Masters Degrees (Food Science)
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Browsing Masters Degrees (Food Science) by browse.metadata.advisor "Agenbag, G. A."
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- ItemYield and quality response of spring wheat cultivars to post anthesis high temperature(Stellenbosch : Stellenbosch University, 1999-10) Molefe, Mary Kneen; Agenbag, G. A.; Stellenbosch University. Faculty of AgriSciences. Dept. of Food Science.ENGLISH ABSTRACT: Knowledge of the growth, yield and quality response of spring wheat cultivars to high temperatures is important to minimise variation that often exists in yield and breadbaking quality of wheat produced in warmer regions. To achieve this, four South African spring wheat cultivars Kariega, Palmiet, SST 55 and SST 57 were grown under controlled conditions at the University of Stellenbosch during 1998 at temperature regimes of 15/10, 20/15, 25/20 and 30/25°C during grain filling. From seeding till anthesis, plants were grown at a temperature of 15/10°C. In this study,. the highest temperature regime of 30/25°C affected all parameters tested, while at lower temperature regimes cultivars responded differently. The 30/25°C temperature regime caused premature senescence of the leaf area which was attributed to a decrease in relative leaf water content. Increased senescence of leaves at this temperature regime, reduced photosynthesis during grain filling, with the result that shriveled kernels with a lower mass kernel -1 were produced and yield plant -1 was reduced by almost 50% compared to that of the control (15/100 C). Other yield components such as kernels ear -1 were less reduced and Kariega was less affected in comparison with the other cultivars. High temperature regimes of 30/25°C during grain filling resulted in increased flour protein content. Mixogram peak heights increased as post-anthesis temperature regimes increased, while Palmiet also showed an increase in dough development time with increasing temperatures. At the highest temperature regime (30/25°C), the respective dough development times for SST 55 and SST 57 were well below the optimum mixing time of 2.5 to 3 minutes set by the baking industry, while the mixograph band widths of Kariega were the narrowest at all temperature regimes tested. This tendency indicated good water absorption properties. These results indicate that quality parameters of Kariega and Palmiet are less sensitive to high post-anthesis temperatures in comparison with SST 55 and SST 57. In general, it is concluded that although this study showed small differences between cultivars, Kariega was consistently different from other cultivars, indicating possible adaptation to hotter environments. However, more cultivars need to be screened before recommendations for such areas can be made.