关键词: 葎草, 雌雄异株, 越冬, 生理反应, 再生策略

Abstract: This research studied the wild dioecious climbing herb Humulus scandens, in order to analyze the differences in physiological response and regeneration strategies between male and female plants, while over-wintering. Various physiological data, including soluble sugar (SS), starch (ST), and pyruvic acid (PA) contents and nitrate reductase (NR) activity of male and female plant parts (young leaves, mature leaves, mature stems, roots) were determined before winter (December 1), during over-wintering (January 15) and after winter (April 15). Survival rate and regeneration rate of plant parts biomass allocation ratio were also determined after wintering, to give insight into differential biomass allocation strategy of male and female plants. The results showed: 1) The ST content in the leaves of male plants before wintering was lower than that in female plants, and the content of SS and ST in mature stems and roots were lower than those in female plants (P<0.05). Male plants resisted cold by increasing SS in leaves, while female plants responded to cold by transferring sugar to the stems and roots. 2) The PA content of male plant leaves and stems was significantly higher than that in female plants before wintering, but PA content in male plant roots was significantly lower than that in female plants (P<0.05). There was no gender difference in NR activity of plant modules (P>0.05). Male plants resisted cold by enhancing the respiration of stems and leaves, while female plants responded to the cold through utilization of substrate reserves in the roots. 3) The content of SS and ST in the regenerated leaves of female plants was higher than in male plants (P<0.05), and the PA content and NR activity in leaves were both lower than in male plants. The PA content increased over winter in the female mature stems yet decreased in male plants (P<0.05). The metabolic activity involved in female plant regeneration was higher than that of male plants. 4) The survival rate of over-wintering male plants was 26.67%, while survival rate of female plants was 76.7%. The survival rate of stems in male plants was only 32.24% of that in female plants (12.50% and 38.77%, respectively). The regeneration rates of plant parts were, for male and female plants, respectively: leaves 5.85% and 1.23%, stems 13.10% and 3.12%, while inflorescence regeneration in female plants was 74.40%. 5) The number of regenerated leaves, the leaf area, and the length of the regenerated stems of female plants were all lower than those of male plants (P<0.05). The total biomass proportion contributed by regenerated stems and leaves was only 0.59% and 1.31%, respectively, while the contribution to total biomass of regenerated inflorescences was 98.09%. The regenerated inflorescence stalk and axis length and floret number of regenerated inflorescences were larger than those of inflorescences observed before winter. Sepals exhibited increased area and greenness, and accounted for 31.26% of total biomass in regenerated plants, and their total area was as much as 625 cm²·plant^-1, compared with a total area of regenerated leaves of 25.51 cm²·plant^-1. During overwintering, male plants resisted cold through physiological response, in which the stored substrates of male stems and roots were lower than those of female plants. Thus the survival rate and regeneration rate of male plants were lower than those of female plants. After wintering, the biomass of regenerated male plants was only 1.57 g·plant^-1 and all of this was allocated to vegetative organs. By contrast, the average biomass of female plants was 32.05 g·plant^-1, and 98.09% of this was allocated to inflorescence formation with sepals instead of leaves being the main photosynthetic organs, providing nutrients for inflorescence formation and nearby flower development.

Key words: Humulus scandens, dioecious, wintering, physiological response, regeneration strategy