Chlorophyll Content in Yacon (Smallanthus sonchifolius) Landraces and Its Relationships with Plant Characteristics

B.Sc. Alejandro Samper Salvador

Master's thesis

Abstract:

Yacon (Smallanthus sonchifolius) is a perennial plant that inhabits the Andean mountains and belongs to the Asteraceae family. The yacon crop has become very popular within some countries for its edible roots as well as for its medicinal and antioxidant properties. Several studies deal with the optimization of the crop for a better yield. To date, there are not studies about the relationships between photosynthetic pigments content and plant characteristics. The main goal of this study was to determine the chlorophyll (a, b) and carotene contents as well as several morphometric parameters in 24 yacon landraces from three different countries (Bolivia, Ecuador, and Peru) and with different ploidy level (octoploids: 2n=58 and dodecaploids: 2n=87). The photosynthetic pigments were firstly assessed with a chlorophyll meter (SPAD) during three months (July, August, and September). For this purpose, three clones of each plant landraces were used and ten SPAD measurements per clone were taken. Furthermore, in September photosynthetic pigments were extracted from fully expanded leaves using 200 mg of fresh material (acetone extraction). Chlorophylls (a, b) and carotene contents were determined with a spectrophotometer using three wavelengths (663, 645, and 470 nm, respectively). At the end of the vegetation period, the morphology of different plant structures and tuberous roots mass were determined. According to the results obtained, the chlorophylls and carotene content were significant lower in September in comparison with July and August (p < 0.05). The results also shown that dodecaploids plants tend to have a higher photosynthetic pigments content and leaf area than the octoploids plants. Related with plant morphology, the leaf area and the width of the stems showed a negative relationship with chlorophyll and carotene contents (p < 0.05). On the other hand, the mass of the tuberous roots was positively related with the plant height (p < 0.05). The plants with a lower leaf size could be more appropriate for its medicinal use due to the higher chlorophyll and carotene contents. It is advisable to harvest the leaves till the end of August. The photosynthetic pigments assessment could be considered as a tool for a better exploitation of the yacon crop.

Keywords

Crop production, Photosynthetic pigments, Plant morphology, Ploidy level, Smallanthus sonchifolius

Language used: English

Date on which the thesis was submitted / produced: 27. 4. 2017

Thesis defence

• Supervisor: Jose Luis Ros-Santaella, Ph.D.

Czech University of Life Sciences Prague

Faculty of Tropical AgriSciences

Master programme / field:
Tropical Agriculture / Tropical Crop Management and Ecology