Reciprocal and maternal effects on growth and form traits in radiata pine in New Zealand

The information from two experiments was used to study reciprocal and maternal effects on several growth and form traits in Pinus radiata. In Experiment 1, 10 families and their reciprocals obtained from a 5 x 5 diallel experiment were planted across three sites. In Experiment 2, 17 parents were used in a partial diallel design and all available crosses were planted at a single site. All three sites for Experiment 1 were assessed at 9 years of age. The site for Experiment 2 was assessed at the age of 6-years. Four growth and form traits, namely diameter at breast height (DBH), straightness (STR), branching (BR) and malformation (MAL) were measured in both experiments while needle retention (NRA) was assessed only in Experiment 1. General combining ability (GCA) effects, in Experiment 1, were found to be significant for all traits. The overall reciprocal effects were, in general, found insignificant at all three sites. Further partitioning of the reciprocal effect revealed that maternal effect was non-significant for all traits at all three sites and non-maternal (or residual reciprocal) effect was Significant only for BR at Site I and for NRA at Site 2. The interaction of reciprocal by site effect was found non-significant for all traits. Analysis of Experiment 2 revealed significant overall reciprocal effects for all traits. Further partitioning of reciprocal effects revealed that maternal effect was significant for all traits except STR, but non-maternal effects were significant for STR and 1311 only. This study showed that existence of maternal and non-maternal effects could vary considerably for different sets of parents. Estimated correlation between parental GCA estimates obtained with-and-without taking into account reciprocal effects were 0.99 for all growth and form traits considered in this study.