Potassium Research and Agricultural Production - The International ...

3.3. Influence 0/ K, Alg alld Ca doses all the cation contel11
The method applied, namely multiple regression analysis, appeared to be particularly
useful for Quantitative evaluation of the influence of graded concentrations of 3 kinds
of cations on their levels in plants. The results are presented in Table 4. The interaction
between K, Mg and Ca ions on the crops of sunflower and summer rape was markedly
differentiated. The significant positive influence on the crop of sunflower sterns and
aboveground mass of rape was due to potassium, while the effects of magnesium and
calcium were not uniformly evident. Potassium had a negative effect on Na content in
rape and on Mg and Ca in both plant species. Magnesium had no significant effect on
K content in plants but had a stronger influence on Ca content, which it lowered, particularly
in sunflower stems. The smaller effect was the influence of calcium on K and
Mg contents.
The influence of graded doses of K, Mg and Ca on the amounts of these cations in sunflower
and rape (according to b'j value) may be presented in the following decreasing
sequence: K, Mg, Ca. This confirms the active, selective uptake of potassium (AI-Badrawy
[I), AI-Hac/raw)', Hllssler [2}. Mellgel [21}).
The effect of the concentrations of K, Mg and Ca in the medium on the levels of these
cations and of Na did not follow a uniform trend in the various organs of sunflower
and papilionaceous plants (table 5).
An exceptionally great negative effect on Na content in leaves, stems and roots of lupin,
leaves and stems of red clover and in leaves of sunflower was exerted by potassium.
The depressing influence of potassium on Mg content was also visible, but did
not attain a significant level. Viro[27J also found an effect of K, diminishing the Mg
content of tomato lea ves and roots, but he did not report the effect to be significant.
Very regular were the negative effects of potassium and magnesium on calcium content,
expressed in relatively high b'j value. The negative reaction of calcium on Mg
content was manifested in all plants except lupin stems, but it was significant only in
the leaves and roots of sunflower. A comparison of b'j values (table 5) permits the cations
to be listed according to diminishing antagonistic activity: Na - K>Ca, Mg;
K - Mg>Ca. Mg - K>Ca. Ca - Mg>K.
The statistical analysis of the regression of cation contents of plants on their concentrations
in the medium was an attempt to gain a more profound insight into the interesting
problem of interaction of the cation contents of plants and of their environment.
3.4. Influence 0/ nitrogen/arms 011 the cation COlltellts
The form of nitrogen applied, particularly with intensive fertilization, plays a significant
role in the content and uptake of cations by plants. 11 is illustrated in Table 6.
The decrease in K content in aboveground mass and in roots occurred in all barley varieties
in stronger degree when N was applied in NH4 form, mainly as urea, than in the
form of ammonium nitrate. This finding does not differ from the results of other authors
(EhrelldorJer [5). Kirkh),. Mellgel [8}. Kirkh)' [9}) although in Kirkhy's investigations
[IOJ the decrease in cation contents in various plant species fertilized with
NH4-N, as compared with N0 3 -N, was much greater than in our investigations and
was specific for individual species. For instance rye reacted by smaller decrease in cation
content induced by NH4-N than did other plants (tomato). Different varieties
originating from distant countries as Great Britain, Germany and Poland behaved in
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