EFFECT OF POTASSIUM FERTILISATION ON THE CONTENT OF SOME
MICROELEMENTS IN POTATO TUBERS
Wyszkowski M., Ciećko Z., & Żołnowski A.
Department of Environmental Chemistry, University of Warmia and Mazury in Olsztyn,
plac Łódzki 4, 10-718 Olsztyn, Poland
Key words: potassium fertilisation, potato tuber, copper, nickel, zinc, manganese, iron
INTRODUCTION
Besides, yield quantity in potato production, the quality indices also play significant role.
Among agrotechnical practices, fertilisation seems to be most important. Mineral fertilisation usually
affect the growth and development of plants in a positive manner, but they often also affect their
biometric features and ionic balance. The changes have not always been positive. Application of high
doses of mineral fertilisers sometimes leads to disproportion in cations accumulation in some plants
organs, for example in potato tubers (PANIQUE et al. 1997, VELTHOF et al. 1996, WARMAN & HAVARD
1998, WASTERMANN & SOJKA 1996, WYSZKOWSKI 1996, WYSZKOWSKI 2001). As compared to those
analysed a century ago, current plants are poorer in magnesium, copper and cobalt and richer in
potassium, phosphorus and nitrates (MARSCHNER 1996).
The aim of the study was to determine the effect of different potassium fertilisation doses on changes
in the content of microelements in potato tubers.
MATERIALS AND METHODS
Field experiments (3-years) with polish potato cultivar Mila of a medium-length vegetative
period were carried out at Experimental Station in Tomaszkowo (near Olsztyn in north-eastern
Poland), which belongs to the University of Warmia and Mazury in Olsztyn. The experimental soil
was composed of sandy loam and had the following properties: pH in 1M KCl – 4.4-5.1; low content of
phosphorus and average content of potassium and magnesium. Forecrops of potatoes were cereals in each
season. The following potassium doses were applied, namely: 0, 66, 132, 198 and 264 kg K per .ha. In
this experiment in all objects was applied nitrogen and phosphorus fertilisation (80 kg N and 35 kg P
per ha). Nitrogen, phosphorus and potassium fertilisers were applied to the soil before planting of
potato. All experimental plots were amended with farmyard manure in the dose of 25 t ha-1. Mineral
fertilisers were introduced in soil in the following formulas: N – 46% urea, P – 46% granulated triple
superphosphate, K – 57% potassium salt. The experiment was conducted in 4 repetitions.
During the harvest in phase of full maturity, samples of the potato tubers were taken. The
samples were then cut up, dried and ground. In these samples, content of the following microelements
were analysed: copper (Cu), nickel (Ni), zinc (Zn), manganese (Mn) and iron (Fe). The content of
microelements was determined by the method of atomic absorption spectrometry (AAS).
RESULTS AND DISCUSSION
For these potatoes which are grown in good soil, with correct fertilisation, correct use of
pesticides and proper execution of any necessary actions, the ratios between elements are appropriate.
Any deviation from these conditions results in shifting the subtle ionic balance in the plants and
changes their qualitative features (WYSZKOWSKI 2001). High potassium doses caused fluctuation in the
content of microelements in potato tubers (Table 1, Figure 1). Increasing potassium doses resulted in higher
contents of copper and nickel in potato tubers. Increase of potassium doses was accompanied by largest
increase of nickel content in potato tubers. The highest increase of nickel content in the conditions of
application of 264 kg K per ha in relation to treatment without K fertilisation amounted to 30% in dry
tuber matter. Application of higher doses of potassium decreased in the average content of iron in potato
tubers. It was resulted in reduction of iron content by 32% in tuber dry matter compared to tubers from
the treatment without K fertilisation. Potassium fertilisation had not significant effect on the content of zinc
and manganese in tested plants.
Content of microelements in tubers was also related to the weather conditions in cropping year
(Table 1, Figure 1). Average and good distribution of the quantity of precipitation as well as air
temperature was friendly to vegetation period and they influenced on uptake of copper, nickel, zinc,
manganese and iron by potato tubers. Rather unfavourable pattern of the weather conditions in the
second year of experiment influenced the decrease of microelements in potato tubers compared to two
other seasons under study. During first and third seasons it was more favourable distribution of
precipitation and air temperature for potato requirements.
Table 1
Content of some microelements in potato tubers according to potassium fertilisation
(average for 3 years), in mg kg-1 d.m.
Potassium doses
in kg K per ha
Content in mg kg-1 d.m.
Cu
Ni
Zn
Mn
Fe
0
2.17
0.37
14.7
14.0
132.5
66
2.17
0.38
16.1
13.8
122.4
132
2.33
0.38
15.7
13.5
115.3
198
2.67
0.46
16.1
14.7
108.9
264
2.63
0.48
16.4
15.3
89.7
Average
2.39
0.41
15.8
14.3
113.7
r
0.925
0.919
0.792
0.756
-0.976
LSD(0,05) for K dose
0.39
0.11
n.s.
n.s.
41.5
Year of experiment
1th year
2.60
0.55
18.9
19.9
172.6
2 year
2.23
0.31
13.7
7.3
83.2
3th year
2.35
0.38
14.8
15.6
85.5
Average
2.39
0.41
15.8
14.3
113.7
nd
r – correlation coefficient,
n.s. - non-significant
The relating reports about effect of mineral fertilisation on content of microelements in plants
are not unambiguous. They show a dependence of potassium on some microelements, which may be
linked to synergism and antagonism, both of which may be modified by the potassium fertlisation. Such
a relationship as this study we were also found in previous experiment (CIECKO & WYSZKOWSKI
2001). The similar (to our experiment) pattern of relationships between NPK fertilisation and copper
content was stated by KOTOWSKA (1992). In her studies the correlation between potassium and zinc
and iron was not similar. However, the high NPKMg doses reduced the content of copper in potato, but
the concentration of manganese and zinc stayed in the norm were borders in RUSZKOWSKA et al.
(1996) experiments. DZIEKANOWSKI et al. (1992) showed that the potassium fertilisation has positive
effect on content of zinc and manganese and negative on concentration of copper in the potato tubers.
The weather conditions have significant effect on yield and chemical composition of potato (KOLBE &
STEPHAN-BECKMANN 1997a, KOLBE & STEPHAN-BECKMANN 1997b). Content of macro- and
microelements is very different throughout the vegetation period. The large differentiation in content
of iron, manganese and zinc in potato tubers in years of investigations was reflection in experiments
of GASIOR (1996) and WARMAN & HAVARD (1998).
copper (Cu)
nickel (Ni)
0.8
mg Ni kg-1 d.m.
mg Cu kg-1 d.m.
3.0
2.5
2.0
1.5
0.6
0.4
0.2
0.0
0
66
132
198
264
0
66
198
264
manganese (Mn)
25
25
20
20
mg Mn kg -1 d.m.
mg Zn kg-1 d.m.
zinc (Zn)
132
15
10
5
15
10
0
5
0
0
66
132
198
264
0
66
132
198
264
iron (Fe)
mg Fe kg-1 d.m.
250
200
1th year
150
2nd year
100
3th year
50
0
0
66
132
198
264
potassium doses in kg K per ha
Fig.1. Content of microelements in potato tubers according to potassium fertilisation and
weather conditions, in mg kg-1 d.m.
CONCLUSIONS
1. Potassium fertilisation increased average contents of copper and nickel, decreased the content of
iron and had not significant effect on the content of zinc and manganese in potato tubers.
2. Average and good distribution of the quantity of precipitation and air temperature was friendly to
vegetation period and they influenced on uptake of copper, nickel, zinc, manganese and iron by
potato tubers.
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