Studies on Flowering Phenology of Clones in Pinus tabulaeformis Seed Orchard

The observation was carried out on the flowering phenology in the initial period and abundant cone period for 46 clones in Pinus tabulaeformis seed orchard located in Henan Province. The differences of flowering phenologies among clones, among ramets within a clone, at different positions within a crown were described, the relationship of flowering phenologies of the same clones in different years were analyzed. The female strobili opened earlier, and ended later than male strobili as well. Receptivity of female strobili lasted for a longer time than male strobili shedding, the receptivity appeared to coincide with the pollen shedding. In different years, 2～3 days differences existed for the flowering time, the flowering time was related with the actively accumulative temperature with more than and equal to 10 ℃. The lasting period showed about 10-day difference for lasting time of flowering period in different years. In the different years, there was big difference in flowering time for different clones, but the sequence of the flowering time for different clones was relatively consistent, the flowering time showed 1～2 day difference for different ramets within a clone. There was big difference in flowering frequency of different dates between strobili facing north and these facing other three directions, strobili facing north opened 1-day later than these facing other three directions. In addition, the relationship between flowering phenology and synchronization index, and differences of pollinated efficiency for different flowering phenology types were discussed.