Polyad

Abstract: Pollen of acacias is transported by insects as polyads, composite pollen grains. The polyad has enough pollen grains to fertilize all ovules within a flower and hence all seed within a pod may be full sibs. Isozyme markers were used to test this hypothesis in two populations of Acacia melanoxylon R.Br. The proportions of fruit pods with multiple paternity detected in two populations were 0.08 and 0.15. The proportions of fullsib pairs within pods estimated by the sibling pair method were 1 and 0.63 for the two populations. Comparison of the diploid paternal genotypes of pods of single paternity showed that the probability of a common pollen source for a pair of pods was high within globular clusters (0.35) or within inflorescences (0.46) but declined to 0.10 or 0.25 within the tree at random. Thus the reproductive system acted to reinforce a hierarchy of paternal correlation within each tree.

Abstract: Polyad quantum numbers have been assigned to 134 vibrational levels of the X1Σg+ state of acetylene with internal energies from 3,000 to 15,000 cm−1. These polyad assignments have been made possible by two advances: (1) the recording of new, rigorously calibrated acetylene A1Au→X1Σg+ dispersed fluorescence spectra, and (2) the development of a numerical pattern recognition technique which identifies groups of transitions in the spectra that terminate on eigenstates with the same polyad quantum numbers. This pattern recognition technique is based on the Extended Cross-Correlation, which has been reported previously in this Journal [J. Chem. Phys. 107, 8349, 8357 (1997)], and requires neither a priori knowledge of the number of polyads in the spectra nor the pattern of spectral lines that is associated with each polyad. No evidence for the breakdown of the polyad quantum numbers is found, at the 7 cm−1 resolution of our spectra, at internal energies up to at least 15,000 cm−1. The ability to assign polyad...

Abstract: Floral phenology and morphology of colchicine-induced auto-tetraploid trees of Acacia mangium Willd. (AM-4x) growing in Vietnam were compared with adjacent diploid A. mangium (AM-2x) and A. auriculiformis A.Cunn. ex Benth (AA-2x). Flowering lasted for several months with a slightly later peak flowering period for A. auriculiformis (December–January), than for A. mangium (November–December). Flower spikes of AM-4x were shorter and had fewer flowers per spike than those of AM-2x, but were longer and had more flowers than AA-2x. Percentages of male to hermaphrodite flowers were less than 23% for all three species/ploidy combinations. Flowers of AM-4x had slightly shorter styles than did AM-2x, but AM-4x stigma and polyad diameters were greater. For all polyad-stigma combinations among species/ploidy levels, at least one polyad could be accommodated. AM-4x had fewer (13) ovules per ovary, compared with AM-2x and AA-2x (14–16). AM-4x set fewer (less than 3) seeds per pod than did AM-2x and AA-2x (7–8 and 5–6, respectively). Foraging behaviour of the main insect pollinators (honeybees) and examination of polyads collected from them suggested interspecific and interploidy pollination would occur. There appeared to be no phenophase or flower structure barriers to interploidy pollination.