Heterosis in Sesame (Sesamum indicum L.) Hybrids of Diverse Parental Lines for Agromorphology Characters in Ethiopia

Heterosis breeding is a technique with potential to improve sesame yield. The productivity of sesame need to be increased significantly to exploit the maximum benefit from the increasing world market demand for this crop as well as to reduce the deficit in edible oil in Ethiopia. The objective of this study was to determine the extent of heterosis for yield and yield related traits in sesame. The present investigation on sesame comprised a full-diallel set of 10 parents and their 90 F1 crosses. The hybrids were produced during the main growing season of 2011. Seeds of all F1 and their parents were planted in randomized complete block design, with three replications at two experimental sites viz., Uke (1383 meters above sea level) and Wama (1436 meters above sea level) of Bako Agricultural Research Center on 12 and 14 June 2012, respectively. The data was recorded for four traits viz., days to flowering, branches per plant, yield per plan (g) and oil content (%). Analysis of variance computed for each location and over locations revealed highly significant differences among the parental lines and F1 hybrids for all the studied traits. The magnitude of mid and better parent heterosis for seed yield ranged from -40.0 to 31.6-% and-40.2 to 23.3%, respectively. The range of standard heterosis for yield and oil content was -41.8 to 13.6% and –5.6 to 7.8%, respectively. Seven crosses of F1 and reciprocal F1 displayed positive and significant standard heterosis for number of branches per plant while a total of 35 (37.6%) crosses of F1and reciprocal F1 had negative better parent heterosis for days to flowering of which 18 (20.0%) displayed negative and significant standard heterosis. A total of 16 crosses (of F1 and reciprocal F1) displayed positive better parent heterosis for seed yield per plant, of which BG006 x EW003-1, EW023-2 x Dicho and BG006 x EW002 crosses of F1and rcecprocal F1 exhibited positive and significant standard heterosis of 10.5, 29.4 and 13.6%, respectively. All except two crosses of F1 displayed positive standard heterosis for seeds oil content of which 74 (82.22%) of crosses exhibited positive and significant standard heterosis. The different magnitude of heterosis displayed by some crosses of F1 and their reciprocal F1 for all characters indicated the presence of maternal inheritance, which suggested the importance of considering the use of female parents in the respective crosses and characters to maximize the exploitable heterosis in hybrids. Generally, the results of the research revealed higher chances of producing heterotic sesame hybrids that combined the highest yield, oil content, early maturity and high number of fertile branches. This suggests that heterosis breeding and/or hybridization could be one of the breeding methods in sesame in Ethiopia to produce heterotic hybrids that combine desirable traits as many as possible or to develop potential recombinant pure lines from segregating generations.