Floral branch traits and flowering characteristics of Magnolia grandiflora under different habitats

To explore the ecological adaptability of annual flowering organs of Magnolia grandiflora L. under different habitats, four habitat types in the Fengxian campus of Shanghai Normal University, including sunny wetland, sunny lowland, shady flatland, and semi-shade flatland, were selected to compare the morphological traits of flowering branches, distribution and reproductive ratio, pollen vigor, and flowering phenology. The main results were： the leaf area and specific leaf area in semi-shade flat and shade flat habitats were higher than those in sunny habitats； the annual branch length, flower diameter and width in the shaded flat were larger than those in the other three habitats, showing larger flowers and leaves and higher branch extension, which were excellent for ornamental purposes. There were not significant differences of flower dry weight among the four habitats, while the significant differences were found in leaf dry weight （F=4.38, p<0.05） and branch dry weight （F=3.31, p<0.05）. The leaf dry weight in semi-shade flat habitats was significantly higher than that in other habitats （F=4.48, p<0.01）. Comparing the distribution of the average dry weight of flowering branch organs, the organic matter allocated more to flowers in the sunny wetland and shady flatland habitats, and the water content showed a trend of flowers > leaves > stems. The distribution and reproductive ratio in sunny wetland habitats was significantly higher than that in other habitats （F=4.48, p<0.01）. Pollen viability differed significantly among the different habitats （F=19.00, p<0.05）, with 20.79% in the sunny lowland and 7.14% in the semi-shade flat land. The plants grown in semi-shade flat habitats started flowering earlier and the period was up to 46 days, and there was no significant correlation between the blooming time and the flowering period. The results improved the understanding of the ecological adaptations of plant floral organs, and provided a reference for the cultivation and application of M. grandiflora.