[Dynamic studies on photosynthetic and growth characteristics of Angecila dahurcia].

Photosynthetic and growth characteristics of Angelica dahurica were studied in order to clarity the relations of photosynthesis, growth and root dry weight, and provide a theoretical basis for its cultivation. Photosynthesis and growth indexes were meas- ured every 25 days. The contents of chlorophyll a, b, a + b, soluble protein and the activities of Hill reaction, Ca(2+)-ATPase, Mg(2+)-ATPase had an increasing trend; They had the highest value in leaf high-speed growth period. Then, they were decreased in root high- speed growth period. The root dry weight showed negative corelation with photosynthetic characteristics indexes except stomatal con- ductance, however, the negative corelation only from net photosynthetic rate and Ca(2+)-ATPase were significant. The vegetative growth period of spring sowing A. dahuricia was divided into three phases: seedling period, leaf high-speed growth period and root high-speed growth period. The root dry weight showed a significantly positive corelation with the root diameter, leaf dry weight, shoot dry weight, aboveground dry weight. There was the competitive relation between aboveground and underground, so underground growth could be es- timated from leaf area and shoot dimeter.

[Effects of shade and competition of Chenopodium album on photosynthesis, fluorescence and growth characteristics of Flaveria bidentis].

It is necessary to elucidate its growth mechanism in order to prevent and control the further spread of Flaveria bidentis, an invasive plant in China. The effects of shading (shading rate of 0, 50% and 80%, respectively) and planting pattern (single cropping of F. bidentis, single cropping of Chenopodium album and their intercropping) on germination rate, fluorescence characteristics and growth characteristics of the two plants were investigated. The results showed that moderate shading contributed to emergence rate, but emergence rate of F. bidentis was not uniform, which was one of important factors as a stronger invader. With the increasing light intensity, net photosynthetic rate (Pn), photochemical quenching (qP), electron transport rate of PS II (ETR), quantum yield of PS II (Y), non-photochemical quenching (qN), water use efficiency (WUE), shoot bio-mass rate (SMR), crown width (CW) and dry biomass (DM) increased, specific leaf area (SLA) decreased, LMR of F. bidentis significantly increased, LMR of C. album changed insignificantly, and the increment of DM of F. bidentis was higher than that of C. album. In 80% shade treatment, Pn and DM of F. bidentis were lower than those of C. album. In natural light treatment, Pn, qN, WUE and relative competitive index (RCI) were the highest, CW and DM of intercropped F. bidentis and Pn, Y of C. album were significantly lower than that of the respective single treatment. F. bidentis had higher light saturation point (LSP) and light compensation point (LCP). In conclusion, the shade-tolerant ability of F. bidentis was weaker than that of C. album, but it was reversed in natural light treatment. The two plants adapted to the weak light in 80% shade treatment by increasing SLA and decreasing LMR. F. bidentis improved competition under natural light by increasing SMR and decreasing CW.