Lynne Wong's PhD thesis

not have many dry leaves attached to them, additional material pertaining to the relevant
variety and replicates were collected from the field, the number of leaves was counted,
weighed and are shown in Table 3.5. Green leaves attached to the samples were also
counted and shown. As tops from the four-stalk sample were insufficient, additional
material was collected from the field. The masses of stalk (internode) with rind, nodes,
rind only, and stalk only, when measured, are also shown in Table 3.5. The mass of cane
is taken as the sum of the mass of stalk with rind and nodes. Results of the dry mass of
these sugar cane components are shown on the right hand side of Table 3.5; they are the
sum of the three sieved fractions after oven-drying. The dry mass result for tops is the
combined mass of the tops from the cane source and the additional material collected.
Similarly, results obtained for the cane varieties aged 44 weeks and 36 weeks are indicated
in Tables 3.6 and 3.7 respectively.
Details of the three sieved fractions after oven-drying (> 2 mm, > 1.18 mm and > 38 μm)
of the sugar cane components of the four varieties aged 52 weeks are shown in Table 3.8,
which also shows details of the two fractions after dry-sieving (> 1.18 mm and
< 1.18 mm). The latter enables the calculation of fibre/fines ratio within each component
part, which, in the case of stalk, implies fibre/pith ratio. Similar results for samples aged
44 weeks and 36 weeks are shown in Tables 3.9 and 3.10 respectively.
During fibre extraction from the cane variety R 570 harvested in 2001, the use of an
assembly of three sieves for wet sieving had not yet been thought of, all the fibre and
fines/pith were retained on the 38 μm sieve. Dry sieving was subsequently effected by
using a 1.18 mm sieve on top of a receiver to ensure separation of fibre and pith/fines.
Details of dry masses of the sugar cane components of R 570 of three ages harvested in
2001 after fibre extraction and dry sieving are shown in Table 3.11. From Tables 3.8 –
3.11, it can be seen that the total mass after dry sieving is greater than the mass after fibre
extraction; this is because the extracted fibres were weighed after oven drying; the dry
sieving was effected much later and the sieved fractions were not re-dried in the oven. The
fibre/fines or fibre/pith ratios are calculated.
3.5.1 Material loss during fibre extraction
From Tables 3.5, 3.6 and 3.7, the material loss in each component after the fibre extraction
process can be estimated. This is shown for cane samples of the four varieties and three
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