Agriculture Reference
In-Depth Information
are iron, boron, manganese, copper, zinc,
molybdenum and chlorine.
Where the uptake of trace elements is
inadequate, deficiency will result in disease.
This can manifest in different ways according
to the element concerned. In general, though,
foliage is affected and may appear deformed,
discoloured, necrotic or weak. Mineral defi-
ciencies may be due to a deficiency in the soil
(true deficiency) or to a block of the element in
question by an antagonistic factor. Such factors
typically interfere with the absorption of the
element by the plant.
The effect of deficiencies is often hard to
detect as it is easily mistaken for a lack of
nitrogen: producing a yellowing of the leaves
and a shortening of the internode distance.
We have no experimental data on the pre-
cise trace element requirements of hemp. We
know only that these three minerals - Cu, Zn
and B - are represented equally throughout the
plant and that their concentrations vary little
over time.
5.2.4 Physical and chemical
characteristics of hemp
and hemp seed
An analysis of the chemical composition of
each of the component parts of hemp is pro-
vided by B. Kurek, of INRA, in Part II of
Chapter 3 of this topic.
5.3 Varieties
The varieties of hemp tested in France by the
FNPC and the FDGEDA of l'Aube, Saône
and Loiret are presented in Tables 5.3, 5.4
and 5.5.
The best hurd yields are obtained from the
late developing varieties, the poorest from the
early varieties. This is due to the growth cycle
of hemp and the fact that vegetative growth
stops at the point of full flowering. The oppo-
site is true where seed yields are concerned.
The fibre content varies slightly according to
the variety but does not appear to be related to
maturity, even if fibre content is higher in the
late developing varieties.
Among the varieties tested over a 12-year
period:
Manganese (MgO)
Manganese levels increase during the growth
cycle in all parts of the plant. Its absence can give
rise to chlorosis and deformity in the leaves.
Table 5.3.
Average yields over a 12-year period for the hemp varieties tested by the FNPC between
1990 and 2001 (non-exhaustive list).
FNCP 2002
Maturity
Hurd yield (t/ha)
Fibre content (%)
Seed yield (ql/ha)
F12
Early maturing
9.06
43.18
12.79
F17
Early maturing
9.06
45.27
12.77
Béniko
Early maturing
9.26
46.93
9.90
S27
Average
9.32
52.60
6.075
F34
Average
9.62
51.88
11.55
Bialobzrsekie
Early maturing
9.81
60.09
8.50
Kompolti
Late maturing
8.94
36.73
Cannakomp
Late maturing
9.51
44.23
E68
Late maturing
9.74
34.25
D405
Late maturing
10.28
35.30
Ilosa
Late maturing
10.37
37.35
F75
Late maturing
10.45
42.61
Carmagnola
Very late maturing
10.87
35.76
Lipko
11.38
49.35
Fibranova
11.38
45.67
D88
Very late maturing
12.29
46.23
