Biomedical Engineering Reference
In-Depth Information
quantity of fiber flax for industrial production is 110-130 kg ha
1
(2,000-2,400
seeds per m
2
), while for seed production is 50-70 kg ha
1
(1,000-1,100 seeds per
m
2
)[
144
]. Nevertheless, higher sowing quantities are published reaching up to
140 kg ha
1
[
145
] or even 170-180 kg ha
1
[
146
] corresponding to a plant density
of 3,000 plants per m
2
. In practice however the optimal stand at harvest time
reaches 1,600-1,800 plants per m
2
[
147
].
With regard to the direction of cultivation (stem, fiber/seed, oil), also the
respective type of harvest is used. The harvesting process for stem and fiber
includes several operations - stem pulling, deseeding, stretching on the field,
retting, turning, and collecting the stem. Sometimes biphasic harvest can be used,
when the stem is pulled and stretched on the field with the bolls. Just after several
days when the stem is turned and colored, the bolls are harvested. Specific machines
are used for the abovementioned operations. On the other hand, the seed harvest
requires a combine harvester. Linseed harvesting by combine has important
impacts in energy, exploitation, and economical parameters [
148
]. The four major
producers of linseed are Canada, China, the USA, and the European Union
(Table
11.6
). Casa et al. [
140
] also mentioned Argentina and India. Linseed
production is still
insufficient
to meet
the demand and the EU is a major
importer [
149
].
For seed production, there should be established rules and requirements in every
country regulating statutory distance from neighboring sources of pollen which
may result in undesirable cross-pollination. These rules include species and cate-
gory of the seeds (level of multiplication), varietal purity, and analytical purity.
Table
11.7
shows the evaluation system used in the UK [
150
]. A similar evaluation
system for seed production is used in the Czech Republic (Table
11.8
)[
151
]. As far
as the varietal purity is concerned, one plant per of other species 30 m
2
from the
variety is acceptable for basic seed production and one plant per 10 m
2
for certified
seeds C1, C2, C3 [
146
]. In the Czech system, there are three plants per 100 m
2
in
categories SE and E and 10 plants per 100 m
2
in category C [
151
].
According to Casa et al. [
140
] and Diepenbrock and Iwersen [
152
], the sowing
dose (density) is not a limiting factor of seed yield. Based on their results, the seed
yield is mainly influenced by soil and climatic conditions compared to sowing dose
which in their case was 200-800 plants per m
2
because the plants with lower plant
number have a tendency to increase the number of capsules per plant. However,
different levels of sowing doses were studied [
153
-
156
]. Currently European
growers use the optimal sowing dose of 800 plants per m
2
(unpublished results).
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