Differential interspecific incompatibility among Populus hybrids in sections Aigeiros Duby and Tacamahaca Spach

In our previous Populus breeding, compatible crosses between P. maximowiczii A. Henry and P. deltoides Bartr. ex Marsh corroborated the potential of interspecific hybrids, despite low seed set. Our current objective was to test the range of incompatibility among intraspecific and interspecific crosses using parental germplasm from the sections Aigeiros Duby (P. deltoides and P. nigra L.) and Tacamahaca Spach (P. maximowiczii). We determined the success rate of crosses, along with seed production and seedling viability. The success of crosses ranged from complete incompatibility to complete compatibility, with 29% to 85% of the transplanted germinants developing into healthy seedlings.