Summary
This thesis focuses on the agronomic study of Petunia. The aim was to find out the best option in the plant management in relation to substrate, fertilizer and irrigation water in order to produce high quality plants. The diagnosis of crop production in the studied area indicated that the existing problems could be summarized in three: the use of water of poor quality, scarce fertilization, and the use of organic soil as substrate. It was confirmed the existence of distinctive sectors within the area of production which differed in the quality of the irrigation water, caused by the variable contribution of the Pampeano and Puelche aquifers to the groundwater salinity. Larger values of growth parameters were observed when underground water was used. For the conditions imposed in this study, the three substrates used had distinct physical and chemical properties which influenced both growth and development and the macronutrient content of the plant tissue. Comparatively it was more advantageous to use the conventional granulated fertilizer than the slow release fertilizer. This was mainly  observed in the growth parameters as the response depended largely on the immediate availability of nutrients, especially in the first 15 days after transplantation. Principal component analysis combined with hierarchical cluster analysis were systematically used in order to study the effect of substrate, type and dose of fertilizer and irrigation water quality on the development of Petunia. Quality Indicators useful in improving Petunia marketing were fresh weight, dry weight, leaf area, flowers per plant, chlorophyll content and flower color intensity. The type of fertilizer and of irrigation water did not affect plant quality in the experiments, although increases in pH and EC in the substrate were observed at the end of this trial. On the early stages of Petunia seedling growth, the specific presence of Na+ in the growing medium showed higher incidence and more negative effects than salinity itself.