Agriculture Reference
In-Depth Information
precrop must suppressed the weeds. Buckwheat, sown as crop, cover crops or for green
manure, may produce allelophatic substances that could inhibit weeds [51] and also follows
crop in rotation.
2.3. Crop management
Species and varieties selection
In common buckwheat exist more than 4500 different varieties and land race populations, but
in every climate special attention should be given to choosing appropriate cultivars, because
of different photoperiodical reactions.
From more than 60 wild species of genus
Amaranthus
, four of them were selected like grain
amaranths. They are different among each others in germination [42], growth, habitus,
inflorescence, ripening and seed colour [53].
The genus
Chenopodium
consists of 150 species, classified into 16 sections. Few plants from
section
Chenopodium
are used for human consumption. Quinoa is the most important species
from genus
Chenopodium
. In the first stage, cultivated genotypes originated from 6 ecotypes
and 4 plant populations from different regions [36]. Also in amaranths and quinoa introduction
of new cultivars must based on previous analyses of trials results in every new climate.
Fertilization
Pseudocereals requirements for nutrients need vary from low to very high. Organic fertilizers
that are left over from the preceding crop or given stable manure in autumn provide adequate
yielding in the organic production system. Modest available level of nutrients results in low
yields, except in case of some heavy metals in amaranths (important remediate plant), and Ca-
bound phosphorus in buckwheat, which efficiency might be influenced by acidify of the
rhizosphere [54] compared to spring wheat. In buckwheat in case of more than 20 g NO
3
-N
kg
-1
dry soil to the depth of 0.3 m fertilization with nitrogen manure is not allowed, due to
possible lodging problems; it should instead be used for the previous crop in the crop rotation
[36]. Although amaranth yield is responsive to available nitrogen in the soil like maize, but a
high level of available nitrogen can negatively affect grain harvest in terms of increased
lodging, and delayed crop maturity [55]. Nitrogen application up to an Nmin target value of
140kg N ha
-1
raised protein concentration in grain of amaranths, and maintained the content
of essential amino acids in protein. Essential amino acids in grain fertilized to the target value
140 kg N ha
-1
was higher (397 g kg
-1
) than the standard requirement for preschool children (339
g kg
-1
). Among essential amino acids, only valine concentration responded to nitrogen supply.
Leucine was the limiting amino acid in grain protein [56, 57]. In quinoa, compensation is
suggested by organic fertilizers at an application rate of about 120 kg of N ha
-1
[58] for the
expected enhancement of grain yield.
Sowing
Buckwheat is often sown as stubble crop, amaranths and quinoa are main crops. Different
sowing methods, including sowing rates variy among buckwheat (mainly suggested 200 - 300;
row spacing is from 12.5 to 25 cm, sowing depth is about 2-3 cm, sowing rate is 1,0 1,5 mil.
