Seed vigor, photosynthesis and early growth of saplings of different triploid Betula families

Breeding scientists have given extensive attention to triploids in trees because of their importance to forestry. Consequently, creating and breeding triploids of good quality has become one of purposes of tree breeding. We chose two autotetraploids (Betula platyphylla, named Q10 and Q65) as female parents and eight hybrid diploids (B. platyphylla × B. pendula, named F1 – F8) as male parents to obtain progenies through controllable pollination, resulting in triploid progenies. Germination rate and germination energy of triploid seeds of Q65 were significantly higher (P < 0.01) than in triploid seed s of Q10. Triploid families with Q65 as female parent had a large quantity of saplings, whereas triploid families with Q10 as female parent had a small quantity of saplings. Triploid families with Q65 as female parent were generally superior in base diameter and height to base diameter ratio when compared to a diploid family. Q65×F3 was preliminarily recognized as the superior family. These results demonstrate that the female parent has a major influence on triploid progenies, although the male parent also has a small influence. The results provided a reference to build seed orchards of triploid birch trees, choose tetraploids as female parents and forecast triploid families of good quality.