Effect of liquid urea ammonium nitrate application at varying depths on root and shoot growth in wheat (Triticum aestivum)

Abstract

An experiment was conducted to optimise the desired concentration of urea ammonium nitrate (UAN), a liquid fertilizer, and its suitable depth of application in wheat (Triticum aestivum L.) during 2016-17 in a completely randomized factorial design. The wheat seed germination was affected both on blotting paper and in soil mixed with different UAN:water dilutions. Viability test showed that when soil was mixed with UAN:water dilution ratio of less than 1:20, all the embryos were destroyed. The cultivar HD 2967 was grown in cylindrical poly vinyl chloride tubes where two different dilution ratio of UAN:water, viz. 1:5 (U1) and 1:10 (U2) were used as fertilizer @120 N kg/ha. The fertilizer was placed at three depths below the seed, i.e. at 1 (D1), 2 (D2) and 3 cm (D3).The shoot and root growth parameters up to 34 days after sowing were recorded. Both fertilizer concentration and depth of its placement significantly affected plant height, root length, root surface area and root tips at 8, 20 and 34 DAS. At higher concentration of UAN (U1), the root growth significantly reduced by about 43% as that of U2after 8 DAS. However, after 34 DAS, it was reduced to16% which shows that the plants were able to overcome the initial shock given by high concentration of UAN. Root surface area was maximum at U2D3(7.04, 18.26 and 40.89 cm²) and minimum at U1D1(0.91, 7.46 and 15.24 cm²) after 8, 20 and 34 DAS, respectively. Root tip numbers were also affected at 8 DAS. However, it was non-significantly affected by concentration and depths at 34 DAS. Deep placement of fertilizer at 3 cm showed significantly better growth of both root and shoot in plants. Higher fresh root weight at all the growth stages was observed in D3, which was at par to D2at 8 DAS. Similarly, highest root and shoot growth were observed at U2D2which was statistically at par to U1D3. The UAN may be applied in 1:10 dilution ratio at 2 cm depth or 1:5 dilution ratio at 3 cm depth below the seed in order to get better growth of seedlings. Hence, sowing machines for wheat shall be developed keeping in mind these application depths of liquid UAN.

Full text

24
Indian Journal of Agricultural Sciences 87 (10): 1288–94, October 2017/Article
Effect of liquid urea ammonium nitrate application at varying depths
on root and shoot growth in wheat (Triticum aestivum)
PREM K SUNDARAM1, INDRA MANI2, ADARSH KUMAR3, SATISH D LANDE4, SUSHEEL K SARKAR5,
K M MANJAIYA6, R N SAHOO7 and SANDEEP K LAL8
ICAR-Indian Agricultural Research Institute, New Delhi 110 012
Received: 03 May 2017; Accepted: 05 June 2017
ABSTRACT
An experiment was conducted to optimise the desired concentration of urea ammonium nitrate (UAN), a liquid
fertilizer, and its suitable depth of application in wheat (Triticum aestivum L.) during 2016-17 in a completely
randomized factorial design. The wheat seed germination was affected both on blotting paper and in soil mixed with
different UAN:water dilutions. Viability test showed that when soil was mixed with UAN:water dilution ratio of
less than 1:20, all the embryos were destroyed. The cultivar HD 2967 was grown in cylindrical poly vinyl chloride
tubes where two different dilution ratio of UAN:water, viz. 1:5 (U1) and 1:10 (U2) were used as fertilizer @ 120
N kg/ha. The fertilizer was placed at three depths below the seed, i.e. at 1 (D1), 2 (D2) and 3 cm (D3).The shoot
and root growth parameters up to 34 days after sowing were recorded. Both fertilizer concentration and depth of its
placement signicantly affected plant height, root length, root surface area and root tips at 8, 20 and 34 DAS. At higher
concentration of UAN (U1), the root growth signicantly reduced by about 43% as that of U2 after 8 DAS. However,
after 34 DAS, it was reduced to16% which shows that the plants were able to overcome the initial shock given by
high concentration of UAN. Root surface area was maximum at U2D3 (7.04, 18.26 and 40.89 cm2) and minimum at
U1D1 (0.91, 7.46 and 15.24 cm2) after 8, 20 and 34 DAS, respectively. Root tip numbers were also affected at 8 DAS.
However, it was non-signicantly affected by concentration and depths at 34 DAS. Deep placement of fertilizer at
3 cm showed signicantly better growth of both root and shoot in plants. Higher fresh root weight at all the growth
stages was observed in D3, which was at par to D2 at 8 DAS. Similarly, highest root and shoot growth were observed
at U2D2 which was statistically at par to U1D3. The UAN may be applied in 1:10 dilution ratio at 2 cm depth or 1:5
dilution ratio at 3 cm depth below the seed in order to get better growth of seedlings. Hence, sowing machines for
wheat shall be developed keeping in mind these application depths of liquid UAN.
Key words: Placement depth, Root and shoot growth, Urea ammonium nitrate, Wheat
1Ph D Scholar (e mail: prem.k.sundaram@gmail.com),2Head
(e mail: maniindra99@gmail.com), 3Principal Scientist (e mail:
adarsh_iari@rediffmail.com), 4Scientist (e mail: satishiari@gmail.
com), Division of Agricultural Engineering; 6Principal Scientist
(e mail: manjaiah@iari.res.in), Division of Soil Science and
Agricultural Chemistry, 7Senior Scientist (e mail: rnsahoo.iari@
gmail.com), Division of Agriculture Physics, 8Principal Scientist,
Division of Seed Science and Technology (e mail: sandeeplal@iari.
res.in), ICAR-IARI, New Delhi; 5Scientist (e mail: susheel@iasri.
res.in), ICAR-IASRI, New Delhi.
Nitrogen management is a crucial component for
sustainable crop production. Granular fertilizers are widely
used in crop production. However, Urea has a major
disadvantage in terms of losses of N through volatilization,
if it is not incorporated into soil soon after application
(Chen et al. 2008).
Rochette et al. (2009) reported that broadcast Urea
lost the greatest proportion of applied nitrogen (64%)
followed by banded (2 cm) urea (31%). Liquid fertilizers
have relatively more fertiliser effectiveness as compared
with granular ones (Holloway et al. 2001). Urea ammonium
nitrate (UAN) is a solution of urea [CO(NH2)2] and
ammonium nitrate [NH4NO3] containing about 28-32%
N. Nitrogen uptake in point injection method of fertilizer
placement was found better than the broadcast method
(Blackshaw et al. 2002). UAN can be injected into the soil
beneath the surface, sprayed onto plant leaves as a source
of foliar nutrition and can be added to irrigation water
for fertigation. Liquid UAN solution is becoming popular
because of its versatility, viz. convenience to mix with other
nutrients and agriculture chemicals, safe to handle and can be
evenly applied in eld. UAN is the most efcient N source
as compared with calcium ammonium nitrate (CAN) and
anhydrous ammonium (AA), as it provides the greatest crop
response and greatest inorganic soil availability (Gagnon
and Ziadi 2010). Fluid fertilizers can be blended to precisely
meet the specic needs of a soil or crop (IPNI 2017).
For the seedling establishment of wheat, a sowing
depth of 2-6 cm is recommended (Hadjichristodoulou et

1289October 2017]
25
the Petri dish was covered with a lid and kept in the dark
for 7 days in an incubator maintained at 20 ± 1°C.
Tetrazolium (TZ) test is a biochemical test to rapidly
estimate seed viability and alternative quick method for
seed’s germination potential (ISTA 2015). It is based on
the change in colour of living tissues in the presence of
a tetrazolium salt solution. This change in colour reects
the activity of specic enzyme systems, closely related to
seed viability (Carvalho et al. 2013). Four replicates of 25
seeds each per lot were taken from the petri dishes after
the above germination test was over. Seeds were bisected
longitudinally through the midsection of the embryonic axis
and then placed in beakers covered (15 ml) with a 0.075%
2, 3, 5 tri-phenyl tetrazolium chloride solution and incubated
at 40°C for 3 h (Santos et al. 2007).
Wheat cultivar (HD 2967) were grown in cylindrical
poly vinyl chloride (PVC) pots (150 mm high, 54 mm
diameter). Each pot contained 420 g of dry soil, which had
been passed through a 5 mm sieve and packed in 20 mm
thick layers to achieve a uniform bulk density of 1.3 g/
cc. The packing was done with a small piston of diameter
50 mm. Two different solutions of UAN:water in the ratio
1:5 (U1) and 1:10 (U2) were used as fertilizer doses (120
N kg/ha), which were placed at three different depths from
seed i.e. at a depth of 1 (D1), 2 (D2) and 3 cm (D3). The
ratios of 1:5 and 1:10 were chosen, as it would be easy for
a farmer to mix water with UAN in the fertilizer tank of
seed drill during sowing operation. Two seeds were planted
at a depth of 3 cm. The initial moisture content of the soil
was 11±0.55% (db).
The length of the shoot was measured daily from
the time of emergence. Plants were used for destructive
measurements from each replication on days 8, 20 and 34
after emergence. The shoots were cut from the roots after
removing and washing the loose soil. The fresh weights
of the two fractions, roots and shoots were immediately
measured. The dry weight of roots was also measured after
oven-drying for 48 hr at 40°C. The root length, root surface
area, no. of root tips of each plant were measured with an
image-analysis system (Win-RHIZO); at Water Technology
Centre, IARI, New Delhi. RHIZO system measured the
root length by scanning the length of the root skeleton.
Measurements of root morphological characteristics were
based on Regent's non-statistical method with overlap
compensation (Arsenault et al. 1995, Aggarwal et al. 2006).
Plants with a high SRL value have more root length for a
given dry-mass and are considered to have higher rates of
nutrient and water uptake (per dry mass). Most interactions
between plant and soil take place at root-soil interface
(Jozefaciuk and Lukowska 2013), meaning more interaction
with more surface area of roots.
Specic root length (SRL) and specic root surface area
(SRA) are indicators of efciency of plant nutrient uptake.
Roots with a small radius have a higher specic root length
(Eissenstat 1992). Plants with a high specic root length are
more competitive for below ground nutrients than plants
with a low specic root length (Eissenstat and Caldwell
al. 1977). It is necessary to place liquid fertilizer at such
a depth which will give better seed germination without
damaging the seeds as well as easy availability of nutrients
to the primary and secondary roots. During designing of
liquid fertilizer seed drill, it is very important to maintain
a vertical gap between seed and liquid fertilizer so that
toxicity have no adverse effect on seed germination, seedling
growth and early plant growth. Bremner and Krogmeier
(1989) reported the adverse effect of urea fertilizers on
seed germination, seedling growth, and early plant growth
in soil. Also, Ammonium at a high concentration inhibits
primary root development (Liu et al. 2013). However, no
such study has been conducted on the effect of UAN solution
on germination and early root growth. Hence, an experiment
was designed to assess the effect of UAN fertilizer on seed
germination and early seedling growth of wheat (Triticum
aestivum L.) seed.
MATERIALS AND METHODS
Two different experiments were conducted to evaluate
the effect of UAN solution mixed with water in different
ratios on the germination as well as early seedling growth
of wheat seed. UAN (28%, w/w) solutions were provided
by National Fertilizer Ltd, Nangal Unit, Punjab. UAN 28
is a clear transparent liquid with a specic gravity of 1.25
(Bijarniya 2016). HD 2967 wheat variety was used in these
studies. The soil used in both the experiments was sandy
loam having pH 7.5 obtained from the experimental farm
of Division of Agricultural Engineering, IARI, New Delhi.
The seed germination percentage was determined
using between the papers in which four replications of
100 seeds were placed in petriplate method (ISTA 2015).
The petriplates were placed in germinator at 20 ± 1°C. The
number of normal, abnormal seedlings and dead seeds were
calculated after 12 days. Seed germination percentage of
wheat variety was calculated on the basis of normal seedling
by following formula:
Per cent germination = No. of germinated seed × 100
Total no. of seed
Seed was germinated with different dilution ratios of
UAN by two methods:
Germination on blotting paper: Three layers of blotting
paper were placed in a Petri-dish of 100 mm diameter.
Four replications of 25 seeds were used for each lot, and
placed on the paper; the Petri dish was covered with a lid
and kept in the dark in an incubator maintained at 20 ±
1°C. Different UAN water dilution ratios (1:0, 1:1, 1:5,
1:10, 1:15, 1:20, 1:25 and 1:30) were used for moistening
of the blotting paper.
Germination with soil: Bremner and Krogmeier (1989)
advised a method for nding out seed germination using
soil. Air-dried soil (40 g) was placed in a 15 mm × 100 mm
Petri dish and moistened with 10 ml of water containing the
UAN solutions. Different UAN water ratio used were 1:0,
1:1, 1:5, 1:10, 1:15, 1:20, 1:25 and 1:30. Four replications
of 25 seeds were used for each lot, and placed on the soil;
EFFECT OF LIQUID UREA AMMONIUM NITRATE ON WHEAT

1290 [Indian Journal of Agricultural Sciences 87 (10)SUNDARAM ET AL.
26
1989). Specic root length and specic root surface area
were calculated as follows (Saidi 2010)
SRL=RL/RW
SRA=RA/RW
where, SRL, specic root length; SRA, specic root surface
area; RL, root length; RA, root surface area and RW, dry
weight of roots.
The data thus obtained on various shoot and root
parameters of wheat were analysed to decipher the treatments
main and interaction effects using SAS 9.3 software in
factorial completely randomized design using general linear
model. The Tukey’s Honest Signicant test was used to
decipher the treatment effects with probability levels.
RESULTS AND DISCUSSION
The initial germination percentage of wheat var. HD
2967 was 99.67%. The effect of urea ammonium nitrate on
seed germination and different parameters of plant growth
are discussed below.
Effect of UAN on seed germination and its viability
Seed germination was affected both on blotting paper
and in soil. There was no germination of seed even when
the water level was increased upto 30 times (Table 1).
However, coleoptiles emerged in soil in 1:30 (UAN:water),
but it became brown, scorched and there was no growth
thereafter. This may be due to toxicity of ammonia ion
released from UAN which is harmful for germinating seeds
both due to the increased osmotic potential of the solution
and through direct ammonia toxicity. The germination of
wheat seed is affected if they are in contact with UAN
solution. Cooke (1962) got similar scorched root tips while
studying the toxic effect of urea on maize plant roots. Hence
proper care must be taken so that both seed and fertilizer
doesn’t come in contact with each other while designing
the sowing equipment.
Seeds picked from blotting paper of each treatment
were non viable during Tetrazolium test, meaning that the
direct contact with UAN solution has killed the embryo of
the seeds. However, the seed lots taken from soil showed
some viable seeds which are presented in Table 2.
To facilitate proper germination of wheat seeds, the
UAN:water dilution ratio should not be less than 1:30.
Here the seed was in contact with the soil and UAN:water
mixture. However, during sowing in eld with the help of
fertilizer applicator, space between seed and liquid fertilizer
need to be maintained so that UAN does not come in direct
contact of seeds. While designing a fertilizer applicator,
water should be mixed as little as possible so that the
applicator acreage is maximum in a single lling of tank.
Application of UAN:water in ratio of 1:30 will require
frequent relling of fertilizer tank in eld. Hence a lesser
ratio should be preferred. Dilution ratio of 1:5 and 1:10
(UAN:water) was selected for further studies as its pumping
is easy than pure UAN.
Effect of UAN concentration and application depth on root
growth parameters
Seedlings emerged uniformly across all treatments
within 5 days, except in pots containing UAN:water (1:5)
and placed at a depth of 1 cm; where it was delayed by
1-2 days.
Root length of wheat seedlings showed signicant
difference of UAN concentration at all the three (8, 20
and 34 DAS) stages. At lower concentration of UAN, i.e.
U1(1:5), the root growth signicantly reduced by about
43% as compared to U2 (1:10) after 8 days (Table 3). The
higher concentration of UAN had a detrimental effect on
the root growth. However, after 34 DAS, the root length
of wheat seedling in U1 (1:5) reduced only by 16% as
compared to U2 (1:10). This suggests that wheat roots
were able to overcome the initial metabolic shock due to
higher concentration of urea ammonium nitrate solution.
This is in accordance with Liu et al. (2013), Britto and
Kronzucker (2002) who concluded that ammonium at a high
concentration usually inhibits primary root development.
Deep placement (D3) of UAN resulted in signicantly higher
root length at all the growth stages over D1 and D2. The
greater depth placement might have caused lesser shock to
the roots of wheat seedling due to lateral contact of roots
with placed fertilizer. Xiaobin et al. (1995) concluded that
excess concentrations of ammonium ion (NH4+) from Urea
can produce seedling damage, due to osmotic stress and
direct ammonia toxicity. However, no seedling damage was
observed during these experiments, but the root growth of
Table 1 Germination behaviour of wheat seed with different
UAN:water solution
Treatment
(UAN:water ratio)
Germination % after seven days
Blotting paper Soil
1:0 No germination No germination
1:1 No germination No germination
1:5 No germination No germination
1:10 No germination No germination
1:15 No germination No germination
1:20 No germination No germination
1:25 No germination No germination
1:30 No germination Scorched Coleoptile
and thereafter no
growth was noticed
Control (only water) 98% 92%
Table 2 Viability (%) determined by the tetrazolium test
performed on four lots of wheat seeds on soil
Seed lot Seed viability (%)
UAN:water
1:0 1:1 1:5 1:10 1:15 1:20 1:25 1:30
1 0 0 0 0 0 28 76 88
2 0 0 0 0 0 36 80 80
3 0 0 0 0 0 24 76 92
4 0 0 0 0 0 28 80 92

1291October 2017]
at par with D2 after 20 DAS. The greater depth placement
might have resulted in lesser shock to the wheat seedling
due to lesser contact of roots with deep placed fertilizer.
Effect of UAN concentration and application depth on root
surface area, no. of tips, SRL and SRA
Surface area of roots of wheat seedlings were found
signicantly affected by UAN concentration as well as
its application at different depths at all the growth stages.
Roots had more surface area at U2 (1:10) than U1 (1:5)
concentration at all the growth stages (Table 5). Higher
concentration of UAN signicantly affected root surface
area even after 34 DAS. Deep placement of the fertilizer
facilitated more root length, thereby increasing its surface
area. Root surface area increased signicantly as the
depth of placement was increased from D1 to D3 after
8, 20 and 34 DAS. Interaction effect of depth with UAN
concentration was also found signicant. Root surface area
was maximum in U2D3 (7.04, 18.26 and 40.89 cm2) and
minimum in U1D1 (0.91, 7.46 and 15.24 cm2) after 8, 20
and 34 DAS, respectively (Table 5). Number of root tips
depicts the growth and efciency of rooting system. Its
number decreased signicantly as the concentration of UAN
increased from U2 (1:10) (241.5) to U1 (1:5) (197.2) after 8
days. However, after 34 DAS, the numbers of tips were at
par at both the dilution level of UAN (Table 5). This may
be due to reduced effect of UAN after a certain interval of
time. Similarly, shallow placement of UAN mixture had a
wheat was hampered signicantly. There was a signicant
interaction between UAN concentration and its application
at different depth (Table 3). Root growth was maximum in
U2D3 and was minimum in U1D1 at all the three growth
stages. Similar trends were also seen with root fresh weight
and root dry weight.
Placement depths signicantly affected the fresh root
weight as well as root dry weight at all the growth stages.
However, at initial stage (8 DAS), they were not affected
by placement depth of 2 and 3 cm. Deep placement (D3)
of UAN resulted in signicantly higher fresh root weight
as well as root dry weight at all the growth stages over D1
(Table 3). Interaction effect of depth with UAN concentration
was also found signicant where U1D3 at 8 and 34 DAS;
and U2D3 gave maximum root dry weight and lowest was
observed in U1D1 at all the growth stages (Table 3).
Effect of UAN concentration and application depth on
plant height and fresh shoot weight
Signicant differences was observed at 34 days due
to UAN concentration where U2 gave higher (9%) plant
height compared to U1 (Table 4), though it was statistically
non-signicant at 8 and 20 DAS. It showed that initial plant
vigour can sustain injuries caused by higher concentration
but at later stage plant growth was affected due to
initial metabolic shock. Deep placement (D3) of UAN
concentration resulted in signicantly higher plant height
at all the growth stages over D1 and D2. However, it was
EFFECT OF LIQUID UREA AMMONIUM NITRATE ON WHEAT
27
Table 3 Root length and weight in wheat as affected by application of different UAN concentrations at varying depths
Treatment Root length (cm) Root fresh weight (g) Root dry weight (g)
8 DAS 20 DAS 34 DAS 8 DAS 20 DAS 34 DAS 8 DAS 20 DAS 34 DAS
UAN:Water
U1=1:5 26.9b121.4b250.8b104.9b183.7b229.4b21.7b36.7b46.4b
U2=1:10 38.1a135.7a291.1a122.9a201.7a249.9a24.9a40.7a49.6a
P-value <.0001 <.0001 <.0001 0.0046 0.0027 0.0040 0.0099 0.0038 0.0145
HSD 1.40 2.45 4.46 11.94 11.10 13.27 2.40 2.59 2.49
Depth of application
D1=1cm 10.3c78.8c151.2c89.6b159.2c199.1c18.6b32.2c39.8c
D2=2 cm 24.4b130.0b280.6b122.1a195.6b229.1b24.9a38.9b45.9b
D3=3 cm 62.8a177.0a381.2a130.0a223.4a290.7a26.4a45.1a58.3a
P-value <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001
HSD 2.08 3.63 6.61 17.69 16.45 19.66 3.55 3.83 3.69
UAN:Water × Depth
U1D15.99 74.68 141.21 61.40 147.80 180.40 13.44 29.76 36.32
U1D217.38 127.60 251.62 121.60 192.00 209.60 24.48 37.58 42.84
U1D357.32 162.06 359.66 131.60 211.40 298.20 27.08 42.84 60.02
U2D114.62 82.98 161.10 117.80 170.60 217.80 23.76 34.68 43.22
U2D231.43 132.30 309.52 122.60 199.18 248.60 25.34 40.20 48.98
U2D368.26 191.87 402.68 128.40 235.40 283.20 25.66 47.36 56.52
P-value 0.0121 <.0001 <.0001 0.0004 0.3776 0.0027 0.0009 0.7289 0.0026

1292 [Indian Journal of Agricultural Sciences 87 (10)SUNDARAM ET AL.
28
Table 4 Plant height and shoot weight in wheat as affected by application of different UAN concentrations at varying depths
Treatment Plant height (mm) Fresh shoot weight (g)
8 DAS 20 DAS 34 DAS 8 DAS 20 DAS 34 DAS
UAN:Water
U1=1:5 32.8a152.1a206.2b99.1b230.7a280.8b
U2=1:10 34.3a157.7a229.1a113.4a220.3a293.4a
P-value 0.5485 0.2671 <.0001 0.0003 0.2731 0.0174
HSD 5.20 10.29 8.49 6.92 19.12 10.18
Depth of application
D1=1cm 23.60c126.10b199.60c84.20b214.82a256.10b
D2=2 cm 33.20b166.10a218.80b114.10a229.01a295.80a
D3=3 cm 43.90a172.50a234.50a120.40a232.78a309.40a
P-value <.0001 <.0001 <.0001 <.0001 0.2677 <.0001
HSD 7.71 15.25 12.57 10.25 28.34 15.09
UAN:Water × Depth
U1D116.80 96.20 180.20 60.60 208.40 241.40
U1D233.80 173.40 213.20 113.40 239.60 294.60
U1D347.80 186.60 225.20 123.20 244.20 306.40
U2D130.40 156.00 219.00 107.80 221.24 270.80
U2D232.60 158.80 224.40 114.80 218.42 297.00
U2D340.00 158.40 243.80 117.60 221.36 312.40
P-value 0.0063 <.0001 0.0311 <.0001 0.2278 0.0719
Table 5 Surface area, tip and relative parameters of root in wheat as affected by application of different UAN concentrations at varying
depths
Treatment Root surface area (cm2)No. of root tips Specic root length (mg) Specic root surface area (cm2/g)
8 DAS 20 DAS 34 DAS 8 DAS 20 DAS 34 DAS 8 DAS 20 DAS 34 DAS 8 DAS 20 DAS 34 DAS
UAN:Water
U1=1:5 3.1b13.1b25.3b197.2b1175.8b1482.7a10.9b32.5a52.6b128.3b347.6a533.5b
U2=1:10 4.2a15.1a29.9a241.5a1267.2a1509.3a15.4a32.7a57.5a170.0a372.4a592.1a
P-value <.0001 <.0001 <.0001 0.0064 0.0416 0.7691 <.0001 0.8552 0.0014 0.0005 0.0799 0.0011
HSD 0.28 0.44 0.65 30.61 87.62 185.37 1.44 2.24 2.82 21.39 27.91 32.57
Depth of application
D1=1cm 1.37c9.57c15.75c181.30b592.80c813.10c5.78c24.66c38.32c79.19c296.56b400.49b
D2=2 cm 3.24b15.06b28.91b216.30ab 1260.40b1563.90b9.76b33.55b61.19b130.21b388.00a629.34a
D3=3 cm 6.24a17.67a38.18a260.40a1811.30a2111.00a23.93a39.48a65.70a238.01a395.43a658.52a
P-value <.0001 <.0001 <.0001 0.0009 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001 <.0001
HSD 0.41 0.64 0.96 45.36 129.84 274.70 2.14 3.32 4.18 31.69 41.36 48.26
UAN:Water × Depth
U1D10.91 7.46 15.24 150.40 459.40 685.20 4.47 25.22 38.95 67.41 252.24 420.89
U1D22.83 14.62 25.15 201.00 1237.60 1619.40 7.11 34.08 58.85 116.15 389.53 587.91
U1D35.44 17.08 35.47 240.20 1830.40 2143.40 21.19 38.08 60.00 201.29 401.11 591.73
U2D11.83 11.69 16.26 212.20 726.20 941.00 7.10 24.10 37.68 90.97 340.87 380.09
U2D23.65 15.49 32.66 231.60 1283.20 1508.40 12.41 33.01 63.52 144.27 386.46 670.78
U2D37.04 18.26 40.89 280.60 1792.20 2078.60 26.67 40.87 71.39 274.74 389.74 725.32
P-value 0.0557 <.0001 <.0001 0.684 0.0205 0.213 0.194 0.259 0.003 0.116 0.010 0.0005

1293October 2017]
29
EFFECT OF LIQUID UREA AMMONIUM NITRATE ON WHEAT
severe effect on number of tips. After 8 DAS, its number
were signicantly affected at depth D1 and D3, but was at
par at D1 and D2 as well as D2 and D3. Number of root
tips signicantly increased as fertilizer application depth
increased after 20 and 34 DAS.
Specic root length was signicantly more at U2
concentration than U1 after 8 and 34 DAS. However, it
was at par after 20 DAS (Table 5). Fertilizer placed at D3
(3 cm) gave signicantly better SRL values than placed
at D2 and D1 after 8, 20 and 34 DAS. There was almost
145% increase in value of SRL after 8 DAS at depth of 3
cm as compared to 2 cm. This may be due to less effect of
UAN to the secondary roots of the wheat seedlings. Since,
UAN mixture may be affecting the primary root of the seed
at shallow depth, thereby could also affect the growth of
secondary root systems. Interaction effect of depth with
UAN concentration was also found signicant on SRL
values where U2D3 at 8, 20 and 34 days gave maximum
value and lowest was observed in U1D1 at 8 days and U2D1
at 20 and 34 days.
Specic root surface area is severely affected by high
concentration of UAN U1 (1:5) than U2 (1:10) at initial
growth period (Table 5). However, there was non-signicant
effect after 20 DAS, but was found signicant after 34 DAS.
After 8 DAS, the deep placement (D3) of fertilizer mixture
signicantly increased the SRA values to 238.01 cm2/g
from 79.19 cm2/g (D1) and 130.21 cm2/g (D2). However,
SRA was at par at a depth of 2 and 3 cm after 20 and 34
DAS. The total root surface of a plant is important for
capturing water and nutrients. More value of SRA means
more surface is available per unit dry weight of root, i.e.
more nutrient and water inow. Hence it is an indicator of
healthy root system.
From the results, it can be concluded that seed became
unviable through coming in contact with UAN (28% N).
The viability of seed was affected at a dilution ratio of
1:20 (UAN:Water) due to toxicity of ammonium ion, hence,
the seed became dead and could not germinate. On the
other hand, the seed was viable at a dilution ratio of 1:30
(UAN:Water) and germination was observed but seedling
establishment was affected. The pot study showed that
space should be maintained while applying UAN along
with seed in the eld. It may be recommended to keep
a vertical gap of at least 2 and 3 cm between seed and
UAN with dilution ratio of 1:5 and 1:10 respectively while
sowing. These results may form the basis of machinery
development for placement of liquid UAN fertilizer with
respect to seed.
ACKNOWLEDGEMENT
First author thank all the authors from Division of
Agricultural Engineering, Indian Agricultural Research
Institute, New Delhi for their support and cooperation
in discussing the issues and for their helpful suggestion
and I also thank National Fertilizer Limited, Noida and
Department of Fertilizer for providing nancial support in
the form of contract research project.
REFERENCES
Aggarwal P, Choudhary K K, Singh A K and Chakraborty D. 2006.
Variation in soil strength and rooting characteristics of wheat
in relation to soil management. Geoderma 136(1-2): 353–63.
Anonymous. 2012. Value added fertilizers and site specic
nutrient management. Policy Paper 57, National Academy of
Agricultural Sciences, New Delhi.
Arsenault J L, Poulcur S, Messier C and Guay R. 1995.
WinRHIZO™, a root-measuring system with a unique overlap
correction method. Horticulture Science 30: 906.
Bijarniya H. 2016. Design and development of foliar applicator
for urea ammonium nitrate. M.Tech thesis, Indian Agricultural
Research Institute, New Delhi.
Blackshaw R E, Semach G and Janzen H H. 2002. Fertilizer
application method affects nitrogen uptake in weeds and wheat.
Weed Science 50(5): 634–41.
Bremner J M and Krogmeier M J. 1989. Evidence that the adverse
effect of urea fertilizer on seed germination in soil is due to
ammonia formed through hydrolysis of urea by soil urease.
Proceedings of the National Academy of Sciences 86: 8185–8.
Britto D T and Kronzucker H J. 2002. NH4+toxicity in higher plants:
a critical review. Journal of Plant Physiology 159(6): 567–84.
Carvalho T C, Krzyzanowski F C, Ohlson O C and Panobianco
M. 2013. Tetrazolium test adjustment for wheat seeds. Journal
of Seed Science 35(3): 361–7.
Chen D, Suter H, Islam A, Edis R, Freney J R and Walker
C N. 2008. Prospects of improving efciency of fertilizer
nitrogen in Australian agriculture: a review of enhanced
efciency fertilizers. Australian Journal of Soil Research
46(4): 289–301.
Cooke I J.1962. Toxic effect of urea on plants: damage to plant roots
caused by urea and anhydrous ammonia. Nature 194: 1262–3.
Eissenstat D M. 1992. Costs and benets of constructing roots of
small diameter. Journal of Plant Nutrition 15(6-7): 763–82.
Eissenstat D M and Caldwell M M. 1989. Invasive root growth into
disturbed soil of two tussock grasses that differ in competitive
effectiveness. Functional Ecology 3(3): 345–53.
Fertilizers Europe. 2015. Annual Overview. http://fertilizerseurope.
com/index.php?id=6 accessed on 10.01.2017.
Gagnon B and Ziadi N. 2010. Grain corn and soil nitrogen responses
to sidedress nitrogen sources and application. Agronomy Journal
103(3):1014–22.
Hadjichristodoulou A, Della A and Photiades J. 1977. Effect of
sowing depth on plant establishment, tillering capacity and
other agronomic characters of cereals. Journal of Agricultural
Science 89(1): 161–7.
Holloway R E, Bertrand I, Frischke A J, Brace D M, McLaughlin
M J and Shepperd W. 2001. Improving fertiliser efciency on
calcareous and alkaline soils with uid sources of P, N and
Zn. Plant and Soil 236(2): 209–19.
IPNI. 2017. Nutrient Source Specics. http://www.ipni.net/
specics-en accessed on 05 Jan 2017.
ISTA, 2015. International Rules for Seed Testing 2015. International
Seed Testing Association, Bassersdorf, Switzerland.
Jozefaciuk G and Lukowska M. 2013. New method for
measurement of plant roots specic surface. American Journal
of Plant Sciences 4: 1088–94.
Leikam D F. 2012. Why UAN solution. Fluid Journal 20(4): 5.
Liu Y, Lai N, Gao K, Chen F, Yuan L and Mi G. 2013. Ammonium
inhibits primary root growth by reducing the length of meristem
and elongation zone and decreasing elemental expansion rate in
the root apex in Arabidopsis thaliana. PLOS ONE 8(4): 1–11.

1294 [Indian Journal of Agricultural Sciences 87 (10)SUNDARAM ET AL.
Rochette P, Angers D A, Chantigny M H, MacDonald J D,
Gasser M O and Bertrand N. 2009. Reducing ammonia
volatilization in a no-till soil by incorporating urea and pig
slurry in shallow bands. Nutrient Cycling in Agroecosystems
84(1): 71–80.
Saidi A, Ookawa T and Hirasawa T. 2010. Responses of root
growth to moderate soil water decit in wheat seedlings. Plant
Production Science 13(3): 261–8.
Santos M A O, Novembre A D L C and Marcos-Filho J. 2007.
Tetrazolium test to assess viability and vigour of tomato seeds.
Seed Science and Technology 35(1): 213–23.
Tachibana Y and Ohta Y. 1983. Root surface area as a parameter
in relation to water and nutrient uptake by cucumber plant.
Soil Science and Plant Nutrition 29(3): 387–92.
Xiaobin W, Jingfeng X, Grant C A and Bailey L D. 1995. Effects
of placement of urea with a urease inhibitor on seedling
emergence, N uptake and dry matter yield of wheat. Canadian
Journal of Plant Science 75(2): 449–52.
30