INTRODUCTION

Watermelon [Citrullus lanatus (Thunb.) Matsum et
Nakai] is believed to have originated in Africa and spread
to other parts of world. Global area under watermelon
cultivation is 37,52,568 ha with annual production of
99,194,223mt (Vasanth Kumar et al, 2012). It is a
commercially important crop in India and the most popular
among melons grown in summer. Watermelon comprises
90% water, therefore, water supply to the crop is very critical
during growth and development of the plant and fruit. Water
shortage causes noticeable gaps in production, with reduction
in leaf area and overall yield. Supply of water throughout
the growth period is important, but absolutely critical during
flowering and fruit development. Drip fertigation is an
important irrigation-cum-nutrient application method in crop
production, particularly, in arid and semi-arid regions where
there is a high competition for available water resources.
Drip irrigation under plastic mulch is an effective way of
supplying water efficiently in watermelon cultivation. This
may reduce total water requirement besides increasing water
use efficiency (Srinivas et al, 1989; Anon., 2002). To reduce
cost of production and environmental pollution, judicious use

J. Hortl. Sci.
Vol. 8(1):60-64, 2013

Influence of various sources and levels of fertilizer applied through fertigation
on hybrid watermelon grown in rabi-summer

M. Prabhakar, S.S. Hebbar and A.K. Nair
Division of Vegetable Crops

Indian Institute of Horticultural Research
Hesaraghatta Lake Post, Bangalore - 560 089, India

E-mail : mpkar@iihr.ernet.in

ABSTRACT

 A field experiment was conducted at Bangalore during 2006-2008 to study the effect of fertigation on growth and
yield of rabi-summer grown watermelon. Seven treatments comprising varying rates and sources of fertilizers were
applied. Application of water soluble fertilizer @ 70:70:70kg N:P

2
O

5
:K

2
O per hectare through fertigation gave

significantly higher vine length, number of branches per plant and leaf area index. In general, fertigation treatments
recorded higher values for number of fruits per plant, fruit weight and total soluble solids than conventional soil-
application of fertilizers. All the fertigation treatments recorded higher average marketable watermelon yield over
conventional soil-application of fertilizers amounting to 7.22 to 26.4% increase. Among fertigation treatments,
though recommended dose of fertilizer applied as water soluble fertilizer resulted in highest marketable-fruit yield,
highest net income (Rs. 229775) and B:C ratio (3.03) was obtained in treatment with 70% of recommended dose of
NPK using conventional fertilizers supplied through fertigation.

Key words: Watermelon, fertigation, rabi, summer, growth, yield, economics

of water and nutrients is very important. Micro-irrigation
and fertigation are among the best option to help economize
water and fertilization use in vegetable cultivation (Clothier
et al, 1985) and for lowering leaching losses (Ristimaki,
1999). Scientific information on fertigation, especially in
watermelon, is very scanty. Hence, the present field
experiment was set up to determine influence of drip
fertigation for supply of different fertilizer sources and levels
on growth, fruit yield and quality in watermelon.

MATERIAL AND METHODS

The experiment was conducted during rabi-summer
seasons of 2006-2007 and 2007-2008 at Indian Institute of
Horticultural Research, Hesaraghatta, Bangalore. Soil at the
experimental site was red sandy-loam, with organic carbon
0.53%, electrical conductivity 0.24 dS/m, neutral pH (6.72),
low available N (160kg/ha), low available P (9.3kg/ha) and
medium available K (138kg/ha). The soil had a capacity for
holding 148mm available water in the top one meter of its
profile. Seeds of watermelon hybrid NS-295 were sown in
rows of 2m width, with 60cm plant-to-plant spacing, during
the first week of November in both years. The experiment



61

Fertigation studies in hybrid watermelon

was laid out in Randomized Block Design, with seven
treatments and three replications. Uniform basal dose of
farm yard manure @ 25t/ha was applied before sowing.
Treatment details with source and amount of various
fertilizers applied are given in Tables 1 and 2.  Reflective
mulch 30 micron thick and 1.2m wide was used.
Conventional fertilizers used in the experiment were urea,
single super phosphate, di-ammonium phosphate and muriate
of potash; whereas, 19 each of N, P

2
O

5
, K

2
O, KNO

3
 and

Ca (NO
3
)

2 
formed the source of water soluble fertilizer.

Recommended dose of fertilizer in the present study
comprised 100kg N, 100kg P

2
O

5
 and 100kg K

2
O per

hectare. Fertilizer was applied at weekly intervals through

inline drippers in all the fertigation treatments.  Soil treatments
received the entire P

2
O

5
 and K

2
O at sowing, and N in two

splits-one at sowing, and the other 28 days later. Irrigation
was based on evaporation replenishment (0.7 Epan) and
imposed daily on all the treatments through inline drippers.
Fertilizers were injected through non-electrical proportional
injector at weekly intervals, starting with seven days after
germination, and continued for upto 75 days after sowing at
equal rates, as per treatments. Growth observations were
taken 60 days after sowing. Meteorological data during crop
growth period for both years is given in Table 3. All
agronomic and plant protection measures were adopted as
per recommended package of practices. The crop was

Table 2.  Source and quantity (kg/ha) of fertilizers applied under various treatments

Treatment Basal dose Top dressing Fertigation
Urea SSP M O P Urea M O P Urea M O P KNO

3
Ca(NO

3
)

2
19:19:19    DAP

T
1

108.7 625 83.0 108.7 83.0 - - - - - -
T

2
108.7 625 83.0 - - 108.7  83.0 - - - -

T
3

- - - - - - - - - 526.0 -
T

4
- 437.5 - - - 152.0  117.0 - - - -

T
5

- 437.5 - - - - - 152.0 323 - -
T

6
- - - - - 93.0  117.0 - - -    152.0

T
7

- - - - - - - - - 368.0 -

SSP - Single super phosphate;    MOP- Muriate of potash;   DAP - Diammonium phosphate;

Table 1. Treatments imposed in the experiment

                                                            Treatment Symbol Basal dose Top-dressing Fertigation
Level of fertilizer(kg/ha) Fertilizer type Application dose and method (kg/ha) (kg/ha) (kg/ha)

Recommended dose Conventional  100% NPK soil application      T
1

  50:100:50    50:0:50  0:0:0
(100:100:100 N:P

2
O

5
:K

2
O)

Conventional  50% NK fertigation      T
2

  50:100:50    0  50:0:50
WSF  100% NPK fertigation      T

3
  0:0:0    0 100:100:100

70% of recommended dose Conventional  NK fertigation      T
4

  0:70:0 70:0:70
(70:70:70 N:P

2
O

5
:K

2
O)

WSF  NK fertigation      T
5

  0:70:0    0 70:0:70
Conventional  NPK fertigation      T

6
  0:0:0    0 70:70:70

WSF  NPK fertigation      T
7

  0:0:0    0 70:70:70

WSF: Water soluble fertilizer

Table 3. Meteorological data during crop growth period

Month            Temperature (oC)                               RH (%) Total Evaporation Wind
       Max.                   Min.           Morning                  Evening rainfall(mm) (mm) speed(km/h)

November 2006 27.2 18.1 84.5 72.8 112.7 2.7 4.9
December 2006 26.6 14.7 80.0 72.6 - 3.7 5.6
January 2007 28.4 11.8 78.8 43.2 - 4.5 5.3
February 2007 29.9 12.9 58.6 29.6 - 5.6 5.5
March 2007 33.2 16.7 53.3 26.2 - 7.1 5.3
April 2007 33.8 19.7 68.9 36.8 53.4 5.5 6.7
November 2007 26.7 13.1 68.2 59.7 2.8 4.2 3.3
December 2007 27.5 11.4 74.2 65.1 - 5.2 3.8
January 2008 28.5 11.9 73.1 53.1 - 3.6 3.9
February 2008 29.7 15.7 60.6 37.0 7.4 4.7 4.5
March 2008 30.1 16.6 55.0 36.8 105.7 6.2 5.0
April 2008 31.8 18.5 62.6 38.8 11.1 4.1 4.9

J. Hortl. Sci.
Vol. 8(1):60-64, 2013



62

harvested at 90 to 100 days after sowing, at fruit maturity
as indicated by a dull sound of the fruit, or, when the fruit
tendril turned to straw colour, or when the fruit base turned
creamy-yellow in colour. Observations on crop growth, yield,
yield parameters and quality were recorded and statistically
analyzed as per Gomez and Gomez (1983).

RESULTS AND DISCUSSION

Growth parameters

All the treatments pertaining to fertigation
(irrespective of source or dosage) resulted in better growth
in terms of vine length, number of branches per plant and
leaf area index compared to conventional soil-application
during both years (Table 4). Among fertigation treatments,
application of 100 and 70% recommended dose of NPK, in
the form of water soluble fertilizer (T

3
 and T

7
), recorded

significantly higher vine length than in N:K fertigation at
70% recommended dose (T

4
 and T

5
) in 2006-07 and than

all the treatments in 2007-2008. Irrespective of dosage and
combination of fertilizers in fertigation, vine length and
number of branches per plant was higher in water soluble
fertilizer treatment than with conventional fertilizers.
Application at 100% recommended or 70% of recommended
rate through fertigation produced significantly higher number
of branches per plant compared to soil-application

treatments. Leaf area index was highest in T
7
 and lowest in

T
4
 and T

1
 during 2006-07 and 2007-08, respectively.

Improvement of crop growth and leaf area in watermelon
has been reported to be better with nutrients supplied through
fertigation rather than by soil application (Zhang, 2011).

Yield and yield attributes

There were no significant differences among
treatments for number of fruits per plant during 2006-07.
But, in 2007-08, all water soluble fertilizer fertigation
treatments (T

3
, T

5
 and T

7
) recorded higher number of fruits

per plant than any other treatment (Table 5). These
treatments were also significantly superior to conventional
fertilizer treatment of soil-application of 100 or 50%
recommended dose (T

1
 and T

2
), and remained at par with

70% NPK application using conventional fertilizer.
Significant differences for fruit weight due to different
treatments were observed but, overall, higher fruit weight
was observed in treatments receiving water-soluble
fertilizers compared to treatments receiving conventional
fertilizers. Application of 50% N:K fertigation (T

2
) resulted

in significantly higher fruit weight (4.89kg) which was at
par with T

4
 and T

6
,
 
and all these treatments were superior

to soil-application treatments in 2006-07. During 2007-08,
fruit weight was comparatively more in crops receiving
water-soluble fertilizers through fertigation compared to all
the treatments involving conventional fertilizers. Total soluble
solids (oBrix), representing fruit quality, did not differ
significantly due to different fertigation treatments. However,
T

7
 (which received 70% recommended dose of water-

soluble fertilizers) recorded highest values for TSS in both
years. Battilani and Solimando (2006) and Andrade Junior
et al (2009) also reported no significant differences in fruit
quality in watermelon with various levels of fertilizers
supplied through fertigation. All the fertigation treatments
recorded higher yield over conventional method of applying
commercial fertilizer as soil-application (T

1
) for upto 7.23

Table 4. Growth of watermelon as influenced by fertigation
treatments

Treatment Vine No. of  branches Leaf area
length(cm) per plant  index

06-07 07-08 06-07 07-08 06-07 07-08

T
1

242.3 255.0 8.2 8.0 2.52 2.50
T

2
281.1 273.0 9.3 8.3 2.54 2.52

T
3

286.6 330.0 10.8 10.0 2.58 2.61
T

 4
235.3 286.0 10.7 8.6 2.49 2.55

T
5

246.8 300.0 10.7 10.8 2.60 2.63
T

6
277.3 305.0 10.9 9.8 2.56 2.62

T
7

303.2 346.0 11.4 11.0 2.63 2.66
CD (P=0.05) 25.49 20.74 1.40 1.41 0.09 0.0872

Table 5. Effect of fertigation level on yield, yield attributes and quality in watermelon

Treatment No. of fruits per plant Fruit weight (kg) TSS (oBrix) Yield (t/ha)

06-07 07-08 06-07 07-08 06-07 07-08 06-07 07-08

T
1

1.31 1.32 4.32 5.32 9.38 9.20 45.61 55.80
T

2
1.30 1.25 4.89 5.75 9.63 9.24 48.91 59.81

T
3

1.40 1.60 4.43 6.15 9.68 10.45 60.20 68.85
T

 4
1.33 1.43 4.68 5.95 9.75 9.56 53.49 63.34

T
5

1.37 1.62 4.37 6.06 9.76 10.48 56.66 66.50
T

6
1.42 1.51 4.69 5.77 9.83 10.46 56.70 65.50

T
7

1.42 1.68 4.45 6.01 9.90 10.56 59.87 68.31
CD(P=0.05) NS 0.19 0.35 0.47 NS NS 7.72 3.46

NS = Non-significant

Prabhakar et al

J. Hortl. Sci.
Vol. 8(1):60-64, 2013



63

Table 6. Economics of watermelon crop in relation to fertigation
treatments

Treatment* Average Gross Gross Net B:C
yield investment income  income ratio
(t/ha) (Rs./ha) (Rs./ha) (Rs./ha)

T
1

50.70 77585 253500 175915 2.26
T

2
54.36 77585 271800 194215 2.50

T
3

64.52 104125 322600 218475 2.09
T

4
58.41 75317 292050 216738 2.87

T
5

61.58 98066 307900 209834 2.14
T

6
61.10 75725 305500 229775 3.03

T
7

64.09 93920 320450 226530 2.41

Sale Price = Rs. 5.00/kg
*For details on treatments, refer Table 1and 2

to 32.00% increase in 2006-07 and 7.18 to 23.38% in 2007-
08. Higher yield obtained with fertigation treatments may
be because of better growth, higher photosynthetic-surface
area coupled with better yield attributes such as number of
fruits per plant and larger fruit size. Gonsalves et al (2011)
reported leaf area index to have a positive effect on the
number of fruits and on productivity in watermelon.
Application of 100% NPK fertigation at recommended dose
through water-soluble fertilizer (T

3
) recorded maximum and

significantly higher yield (60.20 and 68.85 t/ha) than T
1
 and

T
2
, but remained at par with treatments where only 70% of

the recommended dose of NK or NPK was applied as
fertigation (except in T

4
) in the second year. Among other

fertigation treatments, application of 70% NPK
recommended dose through water-soluble fertilizers (T

7
)

recorded the second highest yield, followed by T
6 

in the
first year, and T

5
 in the second year. Use of fertilizer at

70% of recommended dose through fertigation clearly
resulted in higher yield than 50% N:K fertigation + 50%
soil application or complete soil-application of  conventional
fertilizers at recommended dosage. This also indicated that
to realize yields equivalent to or higher than in soil application
of the entire dose or by fertigating with half the
recommended conventional fertilizer, it is possible to save
30% of fertilizer using water-soluble or conventional
fertilizers, applied entirely through fertigation. Kadam et al
(2009) also reported 20% saving in fertilizer using fertigation
in watermelon.

Economics

Details on economics and benefit:cost ratio in
watermelon hybrid NS 295 in relation to various fertigation
treatments tested are presented in Table 6. Highest gross
income (Rs. 3,22,600/ha) was obtained in the treatment
where the entire quantity of water-soluble fertilizers at
recommended dosage was given through fertigation (T

3
),

followed by T
7
 which received 70% recommended dose of

water-soluble fertilizers through fertigation. Lowest gross
income (Rs.2,53,500/ha) was obtained by applying
recommended dose of conventional fertilizer to soil (T

1
).

Though treatment T
3
 resulted in highest gross income, it failed

to earn highest net income owing to higher cost of the water-
soluble fertilizers. As for net income, the best performance
was that of the treatment where 70% recommended dose
of NPK using conventional fertilizers was supplied to the
crop through fertigation. This treatment also resulted in
highest B:C ratio (3.03) by virtue of fetching higher yield
and gross income, and incurring comparatively low gross
investment.

From this study, it is evident that application of 70 or
100% recommended NPK, through fertigation using water-
soluble fertilizers, results in higher yield in watermelon hybrid
grown during rabi-summer season. However, from the point
of view of economics, 70% N:P:K fertigation using
conventional fertilizers is more profitable. Hence, it is
concluded that for better performance and profitability from
hybrid watermelon grown during rabi-summer, supply of
70% recommended dose of NPK through fertigation using
conventional fertilizers, is appropriate.

REFERENCES

Andrade Junior, A.S., de  Dias, N. da S.  Figueiredo Junior,
L.G.M. Ribeiro, V.Q. and Sampaio, D.B. 2009.
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IRRIGA, 14:115-122

Anonymous. 2002. Commercial Vegetable Production Guide.
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Battilani, A. and Solimando, D. 2006. Yield, quality and
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Clothier, B., Scotter, D. and Harper, E. 1985. Three
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Kadam, U.S., Deshmukh, A.D., Ingle, P.M. and Manjarekar,
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64

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J. Hortl. Sci.
Vol. 8(1):60-64, 2013

Prabhakar et al