| In order to study the photosynthetic characteristics of gentianae macrophyllae radix(Gentiana macrophylla Pall.) and the effects of different fertilization levels on the growthperformance and active ingredientsv variation of it, so as to offer a scientific basis andreference for standardized cultivation technology system of this medicinal plant. We selectedthe flowering stage of Gentiana macrophylla Pall. to measure its photosynthetic andeco-physiological characteristics. By setting five fertilization gradients on nitrogen,phosphorus and potassium three levels respectively, to study its active ingredients seasonaldynamics, including Gentiopicroside, Loganic acid, Swertiamarin, Sweroside four speciessecoiridiod glycosides. The main results are as follows:1. The light saturation point (LSP), the light compensation point (LCP), the apparentquantum efficiency (AQY), the maximum net photosynthetic rate (Pmax) and the darkrespiration rate(Rd) were1289.51μmol.m-2.s-1,25.52μmol.m-2.s-1,0.0407,13.99μmol.m-2.s-1,and1.74μmol.m-2.s-1, respectively. The carbon dioxide saturation point (CSP), the carbondioxide compensation point (CCP), the carboxylation efficiency (CE), the maximum rate ofRuBP regeneration (Jmax) and the photo respiration rate (RP) were1246.78μmol.mol-1,78.52μmol.mol-1,0.0525,37.10μmol.m-2.s-1and5.93μmol.m-2.s-1, respectively.2. The diurnal change of the net photosynthetic rate (Pn) showed a bimodal pattern and aclear midday depression. The relativity analysis indicated that the net photosynthetic rate (Pn)of Gentiana macrophylla Pall. was significantly positively correlated with transpiration rate(Tr), stomatal conductance (Gs), stomatal limiting value (Ls) and photosynthetically activeradiation (PAR), but significantly negatively correlated with intercellular CO2concentration(Ci). Based on our results, we could draw the conclusion that transpiration rate (Tr), stomatalconductance (Gs), stomatal limiting value (Ls) were the main environment factors that affectedthe net photosynthetic rate of Gentiana macrophylla Pall.. The results indicate that among thefactors affecting the photosynthetic characteristics of Gentiana macrophylla Pall., some ofthem could be grouped as stomatal limitation factors, while the others could be grouped asnon-stomatal limitation factors.3. Different nitrogen, phosphorus and potassium fertilizer levels have a significant effect on plant height, root length, root diameter, and root dry weight of Gentiana macrophylla Pall..But the influence degree of different levels was different, the effect of nitrogen, phosphorusand potassium application on plant height of Gentiana macrophylla Pall. as follows: N>P>K,high nitrogen can effectively promote the growth of Gentiana macrophylla Pall. plant height,while high phosphorus and potassium application showed a inhibition phenomenon; Theeffect of nitrogen, phosphorus and potassium application on root length of Gentianamacrophylla Pall. as follows: P>K>N, high phosphorus and potassium levels can promoteroot’s elongation, but high nitrogen is not conducive to the growth of root’s elongation, theapplication of N2P2had a greater influence on the lengh of roots than P2K2and N2K2; Theeffect of nitrogen, phosphorus and potassium application on root dry weight of Gentianamacrophylla Pall. followed: N>K>P, the influence of high levels nitrogen and potassiumapplication was beneficial to the increase of root dry weight, while high level phosphorusperformed a inhibition phenomenon, the application of P2K2had a significant effects on rootdry weight of Gentiana macrophylla Pall., which was greater than application of N2P2, N2K2comes second.4. Gentiopicroside and loganic acid content in Gentiana macrophylla Pall. changed varywith its growth periods to rise gradually, which were highest in October, lowest in July. Whilethe swertiamarin and sweroside content change showed a downward trend, namely the highestlevels in July, October’s levels are relatively low. In general, the total content of four kinds ofsecoiridiod glycosides was increasing along with the development of the growth period of theGentiana macrophylla Pall., that is lower in July, the highest in October.5. Low levels of applied nitrogen, phosphorus and potassium can promote the activeingredients accumulation of Gentiana macrophylla Pall., while excessive levels are notconducive to the accumulation of active ingredients. The experiment found that appliedK1N2P2, the total active ingredients iridoid content was the higest in all treatment that reached12.97%. Besides, it can increase the content of loganic acid especially, which made its contentincreased from0.378%in July to1.324%in October, an increase of nearly3.5times.Comprehensive analysis of fertilization on the impact of active ingredients of Gentianamacrophylla Pall., K1N2P2mixed fertilizer was the best choice, K2N2P2comes second. |
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