ABSTRACT
Objective:To investigate the allelopathic effects of water extracts from rhizosphere soil of three medicinal plants Rehmannia glutinosa，Pinellia ternata and Isatis indigotica on seed germination and seedling growth of Polygala tenuifolia， screen the stubble varieties suitable for crop rotation with P. tenuifolia， and provide some scientific basis for continuous cropping obstacles of P. tenuifolia. Method:The bioassay method was used to study the effects of rhizosphere soil water extracts from three medicinal plants Rehmannia glutinosa，Pinellia ternata and Isatis indigotica at concentrations of 0.3，0.6，0.9 g·mL-1 on the germination of P. tenuifolia seed and seedling growth. Result:The rhizosphere soil water extracts of Rehmannia glutinosa and Pinellia ternata showed basically low-promotion and high-inhibition concentration effects on the final germination rate，germination potential，and germination index of P. tenuifolia seeds，while the water extract of Isatis indigotica showed significant allelopathic inhibition effect. All three rhizosphere soil water extracts showed significant allelopathic inhibition effects on the growth index of P. tenuifolia seedlings. Among them，the rhizosphere soil water extract of Rehmannia glutinosa showed lower inhibitory effect on the plant height and root length of P. tenuifolia seedlings than the other two water extracts. The photosynthetic pigment content，proline（Pro） content，and soluble sugar content of P. tenuifolia chinensis seedlings were the highest under 0.3 g·mL-1 soil water extract of Rehmannia glutinosa， with relatively higher content of soluble protein， and relatively lower content of hydrogen oxide（H2O2）. Under the treatment of 0.9 g·mL-1 soil water extract of Rehmannia glutinosa，P. tenuifolia seedlings had the highest peroxidase（POD） and superoxide dismutase（SOD） activities，low catalase（CAT） activity，and lowest content of malondialdehyde（MDA）. Conclusion:Based on the comprehensive analysis of the above experimental data and allelopathic effects，the water extract of rhizosphere of Rehmannia glutinosa can promote the germination of P. tenuifolia seeds to a certain extent，and lay the foundation for seedling resistance to biochemical stress. Therefore， Rehmannia glutinosa is more suitable for crop rotation with P. tenuifolia.
ABSTRACT
RESUMOO objetivo desse trabalho foi verificar o efeito do solo pré-cultivado com plantas aromáticas na germinação e no desenvolvimento inicial de plântulas de alface cv. Simpson. A pesquisa foi realizada na Embrapa Hortaliças, Brasília, em bandejas mantidas em casa de vegetação. O experimento foi conduzido em delineamento experimental inteiramente casualizado, com três repetições e onze tratamentos: solo pré-cultivado com hortelã-comum (Mentha x villosa), hortelã-brava (Mentha arvensis), hortelã-pimenta (Mentha piperita), Mentha spp., capim-citronela (Cymbopogon winterianus), capim-limão (Cymbopogon citratus), manjericão de folha larga (Ocimum basilicum), manjericão de folha roxa (Ocimum gratissimun), tomilho (Thymus vulgaris), sálvia (Salvia officinalis) e solo da mesma área sem cultivo prévio de planta aromática (controle). Aos 30 dias após o semeio, foram avaliadas: índice de velocidade de emergência (IVE), taxa de sobrevivência (TS), número de folhas (NF), comprimento da raiz principal (CRP) e da parte aérea (CPA), massa fresca da raiz (MFR) e da parte aérea (MFPA) e massa seca da raiz (MSR) e da parte aérea (MSPA). Os dados foram submetidos à análise de variância e teste de Tukey a 5% de probabilidade. Houve diferença significativa em relação ao IVE, sendo que o tratamento com C. citratus afetou negativamente a emergência das plântulas. O tratamento com M. arvensis apresentou uma TS de apenas 16% das plantas aos 30 dias após a semeadura. O NF foi menor no tratamento com M. arvensis, diferentemente de todos os demais, exceto S. officinalis. A MRF e MFF foram estimuladas pelo tratamento com T. vulgaris sendo superior a todos os outros tratamentos. Os resultados obtidos permitem concluir que houve efeito negativo de M. arvensis e positivo de T. vulgaris no desenvolvimento inicial de plântulas de alface.
ABSTRACTThis study aimed to verify the outcomesof the soil previously treated with aromatic plants in the germination and early seedling growth of lettuce var. Simpson under greenhouse conditions. The trial was developed at Embrapa Vegetables, in Brasília, Brazil in a completely randomized design with three replications and composed by eleven treatments as follow: soil cultivated with apple-mint (Mentha x villosa), wild mint (Mentha arvensis), peppermint (Mentha piperita), Mentha spp., citronella (Cymbopogon winterianus), lemon grass (Cymbopogoncitratus), basil (Ocimum basilicum), african basil (Ocimum gratissimun), thyme (Thymus vulgaris), sage (Salvia officinalis) and soil from the same area without prior cultivation of aromatic plant (control). The emergence velocity index (IVE), the survival rate (SR), the number of leaves (NL), the length of the main root (CRP) and the shoot (CPA), the fresh mass of the root (MFR) and the shoot (MFPA) and the dry mass of the root (MSR) and the shoot (MSPA), were evaluated 30 days after the sowing. The data were submitted to analysis of variance and Tukey's test at 5% probability. There was a significant difference regarding the IVE, in which the treatment with C.citratus negatively affected seedlingappearance. The treatment with M. arvensis showeda TS of only 16%at 30 days after the sowing. The NF was lower in the treatment with M. arvensis, differently from all the others, excepting the cultivation withS. officinalis. The MFR and the MFPA were stimulated by the treatment with T. vulgaris, which was higher than all the other cultivations. The obtained results showed that M. arvensis had a negative influence,while T.vulgaris presented a positive outcome in the early development of lettuce seedlings.
Subject(s)
Plants, Medicinal/anatomy & histology , Soil Analysis , Lactuca/classification , Germination , Plant Exudates/analysis , Rhizosphere , AllelopathyABSTRACT
This work confirm the allelopathic toxic effect of both cell-free medium in log and death phase of growth of Microcystis aeruginosa on chromosomal changes of Allium cepa root tips and the plumule formation of Zea mays seedlings. The results showed high significant inhibition of mitotic index in Allium cepa root tips in addition, chromosomal abnormalities were also detected. There were morphological change occurred in the plumule formation of Zea mays seedlings. The results revealed that, seed soaked in log phase cell-free medium had less inhibitory effect on plumule formation than that the seed soaked in death phase cell-free medium of M. aeruginosa. This was confirmed by the allelopathic effect of toxins released during death phase of growth was more than log phase.
ABSTRACT
Objective: To study the allelopathic effect of water extract from Tridax procumbens (WETP) on the seed germination and seedling growth of four kinds of crops. Methods: By water extraction, the stems, leaves, and seeds of T. procumbens were extracted, respectively. The seeds and seedlings of the four kinds of crops were treated with WETP, using distilled water as a control, and the differences between the seeds at four kinds of concentration were analyzed. Results: The synthetic action of WETP on Vigna radiata is promoting. With the increasing concentration, the promoting is diminished. But the effects of WETP on Raphanus sativus, Brassica campestris, and Lactuca sativa were promoting at low concentration and inhibition at high concentration. The inhibitory sequences of water extracts of different parts were seeds > leaves > stems, and for the seeds, L. sativa > R. sativus > B. campestris > V. radiata. The inhibition on L. sativa was the most significant. Conclusion: T. procumbens has the allelopathic effect on native plants. Therefore, T. procumbens could be used as herbicide and cover plant for competition to inhibit other weeds. It has a development and application value.
ABSTRACT
O objetivo do presente trabalho foi à verificação do efeito alelopático de Hyptis. suaveolens na germinação de sorgo, alface e rabanete, bem como, a comprovação da existência de compostos com potencial alelopático. Sementes de sorgo, alface e rabanete foram semeadas em substrato constituído de areia, terra e adubo orgânico contendo folhas de H. suaveolens. As análises da germinação foram feitas considerando a protrusão da radícula para o término do evento germinativo. Foi calculado o IVG (índice de velocidade de germinação) e %G (porcentagem de germinação). Os resultados mostraram que sorgo e a alface foram mais susceptíveis ao potencial alelopático de H. suaveolens, sendo que para o rabanete foi observado um efeito benéfico. Entre os tratamentos, o substrato esterilizado e não esterilizado mostraram diferenças entre si. A análise cromatográfica do óleo essencial presente nas folhas de H. suaveolens revelou a presença de compostos com potencial alelopático. Portanto, H. suaveolens, pode apresentar efeito alelopático positivo no IVG de sementes de rabanete e a presença de microorganismos pode ser necessária para que esse efeito alelopático aconteça.
The aim of this study was to verify the allelopathic effect of H. suaveolens on the germination of sorghum, lettuce and radish, as well as to prove the existence of compounds with allelopathic potential. Seeds of sorghum, lettuce and radish were sown in substrate consisting of sand, soil and organic fertilizer containing leaves of H. suaveolens. The germination tests were performed considering the protrusion of the radicle for the conclusion of the germinative event. GSI (germination speed index) and G% (percentage of germination) were calculated. The results showed that sorghum and lettuce were more susceptible to the allelopathic potential of H. suaveolens, while for radishes a beneficial effect was observed. Between treatments, the sterilized and unsterilized substrate showed differences. The chromatographic analysis of essential oil present in the leaves of H. suaveolens revealed the presence of compounds with allelopathic potential. Therefore, H. suaveolens may have positive allelopathic effect on the GSI of radish seeds, and the presence of microorganisms may be necessary for such an allelopathic effect to occur.