Browsing by Author "Jowett, D."
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Item The control of sorghum pests with insecticides in Eastern Uganda(1970) Davies J.C.; Jowett, D.; Serere Research StationTrials carried out over three seasons at Serere Research Stations, Uganda using insecticides for control of sorghum pests, particularly Atherigona varia Rond. (Diptera, Muscidae), are described. Insecticides used included endosulfan, phosphamidon, menazon, DDT and trichlorphon. the most successful control of sorghum shoot fly was obtained with endosulfan, particularly when it was applied six or more times.Item The Grain Structure of Sorghum Related to Water Uptake and Germination(1965) Jowett, D.; E.A.A.F.A.O.A wide range of variability was found in pericarp structure of a range of sorghum varieties. Endosperm type varied from chalky to solid corneous with a complete range of intermediate types. Brown grains were found to contain only a small amount of corneous endosperm. The relation of this character to bird and weevil resistance is discussed. The rate of water uptake is related to grain size, endosperm type and mesocarp thickness, being fastest in small, chalky grains with a thick mesocarp. The relationship with degree of courteousness was slight but very highly significant. Rate of germination depended to some extent on rate of water uptake. Slower germinating grains are to be preferred in tropical conditions. Sorghum grains survived soaking and drying very well so long as they had not germinated. However, grains with endosperm became very fragile after soaking and drying.Item Inheritance of Glume Size and Awn Length In Sorghum(1968) Jowett, D.Genetic studies on the inheritance of awn length and glume size in sorghum indicate that (a) both characters are inherited in a quantitative fashion, (b) short awns and small glumes are strongly (but incompletely) dominant, (c) awnless is apparently due to an accumulation of short-awn alleles, (d) epistasis is important in the inheritance of glume size but not of awn length, and (e) linkage may be important in the inheritance of awn length. Analysis into Mather's D and H components of variance was unsatisfactory owing to the high correlation of D and H. Analysis into Hayman's components of the mean was more satisfactory but cannot be regarded as quantitatively accurate.Item The Relationship Between Sunshine, Rainfall And Crop Yields At Serere Research Station(1966) Jowett, D.; Eriak,u P. O.Partial regressions have been calculated of yield on rainfall and sunshine hours for several crops at Serere Research Station, Uganda. A positive relationship is indicated, between cotton yields and total sunshine hours. No relationship emerges between yields of other crops and cltmatic factors.Item Sorghum Breeding Research(1962) Doggett, H.; Jowett, D.The objectives of the sorghum work have been outlined in earlier reports. The studies of grain characters, and the inheritance studies of glume, awn and goose-neck have necessarily been in abeyance this year, as D. Jowett was in" the U.S.A. on a biometrics course for much of the time. Emphasis has been placed on the assessment of the potential value of diploid hybrid sorghum in East Africa, and the development of tetraploid cultivated hybrids in which the yield increment may be retained for several generations.Item Unequal Seedling Survival Rates In Mixed Plantings of Sorghum Hybrids and Inbrcdsl(1965) Jowett, D.In a recent publication Walker 1 has described an experiment in which he implies that inbred cotton seedlings are selectively weeded out compared with hybrids in multi-line strains at singling (thinning) by African hand labour they tend to leave the most vigorous plants. He uses this as evidence favoring the persistence of hybridity in multiline strains of cotton, for which he claims yield improvement.Item Use of Rank Correlation Methods to Determine Food Preferences(1965) Jowett, D.Certain statistical techniques, useful in collecting and interpreting ordinal data, are described and their applicability in plant breeding explained. It is suggested that these statistical techniques may be particularly valuable to plant breeders in determining taste preferences. A series of experiments are described, investigating the taste preferences of the Iteso of Uganda, who show a strong preference for a mixture of cassava, sorghum and Eleusine millet for food. They do not apparently prefer white sorghum grains for food, nor coloured grains for beer, although such preferences have been recorded elsewhere. They dislike maize and Pennisetum millet. It is suggested that an experimental approach to quality in the breeding of tropical food crops is both desirable and possible, using rank correlation techniques.Item Yields of maize, sorghum varieties sorghum hybrids in the East African Lowlands(1966) Jowett, D. ; Doggett, H.; E.A.A.F.R.O. Sorghum unit, source,1. Sorghum is capable of giving substantial yields under dry conditions where maize fails. 2. Sorghum can consistently out-yield maize in some areas under conditions of apparently adequate or excessive rainfall. 3. Low soil nutrient status, and/or poor soil water relations, interacting with the amount of rainfall were probably responsible for the low maize yields where precipitation in the growing season exceeded 15 in. 4. Some hybrids originating in the USA may be of immediate value in dry areas of East Africa. Such hybrids are generally …
