The purpose of this investigation is to determine the possible presence and the extent of nutritional material in the extracts of the green leaves of a selected group of common trees in an effort to devise simpler and more economical, yet useful and satisfactory, culture media for the use in bacteriological laboratories, particularly those on the secondary level.

Geotextiles have been used for many years in different parts of the world to promote soil conservation and to combat erosion. Such geotextiles may be synthetic (usually some form of plastic, sometimes with wire), or natural (usually some form of fibrous material). Work carried out at the University of Wolverhampton (UK) on the effectiveness of mats made from palm tree leaves sourced from the Gambia, West Africa led to a research project funded by the EU, which ran from October 2005 to February 2009, comprising the participation of four EU countries (UK, Belgium, Hungary and Lithuania) and six developing” countries (Brazil, Gambia, South Africa, Thailand, China and Vietnam). Research carried out in South Africa used mats made from the leaves of the Lala palm (Hyperhene coriacea). These mats are easy to make, flexible, durable and completely biodegradable. They cover approximately 40% of the soil surface, allowing space for vegetation to emerge, and add 1.3 kg of dry organic matter to each m2 of soil. Furthermore, they have a water retention capacity of 1.8 l kg-1 m-2, their N, K, S and P percentages are high, they have low sodium and aluminium values and a favourable C/N ratio. Firstly, trials were done on 20 South African soils and 10 mine tailings materials using a rainfall simulator. The soils varied considerably with respect to their textural, chemical and mineralogical properties as well as annual precipitation and geological origin. Erosion parameters varied greatly within, and to a much lesser extent between, the two different materials. Several significant correlations were obtained. Sediment load (SL) had the best correlation with kaolinite content and with fine sand content, while for runoff, the best correlation was with organic carbon content. When the samples were covered with palm mats values for final infiltration rate (FI) percentage stable aggregates (SA) and inter-rill erodibility (Ki) values were similar to those of bare materials and the amount of runoff was slightly higher. SL, however, was reduced by +65%. The next stage was to carry out a range of field trials, using runoff plots. Plots at four localities (Bergville, Ladybrand, Roodeplaat and Mabula) were used. Results showed that average runoff under the palm mats decreased by between 38% and 70%, compared to bare soil. Sediment concentration under the mats decreased by between 38% and 89%, using three combinations of slope, mat density and mesh size. Splash erosion at Roodeplaat decreased by between 62% and 68%, while re-vegetation at Ladybrand and Mabula increased by between 38% and 58%, with organic carbon content and topsoil accumulation also increasing under the mats. Various trials (using both the rainfall simulator and runoff plots) were carried out to evaluate the effects of reduced mat density and increased mesh size. Results from the other participating countries (25% to 95% reduction in runoff) confirm that there is much potential to use organic, bio-degradable, easy to manufacture geotextiles such as palm leaf mats, especially to combine employment opportunities with enhanced environmental protection in many susceptible areas of South Africa. / Thesis (PhD)--University of Pretoria, 2014. / gm2014 / Plant Production and Soil Science / unrestricted

Το αντικείμενο της μελέτης αυτής είναι η οργάνωση (ταξινόμηση, αναγνώριση, ανάκτηση κλπ.) βάσεων που περιλαμβάνουν εικόνες (φωτογραφίες) φύλλων δένδρων. Η οργάνωση βασίζεται στο σχήμα των φύλλων και περιλαμβάνει διάφορα στάδια. Το πρώτο στάδιο είναι η εξαγωγή του περιγράμματος και γίνεται με διαδικασίες επεξεργασίας εικόνας που περιλαμβάνουν τεχνικές ομαδοποίησης και κατάτμησης. Από το περίγραμμα του φύλλου εξάγονται χαρακτηριστικά που δίνουν την δυνατότητα αξιόπιστης περιγραφής κάθε φύλλου. Μελετήθηκαν στη διατριβή αυτή οι παρακάτω γνωστές μέθοδοι: Centroid Contour Distance, Angle code (histogram), Chain Code Fourier Descriptors. Προτάθηκαν επίσης και καινούριες μέθοδοι: Pecstrum (pattern spectrum), Multidimension Sequence Similarity Measure (MSSM). Οι παραπάνω μέθοδοι υλοποιήθηκαν. Παράχθηκε κατάλληλο λογισμικό και εφαρμόσθηκαν σε μία βάση εικόνων φύλλων επιλεγμένη από το διαδίκτυο. Η αξιολόγηση των μεθόδων έγινε μέσα από έλεγχο της συνολικής ακρίβειας κατηγοριοποίησης (με τον confusion matrix). H μέθοδος MSSM έδωσε τα καλύτερα αποτελέσματα. Μία οπτική αξιολόγηση έγινε σε αναπαράσταση 2 διαστάσεων (biplot) μέσα απο διαδικασία Multidimensional Scaling. / The objective of this thesis is the leaf images data base organization (i.e classification, recognition, retrieval etc.). The database organization is based on the leaf shape and is accomplished in a few stages. The contour recognition and recording consist the first stage and is performed with image processing operations namely clustering and segmentation. From the leaf contour several features are extracted appropriate for a reliable description of each leaf type. The following well known techniques were studied in this thesis: Centroid Contour Distance, Angle code (histogram), Chain Code, Fourier Descriptors. Two new metods were also proposed: Pecstrum (pattern spectrum), Multidimension Sequence Similarity Measure. In the experimental study appropriate software was produced to realize all the above methods which was applied to the leaf data base downloaded from internet. The overall evaluation of the methods was done by means of the classification in precision and using the confusion matrix. Best results were produced by the MSSM method.