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Recolha, multiplicação e caraterização morfológica do orégão (ORIGANUM VULGARE subsp. VIRENS)
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Advisor(s)
Abstract(s)
A subespécie Origanum vulgare subsp. virens (orégão) existe espontaneamente em
Portugal. Trata-se de uma especiaria muito consumida, principalmente nos países do
Mediterrâneo, apesar dos seus recursos genéticos não estarem a ser explorados
corretamente. A colheita, em habitat natural, representa grande risco para a
conservação da diversidade da espécie e, até mesmo em alguns casos, extinção. Os
objetivos específicos deste trabalho foram a avaliação da abundância da espécie em cinco
locais do Alentejo, a caraterização morfológica de 14 acessos silvestres e o estudo da
propagação vegetativa e germinação da semente. Avaliou-se a disponibilidade de orégão
em 5 locais do Alentejo, com recurso ao método dos transeptos lineares e da quadricula
(50x50cm). Aplicou-se uma escala de abundância relativa (de 0 a 5) em relação a visitas
anteriores aos locais. Efetuaram-se 2 ensaios de germinação de sementes, um com
sementes de acessos silvestres e outro comparando a capacidade germinativa de
sementes silvestres versus cultivadas. Fizeram-se 2 ensaios de propagação vegetativa, um
com estacas caulinares terminais dos 14 acessos silvestres e outro comparando estacas
terminais com estacas subterminais e, com estacas refrigeradas (ca. 5.ºC, durante 12
dias). Os 14 acessos foram instalados em ensaio para caracterização morfológica.
Usaram-se os descritores ECPGR, tendo-se considerado 53 descritores (para planta,
caule; folha basal; folha abaixo da inflorescência; inflorescência e; sementes). As
conclusões do estudo, apontam para risco de erosão genética devido às ameaças
identificadas: mobilizações e desmatações, aplicação de herbicidas, sobrepastoreio,
colheita desregrada. As estacas herbáceas terminais foram efetivas para a propagação
vegetativa de orégão, as estacas conservadas em frio tiveram maior crescimento em
altura do que as estacas sem refrigeração. No ensaio de caraterização morfológica foi
observada elevada variabilidade entre acessos; foram definidos 3 grupos de acessos na
análise de clusters; as plantas do grupo 3 apresentaram maior potencial agronómico para
futuros programas de melhoramento de plantas. Será necessário prosseguir estes
estudos com um segundo ano de caracterização para que, as plantas apresentem o seu
pleno desenvolvimento
The subspecies Origanum vulgare subsp. virens (oregano) exists spontaneously in Portugal. It is a very consumed spice, mainly in the Mediterranean countries, although its genetic resources are not being properly exploited. Harvesting in natural habitat represents a great risk for the conservation of species diversity and, even in some cases, extinction. The specific objectives of this work were the assessment of the abundance of the species in five locations in the Alentejo, the morphological characterization of 14 wild accessions and the study of species vegetative propagation and seed germination. The availability of oregano was evaluated in 5 locations in the Alentejo, using the linear transept and grid (50x50cm) methods. A relative abundance scale (from 0 to 5) was applied in relation to previous visits to the sites. Two seed germination tests were carried out, one with seeds from wild accessions and another comparing the germination of wild versus cultivated seeds. Two tests of vegetative propagation were carried out, one with terminal stem cuttings from the 14 wild accessions and another comparing terminal cuttings with sub terminal cuttings and with refrigerated cuttings (ca. 5.ºC, for 12 days). The 14 accessions were installed in an assay for morphological characterization. The ECPGR descriptors were used, considering 53 descriptors (for plant, stem; basal leaf; leaf below the inflorescence; inflorescence and; seeds). The study's conclusions point to the risk of genetic erosion due to the identified threats: mobilization and deforestation, application of herbicides, overgrazing, unregulated harvesting. Terminal herbaceous cuttings were effective for the vegetative propagation of oregano, cuttings kept in cold had greater height growth than cuttings without refrigeration. In the morphological characterization assay, high variability was observed between accessions; 3 access groups were defined in the cluster analysis; the plants in group 3 showed greater agronomic potential for future plant breeding programs. It will be necessary to continue these studies with a second year of characterization so that the plants present their full development
The subspecies Origanum vulgare subsp. virens (oregano) exists spontaneously in Portugal. It is a very consumed spice, mainly in the Mediterranean countries, although its genetic resources are not being properly exploited. Harvesting in natural habitat represents a great risk for the conservation of species diversity and, even in some cases, extinction. The specific objectives of this work were the assessment of the abundance of the species in five locations in the Alentejo, the morphological characterization of 14 wild accessions and the study of species vegetative propagation and seed germination. The availability of oregano was evaluated in 5 locations in the Alentejo, using the linear transept and grid (50x50cm) methods. A relative abundance scale (from 0 to 5) was applied in relation to previous visits to the sites. Two seed germination tests were carried out, one with seeds from wild accessions and another comparing the germination of wild versus cultivated seeds. Two tests of vegetative propagation were carried out, one with terminal stem cuttings from the 14 wild accessions and another comparing terminal cuttings with sub terminal cuttings and with refrigerated cuttings (ca. 5.ºC, for 12 days). The 14 accessions were installed in an assay for morphological characterization. The ECPGR descriptors were used, considering 53 descriptors (for plant, stem; basal leaf; leaf below the inflorescence; inflorescence and; seeds). The study's conclusions point to the risk of genetic erosion due to the identified threats: mobilization and deforestation, application of herbicides, overgrazing, unregulated harvesting. Terminal herbaceous cuttings were effective for the vegetative propagation of oregano, cuttings kept in cold had greater height growth than cuttings without refrigeration. In the morphological characterization assay, high variability was observed between accessions; 3 access groups were defined in the cluster analysis; the plants in group 3 showed greater agronomic potential for future plant breeding programs. It will be necessary to continue these studies with a second year of characterization so that the plants present their full development
Description
Keywords
orégão variabilidade morfológica recursos silvestres propagação.