At that time, quality of wheat products was not as important to producers, consumers, or processors as it is now. The present study was initiated to determine in detail the quality attributes of 10 commercial cultivars and classify them for their utilization in the baking industry. Ten commercial bread wheat cultivars were evaluated in the field for agronomic characteristics and in the laboratory for quality attributes between 1991 and 1993. The cultivars were evaluated for grain yield, test weight, kernel weight, and nine quality parameters. The analysis of variance performed on the data revealed differences between cultivars for grain yield, flour yield, mixograph dough development time, farinograph water absorption, farinograph stability, and loaf volume with and without the addition of bromate. Significant positive relationships also were found among seven characteristics, whereas four relationships were significant and negative.