Allelopathic Effect Of Extracts Research Articles

Allelopathic Potential of Sunflower Genotypes at Different Growth Stages on Lettuce

Allelopathy, a biological phenomenon, is a valuable tool for weed management and minimization of synthetic pesticide use in sustainable agricultural production. The aim of the study was to evaluate the allelopathic potential of nine sunflower genotypes. Water extracts from dry sunflower leaves collected in two growth stages (butonisation and flowering) were tested in two concentrations (1 and 2.5%) on germination and growth of lettuce under laboratory conditions. The allelopathic effect of extracts was influenced by genotype, growth stage and extract concentration. The majority of extracts exhibited negative allelopathic potential with seed germination being the least affected, and root length reduced up to 85% compared to the control. A higher concentration of water extracts resulted in a greater reduction of lettuce growth parameters. On average, extracts collected in the flowering stage inhibited lettuce shoot length to a greater degree. Several genotypes showed a greater negative impact, especially on shoot length and seedlings’ fresh weight. Further investigations of selected sunflower genotypes with the highest allelopathic potential on weed species and studies on phytochemical analysis are needed.

Allelopathic effect of extracts from Panax notoginseng mono-cropped soil on its root rot pathogens

Methanol, ethyl acetate, and water were used to extract the continuous cropping soils of Panax notoginseng, with the solution/soil ratios of 3:1, 6:1, and 9:1. We investigated the effects of those soil extracts on the growth and population of root-rot pathogens of P. notoginseng. Results showed that the methanol, ethyl acetate and water extracts all promoted mycelial growth of Fusarium oxysporum and Fusarium solani after 72 h of plate culture. The response indices of methanol and ethyl acetate extracts on the growth of F. oxysporum were 14.0%-19.8% and 16.2%-20.2%, being higher than that of water extract (8.9%-14.2%), but without significant difference between diffe-rent extraction ratios. However, methanol extract inhibited the mycelial growth of Alternaria spp. The inhibitory effect was highest at the extraction ratio of 3:1, reaching -33.2% to -38.5%. Ethyl acetate and water extracts did not affect the mycelial growth of Alternaria spp. After four weeks of soil culture, methanol, ethyl acetate and water extracts all increased the F. oxysporum populations. The positive effect of water extract was higher than that of methanol (1.68×104-6.73×104 copies·g-1 dry soil) and ethyl acetate (1.77×104-3.72×104 copies·g-1 dry soil) extracts, being 3.49×106-9.56×106 copies·g-1 dry soil. This increment was weakened along with the increase of extraction ratio. Both water extract and methanol extract with low extraction ratio could increase the F. solani populations, while there were no significant effects of methanol, ethyl acetate and water extracts on the population of Alternaria spp. Therefore, the extracts from continuous P. notoginseng cropping soil showed allopathically promoting effects on the growth and population of root-rot pathogens, F. oxysporum and F. solani, which may be one of the reasons for the occurrence of root rot and other soil-borne diseases in replanted P. notoginseng gardens.

Antibacterial activity and allelopathic effects of extracts from leaf, stem and bark of Mt. Atlas mastic tree (Pistacia atlantica subsp. kurdica) on crops and weeds

Antibacterial activity and allelopathic effects of extracts from leaf, stem and bark of Mt. Atlas mastic tree (Pistacia atlantica subsp. kurdica) on crops and weeds

In vitro allelopathic effects of extracts and fractions of five plants on tomato seed germination and vigor index

AbstractIn nature, allelopathic substances are likely to influence the germination of seeds. Callistemon viminalis, Tephrosia vogelii, Senna spectabilis, Cupressus lusitanica, and Polyscias fulva are found around some tomato culture fields in Cameroon. These plants may produce allelochemicals that can influence tomato seed germination and seedling characteristics. Methanol extracts and their fractions were prepared from leaves of these plants and tested on seed germination rate, shoot diameter, root and stem lengths, and vigor index of seedlings. The tested substances did not significantly (p > 0.05) affect the seed germination rate. Aqueous extracts of T. vogelii, C. lusitanica, and C. viminalis exerted the highest inhibition on seed germination while methanol extract, hexane, and ethyl acetate fractions of all the plants induced significant increases in diameters of seedlings. Aqueous extracts were effective on the stem length. All treatments generally reduced the root length. Methanol extracts induced ...

Allelopathic Effect of Extracts of Medicinal Plants on Mungbean in Vivo Conditions

The experiments were conducted at Chaudhary Sarwan Kumar Krishi Vishavidhyalaya,Palampur, Himachal Pradesh, India to see the allelopathic effect of medicinal leaf extracts of Ocimum sanctum L., Calotropis procera(Ait.) Ait.f and Astragalus tribuloides Delile on the plumule length of mungbean (Vigna radiata L. Wilczek) in vivo conditions. The results indicated that different extracts such as alcoholic,aqueous acidic and alkaline extract of Ocimum sanctum L., Calotropis procera(Ait.) Ait.f and Astragalus tribuloides Delile showed different plumule length of mungbean in vivo conditions. All the extracts of Ocimum sanctum L.showed no effect in comparison of control. The alcoholic extract of Calotropis procera(Ait.) Ait.f, produce considerably higher as compared to control followed by aqueous, acidic but alkaline extract showed negative effect on plumule length of mungbean. However, the alcoholic and alkaline extracts of Astragalus tribuloides Delile showed positive effect than aqueous acidic extract on the plumule of mungbean.

Allelopathic effects of extracts from tuberous roots of Aconitum carmichaeli on three pasture grasses

The tuberous roots of Aconitum carmichaeli are largely used in traditional Chinese medicine and widely grown in Jiangyou, Sichuan, China. During the growth process, this medicinal plant releases a large amount of allelochemicals into soil, which retard the growth and development of near and late crops. Therefore, a pure culture experiment was thus carried out by seed soaking to study the allelopathic effects of extracts from tuberous roots of A. carmichaeli (ETR) on the seed germination and young seedling growth of Lolium perenne, Trifolium repens, and Medicago sativa, the late pasture grasses after cultivation of A. carmichaeli. The results showed that three pasture grasses varied significantly in seed germination and young seedling growth in response to ETR concentrations. Seed germination of M. sativa was stimulated by low ERT concentration (0.01 x g(-1)), while all of pasture grass seeds germinated poorly in solution with 1.00 g x L(-1). Seed soaking with 1.00 g x L(-1) also inhibited significantly the growth of pasture young seedlings, with M. sativa showing the highest seedling height reduction of 42.05% in seeding height, followed by T. repens (40.21%) and L. perenne with about 11%. Cultivation of L. perenne could thus be beneficial to increase whole land productivity in A. carmichaeli-pasture grass cropping systems. In addition, hydrolysis of protein, starch, and inositol phosphates was blocked and free amino acids, soluble sugars and phosphorus were decreased in seeds by seed soaking with ETR, which could be one of the reason for the inhibition of seed germination. There was a significant reduction in root vigor, nitrate reductase, and chlorophyll after the seed treatment with ETR, indicating the suppression of nutrient uptake, nitrate assimilation, and photosynthesis by allelopathic chemicals in ETR, which could lead to the slow growth rate of pasture grass seedlings.

Growth limiting effects on various terrestrial plant species by an allelopathic substance, loliolide, from water hyacinth

Water hyacinth (Eichhornia crassipes) is one of the most noxious invasive aquatic plants in many countries due to its rapid growth and reproduction rate. Most practical methods to control water hyacinth are mechanical removal of the plants, and chemical and biological controls with large expense for those treatments. For recovery of control costs, beneficial use options for water hyacinth after mechanical removal would be helpful. Therefore, we investigated possible allelopathic effects of extracts and isolated allelopathic substances in water hyacinth. An aqueous methanol extract of water hyacinth inhibited the growth of roots and shoots of cress (Lepidium sativum), lettuce (Lactuca sativa), alfalfa (Medicago sativa), timothy (Phleum pratense) and ryegrass (Lolium multiflorum). Increasing extract concentration increased the inhibition. These results suggest that water hyacinth may cause allelopathic effects and contain allelopathically active substances. The extract was then purified by several choromatographic runs with monitoring the inhibitory activity during all purification steps, and a main allelopathically active substance was isolated. The chemical structure of the substance was determined by spectral data as loliolide. Loliolide inhibited the growth of cress and ryegrass at concentrations greater than 3 and 10μM. The concentrations required for 50% inhibition of the root and shoot growth ranged from 12.7–27.5 to 27.5–49.7μM for cress and ryegrass, respectively. These results suggest that loliolide may be an allelopantic substance and contribute to the growth inhibitory effect of water hyacinth. A water extract of water hyacinth also inhibited all test plant species extract-concentration dependently and contained loliolide. In addition, powder of water hyacinth inhibited germination of barnyard grass in the greenhouse condition with powder-concentration dependently. Therefore, water hyacinth may potentially be useful as soil additive materials to control weeds in the sustainable agriculture.

Allelopathic Effects of Extracts from Maize Roots and Rice Husks’ Residues on the Germination and Growth of Bidens pilosa L.

Screen house experiment was conducted to examine the allelopathic effects of the extracts from residues of maize root and rice husk on the germination and growth of Bidens pilosa L. The extracts brought about considerable inhibitions in all the growth parameters of the extract-treated seeds examined. The degree of retardation of both extract treated seeds increased with increase in the concentration of the extracts which showed that the inhibition was concentration dependent. The results obtained showed that the degree of retardation appeared to be more pronounced in B. pilosa seeds treated with extract from maize roots in growth parameters such as number of leaves at harvest and leaf area, relative growth rates, dry roots and shoot weights were inhibited. Similarly the degree of retardation was more pronounced in rice husk extract-treated seeds in growth parameters such as germination percentage and speed of germination. Statistical analysis (P < 0.05) revealed that there were significant differences in germination %, dry shoot weights of B. pilosa seeds treated with 40 g and 50 g maize roots extract concentrations when compared to the control experiment while other concentrations showed no significant difference to control experiment. Also, speed of germination, number of leaves at harvest and leaf area of B. pilosa seeds treated with extracts from residues of maize roots showed significant differences when compared with the values obtained from the control experiments. However, there were no significant differences in the all the growth parameters with rice husk treated seeds compared to control experiments. Similarly, no significant difference was observed in the relative growth rate of B. pilosa seeds treated with maize root extracts compared to control experiments.

Allelopathic effects of extracts from fibrous roots of Coptis chinensis on two leguminous species

An experiment was carried out to study the allelopathic effects of Coptis chinensis fibrous root extracts (CRE) on the germination and seedling growth of Vicia faba and Pisum sativum in order to alleviate the allelopathic effects and increase land productivity. The seeds of both garden pea (P. sativum) and broad been (V. faba) were germinated in CRE solution of various concentrations, the germination rate, seedling growth and related physiological indexes were measured. The result indicated that there were no significant effects of CRE in low concentrations on seed germination, including both the rate and index, and seed vitality and membrane permeability. With the increment of CRE concentrations, however, the high seed membrane permeability and germination inhibition were observed. For example, the germination rates were reduced by 23.4% (P. sativum) and 9.5% (V. faba), respectively, in CRE solution with 800 mg . L-1. Simultaneously, soluble sugars and the free amino acids in the seeds were lower than those in the control (without CRE) after soaking seeds in CRE solutions. In addition, the seedling growth and nitrate reductase activity were stimulated by CRE at low concentrations in contrast to high concentrations which behaved otherwise and inhibited the nutrient utilization in endosperm. Therefore, the large amount of allelochemicals released from the roots and remains of C. chinensis in soils could inhibit the seed germination and seedling growth of legumes, which may lead to decrease even fail crop yields after growing this medical plant.

Variação sazonal na alelopatia de extratos aquosos de Coleus barbatus (A.) Benth. sobre a germinação e o desenvolvimento de Lactuca sativa L.

O objetivo deste trabalho foi avaliar o efeito alelopático de extratos de Coleus barbatus sobre a germinação e desenvolvimento de plântulas de alface. Os experimentos foram conduzidos em laboratório, em diferentes concentrações de extratos obtidos de folhas de falso-boldo (0; 7,5; 15; 22,5; 30%), coletadas nas quatro estações do ano, obtidos por trituração, maceração, infusão e decocção. As sementes de alface foram distribuídas sobre placas de petri umidecidas com 10 mL de solução. Os resultados mostraram que os extratos de folhas afetaram a germinabilidade de sementes de alface apenas na concentração de 30% do extrato preparado por decocção de folhas coletadas no inverno. O índice de velocidade de germinação apresentou redução significativa nos extratos triturados preparados no outono e inverno; na maceração de folhas coletadas no verão e outono e no extrato de decocção preparado no inverno. Os extratos estimularam o crescimento da parte aérea das plântulas de alface, ao passo que, o comprimento das raízes foi afetado pelos extratos, ora inibindo, ora estimulando o crescimento das mesmas. Os extratos de folhas de falso-boldo coletadas nas quatro estações do ano apresentaram efeito alelopático sobre a germinação e o desenvolvimento da alface, sendo que estes variaram em função da sazonalidade da coleta, da forma de obtenção dos extratos e das concentrações testadas.

Allelopathic effects of extracts from several plant species on seed germination and seedlings growth of Lactuca sativa L

The ability of a plant species to inhibit germination of other plants is an untapped resource for weed control in crops that could revolutionize organic crop production. The main objective of this study was to evaluate the allelopathic potential of aqueous (5 and 10%, w/v) and methanolic (50mg ml-1) extracts from several plant species (Arbustus unedo L., Ericaceae; Daphne gnidium L., Thymeleaceae; Myrtus communis L., Myrtaceae; Olea europea L., Oleaceae; Pistacia lentiscus L., Anacardiacceae; Quercus suber L., Fagaceae; Ruscus aculeatus L., Liliaceae, Rhododendron ponticum subsp baeticum (Boissier &amp; Reuter) Handel-Mazzetti, Ericaceae) on seed germination and seedling growth of Lactuca sativa. To test the phytotoxicity 500µl of the extract were added separately over filter papers (9cm diameter) in Petri dishes. It was observed that methanolic extracts from M. communis and R. aculeatus completely inhibited seed germination, and almost all the extracts tested reduced seed germination and/or seedling growth. The inhibition of root growth was generally higher than of shoot growth, with the highest percentages of root inhibition being observed with the aqueous extracts of D. gnidium (80 and 72% for the extract at 5 and 10%, respectively) and R. aculeatus (74 and 78%), and with the methanolic extract of Q. suber (74%). Besides inhibiting seedling growth other morphological abnormalities occurred in the presence of the extracts. Roots of treated plants were thicker with a brownish color as compared to controls. Studies are being conducted to investigate the phytotoxic effect of the extracts on physiological and biochemical processes during germination and seedlings growth.