Effects of drought stress on physiological and biochemical and chemical components of Cinnamomum cassia seedlings / 中国中药杂志

Six month old Cinnamomum cassia seedlings were used to simulate drought stress with polyethylene glycol(PEG 6000). The physiological indicators(osmotic substances, antioxidant enzymes, etc.) and chemical components of seedlings under different drought levels and the correlation between the two were studied. The results showed that the chlorophyll content and relative water content decreased gradually with the increase of PGE 6000(0, 5%, 10%, 15%) concentration and time(3, 5, 7 d), while the soluble protein content, soluble sugar content and catalase(CAT) activity increased, but the rising rate slowed down with the time. The activities of peroxidase(POD), superoxide dismutase(SOD), malondialdehyde(MDA) and proline content increased at first and then decreased. The content of coumarin, cinnamaldehyde, cinnamic acid and dimethoxycinnamaldehyde decreased, while the content of cinnamyl alcohol continued to increase.Under drought stress, the fluorescence signals of reactive oxygen species and no contents in roots of C. cassia seedlings were significantly stronger than those of the control.Further correlation analysis showed that coumarin content, di-methoxycinnamaldehyde content and osmoregulation substance content were significantly negatively correlated(P<0.05), cinnamic acid content was significantly negatively correlated with POD and SOD activities(P<0.01).It was found that C. cassia seedlings showed a certain degree of drought tolerance under short-term or mild drought stress, but if the drought exceeded a certain degree, the physiological metabolism of the seedlings would be unbalanced.

Effect of Polygonum multiflorum-Andrographis paniculata intercropping system on rhizosphere soil actinomycetes community structure and diversity of P. multiflorum / 中国中药杂志

To investigate the effect of Polygonum multiflorum-Andrographis paniculata intercropping system on rhizosphere soil actinomycetes of P. multiflorum, the community structure and diversity of soil actinomycetes were studied by using the original soil as the control group and the rhizosphere soil actinomycetes communities of P. multiflorum under monoculture and intercropping systems as the experimental group. In this study 655 221 effective sequences were obtained with an average length of 408 bp. OTU coverage and rarefaction curve showed that the sequencing could represent the real situation of soil actinomycetes. According to the results of alpha diversity analysis, the diversity soil actinomycetes varied as follows: original soil>intercropping soil>monoculture soil. The soil actinomycetes community structure and the relative abundance of dominant genera were significantly changed by both monoculture and intercropping, especially monoculture. OTU clustering and PCA analysis of soil samples showed that all the soil samples were divided into three distinct groups and the original soil was more similar to intercropping soil. In addition, intercropping increased the relative abundance of some beneficial actinomyces, such as Kitasatospora and Mycobacterium, which was beneficial to maintain soil health and reduce the occurrence of soil-borne diseases. The results show that, P. multiflorum-A. paniculata intercropping reduced the change of community structure and the decrease of diversity of soil actinomycetes caused by P. multiflorum monoculture, and made the actinomycete community in rhizosphere soil of P. multiflorum close to the original soil.

Effect of different water conditions on Panax notoginseng seeds after-ripening and germination physiology / 中国中药杂志

Effect of different water conditions on the physiological indexes (e.g.seed water content, vigor, antioxidase activities)of Panax notoginseng seeds were studied under process of after-ripening and germination.The results showed show that compared with 2.5% treatment, under the treatment of 5%, P.notoginseng seeds possessed stable seed water content, the seed vigor was exceed by 51%,variation of antioxidant enzyme (SOD, POD, CAT) activity and malondialdehyde (MDA) content were small, crude fat and total sugar content decreased significantly.With the increase of PEG 6000 concentration, the germination characteristic indexes obviously decreased, antioxidase activities increased firstly and decreased afterwards, content of MDA, soluble protein and total sugar increased obviously.There were significant positive correlation between germination characteristic indexes and osmotic substance content(r>0.900, P<0.01), and significant negative correlation with MDA (r>0.900, P<0.01).In conclusion, because the characteristic of dehydration intolerance of P.notoginseng seeds, 5% water content of sand burying stratification treatment was the best for after-ripening, 15% concentration of PEG 6000 treatment was the highest tolerance limit of germination process.

Physiological response and bioaccumulation of Panax notoginseng to cadmium under hydroponic / 中国中药杂志

The physiological response and bioaccumulation of 2-year-old Panax notoginseng to cadmium stress was investigated under a hydroponic experiment with different cadmium concentrations (0, 2.5, 5, 10 μmol · L(-1)). Result showed that low concentration (2.5 μmol · L(-1)) of cadmium could stimulate the activities of SOD, POD, APX in P. notoginseng, while high concentration (10 μmol · L(-1)) treatment made activities of antioxidant enzyme descended obviously. But, no matter how high the concentration of cadmium was, the activities of CAT were inhibited. The Pn, Tr, Gs in P. notoginseng decreased gradually with the increase of cadmium concentration, however Ci showed a trend from rise to decline. The enrichment coefficients of different parts in P. notoginseng ranked in the order of hair root > root > rhizome > leaf > stem, and all enrichment coefficients decreased with the increase of concentration of cadmium treatments; while the cadmium content in different parts of P. notoginseng and the transport coefficients rose. To sum up, cadmium could affect antioxidant enzyme system and photosynthetic system of P. notoginseng; P. notoginseng had the ability of cadmium enrichment, so we should plant it in suitable place reduce for reducing the absorption of cadmium; and choose medicinal parts properly to lessen cadmium intake.

Effect of Panax notoginseng seedlings physiological response under simulated drought stress by polyethylene glycol (PEG 6000) / 中国中药杂志

The physiological effects of Panax notoginseng seedlings under simulated drought stress by PEG 6000 on antioxidant enzymes, osmotic substances and root activities were studied. The results showed that the activity of POD and APX in roots and leaves kept rising with increasing processing concentration and time. However, on the one hand, at the same processing time, SOD in roots and leaves firstly increased and then decreased with the increase of processing concentration. On the other hand, at the same processing concentration, SOD kept rising with the extension of processing time. In addition, the activity of CAT in roots and leaves tended to increase with the increasing concentration at the same processing time, while it increased at first and then decreased with the extension of time at the same concentration. The activity of SOD and APX in stem did not change obviously, whereas CAT activity in stem increased with the increasing processing time and concentration. With the increase of processing concentration and the extension of processing time, the MDA, soluble protein, proline content and root activity in leaves and roots apparently rose. Moreover, fluorescence signal of H2O2 and NO in root tip enhanced as the processing concentration increased after treated for 1 d. In summary, P. notoginseng seedlings could deal with drought stress by means of adjusting the system of antioxidant enzyme, permeating stress substances and impeded stress signal substances. Thus, when the concentration of PEG 6000 was more than 5%, it would have harm on P. notoginseng seedlings.

Effects of stereoscopic cultivation on soil microorganism, enzyme activity and the agronomic characters of Panax notoginseng / 中国中药杂志

Compartments of soil microorganism and enzymes between stereoscopic cultivation (three storeys) and field cultivation (CK) of Panax notoginseng were carried out, and the effects on P. notoginseng agronomic characters were also studied. Results show that concentration of soil microorganism of stereoscopic cultivation was lower than field cultivation; the activity of soil urea enzyme, saccharase and neutral phosphatase increased from lower storey to upper storey; the activity of soil urea enzyme and saccharase of lower and upper storeys were significantly lower than CK; agronomic characters of stereoscopic cultivated P. notoginsengin were inferior to field cultivation, the middle storey with the best agronomic characters among the three storeys. The correlation analysis showed that fungi, actinomycetes and neutral phosphatase were significantly correlated with P. notoginseng agronomic characters; concentration of soil fungi and bacteria were significantly correlated with the soil relative water content; actinomycete and neutral phosphatase were significantly correlated with soil pH and relative water content, respectively; the activities of soil urea enzyme and saccharase were significantly correlated with the soil daily maximum temperature difference. Inconclusion, The current research shows that the imbalance of soil microorganism and the acutely changing of soil enzyme activity were the main reasons that caused the agronomic characters of stereoscopic cultivated P. notoginseng were worse than field cultivation. Thus improves the concentration of soil microorganism and enzyme activity near to field soil by improving the structure of stereoscopic cultivation is very important. And it was the direction which we are endeavoring that built better soil ecological environment for P. notoginseng of stereoscopic cultivation.