|其他摘要||The leaf traits, gas-exchange response curves, chlorophyll fluorescence and growth parameters were examined in three-year old Incarvillea delavayi grown at four nitrogen concentrations, and in I. mairei var. grandiflora with root tuber weighting from 2.0 to 3.0 grams grown at three phosphorus concentrations. The main aims were to judge if nitrogen and phosphorus had a significant effect on each Incarvillea species respectively, and to find out the mechanisms. Through this work, it hopes to provide theoretical advice for their domestication and planting from the photosynthetic physiological point of view.
The results showed that:
1、 Effects of nitrogen on photosynthesis and growth of I. delavayi
①As nitrogen supply increased, the leaf nitrogen content (N) , chlorophyll content (Chl), fraction of leaf nitrogen allocated to the photosynthetic components (PR、PB and PL) and nitrogen content in photosynthetic componets (Np) increased correspondingly, while the specific leaf area (SLA) decresesed.
②The maximum net CO2 assimilation rate at ambient CO2 concentration (Amax), the maximum rate of potential electron transport (Jmax), and the maximum rate of carboxylation (Vcmax) significantly increased with nitrogen. And the ratio of Jmax to Vcmax had significant differences under different nitrogen levels.
③The maximum photochemical efficiency of PSII (Fv/Fm) in the plants under 0g/Kg nitrogen application condition was much lower than those of the others. And with the increasing of nitrogen supply, the quantum yield of PSII photochemistry (ΦPSII), the efficiency of excitation capture by open PSII reaction centers (Fv´/Fm´), and the photochemical quenching coefficient (qP) increased, yet non-photochemical quenching coefficient (qN) decreased.
④The relative growth rate (RGR) of the whole plant was different between the treatments, but the ratio of roots to shoots was not.
In conclusion, nitrogen could improve the photosynthetic capacity of I. delavayi by altering the leaf structures, nitrogen partitioning and photosystem II’s (PSII) activity, as a result, the plants indicated a higher speed of growth. And according to the results, the optimum amount of nitrogen needed by three-year old I. delavayi was about 220-230mg/Kg.
2、Effects of phosphorus on photosynthesis and growth of I. mairei var. gradiflora
①With the phosphorus supply increasing, the leaf phosphorus content of I. mairei var. gradiflora increased substantially, whereas SLA, Chla, Chlb, Chla/Chlb and the total chlorophyll content changed little.
②Amax and Jmax were positively affected by phosphorus, while the other photosynthetic parameters, such as AQE, Vcmax and TPU, were not significantly affected by phosphorus.
③Among all the treatments, Fv/Fm of I. mairei var. gradiflora changed little, all lying between 0.80-0.85. And with the increase of phosphorus supply, ΦPSII, Fv´/Fm´, and qP increased, while qN decreased.
④In spite of the different phosphorus concentration, RGR and the ration of roots to shoots of I. mairei var. grandiflora did not differ between the treatments.
In a word, phosphorus could improve the photosynthesis of I. mairei var. gradiflora by enhancing PSII’s activity, but it had no important effects on its RGR. Consequently, the conclusion was that I. mairei var. gradiflora only needed small amount of phosphorus for its growth.|