Papers by Keyword: Allelopathy

Abstract: Eupatorium adenophorum (croftonweed), one of the most destructive alien species in China, has been demonstrated or indicated to have inhibitory effects on other species in laboratory bioassay. However, allelopathic compounds of E. adenophorum may play other roles more than interspecific interference. Here we investigated whether E. adenophorum aqueous leachates could influence conspecific seed germination and seedling growth with laboratory bioassay and found that it could inhibit seed germination and reduce seedling root elongation of E. adenophorum. Then we examined interactions between E. adenophorum leachate and natural soil on germination and seedling growth of E. adenophorum itself. The results showed that soil from different habitats altered the allelopathic effects usually observed in laboratory bioassay. In the heavily invaded site, E. adenophorum were inhibited by E. adenophorum leachates; whereas, in two lightly invaded sites, germination and seedling growth of E. adenophorum was significantly facilitated. We can infer that allelochemicals from E. adenophorum play a dramatic role in regulating its population density.

Abstract: Biogenic volatile organic compounds are a class of small molecule compounds produced by the plant secondary metabolites. Although the contents are relatively low, but have strong ecological effects. In plant communities, the plant can hinder the growth of competing plants around by releasing BVOCs, and it could also enhance the ability to resist predators. At the same time, it can inhibit the pathogenic microorganisms and enhance the disease resistance. In addition, BVOCs can regulate the body's mental and physical state to exert the health effects. Therefore, the study of the BVOCs’ ecological functions is of great significance.

Abstract: Wedelia trilobata (L.) Hitche is a widespread alien invasive weed in south China and has been reported to show allelopathic potential causing biological suppression on some plants. In this study, the allelopathic effects of aqueous extracts from the leaves of W. trilobata were tested on the seed germination, shoot growth and total chlorophyll content of rape (Brassica campestris L.) using Petri dish bioassay. The results showed that the aqueous extracts at the concentration from 25% to 100% caused a significant reduction in the germination percentage, shoot length and total chlorophyll content of rape. This inhibitory effect was concentration-dependent. These results suggested there was a strong potential phytotoxic effect of W. trilobata on rape and this effect might reduce the production of some crop species.

Abstract: Allelopathic effects of dried macroalga Ulva pertusa (Chlorophyta) on photosynthesis of the microalgae Skeletonema costatum (Bacillariophyta) were evaluated using coexistence culture systems. S. costatum was cultured with different biomass of dried U. pertusa under controlled laboratory conditions for three days. The chlorophyll a (Chl a) fluorescence transient O-J-I-P curve coupled with its specific parameters in S. costatum was established. The Chl a fluorescence transients were recorded in vivo at high time resolution and analyzed according to the JIP-test which can quantify photosystem II activity. A clear dose-dependent relationships were observed between the dried biomass of U. pertusa and its inhibitory effect on S. costatum. A decrease in the O-J-I-P curve expressed as Chl a fluorescence intensity along with its specific parameters were observed, which was also time-dependent. The main photosynthetic inhibitory targets of the macroalga on the microalga, according to the JIP-test, can be expressed as a decrease in the number of active reaction centers and the blocking of the electron transport chain. The results of the present study suggest that dried fragments of U. pertusa effectively inhibit photosynthesis in S. costatum.

Abstract: Allelopathic effects of dried macroalga Ulva pertusa (Chlorophyta) on photosynthesis of the microalgae Skeletonema costatum (Bacillariophyta) were evaluated using coexistence culture systems. S. costatum was cultured with different biomass of dried U. pertusa under controlled laboratory conditions for three days. The chlorophyll a (Chl a) fluorescence transient O-J-I-P curve coupled with its specific parameters in S. costatum was established. The oxygen evolution rate was measured, the Chl a fluorescence transients were recorded in vivo at high time resolution and analyzed according to the JIP-test which can quantify photosystem II activity. A clear dose-dependent relationships were observed between the dried biomass of U. pertusa and its inhibitory effect on S. costatum. The rate of light-saturated maximum photosynthetic oxygen evolution (P_max) was markedly decreased by different biomass of dried U. pertusa, while dark respiration rate (R_d) was increased. A decrease in the O-J-I-P curve expressed as Chl a fluorescence intensity along with its specific parameters were observed, which was also time-dependent. The main photosynthetic inhibitory targets of the macroalga on the microalga, according to oxygen evolution rate and the JIP-test, can be expressed as, the damage to the oxygen-evolving complex, a decrease in the number of active reaction centers and the blocking of the electron transport chain. The results of the present study suggest that dried fragments of U. pertusa effectively inhibit photosynthesis in S. costatum.

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: Microbial biofilm plays a major role in aquatic ecosystems by acting as an important food source for fish and other aquatic creatures as well as a refuge for microorganisms. With this in mind, promoting bacterial biofilm formation on a matrix or a carrier is an important low cost strategy in keeping water ecosystem balance. In industrial wastewater processes, many biofilm carriers are built according to the microbial biofilm principle with the homophylic carrier used to treat the contaminative nature water bodies being absent. So we developed a novel biofilm carrier made from high polymer for in situ biofilm technology to improve natural water bodies and named the new carrier device as Artificial Aquatic Mats (AAMs). An investigation to research such device was performed in order to determine the influence of this novel photoautotrophic biofilms carrier on the changes of water quality and phosphorus (P) forms in sediments and to compare the effects of AAMs and carbon fiber carriers (CFC) treatment. Transparency of water appears to possibly be enhanced by the treatments of AAMs and CFC by inhibiting the harmful algae growth for allelopathy. Experimental results revealed, in a same projective area, the transparency cleaned by AAMs increased faster than that of CFC. Both devices had a certain positive effect on decreasing total phosphorus (TP) of water. In the control, there was a persistent large variationnot only the occurrence of algae blooms but also in the changes of both total P (TP) and P form concentrations in the sediments. TP concentrations in sediments of AAMs treatment remained higher than the CFC treatments throughout the experiment. With the exception of the Labile-P, the change in trend lines of all of the P forms in the two treatments did not deviate from one another. Organic matter (OM) was the most important P sink because the contributions of OM were well correlated with the TP and Labile-P. Statistical analysis in Ca-P and Residual-P showed that the AAMs-treatment could more prevent phosphorus from releasing from sediment into water column than that of CFC-treatment.

Abstract: The allelopathy of the exotic invasive plant, Solidago canadensis L. was studied. S. canadensis leaves were extracted with water and partitioned against ethyl acetate and n-butanol sequentially. The two organic fractions, original water extract and the residual water after the organic solvent extraction were tested for inhibitory activity on seed germination and seedling growth of wheat (Triticum aestivum), setaria (Setaria viridis) and its own species. Germination rate, vigor and index were recorded as germination parameters, and radicle and plumule growth and fresh weight of seedlings were recorded as seedling growth parameters. Results showed that the water extracts of S. Canadensis leaves had significant impacts on the seed germination and seedling growth of the three tested plants. n-Butanol fraction showed the strongest allelopathic effect, while the residual water after the organic solvent extraction had no significant phytotoxic effect compared with the control. n-Butanol fraction at 0.5 mg•ml-1 could significantly inhibited the seed germination of the same species, and that at 5 mg•ml-1 could significantly inhibited the seedling growth of the same species. n-Butanol fraction at 1.5 mg•ml-1 could significantly inhibited the seed germination and seedling growth of wheat. n-Butanol fraction at 5 mg•ml-1 could significantly inhibited the seed germination and seedling growth of setaria. The allelochemicals were mainly contained in n-butanol fraction of water extracts from S. canadensis leaves.

Abstract: The effects of the dried macroalga, Gracilaria tenuistipitata (Rhodophyta), on photosynthesis of a highly stress-resistant microalga, Phaeodactylum tricornutum were studied. P. tricornutum was cultured with dried G. tenuistipitata under controlled laboratory conditions for three days. All oxygenic photosynthetic organisms tested so far exhibit a polyphasic rise of fluorescence transients during the first second of illumination. These phases are labeled as O, J, I, P. The chlorophyll a (Chl a) fluorescence transient O-J-I-P curve coupled with its specific parameters in P. tricornutum was established. The Chl a fluorescence transients were recorded in vivo at high time resolution and analyzed according to the JIP-test which can quantify photosystem II activity. A clear dose-and time-dependent relationships were observed between the dried biomass of G. tenuistipitata and its inhibitory effect on Pyramimonas sp. A decrease in the O-J-I-P curve expressed as Chl a fluorescence intensity along with its specific parameters were observed, which was also time-dependent. The main photosynthetic inhibitory targets of the macroalga on the microalga, according to the JIP-test, can be expressed as a decrease in the number of active reaction centers and the blocking of the electron transport chain. The results of the present study suggest that dried fragments of G. tenuistipitata effectively inhibit photosynthesis in P. tricornutum and could thus be potential candidates for use in the control and mitigation of harmful algal blooms.

Abstract: In order to ascertain the allelopathy of Reed on Alligator Weed, the water culture experiments were performed to investigate the effects of aqueous extract on the growth, physiological and biochemical mechanism in Alligator Weed. The results showed that aqueous extract of Reed inhibited the growth of Alligator Weed, and the inhibition became stronger as the concentration of the extract increased. Some results from physiological and biochemical mechanism of treated Alligator Weed indicated that with the increase of extract concentration, photosynthetic pigment contents, root activity and CAT activity decreased, while P and MDA contents increased; N content decreased first and then up to normal. The results showed that aqueous extract of Reed inhibited the photosynthesis, CAT activities of Alligator Weed but increased the MDA content of Alligator Weed.