Grain number per spike was studed in 6 winter wheat varieties and all their 30 direct and reciprocal F1 hybrids. Parents
included 4 released Romanian variety, the old american Atlas 66 and a dwarf breeding line, Oradea 79. This line has a low number of
grains/spike, but is important in breeding program for here reduced height. General and
genetic effects were estimated using Griffing’s method 1, model 1, as modified by Cabulea (1983).
For this diallel crosses, gene interactions and the interaction between cytoplasm and nuclear genes were highly significant and
the ratio of additive and non-additive effects was close to one.
The variety Fundulea 29 showed the highest general combining ability and it is recommended as a good parent for increasing
grain number/spike. Mid-parent heterosis was significant in 9 out of the 30 cases, mostly in hybrids involving the breeding line Oradea 79.
In 3 cases the number of grains/spike of F1 hybrids was significantly lower than the average of the parents. The breeding line Oradea 79 had
a significant negative general combining ability, but showed significant positive specific combining ability in most crosses, as well as a
significant positive effect of its cytoplasm. These results are considered to indicate that there are chances of improving the grain
number/spike in some crosses with Oradea 79.
In Hungary, we examined eight features of twelve direct cross hybrids over a period of three years. The twelve hybrids were derived from direct and reciprocal crosses of four parental lines. We did not find significant differences in the cases of stalk diameter and leaf number in the average of 3 years in any of the hybrids. Statistically expla...inable differences in primary branches were observed in hybrids UDH5 and UDH8 and also in UDH6 and UDH11. It was evident in both instances that degrees of heterosis in reciprocal crosses far exceeded those of direct ones. High tassel branch number was dominant over the low one; consequently, parents with higher tassel numbers enforced their effects during the formation of this trait in hybrids. We experienced positive correlation (r=0.67**) between plant height and main ear height. A positive correlation (r=0.89**) was also found between the tassel length of the main axis above the lowest and the upper side branch. We observed a medium correlation (r=-0.42**) between the number of primary lateral branches and plant height. The number of primary lateral branches showed the highest heterosis. These results can be utilized in practical selection and seed production.