Evaluation of Tuber Size and Nitrogen Fertilizer on Nitrogen Uptake and Nitrate Accumulation in Potato Tuber
In order to investigate tuber size and nitrogen fertilizer
on nitrogen uptake and nitrate accumulation in potato tuber cultivar Agria,
a factorial experiment based on randomized complete block design with
three replications was carried out in Ardabil, Iran, in 2006. Factors
were nitrogen fertilizer level (0, 80, 160 and 200 kg ha-1
net nitrogen) and tuber size (<40 = small, 40-80 = medium and >80
= large, g). Results showed that the most tuber yield, No. of tuber per
plant, mean tuber weight and tuber dry weight were resulted at medium
tuber size. Also, the most tuber yield, mean tuber weight, tuber dry weight
and tuber nitrogen percent were observed at 160 kg ha-1 nitrogen.
The most nitrogen taken up in tuber and aerial parts and nitrate accumulation
in fresh and dry weight was gained at 200 kg ha-1 nitrogen
and medium size. The most important result from this study was that nitrogen
application over the favorite values, resulted in reduction of crop production
along with increasing nitrate accumulation in tubers. So, nitrogen value
of 160 kg ha-1 and medium tuber size to get the highest yield
and suitable planting and eating usages are recommended, respectively.
Potato (Solanum tuberosum L.) is an annual plant farm Solanum
genus, Solanaceae family including 200 cultivars from which 8 cultivars are
agronomical (Khajehpour, 2004). It belongs to cool and
temperate zones with altitude of 2000 m (Koocheki et al.,
1993). Potato tuber is a part of stem which have adapted for storage of
matters and reproduction of plant. In other words, it comprises of transformed
stem whose lateral buds have been gathered together named eyes (Khajehpour,
2004; Beukema and Zaag, 1990). Tuber size may be stated
as tuber diameter or weight. In most cases, it is shown as tuber weight (Beukema
and Zaag, 1990). Nitrogen is one of the most important elements for plants
and its great effete is on quality and quantity of crop. The best results can
be obtained while so- 60% of nitrogen applies at planting date and the rest,
after tubering. Uppermost values may be determined using soil and petiole nitrogen
content tests (Evanylo, 1990). Schulz
et al. (1998) reported that larger mini tubers, significantly produce
more tubers. Jenkins and Nelson (1992) found that nitrogen
increased number of large tubers per plant and this way, increased the yield
of each plant. Application of sufficient values of nitrogen in early season,
results in expanding leaf area and increasing plant capacity for photosynthesis
(Khalghani et al., 1997). Vander
Zaag et al. (1990) reported that while nitrogen application reached
to 185 kg ha-1, the highest tuber yield was gained and mean tuber
weight was higher than those of other nitrogen rates. If nitrogen values excesses
the favorite level, both mean tuber weight and No. of tuber, are decreased (Kleinhenz
and Bennet, 1992). Nitrogen deficit in early season can reduce tuber yield
reducing tubering (Joern and Vitash, 1995). Potato is
a nitrate accumulator plant. Inappropriate rates of nitrogen causes to accumulation
of this element highly in crops which usually don`t accumulate it. Carter
and Bosma (1974) measured the most tuber nitrate content at the highest
nitrogen application rate. Saffigna and Keeney (1977)
showed that with increasing nitrogen concentration at root zone, total nitrogen
content in plant tissues was increased and also shown that nitrate levels in
plant correlated with the available nitrogen for plant. Non- mineral fertilizers
in comparison with mineral ones, release nitrogen gradually for plant nutrition
but the other types, do this very rapidly and lead to increase of plant nitrate
concentration. The aim of this study was evaluating the rate of nitrogen uptake
and accumulation in potato tuber under different tuber sizes and nitrogen levels
and was determining the best values of mentioned factors in order to obtaining
high yields with the lowest nitrate accumulation of tuber.
MATERIALS AND METHODS
In order to evaluation of tuber size and nitrogen fertilizer on nitrogen uptake
and nitrate accumulation in potato tuber Agria cultivar, a factorial experiment
based on randomized complete block design was carried out with three replications
in Ardabil, Iran, in 2006. First factor was nitrogen level (0, 80, 160 and 200
kg ha-1 net nitrogen) and second was tuber size (<40 = small, 40-80
= medium and >80 = large, g). Nitrogen was of urea source and applied in two
stages, planting date and earthling up stage. Based on soil test from depth
of 0-30 cm, Total Saturated Electrical Conductivity (TSEC) was 3.68 mmhos cm-1,
soil pH was 8.09, total nitrogen was 0.56% and soil texture was loamy sand.
Rows were spaced 60 cm. Plots were included six rows each 3 m. In order to preventing
nitrogen effects in adjacent plots, they were placed 1.5 m distance. Tubers
of 60-70 g were sown in 13 May 2006. Sowing depth was 12-13 cm. Last harvest
was assigned for yield. Promoting storage capability, 10 days before harvest,
aerial parts were removed (Khajehpour, 2004). Sampling
was done from 2 m2 plot area, then, tubers were transferred to the
laboratory. Before measurements, tubers were washed along with roots and stools.
Different plant tissues were dried separately for 48 h in 75 Â°C and weighed.
Nitrate accumulation of tuber was calculated by sulfosalicylic acid method using
spectrophotometer device (Cecile, France). Calculation of nitrogen uptake rate
was made according to the Hashemidezfooli et al. (1998):
||Nutrient Element Uptake
Results were analyzed by SAS software, mean comparisons were done via
Duncan`s multiple range test and graphs were drawn by Excel software.
RESULTS AND DISCUSSION
Results showed that main effect of nitrogen except for No. of tuber,
was significant on other measured traits (p<0.01). Main effect of tuber
size, except for nitrogen uptake per plant and nitrate accumulation as
fresh and dry weight of tuber, was significant on other measured traits
(p<0.01). Also, interaction effect of tuber sizexnitrogen rate was
significant (p<0.01) on traits other than nitrogen percent of tuber
and aerial parts, nitrogen uptake by whole plant and No. of tuber.
|| Mean nitrogen taken up in aerial parts affected by
tuber size and nitrogen levels
|| Mean nitrogen taken up in tuber affected by tuber size
and nitrogen levels
|| Mean comparisons of nitrogen levels and tuber sizes
on measured traits
|*Numbers with same letter(s) in each column, have no
significant differences to each other
|| Mean nitrate accumulation in fresh weight affected
by tuber size and nitrogen levels
|| Mean nitrate accumulation in dry weight affected by
tuber size and nitrogen levels
|| Mean tuber weight affected by tuber size and nitrogen
Nitrogen Uptake and Nitrogen Percent
Medium tuber size significantly had the most nitrogen percent in tuber
and aerial parts than other sizes. With increasing nitrogen level, nitrogen
percent significantly increased as well, so, the most rates in aerial
parts belonged to 200 kg ha-1 nitrogen and in tuber, belonged
to 160 kg ha-1 nitrogen (Table 1).
Medium size significantly had the most nitrogen absorption in aerial parts
and whole plant than other sizes. With increasing nitrogen usage, nitrogen absorption
in aerial parts tuber and whole plant was increased. Among the nitrogen levels,
200 kg ha-1 nitrogen led to the most value (Table 1).
Evaluating interaction effect (Fig. l, 2)
it can be realized that the most significant effect belongs to medium sizex200
kg ha-1 nitrogen. So, it can be concluded that with increasing absorbed
nitrogen not only the increase of yield was not achieved, but also it was reduced
of course, nitrogen uptake up to 160 kg ha-1 increased yield but
more values decreased it. Probably this may as a result of inability of plant
to use more rates of applied nitrogen and hence, changing nitrogen to nitrate
and consequently more nitrate accumulation in plant and as will be described
later. Westermann et al. (1988) reported that
while nitrogen utilization was done at stage of tuber growth, nitrogen utilization
was done at stage of tuber growth, nitrogen firstly accumulated in stem and
leaves but at the maturity stage of tuber, found that with increasing nitrogen,
its uptake by tuber was increased and the most value was obtained at 200 kg
With increasing nitrogen from zero to the last level, nitrate content
in tuber dry and fresh weight significantly was increased and reached
to the digest rate.
Same results have been obtained by Joern and Vitosh (1995)
as well. In 200 kg ha-1 nitrogenxlarge tuber size, the most nitrate
accumulation was observed (Fig. 3, 4). In
all nitrogen levels, Agria cultivar has accumulated fewer nitrates in fresh
and dry weight of tuber. Also, it is clear that application of excessive values
of nitrogen, in addition to reducing yield, increased nitrate accumulation.
Yield and Yield Components
Results showed that the large and medium tuber sizes jointly caused the
most number, dry weight and yield of tuber (Table 1). Wurr
et al. (1992) and Lommen (1995) reported that
with increasing the weight of planted tuber, number of produced tubers per plant
was increased. Schulz et al. (1998) realized that
the larger planted tubers significantly produced more tubers Marknielson
and Weller (1989) reported that in increase on stem No., tuber No. and tuber
yield Beraga and Caeser (1990) and Kleinhenz
and Bennet (1992) indicated that nitrogen affecting on large tuber No. increased
yield. With application of nitrogen up to 160 kg ha-1, dry weight,
mean weight and tuber yield was increased and then, was decreased (Table
1). This may attributed to over expanding of aerial parts as a result of
improper nitrogen values application (over the 160 kg ha-1 nitrogen)
and consequently, increase of intra-competition of plant to gain environmental
sources such as water and minerals which caused the significant decrease in
yield and yield components at 200 kg ha-1 nitrogen. It seems that
over-usage of nitrogen may highly expand the stems and leaves, thus, tubering
is delayed and so, yield reduction and low tuber quality is occurred.
|| Mean tuber dry weight affected by tuber size and nitrogen
|| Mean tuber yield affected by tuber size and nitrogen
Medium tuber sizex160 kg ha-1 nitrogen was led to the most dry weight,
mean weight and tuber yield (Fig. 5, 6,
7). Lommen (1995) reported that with
increasing tuber size, tuber dry weight was increased, as well.
Mollerhagen (1993) and Osaki et
al. (1995) confirm these results. Applied nitrogen less affects No.
of tuber but its most effect is on tuber size (Struik et
al., 1990). But if nitrogen rates pass the favorite values, both mean
tuber weight and No. of tuber were decreased (Kleinhenz and
Bennet, 1992). Lommen (1995) reported that small tubers
caused lower yields large tubers resulted higher yields.
It observed that the most nitrate content in dry and fresh weight of
tuber was obtained at 200 kg ha-1 nitrogenxlarge tuber size
and the highest tuber yield was achieved at 160 kg ha-1 nitrogenxmedium
tuber size. Nitrate accumulation at 160 kg ha-1 nitrogen was
measured of 298.03 mg kg-1 tuber dry weight and 128.43 mg kg-1
tuber fresh weight. In this level, nitrate content in fresh and dry weight
of tuber, was lower than critical level so, application of 160 kg ha-1
nitrogen, to obtain the most tuber yield and the least nitrate accumulation
for Agria cultivar in Ardabil, Iran, is recommended. Referring to mean
tuber yield in Ardabil region of 28.7 t ha-1 and its comparison
with the yield resulted in this study, it can be said that this recommendation,
is beneficial. Also, it is suitable for edible and planting usages.
This research was supported by the Central Laboratory of Agricultural
Faculty, University of Mohaghegh Ardabili. Valuable experimental support
by Aziz Jamaati-e-Somarin is greatly appreciated. This study was extracted
from M.Sc. Thesis of Mahmoodreza Saeidi.
Beraga, L. and K. Caeser, 1990.
Relationships between number of main stems and yield components of potato (Solanum tuberesom
L. cv. erntestolz) as influenced by different day length. Potato Res., 33: 257-267.CrossRef | Direct Link |
Carter, J.N. and S.M. Bosma, 1974.
Effect of fertilizer and irrigation on nitrate, nitrogen and total nitrogen in potato tubers. Argon. J., 66: 263-266.Direct Link |
Beukema, H.P. and D.E. Van-der -Zaag, 1992.
Introduction to potato production. Pudoc, Netherlands, pp: 208.
Evanylo, G.K., 1990.
Rate and timing of nitrogen fertilizer for white potatoes in Virginia. Am. Potato J., 66: 461-470.CrossRef |
Hashemidezfooli, A., A. Koocheki and M. Banayanavval, 1998.
Crop Plant Inprovement Translation. 3rd Edon., Jehad Daneshghahi Mashad press, Mashad, Iran
Jenkins, P.D. and D.G. Nelson, 1992.
Aspects of nitrogen fertilizer rate on tuber dry-matter content of potato cv. Record. Potato Res., 35: 127-132.CrossRef |
Joern, B.C. and M.L. Vitosh, 1995.
Influence of applied nitrogen on potato. Part I: Yield, quality and nitrogen uptake. Am. Potato J., 72: 51-63.CrossRef | Direct Link |
Khajehpour, M., 2004.
Industrial Crops Production Jahad Daneshgahi Isfahan. Isfahan University Press, Iran, pp: 201-225
Khalghani, J., F. Rahimzadeh Khoei, M. Moghaddam and H.R. Mashadi, 1997.
Growth analysis of potato under different levels of nitrogen and plant density. Agron. Sci. J., 7: 58-58.
Kleinhenz, M.D. and M.A. Bennet, 1992.
Growth and yield of potato (Solanum tuberosum
L.) cultivars Atlantic and Monona as influenced by seed type and size. Am. Potato J., 69: 117-129.CrossRef | Direct Link |
Koocheki, A., M. Hosseini and M. Nassiri, 1993.
Relationship Between Water and Soil in Crop Plants Translation Jahad Daneshgahi Mashad. 1st Edn., Mashad University Press, Iran
Lommen, W.J.M., 1995.
Basic studies on the production and performance of potato minitubers. WAU Dissertation No. 1912, Record No. 291479. http://library.wur.nl/WebQuery/wurpubs/lang/28235.
Marknielson, W.M.I. and L.D. Weller, 1989.
Potato seed productivity: Factor influencing eye number per seed piece and subsequent performance. Am. Potato J., 66: 151-160.CrossRef | Direct Link |
Mollerhagen, P.J., 1993.
The influence of nitrogen fertilizer application on tuber yield and quality in three potato varieties grown at different locations in Norway. Norsk Landbruksforskk., 7: 279-296.
Osaki, M., H. Ueda, T. Shinano, H. Matsui and T. Tadano, 1995.
Accumulation of carbon and nitrogen compounds in sweet potato plants grown under deficiency of N, P, or K nutrients. Soil Sci. Plant Nutr., 41: 557-566.Direct Link |
Saffigna, P.G. and D.R. Keeney, 1977.
Nitrogen and chloride uptake by irrigated russet Burbank potatoes. Argon. J., 69: 258-264.CrossRef | Direct Link |
Schulz, S., G.J. Wells, B.K. Bania, T.P. Barakoti and G. Kharel et al
Decentralized on-farm seed potato production from pre-basic minitubers: A case study from Nepal. Exp. Agric., l34: 487-495.CrossRef |
Struik, P.C., A.J. Havercort, D. Vreugdenhil, C.B. Bus and R. Dankerts, 1990.
Manipulation of tuber size distribution of potato crop. Potato Res., 33: 417-432.CrossRef |
Vander zaag, P., A.L. Demgnate and E.E. Ewing, 1990.
Influence of plant spacing on potato (Solanum tuberosum
L.) morphology, growth and yield under two contrasting enviroments. Potato Res., 33: 313-323.CrossRef | Direct Link |
Westermann, D.T., G.E. Kleinkopf and L.K. Porter, 1988.
Nitrogen fertilizer efficiency on potatoes. Am. J. Potato. Res., 65: 377-386.CrossRef | Direct Link |
Wurr, D.C.E., J.R. Fellows and E.J. Allen, 1992.
Determination of optimum tuber planting density in the potato varieties Pentland Squire, Cara, Estima, Maris Piper and King Edward. J. Agric. Sci., 119: 35-44.CrossRef | Direct Link |