Allelopathic Research Articles

Allelopathy - the solution is indirect.

Allelopathy - the solution is indirect.

Аллелопатическая активность у семян овощных сельдерейных культур

Аллелопатическая активность у семян овощных сельдерейных культур

赤潮过程中“藻-菌”关系的研究进展

微生物对促进海洋物质循环，维持水生环境的生态平衡具有重要作用。在赤潮事件中，基于微生物（尤其是细菌）的多样性和重要性，它们与藻类之间的相互关系成为了研究的热点。过去20年里，人们从不同角度对“藻-菌”间的关系进行了探索，包括物理学过程、生物学过程、环境过程以及化学过程。就化学过程而言，它作为一种较早出现的技术，在以往的研究中带给人们许多认识藻菌关系的方法。随着学科的渗透，化学法有了拓展与延伸，为人们认识藻菌关系带来了新的契机。从化学生态学领域来梳理“藻．菌”关系中涉及的现象和行为，包括菌对藻的有益面、菌对藻的有害面、以及藻类应答细菌行为的化学途径；并从信号语言（群体感应、化感作用）的角度来阐释两者之间的互生或克生关系。通过文献综述的方式来解读藻菌关系的互作过程和机理，为认识赤潮的发生和防控方法提供借鉴。

Allelopathy comparison between Castanea mollissima and C. dentata

Allelopathy comparison between Castanea mollissima and C. dentata

Allelopathic influence of the aqueous extract of Jatropha curcas L. leaves on wild Cichorium intybus.

The communication presents an evaluation of the allelopathic effect of the aqueous extract of physic nut (Jatropha curcas L.) leaves on the early development of wild chicory (Cichorium intybus) seedlings. The experiment was performed in Palotina City, State of Parana, Brazil. The physic nut leaves were harvested and then crushed in a blender using the proportion of 1 L of distilled water for each 200 g of leaves resulting in a crude extract of 100%. The experiments were conducted in 6 trials with 8 repetitions. The dilutions of 80, 40, 20, 10, 5 and 0% (only distilled water) were made using the crude extract. Data was subjected to statistical analysis (regression at 1% of probability). Aqueous extract of physic nut leaves showed an inhibitory allelopathic effect on the development of wild chicory (sugarloaf variety) which increased with enhanced concentration, presenting negative linear tendency, except for the variable fresh weight of shoots. Key words: Jatropha curcas L., Cichorium intybus, allelopathy.

Comparative analysis of volatile constituents in Bacillus thuringiensis (Bt) cotton (RCH 2 Bt) and non-Bt cotton by gas chromatography-mass spectrometry

The differences in composition and concentrations of volatile allelochemicals between transgenic Bacillus thuringiensis (Bt) cotton and non Bt cotton leaves were compared and analyzed by using gas chromatography-mass spectrometry (GC-MS). The dominant compounds present in both non Bt and Bt cotton leaves were α-caryophyllene (4.62, 1.42), β-myrcene (3.67, 3.68), β-carene (0.31, 0.80), benzene acetaldehyde (0.88, 0.48), heptanoic acid (2.0, 0.67), 1-methoxy, 2-methyl benzene (0.67, 0.30) and acetic acid, phenyl methyl ester (4.32, 2.48). The differences in main components and ratios of volatile allelochemics between Bt cotton and non Bt cotton suggested that, the expression of Bt toxin protein in cotton was found to have an impact on their volatile profiles.

First Report of Microcystins and Anatoxin-a Co-occurrence in San Roque Reservoir (Córdoba, Argentina)

Fil: Ruiz, Marcia. Secretaria de Ambiente y Desarr.sustentable de la Nacion. Instituto Nacional del Agua y del Ambiente(cordoba); Argentina

Trade-off responses of the clonal plant water lettuce (Pistia stratiotes L.) to the allelopathy of Crofton weed (Eupatorium adenophorum Spreng).

Allelopathic interference is considered an ecologically acceptable and effective means of biological control of invasive weeds, but little is known about phenotypic plasticity and the physiological integration of clonal plants in response to allelopathic interference. We used the clonal invasive aquatic water lettuce as a target for allelopathic control by spraying it with a crofton weed filtrate that contained strong allelochemicals. The growth of single-parent water lettuce was inhibited early on in the experiment when adult leaves gradually faded and new leaves grew slowly. However, as offspring ramets grew, the total number of ramets, leaf coverage, and biomass were all significantly greater in allelopathic treatments than in the control, although individual offspring ramets were smaller on average than in the control. This is an indication that the effects of allelopathic control on the water lettuce are: overcompensation in growth, and a trade-off between average size and the number of offspring. Th...

Nutritional Adaptations in Migrating Birds

ABSTRACT Prior to migration, many birds accumulate large stores of lipids as the primary energy for their migratory flights. Fat accumulation is associated with a seasonal shift in food selection, an increase in premigratory daily food intake, and an increase in utilization efficiency of ingested food. Seasonal frugivory is the most striking seasonal change in diet composition of many migrants. The adaptive role of seasonal facultative frugivory has only rarely been investigated. Fruits seem to provide a particular nutritional quality, namely fatty acids, which promote the accumulation of premigratory fat of a particular quality. Moreover, plant secondary compounds seem to play a role in migratory fat accumulation, and there is evidence that several plant allelochemicals that are consumed with the fruits increase appetite and stimulate tissue anabolism. The nutritional mechanisms, however, are as yet unknown.

Environmental conditions and endogenous mechanisms involved in secondary dormancy of seeds

ABSTRACT Secondary dormancy, is defined as the dormancy developing in seeds after harvest or dispersal. Under field conditions secondary dormancy is part of cyclic changes in the level of dormancy that often follow a seasonal pattern. It develops when germination is inhibited, e.g. by burial in soil. Temperature, absence of light or oxygen, presence of volatile or allelopathic inhibitors and moisture conditions are among the factors which may contribute to inhibition of germination and thus to development of dormancy. Decreasing light sensitivity is part of the development of secondary dormancy. It is partly attributed to photo- or dark-reversion of the far-red absorbing form of phytochrome (Pfr), pre-existing in the seeds or newly formed, to Pr. Changing levels of Pfr at its primary site of action, possibly being a membrane, are also held responsible for the decreasing light-sensitivity. Secondary dormancy is not related to a deterioration of the seeds. A specific relationship with any particular metabol...

Potential allelopathic effects of Xanthium italicum Moretti on wheat.

The allelopathic potential of invasive Xanthium italicum Moretti on seedling growth of wheat (Triticum aestivum Linn) was investigated. Aqueous (0.05 g/ml) and ethanol (1 mg/ml) extracts reduced root elongation of wheat seedlings by 71 and 87%, respectively; chloroform fraction of the ethanol extract exhibited the strongest phytotoxic effect as compared to other fractions, inhibiting root growth of wheat seedlings by 95% at 1 mg/ml. Incorporation of X. italicum plant residues (20, 50 and 100 g/kg soil) into soils affected not only photosynthetic pigment content, but also photosynthetic parameters of wheat seedlings. Chlorophyll a, b and carotenoid contents of wheat seedlings decreased significantly when plant residues were applied at 100 g/kg soil. Net photosynthetic rate (Pn), transpiration rate (Tr) and stomatal conductivity (gs) decreased greatly when seedlings were treated with plant residues at 20, 50 and 100 g/kg soil, whereas CO2 concentration (Ci) increased significantly at 50 and 100 g plant residue/kg soil. Shoot length, fresh and dry weight were also significantly affected starting from 20 g plant residue/kg soil treatment in a dose-dependent manner. Furthermore, our results indicated that soil conductivity, soil pH and soil nutrients were unlikely responsible for the aforementioned changes. Our results suggest that allelopathy might contribute to the invasion success of X. italicum, and its invasion could possibly pose potential threat to wheat production in China. Key words: Allelopathy, phytotoxin, wheat, Xanthium italicum.

SCREENING OF SELECTED TERRESTRIAL PLANTS FOR THEIR EFFECTS ON SEED GERMINATION OF THREE AGRICULTURAL CROPS

The allelopathic effect of leaf exteracts of of selected terrestrial plants on seed germination of some agricultural crops were investigated. For certain plants, the seed germination decreased in comparison with control (treated with distilled water) while in some cases it increased or remained the same as that of control.The plants which exhibited a decreased seed germination in comparison with the control were proposed to posess allelopathic effect . Thus it can be concluded that the plants that exhibited an allelopathic effect can be used as a potential candidate for isolation and identification of allelochemicals, which would be helpful to be developed as organic herbicides that are environmentally safe and less cost effective.

CEREAL CROP RESIDUE AS AN ALLELOCHEMICAL SOURCE AND THE IMPORTANCE OF MINERAL FERTILIZERS IN ITS DEGRADATION

The authors has made several experiments, in pots and in the field, for studying the effect of wheat and barley straw applied in soils in normal and excessive quantities over the growth of bean, beet and parsley. The experiments showed that when applied in a dosage of over 9 t/ha the straw represented an important source of allelopathic compounds, that significantly decreased the crop yield This decrease was not accompanied by a decrease in the N % percentage in plants, as it usually happens in the case of N deficiency in nutrition, but, on the contrary, the N % content increased while the crop yield decreased. The conclusion was that the yield decrease due to large amount of straw applied to the soil was not generated by N deficiency in nutrition, but to the antiauxinuic action of allelochemicals at root level The N fertilizer favor microorganism’s development and decompose allelochemicals in order to obtain the carbon necessary for their growth Rhizobium was more sensitive at the noxious action of allelochemicals, as compared to the host plant. Cereal crop residue increased the N and organic carbon content in soil and K accessibility.

Effect of Parkia Biglobosa (JACQ) G. Don. Pod Extracts on its Seed Germination and Seedling Development.

The pod extracts at different concentrations influenced the seed germination and seedling vegetative growth of twenty-six different Parkiabiglobosa(JACQ) G. Don Samples. Aqueous Parkia pod extracts of various concentrations (5, 10, 15 and 20g in 100ml of water) were used for the planting of the Parkia seeds and water as control. Significant (at p=0.05) reduction was observed in concentration of 20g of Parkia pod. The seed germination, epicotyl and hypocotyl lengths of the seedlings of the different Parkia trees exhibited varying responses to the extracts at various concentrations among the twenty-six Parkia biglobosa tree seeds used for the germination study within the three weeks of the experiment. The retardation in the seedlings vegetative growth was suspected to influence by the allelopathic components in the pod extracts. The varied responses of the Parkia seedlings to these extract concentrations were assumed to be either from the pod used which were selected from all the tree samples or that the seedlings were sensitive to an allelophatic chemicals of their own pod extracts or to other pods extracts.

Allelopathic effects of decomposing garlic stalk on some vegetable crops

This study was carried out to examine the allelopathic effects of decomposed stalk of three garlic cultivars on the growth of the receiver vegetable crops: namely tomato, Chinese cabbage, lettuce, carrot, cucumber and hot pepper in a pot trial. The results showed that all three garlic cultivars have different allelopathic effects and each cultivar showed different allelopathic effects upon different vegetable crops or the same vegetable crop at different concentrations of decomposed garlic stalk. The activities of protective enzyme SOD in receiver vegetable crops appeared first, increased and then decreased with the increasing content of decomposed garlic stalk. The MDA contents in the receiver vegetable crops showed an increasing trend; however, there was no apparent regularity on POD and CAT contents. In general, the decomposed stalk of three garlic cultivars showed allelopathic inhibitory effects on all the index of carrot and lettuce but promotion effects on Chinese cabbage. Therefore, among all the receiver vegetable crops in this study, Chinese cabbage was concluded to be optimal successive crop for garlic.

Juglone: A therapeutic phytochemical from Juglans regia L.

Juglans regia L. is a monoecious, heterodichogamous, deciduous tree species valued for its high-quality timber as well as its nuts. It belongs to the family Juglandaceae. Though, it is native to Central Asia, India, Nepal China and some part of Europe, it is being grown commercially in the USA, France, Italy and Spain for nut production. The nuts and plant parts of J. regia contain the aromatic secondary metabolite juglone (C10H6O3) (1, 4 – naptha quinone, 5 hydroxy – 8CI). Juglone is a well-known allelopathic agent and being used in commercial hair dye and also has therapeutic properties. Juglone is commercially extracted from the husks of walnuts, but fresh leaves of J. regia contain significant amounts of juglone (up to 0.5 / 100 g dry weight) to be a good source of the chemical. Juglone is understudy for anti-carcinogenic effects. In human intestinal neoplasia juglone checked multiplicity of tumour cells and is also a strong inhibitor of peptidyl-prolyl isomerase Pin1 which is overexpressed in several types of cancer affected cells. Juglone increases efficacy of anti cancer drugs as well. Key words: Phytochemical, medicinal, anticarcinogenic, antitumor, allelopathic.

Antifungal activity of leaf extracts of some medicinal trees against Macrophomina phaseolina

Present study was carried out to investigate the antifungal activity of leaf extracts of four medicinal trees namely Syzygium cumini (L.) Skeels, Eucalyptus citriodora Roxb. (family Myrtaceae) Azadirachta indica L. and Melia azedarach L. (family Meliaceae), againstMacrophomina phaseolina (Tassi) Goid, the cause of charcoal rot disease in more than 500 plant species. Three organic solvents viz. methanol, chloroform and ethyl acetate were used for extraction from the leaves. Antifungal bioassays were carried out by using leaf extracts of 0.3, 0.6, …, 1.5% w/v concentrations in 100 ml conical flasks containing 15 ml of malt extract broth. In general, all the extracts significantly reduced the biomass of the target fungal species. However, there was significant difference among the plant species and extracting solvents for their antifungal activity. Highest antifungal activity was exhibited by ethyl acetate extract of A. indica followed by chloroform extract of the same tree species where different concentrations of these extracts reduced the fungal biomass by 81 to 90% and 78 to 84%, respectively as compared to control. Present study concludes that the leaf extracts of allelopathic trees especially ethyl acetate and chloroform extracts of A. indicacontain natural fungicides which can be used for the management of M. phaseolina. Key words: Allelopathic trees, charcoal rot, leaf extracts, Macrophomina phaseolina,natural fungicides.

Phytotoxic effects of Stellera chamaejasme L. root extract

Stellera chamaejasme is a traditional Chinese medicinal plant with a wide range of medicinal properties and biological activity. In order to evaluate the phytotoxity of S. chamaejasme, the effects of aqueous extracts (6.25, 12.5, 25, 50 and 100 g/L) prepared from roots was studied on the seed germination and seedling growth of rapeseed (Brassica napus), sesame (Sesamum indicum), wheat (Triticum aestivum) and maize (Zea mays). The treatments with high concentration extract (50 and 100 g/L) significantly reduced the germination rate of four crops compared with the control but the treatments with low concentration extract (from 6.25 to 25 g/L) had no obvious inhibitory effect. The mean germination time (MGT) of rapeseed and sesame increased with increasing extract concentration generally. The MGT of wheat and maize extended only at above 50 g/L concentration and at 100 g/L concentration respectively, whereas the treatments at 6.25, 25 and 50 g/L had a decreased effect on MGT of maize. The concentration-dependent effects were also found on shoot length, root length, number of lateral roots and dry weight of rapeseed, wheat and sesame seedling. Lower concentration extract treatments (6.25, 12.5 and 25 g/L) significantly promoted the seedling growth of maize, whereas the higher concentrations extracts had inhibitory effect. The results demonstrated that the high concentration aqueous extracts from S. chamaejasme had strong phytotoxity on seedlings growth of tested species. Dicotyledonous plants (rapeseed and sesame) were more sensitive to S. chamaejasme extract than monocotyledonous plants (wheat and maize). This result might be an important reference for further investigating the phytotoxic effect ofS. chamaejasme for weed control. Key words: Stellera chamaejasme, phytotoxity, allelopathy, germination, seedling growth.

The Behavior of the Radish (Raphanus sativus L.) and Red Beet (Beta vulgaris L. var. conditiva Alef) in the Successive Crops, following the Lettuce (Lactuca sativa L.), Spinach (Spinacia oleracea L.), Small Radish (Raphanus sativus L. var. sativus) ...

Successive crops can increase the productivity and the economic efficiency of the vegetable production. Their success depends on the correct choice of suitable species and varieties in each area. Many authors have shown positive associations between the crops in succession but they also shown some types of crops that presents incompatibilities, caused by plants health issues, insufficient mineral supply, or allelopathic effects. In particular, it can be discussed on the negative relationship between species of the Chenopodiaceae Family (Becker-Dillingen, 1965, Hosslin et al., 1964) as well as the positive allelopathic effects between the species of the Brassicaceae Family (Jimenez-Ossorino and Gliesman, 1987). There have been studied two root crops: radish and red beet. These kinds of crops are finding favorable growing conditions in the pedoclimate of Bistrita County, and they were preceded in the same season by lettuce, spinach, small radish and spring onion. Thus there were eight experimental variants, arranged in randomized blocks of three repetitions each. The experiments were conducted between 2000 and 2001 on the experimental crop area owned by Bistrita’s Agricultural College.

In Search of Allelopathy from Common Alliaceae Crops for Managing Weeds in Coriander: An Overview

In Search of Allelopathy from Common Alliaceae Crops for Managing Weeds in Coriander: An Overview