Effect of different nitrogen forms and ratio on growth and active ingredient content of Platycodon grandiflorum / 中国中药杂志

To providing evidence about nitrogen adequate application of Platycodon grandiflorum, the pot culture experiment was conducted to study the effect of nitrogen on the growth, physiological metabolism and the quality of P. grandiflorum. The activity of NR, GS and SOD, POD and CAT were determined. And the nitrate and ammonium nitrogen content, photosynthetic characteristics, active components of P. grandiflorum were determined. The results showed that the nitrate nitrogen content and P. biomass reached its maximum value, when NH4(+)-N/NO3(-) -N was 0: 100, the activity of NR. The activity of GS was the highest at the NH4(+) -N/NO3(-) -N ratio of 25:75 and ammonium nitrogen content was the highest at 75:25. The activity of SOD decreased and then increased with the increasing of NO3(-) -N. At the NH4(+) -N/NO3(-) -N ratio of 25: 75, the activity of CAT had its maximum value and the content of MDA had the minimum value. At the same time, the content of platycodon D was the highest at this treatment. The studies had shown that different nitrogen forms and ratio had a significant effect on the characteristics of photosynthetic physiology, nitrogen metabolism and resistance adjustment, growth and the quality of P. grandiflorum. The NH4(+) -N/NO3(-) -N ratio of 25: 75 was a suitable ratio of nitrogen forms for the growth of P. Grandiflorum and accumulating the content of platycodon D.

Effects of Ca2+ and SA on physiological and photosynthesis of Platycodon grandiflorum under high temperature stress / 中国中药杂志

In order to reveal feasibility of different concentrations of Ca2+ and SA on Platycodon grandiflorum under high temperature stress, the effects of Ca2+ on physiological index and related photosynthetic parameters were studied. Pot cultured P. grandiflorum leaves under the same outdoor conditions were sprayed with CaCl2 and SA separately, and then placed in the high incubator [35 degrees C/25 degrees C (day/night), light intensity 3 600 lx], and sprayed with distilled water at 25 degrees C and under high temperature stress were set as the control. The related photosynthesis, relative conductivity, contents of proline, malondialdehyde, soluble protein, activities of SOD and CAT, ASA and GSH content were measured. The results show that the 6 mmol x L(-1) CaCl2 and 1.5 mmol x L(-1) SA enhanced the activities of SOD and CAT, the contents of proline and soluble protein, and effectively reduced the damage of heat stress on cell membrance. At the same time, the exogenous Ca2+ and SA increased the contents of chlorophyll and carotenoid, the efficiency of leaf photosynthesis and ASA and GSH content, and thus effectively resisted the oxidative stress caused by high temperatures, but with the increasing concentration of spraying, P. grandiflorum decreased the ability to resist high temperature stress. In conclusion, the foliage spraying CaCl2 and SA could reduce the damage of high temperature stress on P. grandiflorum leaves.