[Response of growth and photosynthetic characteristics of Polygonatum cyrtonema to shading conditions].

The purpose of this experiment was to study the effects of different shading conditions on the growth,physiological characteristics and biomass allocation of Polygonatum cyrtonema,which offered a theoretical basis for its cultivation.Different light environments(100%,80%,60% and 35% light transmittance) were simulated with shading treatments.Growth and photosynthetic indexes of P.cyrtonema were measured and the variances were analyzed.The results show that shading decreased superoxide anion radical(O-·2)production rate and hydrogen peroxide(H_2O_2) accumulation,kept the activity of SOD,POD and CAT enzyme at a high level.Furthermore,The content of chlorophyll a and chlorophyll b,net photosynthetic rate(Pn),stomatal conductance(Gs),transpiration rate(Tr),maximal photochemical efficiency of photosystem Ⅱ(Fv/Fm),photochemical quenching index(q P) and effective quantum yield of photosystem II(ΦPSⅡ) of P.cyrtonema were increased while the intercellular CO2 concentration(Ci),Foand NPQ were decreased by shading.Shading is beneficial to P.cyrtonema growth,can increase the total biomass P.cyrtonema.The allocation proportion of biomass on the aerial portion of P.cyrtonema increased but underground parts decreased with increasing shading conditions.In this study,P.cyrtonema can grow well in shading conditions,shading is beneficial to the formation of the yield and quality of the rhizomes of P.cyrtonema,especially in 65% light transmittance.

[Effects of constant low temperature on cold resistance of different strains Polygonatum odoratum].

In this paper, the five strains of Polygonatum odoratum were used as the experimental materials to test the supercooling point, freezing point, the degree of supercooling, the transition stage time, cooling time and water composition of the plant tissue. The cold resistance of P. odoratum was analyzed with the Gray Correlation Method. The results showed that the cold resistances of the five strains of P. odoratum were different, and the water content of plant tissue had some relevance with freezing point and supercooling point, whereas, it could not be measured when the moisture content was too low. The order of cold resistance of the five strains of P. odoratum was ZJCY, DYYZ, XYYZ, CYYZ and JZ I.

[Studies on phonological phases of cultivated Polygonatum].

OBJECTIVE: To determine the phonological phases of cultivated Polygonatum by investigating the dynamic pattern of its growth and development, which would provide the guides for normal planting in the field. METHODS: Fix-point and real-time observation combining with comprehensive survey were used in the field. RESULT: Cultivated Polygonatum had obvious processes of development including emergence of seedlings, extension of leaves, growth of stems and leaves, floral initiation, flowering, seed setting, death of plant-germinating-in-spring, plant shoot regeneration and hibernating shoot emergence, and hibernation with dead aerial part of plant. There were small differences in these processes of development among species and sites, but the whole phonological pattern hold relatively constant. CONCLUSION: The phonological phases of Polygonatum with eight stages, including seedlings emergence stage, plant extension stage, leaves extension stage, anthesis stage, seed stage, aerial part death stage, germination-in-autumn stage, and hibernation stage, were finally determined.