Despite the importance of taro (Colocasia esculenta L. Schott) as a food security crop,
scientific research on it is scanty in South Africa. Production site, planting date and
fertiliser regime affect crop performance and quality, particularly that of cultivars,
because they tend to be adapted to specific localities. Storage temperature and packaging
method on the other hand affect the shelf-life. To investigate performance and quality of
three taro cultivars in response to planting date and fertilisation, a study was carried out at
two sites in KwaZulu-Natal, South Africa (Ukulinga and Umbumbulu), during the
2007/2008 growing seasons. The effect of two storage temperatures (12o
C and ambient
temperature) and three packaging methods (polyethylene bags, mesh bags and open
boxes) on cormel quality following storage was also investigated for three cultivars.
Delayed planting negatively affected the number of cormels plant-1 and fresh cormel
mass plant-1
. Fertilisation and cultivar affected the number of cormels plant-1 and fresh
cormel mass plant-1 only when planting was done in October and November at both sites.
Fertilisation increased the number of cormels plant-1 for all cultivars except Dumbedumbe. Dumbe-dumbe had the lowest number of cormels plant-1 but the highest number
of marketable cormels plant-1
. Dumbe-dumbe showed the lowest fresh cormel mass
plant-1 in October and the highest in November at Ukulinga. Fertisation increased fresh
cormel mass plant-1 in October at Umbumbulu. Dry matter content was negatively
affected by fertilisation at Ukulinga. The response of dry matter content, specific gravity,
protein, minerals, reducing sugars and starch content was variable depending on cultivar.
Delayed planting negatively affected starch content for Dumbe-dumbe and Pitshi at
Ukulinga. Fertilisation decreased starch content of Pitshi, while delayed planting
increased sugar content for Dumbe-dumbe and decreased it for Mgingqeni and Pitshi at
Umbumbulu. Dumbe-dumbe had higher starch content and higher reducing sugars.
Considering all growth and quality parameters, it is recommended that Dumbe-dumbe is
the best taro cultivar for crisping and the best time to plant it is October with 160 kg N
ha-1 of organic fertiliser and November with 320 kg N ha-1 at Ukulinga whereas at
Umbumbulu the best time to plant Dumbe-dumbe is October with 320 kg N ha-1 of the
fertiliser. Starch granules degradation, alpha-amylase activity and sprouting increased
v
with storage time and storage temperature. Cormels of Mgingqeni stored in polyethylene
bags showed highest alpha-amylase activity and sprouting. Reducing sugar content
increased and starch content decreased with time in storage and decline in storage
temperature. It is recommended that taro cormels be stored in mesh bags at 12o
C.
The chapters of this thesis represent different studies presented as different papers.
Chapter 1 is a general introduction to explain the study background and hypothesis.
Chapter 2 is a general review of literature. Chapter 3 is on growth, development and yield
of taro in response to planting date and fertilisation. Chapter 4 is on the influence of
planting date and organic fertiliser on crisping quality of taro cormels. Chapter 5 is on
changes in the surface morphology of starch granules and alpha-amylase activity of taro
during storage. Chapter 6 is on the effects of pre- and post-harvest practices on starch and
reducing sugars of
Order an Essay Now & Get These Features For Free:
Turnitin Report
Formatting
Title Page
Citation
Outline
