Sorghum [Sorghum bicolor (L.) Moench] production in Africa is widespread with low yields due to low inputs and the lack of sorghum hybrids. This situation has forced most of these farmers to grow maize hybrids since they are readily available in the seed market. Sorghum hybrids could be used if their potential was demonstrated. The objective of this study is to document the level of heterosis in Southern Africa sorghum germplasm. The performance of 52 F1 grain sorghum hybrids and their parental lines was evaluated in four environments. Measurements for grain yield, panicle exsertion, days to mid anthesis and plant height were analyzed to obtain estimates of high parent heterosis. High parent heterosis was observed to be 37.18% for yield, 82.77% for exsertion, -0.02% for days to mid anthesis and 23.7% for height. ICSR-939 and (87EON366*90EON328)-LD30 can be used as testers to develop more female lines for further hybrid seed production in breeding programs because they had the highest general combining ability. Protein content averaged 11.69%. ATx635 had significantly higher protein content than ATx631 (13.49% compared to 9.69%, respectively) and its hybrids had more protein than ATx631 hybrids (11.6% compared to 10.67% for ATx631). Mean heterosis for protein content was negative at -12.5%. This shows that hybrids had lower protein content than their parents since protein content is negatively correlated to grain yield (-0.35**). Starch content averaged 72.13% and ATx631 hybrids had more starch than ATx635 hybrids (73.16 compared to 72.37% respectively). Two hybrids, ATx.631/(87EON366*90EON328)-LD30 and ATx631/ ((TAM428*SV1)*CE151)-LD3 had the highest yields (5.04 t/ha and 4.93 t/ha, respectively). These hybrids also had small grains with good hardness and acceptable whiteness. They had good exsertion, flowered in good time and had acceptable plant heights. These two hybrids were compared to regional check varieties Macia and Tegemeo for all traits and they were either superior or within an acceptable range. These two hybrids are therefore recommended for release in the region. There is need therefore to start working on the various components of seed systems in the region so that seed of these two hybrids is made available to farmers who need the seed.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

No description available.

Calving rate, weaning rate, birth weight, weaning weight, and ADG from 1997 to 2011 were investigated in Angus, Nellore, F_(1) Nellore-Angus, first generation 3/8 Nellore 5/8 Angus produced as following: (1/2 Nellore 1/2 Angus sires and 3/4 Angus ¼ Nellore dams, 3/4 Angus 1/4 Nellore sires and 1/2 Angus 1/2 Nellore dams, and ¾ Nellore 1/4 Angus sires and Angus dams), and second generation 3/8 Nellore 5/8 Angus cows. The objectives were to estimate heterosis in Nellore-Angus crosses for cow reproductive traits and maternal effects on traits of their calves. The F_(1) cows expressed 0.20 ± 0.02 heterosis for calving rate, while both first and second generation 3/8 Nellore 5/8 Angus expressed 0.13 ± 0.02. the first generation 3/8 Nellore 5/8 Angus produced out of 3/4 Angus 1/4 Nellore sires and 1/2 Nellore 1/2 Angus dams expressed 0.14 ± 0.03 heterosis for calving rate. The F1 Nellore-Angus expressed 0.23 ± 0.03 heterosis for weaning rate and the 3/8 Nellore 5/8 Angus produced out of 3/4 Angus 1/4 Nellore sires × 1/2 Nellore 1/2 Angus dams and the second generation 3/8 Nellore 5/8 Angus expressed 0.14 ± 0.07 and 0.15 ± 0.05, respectively. No heterosis was expressed for birth weight in any breedtype group. Multiple attempts to analyze weaning weight and ADG and estimate heterosis resulted in excessive adjustments to least squares means. Young and oldest cows weaned lighter calves than others. F_(1) cows weaned heavier calves at most ages. Nellore-sired F_(1) calves were heavier at weaning than the reciprocal cross. Calves out of cows of intermediate ages had larger preweaning ADG than calves born to 2- and 3-yr-old and to aged cows. Generally, calves out of F_(1) Nellore-Angus cows had larger ADG than those out of cows of other breedtypes. Nellore-sired F_(1) heifers had lower ADG than Angus-sired F_(1) heifers. In general, bull calves had larger ADG than heifers. Non-F_(1) crossbred cows expressed slightly larger heterosis than what would be expected by the dominance model. Heterosis expressed by second generation 3/8 Nellore 5/8 Angus for calving and weaning rate did not appear to differ from the first generation.

Thesis (Ph.D. 1977) from the Department of Agronomy, University of Adelaide.

Thesis (Ph. D.)--University of Wisconsin, 1965. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

No description available.

No description available.

No description available.