Are maternal and reciprocal effects important in breeding the inter-specific hybrid between Acacia auriculiformis and A. mangium?

Controlled pollination (CP) was used to produce four reciprocal crosses of the interspecific hybrid between Acacia auriculiformis and A. mangium, and one additional reciprocal cross within each parental species. There were no reciprocal effects on seed yield index (filled seeds per 100 flowers pollinated) and germination success for filled seeds. The CP families, together with four additional CP hybrid families, one open-pollinated (OP) family from seed orchards of each parental species and a commercial Acacia hybrid (A. mangium × A. auriculiformis) clone were planted in a field trial in central Vietnam. Forty months after planting the pure-species A. mangium families, with diameter at breast height (DBH), averaging 10.8 cm, grew faster than those of A. auriculiformis (mean 8.5 cm). Nursery gate survival and mean height and diameter at breast height at 40 months of the interspecific hybrid families were not affected by crossing direction. The mean height and DBH of all hybrid families was close to the mid-point of the two parental species. Inheritance of phyllode length and breadth was non-additive; interspecific hybrid families had phyllode length and width much closer to that of A. auriculiformis than to A. mangium, however there was no consistent reciprocal effect for these traits. It is concluded that, at least for the test environment under study, crossing direction is not likely to be of practical importance in hybrid breeding of these species.