STUDIES ON THE REPRODUCTIVE BIOLOGY OF NOTHOFAGUS SPECIES

TORRES, CRISTIAN; PUNTIERI, JAVIER GUIDO; STECCONI, MARINA

Bariloche

Congreso; Southern Connection Congress; 2010

CONICET, Universidad Nacional del Comahue

In monoecious wind-pollinated species, like those of Nothofagus, the distribution of flowers in time and space is relevant to facilitate pollen flux and avoid selfing (in self-incompatible species). For some Nothofagus species it is well known that the production of viable seeds exhibits notable between-year fluctuations, being low in most years. The reasons for these variations are unknown. We hypothesized that deficient pollination may have a significant effect on low seed sets in these species. The aim of this study is to deal with this issue through the application of manual pollinations and the study of the distributions of pistillate and staminate flowers. We performed manual intra-individual and intra- and inter-specific pollinations in nursery N. nervosa and N. obliqua trees. In a natural population of N. nervosa and N. obliqua we compared the production of viable seeds between natural and manually pollinated flowers and assessed the role of flower position on the tree on seed set. The manual pollination technique resulted useful for small-scale seed production. The study of the phenological stages of flowering shoots allowed us to conclude that it is highly probable that pistillate and staminate flowers within a shoot have overlapping antheses. Preliminary data about compatibility relationships between Nothofagus species and inter-specific hybrids also resulted from this study. In N. obliqua, the proportion of viable seeds depended on the position of the flowering shoot in the main branch.