Growth traits of triploid progenies in one year old from different crosses of Betula platyphylla Suk.

Triploid progenies of 20 crosses were obtained by controlledpollination using four autotetraploid Betula platyphylla (Q14, Q19, Q33 and Q34) as female and five diploid hybrid B. platyphylla ×B. pendula (M1, M2, M3, M4 and M5) as male and tested in a nursery. This paper presents early growth measurements and the results indicat that cross had a significant effect on height and base diameter growth. Variances of general combining ability and specific combining ability for both height and base diameter were significantly different from zero. Based on the results of growth, general combining ability and specific combining ability,two autotetraploids(Q19 and Q34) were identified as good female parents, two diploid hybrids (M1 and M2) as male parents, and Q34×M2 and Q34×M1 as the best crosses.