An understanding of the seed dynamics of endangered plant species, such as Magnolia zenii Cheng, is important for successful conservation. This study examined the morphological, physiological and biochemical changes that occur in M. zenii Cheng during seed development to determine the appropriate harvest stage. The appearance of the seeds was influenced by the physiological and biochemical changes occurring during the developmental period, during which the colour of the fruits changed from green to red, while that of the seed changed from light brown to dark brown. There was a significant decrease in the seed moisture content from 90 to 120 days after flowering (DAF); however, there was no significant change from 135 to 165 DAF. The seeds from 135 DAF onwards showed developed cotyledonary embryos. The seed viability exceeded 95% from 135 DAF onwards; however, the germination percentage was 0, hypothesising that the seeds of M. zenii Cheng might exhibit physiological dormancy under certain conditions of this experiment. There was a significant increase in the fat, soluble sugar and soluble starch content of the seeds while approaching maturity.There were significant changes in malate dehydrogenase (MDH), glucose-6-phosphate dehydrogenase (G-6-PDH), 6-phosphogluconate dehydrogenase (6-PGDH) and β-amylase activities in the seeds during the developmental period. At 135-165 DAF, the MDH activity remained stable, whereas that of 6-PGDH reached its maximum, indicating that the seeds underwent vigorous metabolism. The findings of this study provide a theoretical basis for researching seed dormancy and seed harvest time.
| INTRODUCTIONMagnolia zenii Cheng is a deciduous tree belonging to the subgenus Magnolia and family Magnoliaceae and is endemic to China. The existing natural communities are distributed on the northern slope of Baohua Mountain in Jurong City, Jiangsu province (Xu et al., 2001). M. zenii Cheng is a precious ornamental garden tree, and its flowers and fruits can be used as medicine. Recent studies have shown that the seed extract of M. zenii Cheng has antiinflammatory and anti-tumour effects (Song et al., 2012(Song et al., , 2013Song & Li, 2012a, 2012b. However, owing to the limited environment range of M. zenii Cheng and interspecific competition, the population of adult and seedlings of M. zenii Cheng in the wild is