摘要：Information on heterosis and inbreeding depression for yield and agronomic characters is essential for sunflower （Helianthus annuus L.） breeding programs. This research was conducted to evaluate heterosis and inbreeding depression for yield and agronomic characters of hybrids involving eight sunflower inbred lines. These inbred lines were crossed in 8×8 half diallel to obtain 28 F The 28 hybrids were self-pollinated to produce the F2 generation. The 8 parents, 28 F1 hybrids and 28 F2 populations hybrids were evaluated using a randomized complete block design with three replications at two locations in Nakhon Ratchasima （SUT Farm and National Corn and Sorghum Research Center） in 2009. Mid-parent heterosis and inbreeding depression were estimated for yield, head diamete oil content, 1,000-seed weight and plant height. Significant differences were found among the parents, F1 hybrids and F2 populations for all traits. F1 hybrid means were significantly higher than the parental means for all traits. In addition, F1 hybrids considerable heterosis and heterobeltiosis when compared with the mid-parent and better parents, respectively. Yield, showed oil content and plant height showed highly positive heterosis in F1 hybrids, ranging from 14.48 to 49.45%, 8.88 to 33.22% and 9.51 to 29 respectively. Similarly, heterobeltiosis were positive significant for yield （19.22 to 49.04%）, oil content （8.65 to 28.30%） and height （2,83 to 27.61%）. However, 1,000-seed weight showed a low level of heterosis in F1 hybrids （-9.36 to 8,07%） oil content, 1,000-seed weight and plant height in F2 populations were lower than their respective Fi hybrids the F2 populations was comparatively high for yield, oil content and plant height. The cross of lines 5A×for yield （49.45%） and 1,000 seed-weight （8.07%） but low 25%, plant Means for yield, Inbreeding depression in 2A gave the highest heterosis inbreeding depression for yield （10.06%）. Based on the mean performance and heterotic effects for seed yi

摘要：Five varieties of durum wheat were crossed in full diallel fashion through 2010/2011 growing season. The five parents and their 20 F1 progenies were grown in 2011/2012 at the farm of faculty of agricultural and forestry, Duhok university, Iraq, using randomize complete block design with three replications to estimate heterosis, heritability and some genetic parameters for yield and its components. The results showed highly significant difference among genotypes for all studied traits. The parent Um Raby-5 had a positive general combining ability effect for most traits including grain yield. The crosses （Kokorete71× LD - 357E）, （Crezo × Um Rahy-5）, （Cimeto×Um Raby-5）, （Cimeto×crezo） and （Cimeto × Kokorete 71） exhibited significant desirable specific combining ability effect for most traits. The dominance was greater than additive almost traits. Heritability inbroad sense was high but heritability in narrow sense was low. The expected genetic advance as percent of traits mean was low for all traits. Most crosses showed significant positive heterosis for most traits and two crosses, （Crezo Cimeto） and （Cimeto Urn Raby-5） had the highest positive heterosis for the most studied traits including grain yield.

摘要：In present study, under North Carolina design Ⅱ, 5 sterile lines and 2 restorer lines were analyzed by crossing test so as to study the combining ability, habitability and correlation of each major agronomic characters. The results showed that plant height, panicle length, filled grains per plant, grains per plant, 1 000-grain weight, yield per day, yield per plant by parent gene additive effect, seed set of parent gene additive and the additive effect work together, additive effect played a relatively important role, effective tillers per plant by additive genes of the parents and the additive effect had more consistent effects on offspring traits. General combining ability effect analysis showed that the better parents were P1A and R102. The special combining ability of plant height and panicle length in hybrid rice combination was mainly correlated with the general combining ability of restorer line, whereas not with the general combining ability of parent. For the other 7 traits, if the general combining ability of both parents was higher, the special combining ability of hybrid F1 combinations was also higher. The best combination of special combining ability of 9 traits in hybrid rice was P2 A/R102, followed by P1 A/R102.