Advanced Materials Research Vols. 726-731

Abstract: In order to evaluate the allelopathic potential of an exotic invasive weed, Parthenium hysterophorus L., the effect of different concentrations of aqueous extracts (5%, 25%, 50%, 75% and 100%) prepared from leaves of P. hysterophorus were studied on the seed germination and seedling shoot growth of two common native herbs, Plantago asiatica L. and Youngia japonica (L.) DC., through laboratory bioassays. The aqueous leaf extracts at the concentrations of 25%, 75% and 100% significantly inhibited the seed germination and seedling shoot growth of two target species. There was complete failure of seed germination of Y. japonica in 75% and 100% aqueous leaf extracts. The inhibitory effect increased with increasing extract concentration. These results suggested that allelopathy may play a role in the impact of P. hysterophorus invasion on native plant recruitment of invaded communities in southern China.

Abstract: Seedlings of sweet sorghum were supplied with 0.1 mmol L^-1, 2 mmol L^-1, 5 mmol L^-1 and 10 mmol L^-1 nitrogen fertilizers under 0% or 0.6% NaCl conditions. Then the growth parameters of the seedlings including photosynthetic gas exchange and leaf chlorophyll a fluorescence were determined. Results showed that the seedlings grew worse under 0.6% NaCl. Furthermore, with the increase of nitrogen level, the net photosynthetic rate (Pn), transpiration rate (Tr), the maximum photochemical efficiency of PSII (PHI(Po)) , the driving force on light absorption basis (D.F), the active reaction centers per cross section (RS/CSm), trapped energy per cross section (TRo/CSm) and PQ size of photosystem (PS) II (Sm) all increased and reached the peak at 5 mmol L^-1 nitrogen level. On the other hand, heat dispassion per cross section (DIo/CSm) and the close extent of PS II reaction center (Vj and M₀) all decreased with nitrogen level. The results indicated that the optimum nitrogen level for sweet sorghum is about 5 mmol L^-1.

Abstract: The effects of climatic change on winter wheat yield in Shangqiu City are quantitatively analyzed with the predictive results of future climate change. The results show that winter wheat yield in Shangqiu City presented a fluctuated increase for overall trend. Principal component analysis indicates that air temperature, precipitation, evaporation and extreme temperatures are the main factors affecting winter wheat yield, and excessive evaporation and extremely-low temperatures are unfavorable for wheat production. The warm-and-wet climate in Shangqiu is beneficial for improvement of winter wheat production, while the cold-and-dry climate is unbeneficial.

Abstract: As an essential macroelement for all living cells, phosphorus plays a significant role in agricultural production systems. To better guide the establishment of the biofuel production systems of hybrid pennisetum, a popular energy plant with important potential in saline land, the effects of nutrient phosphorus on the growth, photosynthesis and ion homeostasis of hybrid pennisetum under salt treatment were examined with greenhouse pot experiments. Plant seedlings subjected to phosphorus deficiency (0.1 mmol·L^-1 P and 0.2 mmol·L^-1 P) increased in ratio of root to shoot and decreased in biomass. On the other hand, salinity inhibited the growth of hybrid pennisetum, but the effects of salinity on energy plants (Pennisetum americanum ×P. Purpureum) were influenced by the concentration of nutrient phosphorus. Salinity was more injurious to hybrid pennisetum seedlings in combination with a lower concentration of phosphorus (0.1 mmol·L^-1 P, 0.2 mmol·L^-1 P and 0.6 mmol·L^-1 P) than it was with a higher concentration of phosphorus (1.0 mmol·L^-1 P) (that gave optimum yields in the absence of salinity). In addition, no significant differences were observed between 1.0 mmol·L^-1 P and 1.4 mmol·L^-1 P levels at either NaCl level, indicating that 1.0 mmol·L^-1 P was enough for the enhancement of both growth and tolerance to NaCl in hybrid pennisetum.

Abstract: Effects of salinity and nitrate nitrogen (NO₃^--N) on growth, ion accumulation, chlorophyll content, chlorophyll fluorescence, and photosynthetic characteristics of sugar beet cultivar KWS3418 were investigated in a greenhouse experiment. Seedlings were exposed to 0 and 1% NaCl in 0.5, 5 or 10 mM NO₃^--N treatments for 25 days. The results showed that increasing NO₃^- supply improved shoot and root dry weights, decreased the Cl^- concentration in leaves and roots regardless of NaCl concentration. Higher NO₃^--N supply also increased concentration of chlorophyll, net photosynthetic rate (Pn), actual PSII efficiency (ΦPSII) in leaves and soluble sugar concentration in roots. The results indicate that increasing NO₃^- supply can help sugar beet to mediate ion homeostasis, to increase the ability of photosynthesis, and subsequently to increase the growth under high salinity. The interactive effects of salinity and nitrate availability can significantly increase soluble sugar in roots of sugar beet.

Abstract: The optimum conditions for the extraction and separation of chondroitin sulfate from tilapia (Oreochromis niloticus) byproducts were studied in the paper. The chondroitin sulfate was extracted by the combination of ultrasonic and microwave. On the basis of the single factor tests, the response surface methodology was taken to study the optimum process of extraction. Results show that the best conditions for the extraction and separation of chondroitin sulfate from tilapia byproducts are: the ultrasonic power is 50W, the microwave power is 98W, the extraction time is 120s, the ratio of solid to liquid is 1:50 (g/mL), and under these conditions, the extraction rate of chondroitin sulfate is 2.513%.

Abstract: Understanding the adaptive characters of some important species is not only very important for restoration biology, but also very important for environmental protection and resource collection. Stipa grandis P. Smirn is an important dominant species in the middle and eastern parts of Inner Mongolia steppe. The present study took morphological traits into account in order to examine the adaptive characters of S. grandis to local environmental conditions. At four sampling sites presenting various climatic characteristics and community characteristics, 22 morphological traits were measured in the end of the growth season. Four populations were categorized into two sub-groups based on Euclideans distances of morphological traits, and Mantels tests showed significant relationships between Euclideans distances of morphological traits and climatic divergence. The divergence of morphological traits seemed to be shaped by climatic difference in a certain sense, but the effects of other environmental factors could not be neglected. Such information is important for a better understanding of the adaptive strategy of S. grandis in northern China and will be useful for policy makers to work out a plan to protect and to utilize this important species.

Abstract: To better understand the succession process of vegetation restoration from the active sand dune to the inter-dune lowland, species diversity which refers to species richness and abundance across scales and along the slope were studies in Horqin Sandy Land, China. A 0.25 ha square sampling plot, which sampled on the ecotone, was divided into five grain sizes and equal distance intervals along the slope from the top to the bottom. The results showed that both species abundance and richness increased as the grain sizes increased and along the slope, but the decreasing CV values indicated that species diversity gradually vary from heterogeneity to relatively homogeneity. In conclusion, species abundance and richness showed asynchronous changes and their relationship are more closely across scales than along the slope. Except that, more studies on the biotic and abiotic factors interaction concerning the vegetation patterns of sand dune ecosystems should be conducted. These could not only improve our understanding the mechanisms of vegetation invasion and succession, but also be beneficial for vegetation management and biodiversity conservation in semi-arid sand dune ecosystems.

Abstract: Some chemical compounds in low polar fractions of Mikania micrantha H.B.K. extracts can strongly influence seeds germination and seedling growth of Raphanus sativus. In this study, we provide evidence that the chemical compounds in a low polar fraction chromatographed on normal phase silica gel columns from petroleum ether extract of M. micrantha have strong activity to inhibit the seeds germination and seedling growth of Raphanus sativus. Two main chemical constituents, α-Bisabolol and Eudesma-5,11(13)-dien-8,12-olide, in the active fraction were confirmed by GC-MS analysis. Key words: Mikania micrantha H.B.K., Raphanus sativus, plant growth regulation activity, fraction, GC-MS

Abstract: This paper summarized and compared the characteristics of trehalose synthase (TS) from various bacteria and the research progress on TS gene engineering. The results show that analysis of TS structure and molecular modification are the research hotspots in TS gene engineering.