The human diet of the local population in the province Uíge, Angola mainly consists of carbohydrate rich plants originating from America or Asia. Acidic soils lead to various deficiency syndromes and low livestock yield. The aim of this study is to evaluate the nutritional potential of 14 native plants from Africa (Aframomum alboviolaceum, Aframomum angustifolium, Aframomum giganteum, Antidesma venosum, Clitandra cymulosa, Landolphia buchananii, Landolphia lanceolata, Landolphia owariensis, Oncoba welwitschii, Parinari capensis, Piper umbellatum, Pseudospondias microcarpa, Tristemma mauritianum, Vitex madiensis subsp. madiensis). The amino acid composition, beta-carotene, vitamin B1, B2, C and E content was determined for the respective edible plant part. Fruits of P. capensis were found to be rich in beta-carotene. The pulp of O. welwitschii shows a high nutritional value (high in vitamin B1, B2, C, E and in indispensable amino acids). Leaves of P. umbellatum are determined as convenient substitutes for the human nutrition containing beta-carotene, vitamin B1, B2, C and E. The integration and cultivation of studied plants indicate positive health effects, supplying different amounts of frequently lacking vitamins and beneficial ratios of indispensable amino acids. Studies examining dependencies between site location, ripeness, storage or transportation are urgently needed as they directly influence the micronutrient content.

Angola suffers from a high child mortality rate and a prevalence of anemia due to malnutrition. The aim of this study is to provide a comprehensive overview of the mineral content of 43 wild edible plants. A total of 24 different elements (aluminum, antimony, arsenic, cadmium, calcium, chromium, cobalt, copper, iron, lead, lithium, magnesium, manganese, molybdenum, nickel, potassium, selenium, silicon, sodium, strontium, titanium, thallium, vanadium, zinc) were analyzed by inductively coupled plasma atomic emission spectroscopy to identify nutritional beneficial and hazardous plants. For the majority of studied species (31 of 43) data lack completely. For the remaining, only macronutrient contents are published yet, determining their (ultra)trace element and heavy metal contents for the first time. None of the examined plants pose a risk to human health due to low heavy metal contents, seasonality, and low amounts of consumed plant parts. Iron and zinc rich plant parts, such as fruits of Canarium schweinfurthii, or leaves of Crassocephalum rubens, Solanum americanum, and Piper umbellatum could help combating deficiency syndromes. The genus Landolphia shows to be an aluminum hyperaccumulator with aluminum contents >1000 mg/kg. Results of this study serve as a database for upcoming research. The nutritional value of edible plants is evaluated.

In der vorliegenden Arbeit wurde der Einfluss von Lichtbedingungen auf den Ertrag und die nutritive Qualität der Versuchspflanze Persicaria odorata untersucht. Die Experimente wurden unter praxisnahen Bedingungen im Gewächshaus (Sonnenlicht) und Klimakammern (Dreiband-Leuchtstoffröhren) unter Berücksichtigung eines breiten Inhaltsstoffspektrums, mehreren Versuchsreihen, Lichtmodifizierungen anhand von Zusatzbestrahlungen mit LEDs und Überdeckungen mit photoselektiven Folien sowie dem Anwenden verschiedener statistischer Auswertungsverfahren durchgeführt. Die Tageslichtsumme beeinflusste das Pflanzenwachstum positiv. Beispielsweise wurde die Frischmasse bei einem Anstieg der Tageslichtsumme um 1% mit gleichbleibender spektralen Lichtzusammensetzung um 0,96% (Gewächshaus) bzw. 0,64% (Klimakammer) erhöht. Versuche mit monochromatischen LEDs zeigten, dass spektralbereichsabhängige Erhöhungen der Tageslichtsumme die Biomassesteigerungen verstärkten. Den deutlichsten Effekt im Hinblick auf die Frischmassebildung hatte das kurzwellige Blaulicht (443 nm). Bezüglich der Inhaltsstoffe zeigte insbesondere das kurzwellige Grünlicht (515 nm) einen positiven Effekt. Dieser Spektralbereich wird jedoch durch die traditionell in Gewächshäusern eingesetzten Natriumhochdrucklampen kaum emittiert. Auch sind die bisher häufig eingesetzten Bestrahlungen mit Blau- und Rotlicht in kontrollierten Anbausystemen zwar wichtig für den Aufbau von Biomasse, jedoch nicht optimal im Hinblick auf den Nährwert. Die Ergebnisse zeigen, dass die Belichtung im Gartenbau sorgfältig ausgewählt werden sollte, jedoch während strahlungsschwachen Monaten eine effektive Möglichkeit ist, den Ertrag und die nutritive Qualität von P. odorata deutlich erhöhten. Durch Modifikationen der Lichtbedingungen ist es möglich den Ertrag und Nährwert pflanzlicher Erzeugnisse zu steigern und dadurch die Versorgungslage mit gesundheitsfördernden bzw. essentiellen pflanzlichen Inhaltsstoffen zu verbessern. / This thesis examined the impact of light conditions on the nutritive quality of the test plant Persicaria odorata. Experiments took place in a greenhouse (sunlight) and climate chamber (fluorescent tube) and under consideration of a wide range of nutritive compounds, several test series, different light modifications and the use of various statistically evaluation procedures. This thesis demonstrates that varying light conditions increase nutritive value and yield under realistic conditions. Increasing the day light integral by 1% improved the fresh mass of 0,96% (greenhouse) and 0,64% (climate chamber). Experiments with monochromatic LEDs proved a high increase of biomass by spectral range dependent enhancements of the day light integral. For example, in the greenhouse, fresh mass was mostly affected by short wave blue radiation (443 nm). Additionally, the day light integral influenced the accumulation of nutrients. Higher contents of polyphenols and flavonoids in the climate chamber and the reactions on additional monochromatic LEDs proved again that it is more effective to increase day light integral by a specific enhancement of certain spectral ranges. The highest increases were achieved by supplementing spectral ranges that are not included in the emission spectrum of commonly used high pressure sodium lamps. Results also indicate that controlled agriculture’s frequently used lighting systems which emit blue and red light can improve plant growth, but it is not optimal regarding the nutritive quality. Adding short wave green light (515 nm) could increase biomass and improve the nutritive quality considerably. This thesis demonstrates that additional lighting in horticulture is an effective method to improve yield and nutritive quality of herbal vegetables in light deprived northern regions. By altering the emission spectrum of traditional artificial lighting systems, it is possible to increase yield and simultaneously improve the nutritive value of vegetables.