[en] ABSTRACT The ornamental sector is very important for the modern horticultural production, and this statement is el-founded, both from the economical point of view and also when considering the development of new technologies. Within the subsector dealing with production of season plants in pots Viola x wittrockiana occupies a central position, mainly in the period from autumn to beginning spring. Therefore, the main objective of this Ph. D. thesis was to study the commercial substrates used for growing this season plant, its physical and chemical properties (before and after the plant has been cultivated), and also the chemical composition of root, aerial part and flowers. First, it was tried to correlate the above mentioned variables determined in the laboratory with other characteristics which are of great interest for commercialisation such as plant quality, and flower and plant diameter, and root development. In addition the technologies of production employed as well as the performance of technical know-how of the managers of the garden centres studied and its work teams have been studied. For this purpose an specific evaluation form has been developed within the frame of this Ph.D. Sampling of substrates and plant material, laboratory analysis and surveys conducted by application of evaluation forms have been performed from January 2009 to March 2010. Data have been recorded and analysis have been made from 17 samplings taken on garden centres belonging to 13 producers of ornamental plants. The studied garden centres were located in he Spanish regions of Castile and Leon and Galicia as well as in the North of Portugal. The following physical an chemical properties have been analyzed in the substrate: water volume (WV), air volume (AV), total porosity (PS), particle or solid density (PD) percent of contraction (S), bulk density (DBD), dry matter (DM), moisture (WM), organic matter (OM), ashes, potential of hexogen (pH), electrical conductivity (CE), and carbon to nitrogen ratio (C/N). In addition, macro- and micronutrients have been also analyzed in the substrates before sowing and after harvesting of the ornamental plant, as well as in roots, aerial parts and flowers. The values of the soil physical properties of the substrates studied, both before sowing and after harvesting are within the optimal range for adequate plant growth recommended by different authors. Most of the samples analyzed also showed pH and electrical conductivity values within intervals recommended for optimal plant growth; there were however samples with high values of electrical conductivity. In general, the carbon to nitrogen ratio was higher than the optimal values recommended; however this did not meant a problem for plant growth and development, most likely because the commercial substrates employed were bases on very stable peats, with low mineralization. Concentrations of heavy metals extracted with a 1:5 water solution were much lower than limits considered in the legislation as indicators of contamination, showing that there was no risk for environmental contamination. On the other hand, the macro- and micronutrient concentrations, both before sowing and after harvesting were below the recommended range of optimal values. However the low levels of nutrients showed not an effect on plant quality; which could be attributed to the fact that producers have mainly applied fertilizers by fertirrigation and also to manage occasional nutrient deficiencies using leaf fertilization; thus producers have been able to give to the plants just what they need for each stage of development. Application of Surrey tests showed that most of the garden centres or nurseries studied were characterized by a medium to high performance in technology, which was reflected on an average note of 7.88. On the other hand, levels of technical performance and formation received an average note of 6.82. Regarding plant quality evaluation, on average ornamental garden centres studied showed the following values: A1 = 39.65%; A2 = 44.65% and B = 15.64%. For the root quality the notes obtained ranked as follows: 10 = 5.65 %; 8 = 34.82%; 6 = 37.58%, and 4 = 19.35%. It follows that both, plant quality and root development criteria most of the samples studied have been found to be included within the interval of values which are required by the market. Moreover, mean diameter values of 15.58 cm for plants and 7.79 cm for flowers are higher than the respective mean values demanded by the markets. It follows that both, the methodology used to analyze morphological quality and the test survey model applied to evaluate ornamental garden centres have been shown to be efficient to accomplish this Ph. D. work.

[gl] O sector ornamental ten unha grande importancia na produción hortícola moderna, tanto dende o punto de vista económico coma no desenvolvemento de novas tecnoloxías. No subsector da producción de plantas de tempada en macetas, a Viola x wittrockiana ocupa unha posición destacada, principalmente no período que vai dende outono ata o inicio da primavera. Neste sentido, o principal obxectivo desta tese foi o de estudar tanto os substratos comerciais utilizados e as súas propiedades físicas e químicas (antes e despois do cultivo da planta), como as propiedades químicas da raíz, da parte aérea (PA) e flor, intentando correlacionar estas variables tanxibles e determinables no laboratorio, con outras de grande importancia no momento da comercialización, como son a calidade e diámetro da planta e das flores e o desenvolvemento radicular. Ademais, estudáronse as tecnoloxías de produción utilizadas e o nivel de coñecemento técnico dos responsables dos viveiros e dos seus equipos de traballo, mediante un modelo de cuestionario de avaliación desenvolvido especificamente para esta tese. A toma de mostras de substratos e material vexetal, as análises de laboratorio e a aplicación dos cuestionarios levouse a cabo entre xaneiro de 2009 e marzo de 2010. Para iso tomáronse datos e efectuáronse análises a partir de 17 mostraxes realizadas en viveiros de 13 produtores de plantas ornamentais situados nas rexións españolas de Castela e León e Galicia, ademais de no norte de Portugal. Os parámetros físicos e químicos analizados no substrato foron os seguintes: Volume de auga (WV), volume de aire (AV), porosidade total (PS), densidade de partícula (PD), valor de contracción (S), densidade aparente (DBD), materia seca (DM), humidade (WM), materia orgánica (MO), cinzas, potencial hidróxeno (pH), condutividade eléctrica (CE) e relación Carbono/Nitróxeno (C/N). Ademais, analizáronse os macro e micro nutrientes nos substratos final e inicial, así como nas raíces, parte aérea e flores. Os parámetros físicos analizados, tanto no substrato inicial coma no final, están dentro dos valores recomendados por diversos autores. Así mesmo, o pH e a condutividade eléctrica das mostras encóntranse na súa gran maioría dentro das marxes recomendadas. A relación Carbono/Nitróxeno (C/N) presentouse, de modo xeral, superior aos niveis recomendados, non obstante ao tratarse de turbas moi estables, isto non significou un problema no desenvolvemento das plantas. As concentracións de metais pesados quedaron por debaixo dos máximos recomendados por diversos autores, indicando así que non existiron altos riscos de contaminación ambiental. Os resultados de macro e micro nutrientes nos substratos iniciais e finais ofreceron valores inferiores aos recomendados, pero non se viu afectada a calidade das plantas obtidas xa que os produtores realizan aboado por fertirrigacion, subministrando o que as plantas necesitan en cada etapa do seu desenvolvemento e tamén solucionado eventuais carencias con subscritores foliares.Coa aplicación dos cuestionarios, púidose observar que a gran maioría dos viveiros estudados presentaban un nivel de tecnoloxía medio/alto, que se reflicte na nota media dos viveiros de 7,88. Por outra parte, o nivel de capacitación técnica e formación, obtivo unha nota media de 6,82. En relación á avaliación da calidade das plantas, a media dos viveiros analizados deu como resultado uns valores de A1 =39,65%; A2 =44,65% e B =15,64%. En canto á calidade de raíces, as notas medias dos viveiros foron: 10 = 5,65%; 8 = 34,82%; 6 = 37,58% y 4 = 19,35%. É dicir, tanto no referente á calidade das plantas coma ao desenvolvemento radicular a gran maioría das mostras inclúense dentro do rango esixido polo mercado. Os diámetros medios foron 15,58 cm para as plantas e 7,79 cm para as flores, superando os valores medios esixidos polo mercado. Polo tanto, a metodoloxía utilizada para as análises da calidade morfolóxica e o modelo dos cuestionarios utilizados na avaliación dos viveiros mostráronse eficaces para o desenvolvemento deste traballo de tese.