Despite the importance of taro Colocasia esculenta L Schott as a food Free Essay Example

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

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