Effects of N and K Applications on Agronomic Characteristics of Two Iranian and Landrace Rice (Oryza sativa L.) Cultivars
Nutrition elements like nitrogen and potassium are restricting
yield performance of rice cultivars and affecting on their characteristics.
In order to consider effects of different amount of nitrogen and potassium on
yield and chemical compounds of two rice cultivars (Tarrom and Neda which are
landrace and improved Iranian genotypes, respectively), current experiment has
been undertaken in 2004 and 2005. Four levels of nitrogen fertilizer (0, 50,
100 and 150 kg N ha-1 from urea source) and four levels of potassium
fertilizer (0, 75, 150 and 225 kg K2O ha-1 from potassium
sulfate source) have been applied in a split-factorial based on randomized block
design with three replications. Nitrogen fertilizer has been applied in three
different stages of plant growth (
in tillering and
in flowering initial stages) and potassium fertilizer has also been applied
in two growth stages (½ in transplanting and ½ in shooting stages).
Results indicated that application of nitrogen has increased plant height, number
of tiller, length and width of flag leaf, length of panicle, number of grain
per panicle, grain yield, amount of dry matter, biological yield, harvest index,
leaf potassium, leaf nitrogen, 1000 grain weight and reducing percentage of
hallow grain. Also, applied potassium has positive effects on all of above mentioned
yield components except harvest index and 1000 grain yield. Neda cultivar was
better than Tarrom genotype for most of the measured traits. Interaction of
nitrogen and potassium were affected significantly on number of tiller per plant,
grain yield, amount of dry matter and biological yield in Neda cultivar and
on length of flag leaf, number of grain per panicle, grain yield, amount of
dry matter, biological yield, harvest index and 1000 grain yield in Tarrom genotype.
Rice plays the most important role for feeding of millions of Asian people,
where more than 90% of the world’s rice is grown and eaten (IRRI,
1989). Also, north of Iran as one of the main areas for producing rice
inside the country, plays a critical role for feeding Iranian consumers.
Rice is the second important crop both in crop production and in human
nutrition worldwide. One of the main problems of rice production in about
500,000 ha of northern riceland of Iran is soil deficiency for most of
macronutrients. Two of these elements are nitrogen and potassium. FAO
(2000) has predicted that the demands for rice will outstrip its production.
For overcoming this problem breeders in Asia tries severely to release
higher yielding cultivars and for further increasing rice production,
Chinese rice breeders developed rice hybrid cultivars, which claims that
they gave a 20-30% higher yield in comparison to the best high yielding
varieties (Lin and Yuan, 1980).
For higher production of yield using new hybrid cultivars, nitrogen is
one of the main parts of rice production technology and also potassium
is an important component for some of quality characteristics of rice
(Prasad and De Datta, 1979; De Datta and Craswell, 1982; Kropff et
al., 1993). The main reasons of nitrogen deficiency which is widely
reported in lowland rice growing soils worldwide (Kundu et al.,
1996; Fageria and Baligar, 1996), are loss of nitrogen through leaching,
volatilization, surface runoff and denitrification (Prakasa Rao and Prasad,
1980; Fillery et al., 1989; Buresh and De Datta, 1990; Prasad,
1998; Prasad et al., 1999; Fageria and Barbosa Filho, 2001; Kumar
and Prasad, 2004).
Generally, forms and amounts of applied fertilizers influence to a great
extent on the yield and quality of rice (Wery et al., 1988; Gunes
et al., 1995; Sidiras et al., 1999). Also, use of nitrogen
and potassium efficient genotypes is one of the critical complementary
strategies in improving rice yield and reducing cost of production. Nitrogen
and potassium efficiency should be taken into account for improving new
cultivars. Increasing high quality rice yield per unit area through use
of appropriate nitrogen and potassium management practices has become
an essential component of modern rice production technology (Fageria and
Barbosa Filho, 2001). Practice of proper management strategies like adequate
rate and timing of application and use of efficient crop genotypes, may
increase rice yield and influence cost of production, simultaneously.
The objective of present study was to evaluate yield components of rice
cultivars when receiving different amounts of nitrogen and potassium fertilizers.
MATERIALS AND METHODS
This experiment has been undertaken on field trial, on rice cultivars
Neda and Tarrom (two Iranian improved and landrace rice cultivars, respectively)
in 2004 and 2005. The farm soil contained 515 g kg–1
clay, 295 g kg–1 silt, 90 g kg–1 sand,
23.4 g kg–1 total nitrogen, 213 mg kg–1 available
potassium and 23.6 percent lime. Four levels of potassium fertilizer (0,
75, 150 and 225 kg k2 O ha–1 from potassium
sulfate source) and four levels of nitrogen fertilizer (0, 50, 100 and
150 kg N ha–1 from urea source) have been applied. Half
of the amount of potassium fertilizer was added in transplanting date
and the rest was added in shooting stage and
of the amount of nitrogen fertilizer was used in transplanting time,
was added in tillering stage and the rest was added in flowering initiation
stage. A split-factorial design with 3 replications based on a randomized
complete block design with sub-plot size of 3x4 m and plant space of 25
cm have been used and 3 seedlings were transplanted per a hill. Samples
were taken from flag leaf in heading stage to determine the amount of
leaf mineral elements. Amount of leaf potassium and nitrogen were measured
and plant height, panicle length, length and width of flag leaf, number
of tillers, number of grains per panicle, number of hollow grains, 1000
grain weight, grain yield, biological dry matter and shoot dry matter
were also determined.
To calculate grain harvest index, the grain yield at 14 humidity percent
were divided on biological dry matter which is summation of grain yield
and shoot dry matter. Nitrogen and potassium efficiency for plant height,
number of tiller, length of flag leaf, number of grain per panicle, grain
yield, shoot dry matter, biological dry matter and harvest index were
calculated using the following formulas (Fageria, 1998; Fageria and Barbosa
Nitrogen efficiency for each trait (NE) = (Nf-NU/Na)
where, Nf is the measure of corresponded trait of high level
of nitrogen fertilized plot, Nu is the measure of corresponded
trait of low level of unfertilized plot and Na is the quantity
of N applied (kg).
Nitrogen efficiency for harvest index = (NEY/NETDM)
where, NEY is the nitrogen efficiency of grain yield and NETDM
is the nitrogen efficiency of biological dry matter.
Potassium efficiency for each trait (KE) = (Kf-KU/Ka)
where, Kf is the measure of corresponded trait of high level
of potassium fertilized plot, Ku is the measure of corresponded
trait of low level of unfertilized plot and Ka is the quantity
of K2O applied (kg).
Potassium efficiency for harvest index = (KEY/KETDM)
where, KEY is the nitrogen efficiency of grain yield and KETDM
is the potassium efficiency of biological dry matter.
The statistical analyses of data were conducted by analysis of variance
and the F-test was used to determine treatment significance using MSTATC
statistical software. Duncan's multiple range test was used to compare
treatment means at 5 and 1% probability levels.
RESULTS AND DISCUSSION
Table 1 demonstrates significant and non significant
effects of N and K applications for tested rice cultivars within two years
on 14 agronomic important traits. Cultivars, nitrogen and potassium affect
significantly on all of considered traits including plant height, number
of tillers, leaf length, leaf width, panicle length, number of seeds per
panicle, grain yield, shoot dry matter, straw plus grain dry matter, harvest
index, leaf potassium contents, 1000 grain weight, leaf nitrogen contents
and percentage of hallow grain. Although the effects of these three factors
were highly significant, there was seldom significant effects for their
interaction with year or with each other. The differences among interaction
of cultivar and nitrogen were significant for all traits except K uptake
in leaf (Table 2). However, only plant height, K uptake
in leaf, hollow grain and number of tillers showed significant differences
in interaction of cultivar and potassium. Interaction of nitrogen and
potassium illustrated non significant effects for most of measured traits
except for plant height, number of grain per panicle and biological dry
matter. Finally, significant results have been achieved only for number
of tillers, shoot and biological dry matter and harvest index due to effects
of three way interactions among nitrogen, potassium and cultivar.
||Significance of F values derived from analysis of variance
of yield and yield components of two cultivars, four N and four K
|Y = Year C = Cultivar N = Nitrogen K = Potassium **
(p<0.01) * (p<0.05) ns = not significant
||Reaction of yield and yield components of rice cultivars
to different levels of N and K application
|Mean values with the different letter(s) are significantly
different, C = Cultivar, T = Tarrom, N = Neda N0 = without N N1 =
50 kg N ha–1 N2 = 100 kg N ha–1
N3 = 150 kg N ha–1 K0 = without K K1 = 75 kg K2O
ha–1 K2 = 150 kg K2O ha–1
K3 = 225 kg K2O ha–1
Nitrogen and potassium efficiency for 10 considered traits showed that
there are differences between Neda and Tarrom cultivars for both of macronutrients
(Table 3). Nitrogen efficiencies were higher than potassium
efficiencies in all of studied traits, except in width of flag leaf. These
efficiencies were not high enough for height, number of tillers, length
of flag leaf, length of panicle, number of grain per panicle and harvest
index, however, for grain yield, shoot dry matter and biological dry matter
they were high enough. Nitrogen plays an efficient role with 18.77 and
18.47 for Tarrom and Neda, respectively. However, role of potassium with
2.378 and 2.919, respectively for Tarrom and Neda seems not to be so efficient.
Similar trends have governed on N- and K-efficiencies of Tarrom and Neda
for traits shoot and biological dry matter (Table 3).
Plant height and number of tiller: Plant height and number of
tiller per plant in both cultivars were different and nitrogen and potassium
have significantly affected on these two characters. Number of tiller
per plant in Neda was greater than Tarrom. Also, interactions of cultivar
and nitrogen and cultivar and potassium on these two traits were significant.
Three way interactions of cultivar, nitrogen and potassium were significant
only on number of tiller per plant but not on plant height (Table
||Efficiency of nitrogen and potassium application in
different rice cultivars for measured traits
Cultivars Tarrom and Neda showed different trends for various levels
of nitrogen and potassium applications for the measured traits. By increasing
nitrogen level plant height increased from 67.42 to 79.38 cm and from
92.75 to 108.40 cm in Tarrom and Neda, however, increasing potassium level
increased plant height from 71.90 to 76.21 cm and from 94.67 to 104.30
cm in Tarrom and Neda, respectively (Table 2).
The efficiency of nitrogen application for plant height in Neda (0.10)
was greater than Tarrom (0.08). The same trend has governed on the efficiency
of potassium application on plant height, means that Neda with 0.050 has
used potassium fertilizer more efficient than Tarrom with 0.023 (Table
Due to nitrogen application, number of tiller per plant in Tarrom and
Neda changed from 26.88 to 31.88 and from 31.08 to 33.04 tillers per plant,
respectively (Table 2). A number of researchers have
reached into a result that application of nitrogen can increase number
of tillers in rice cultivars (Imam and Nicknejad, 1994; Fageria and Barbosa
Filho, 2001; Shen et al., 2003; Qian et al., 2004). Nevertheless,
potassium application also increased number of tillers per plant from
23.83 to 26.00 and from 26.88 to 31.17 in Tarrom and Neda, respectively
(Table 2). The result of increasing number of tillers
due to potassium application has also been supported by some other considerations
(Bansal et al., 1993; Pandey et al., 1993; Kalita et
al., 1995; Ojha et al., 2000).
Interactions of nitrogen and potassium on plant height and number of
tillers per plant showed no significant effect with the exception of significant
outcome for number of tiller per plant in Neda (Table 4).
Length and width of flag leaf and length of panicle: There were
significant variations in two studied cultivars for length and width of
flag leaf and length of panicle so that, these characteristics have been
affected by nitrogen and potassium application. Also, interaction effects
of cultivar and nitrogen on length and width of flag leaf and length of
panicle were significant (Table 1). Length of flag leaf
has significantly increased by nitrogen application from 19.63 to 29.25
cm and from 24.83 to 28.13 cm in Tarrom and Neda, respectively (Table
2). Potassium application has also changed length of flag leaf from
22.79 to 26.29 and from 25.54 to 27.88 cm in Tarrom and Neda, respectively
(Table 2). Length of panicle has been influenced by
nitrogen and potassium applications, so that; it changed from 17.88 to
27.42 and from 22.71 to 26.50 and also from 20.96 to 23.92 and from 24.08
to 26.38 cm in Tarrom and Neda by nitrogen and potassium applications,
respectively (Table 2). Bansal et al. (1993)
have also measured an increase in length of panicle because of nitrogen
The efficiency of nitrogen application for length of flag leaf in Neda
(0.02) was smaller than Tarrom (0.06). The same trend has governed on
the efficiency of potassium application on length of flag leaf, means
that Neda with 0.013 has used potassium fertilizer less efficient than
Tarrom with 0.019; however, these efficiencies were not important in width
of flag leaf in both genotypes (Table 3).
Grain number per panicle and grain yield: There were significant
differences in traits grain number per panicle and grain yield between
both of the studied cultivars. These two characters were under influence
of nitrogen and potassium applications. Interaction effects of cultivar
and nitrogen on both traits and interaction of nitrogen and potassium
on grain number per panicle were significant (Table 1).
Application of nitrogen causes an increase in grain number per panicle
from 94.23 to 130.46 in Tarrom and from 109.20 to 143.30 in Neda and in
grain yield from 3099 to 5915 kg ha–1 in Tarrom and from
3193 to 6104 kg ha–1 in Neda, respectively (Table
2). These results are in accordance with the results of Bansal et
al. (1993), Fageria and Barbosa Filho (2001), Fageria and Baligar
(2001) and Shen et al. (2003).
Application of potassium cause also an increase in grain number per
panicle from 106.29 to 116.17 in Tarrom and from 118.00 to 130.90 in Neda
and in grain yield from 4527 to 4971 kg ha–1 in Tarrom
and from 4651 to 5196 kg ha–1 in Neda, respectively (Table
2). Bansal et al. (1993), Sreemannarayana and Sairam (1993),
Pandy et al. (1993), Kalita et al. (1995), Brouhi et
al. (2000) and Ojha and Talukdar (2000) have measured an increase
in both traits using potassium fertilizer.
Nitrogen and potassium interactions on grain number per panicle and grain
yield were significant (p<0.05). Treatment N3K3 produced greatest number
of grain and grain yield in both cultivars with 136 and 137.5 grains and
6136 and 6293 kg ha–1, respectively (Table
4). Increasing in grain yield because of simultaneous application
of nitrogen and potassium has been reported by Zhan and Wang (2005).
||Interactive effect of N and K on yield and yield components
|Mean values with the different letter(s) are significantly
different, T = Tarrom, N = Neda
The efficiency of nitrogen application for length of panicle and grain
yield in Neda (0.03 and 18.47) was smaller than Tarrom (0.06 and 18.77),
respectively. The same trend has governed on the efficiency of potassium
application on grain number per panicle, means that Neda with 0.016 has
used potassium fertilizer more efficient than Tarrom with 0.012. However,
the trend in grain yield is vise versa with 2.919 and 2.378 in Neda and
Tarrom, respectively (Table 3).
Shoot and biological dry matter: There were significant differences
among cultivars for amount of shoot and biological dry matter (Straw +
Grain). Nitrogen and potassium application and interactions between cultivar
and nitrogen and among cultivar, nitrogen and potassium were significant
(p<0.01) in production of amount of shoot and biological dry matter
(Table 1). Application of nitrogen in Tarrom causes
an increase in the amount of shoot dry matter from 5035 to 6089 kg ha–1
and biological dry matter from 8130 to 12000 kg ha–1
whereas, in Neda shoot dry matter increased from 4633 to 6857 kg ha–1
and biological dry matter increased from 7908 to 12920 kg ha–1
(p<0.01). The same results were obtained from Bansal et al.
(1993), Fageria and Baligar (2001), Fageria and Barbosa Filho (2001) and
Shen et al. (2003). However, potassium increased shoot dry matter
from 5386 to 5624 kg ha–1 and biological dry matter from
9926 to 10580 kg ha–1 in Tarrom. Shoot dry matter have
been increased from 5807 to 6216 kg ha–1 and biological
dry matter from 10500 to 11420 kg ha–1 (Table
2). The outcomes were in accordance with the achievements of Brouhi
et al. (2000).
The efficiency of nitrogen application for shoot and biological dry matter
in Neda (14.83 and 32.75) was greater than Tarrom (7.03 and 25.80), respectively.
The same trend has governed on the efficiency of potassium application
on shoot and biological dry matter, means that Neda with 1.976 and 4.553
has used potassium fertilizer more efficient than Tarrom with 1.275 and
3.503, respectively (Table 3).
Simultaneous application of nitrogen and potassium had significant effects
on shoot dry matter and biological dry matter. In Tarrom, the highest
amount of shoot dry matter was obtained from treatment N2K3 (6458 kg ha–1)
and the highest amount of biological dry matter was measured by 12340
kg ha–1 in treatment N3K3. Meanwhile, in Neda, both of
the highest amount of shoot and biological dry matter were obtained from
treatment N3K2 (7022 and 13310 kg ha–1, respectively)
(Table 4). This finding was emphasized by Zhang and
Wang (2005) that interactions between nitrogen and potassium could increase
the amount of dry matter.
Harvest Index, 1000 grain weight and percentage of hollow grain:
Harvest index, 1000 grain weight and percentage of hollow grain in Tarrom
and Neda were significantly different in present experiment (Table
1). Nitrogen and potassium application and interaction of cultivar
and nitrogen had a significant effect on these traits. Harvest index was
significantly influenced by interaction of cultivar, nitrogen and potassium
and percentage of hollow grain was significantly affected by nitrogen
and potassium application, respectively. In Tarrom cultivar application
of nitrogen increases harvest index from 0.381 to 0.493 and reduces percentage
of hollow grain from 23.4 to 10.15%. Also, in Neda cultivar, harvest index
has increased from 0.409 to 0.474 and percentage of hollow grain reduced
from 7.81 to 5.98%. However, 1000 grain weight which was not influenced
by nitrogen application in Tarrom has increased from 27.65 to 28.08 g
in Neda (Table 2). Application of potassium have increased
harvest index from 0.451 to 0.464 and from 0.439 to 0.455 and reduced
percentage of hollow grain from 20.95 to 12.28% and from 8.61 to 5.35%
in both Tarrom and Neda cultivars, respectively (Table 2).
Simultaneous application of nitrogen and potassium has significantly affected
on harvest index, 1000 grain weight and percentage of hollow grain. Highest
amount of harvest index was obtained from treatment N2K2 with 0.499, highest
1000 grain weight was obtained from N3K0 treatment with 24.49 g and lowest
percentage of hollow grain was obtained from treatment N3K3 (4.62 g) in
Neda cultivar (Table 2).
The efficiency of nitrogen application for harvest index in Neda (0.56)
was smaller than Tarrom (0.73). The same trend has governed on the efficiency
of potassium application on harvest index, means that Neda with 0.64 has
used potassium fertilizer less efficient than Tarrom with 0.68 (Table
3). The efficiencies of nitrogen and potassium were ignorable for
1000 grain weight and percentage of hollow grain in both genotypes.
Leaf nitrogen and potassium: The amount of leaf nitrogen and leaf
potassium was different in both of the studied cultivars. Meanwhile, cultivar
by nitrogen and cultivar by potassium interactions showed significant
differences (Table 1). Increasing the potassium application
increased the leaf potassium contents from 1.852 to 2.083% and from 1.745
to 2.044% in Tarrom and Neda, respectively (Table 2).
Although there have been shown increasingly changes in leaf nitrogen contents
by nitrogen application, none of cultivars showed significant variation.
Also, non significant effects have been exhibited when nitrogen and potassium
were simultaneously applied (Table 2).
Nitrogen and potassium application have significantly affected on economic,
agronomic and physiological plant characteristics. Grain yield, shoot
and biological dry matter, plant height and other components of yield
are positively under influence of nitrogen or potassium application; however,
hollow grain is an exception. Efficiencies of nitrogen or potassium application
play different roles in various traits. Nitrogen or potassium may increase
grain yield, shoot and biological dry matter, number of grain per panicle,
length of panicle, length and width of flag leaf in both tested genotypes.
Neda as an improved cultivar which carries a number of agronomical important
genes showed better performance than Tarrom as a landrace cultivar. Application
of 150 kg N ha–1 with 225 kg K2O ha–1
(treatment N3K3) showed higher results in most of studied traits. Doing
experiment with more genotypes and precise levels of N and K applications
may result in more clear achievements.
Thanks from the University of Mazandaran for funding, from staffs of
Sari Agricultural Campus, Soil Science Department for their helps.
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