Mpofu, Leo Thokoza (2005-12). Evaluation of the heterotic potential of sorghum [Sorghum bicolor (L.) Moench] adapted to the southern Africa region. Master's Thesis.
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.