INTRODUCTION

Cassava cultivation is amenable for growing
intercrops as it is a long duration crop. Like many other
crops, cassava crop also suffers from competition by weeds
for space, light, water and nutrients (Davis and Gardner,
1985). The early stages of growth are normally susceptible
for competition by weeds and hence keeping the crops weed
free during this phase is the pre-condition for higher
productivity. However, control of weeds in intercropping
systems through cultural or mechanical methods is difficult
due to narrow inter-row spacing. Therefore, the present
investigation was undertaken to assess the production
potential of intercropping system of cassava with various
methods of weed control under rainfed condition.

MATERIAL AND METHODS

A field experiment on cassava intercropping in the
garden land conditions was conducted in the month of
August during 2003-04 and 2004-05 at Agricultural College
and Research Institute, Madurai. The parameters regarding
the soil fertility status of the experimental area were
recorded. The pH and EC of the soil were 7.4 and 0.42 m
mho/cm respectively. The physical parameters including
clay– 25.1%, silt -11.5%, fine sand -37.4%, coarse sand-
22.8% and bulk density -1.48 g / cc and the chemical

Weed management studies in cassava (Manihot esculenta L.) intercropping systems
under irrigated conditions

S. Padmapriya, R. Balasubramanian1 and V.A. Sathiyamurthy
Horticultural College and Research Institute

Tamil Nadu Agricultural University, Coimbatore-641 003, India
E-mail: spadmapriyaa@yahoo.co.in

ABSTRACT

A field experiment was conducted during 2003-04 and 2004-05 to asses the production potential of
intercropping of cassava (Manihot esculenta L.) with groundnut (Arachis hypogea), vegetable cowpea (Vigna
sinensis) and black gram (Vigna mungo) in relation to various weed control practices. Intercropping influenced
the population of grasses, sedges, BLW and total dry matter production of weeds. Weed management caused
significant improvement in growth, yield and economic returns of cassava system. Best results were achieved
with intercropping of vegetable cowpea with pre-emergence application of fluchloralin 0.75 kg/ha + one hand
weeding 4 weeks after planting followed by application of alachlor @ 1.5 kg/ha + one hand weeding 4 weeks
after planting.

Key words: Cassava, intercropping, weed control, yield, economics

characters such as available N – 218.3 kg/ha, available P
2
O

5

– 12.74 kg/ha, available K
2
O – 271.82 kg /ha and organic

carbon – 0.49% were also recorded. The experiment was
conducted in split plot design replicated thrice. The
treatments consisted of six intercropping systems,
groundnut (I

1
), vegetable cowpea (I

2
), blackgram (I

3
),

groundnut followed by blackgram (I
4
), cowpea followed

by blackgram (I
5
) and pure crop (I

6
) as main plot and six

weed control measures viz., pre-emergence application of
pendimethalin 0.75 kg/ha + one hand weeding during 4
WAP (W

1
), Pre-emergence application of alachlor 1.5 kg/

ha + one hand weeding during 4th week after planting (W
2
),

pre-emergence application of fluchloralin 0.75 kg/ha + one
hand weeding during 4 WAP (W

3
), hand weeding twice

during 4 and 15 WAP (W
4
), hand weeding thrice during 4,

12 and 20 WAP (W
5
) and hand weeding four times during

4, 8, 12 and 20 WAP (W
6
) as sub-plot treatments.

Disease free setts of 20 cm length of cassava variety
Sree Vijaya were prepared and planted at a spacing of 90 x
90 cm and planted at the onset of monsoon. Seeds of
groundnut, cowpea and black gram were dibbled in lines at
a spacing of 30 x 20 cm accommodating two rows of
intercrops between the rows of cassava. A fertilizer dose of
90:90:240 NPK Kg ha-1 was uniformly applied to all the
plots. The entire dose of phosphorus, 50% of recommended

1 Present Address: Department of Agronomy, AC & RI, Madurai-625 104

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142

dose of nitrogen and 50% of K were applied basally at the
time of planting and the remaining 50% of the recommended
dose of nitrogen and potassium were top dressed in two
equal splits at third and fifth month, respectively. The pre-
emergence herbicides used in the study viz., pendimathalin,
fluchloralin and alachlor are highly selective in nature to
control most annual grasses and certain broadleaf weeds in
field corn, potatoes, rice, cotton, soybeans, tobacco, peanuts
and sunflowers. Incorporated into the soil by cultivation or
irrigation is recommended within 7 days following
application. Cultural operations pertaining to crop
production and protection were followed.

RESULTS AND DISCUSSION

Weed flora

The weed flora in the experimental field consisted
of a mixed population of grasses, viz., Cynodon dactylon
(L.) Pers., sedges Cyperus rotundus L. and broad leaved
weeds, viz., Euphorbia hirta, Trianthema portulacastrum
and Achyranthus aspera as the most dominant species in
the experimental plot.

Weed density, dry matter production and weed
control efficiency

In general, weed infestation was higher in 2003-
04 than in 2004-05. This was mainly because of even
distribution of rainfall over entire period of cropping season
in 2003-04 as compared to 2004-05 (Fig 1). The results
revealed that sedges were found to be dominant followed
by grasses and broad leaved weeds. Integrated weed
management had noticeable effect on population of of weeds
compared to hand weeding alone. Among the different weed
management practices, the lowest weed density of grasses

(8.25 no/m2), sedges (14.67 no/m2), BLW (7.09 no/m2) and
total weed DMP (23.32 g/m2) was recorded with application
of Fluchloralin (0.75kg/ha) + 1HW (Table.1). Regarding
the weed control efficiency, intercropping with cowpea
registered the highest value of 44.5%. Similarly, application
of Fluchloralin (0.75kg/ha) + 1HW resulted in the highest
weed control efficiency of 44.6%. Panwar et al (1985) also
reported that application of fluchloralin at 1 and 2 kg/ha
were more effective than two hand weeding on 15 and 30
DAS. The mode of action and selective mechanism of
fluchloralin affects the germination of the weed seeds and
physiological growth process thereby reducing the weed
population (Matsunaka, 1979). With regard to the
intercropping practices, significant reduction in the dry
matter production (24.80g/m2) was observed with vegetable
cowpea compared to other intercrops. The next best
treatment was intercropping of cowpea followed by
blackgram with the total weed DMP of 25.07g/m2 (Table
1). Wilson and Adeniran (1976) reported that intercropping
with legumes ensured better coverage of soil thereby
diminishing the light penetration to the soil thus reducing
the weed growth.

Growth and yield attributes of cassava

Growth attributes of cassava, viz., plant height and
DMP revealed highly significant differences due to different
weed management and intercropping practices. It could be
inferred that the intercrops had definite role on the growth
and development of cassava main crop. The mean plant
height was the highest (264.95 cm) when vegetable cowpea
was sown as intercrop and fluchloralin herbicide combined
with one hand weeding at 4 WAP registered increased mean
plant height (267.25 cm) (Table 2). Intercropping of cassava

Fig 1. Details of rainfall received during the cropping period

Padmapriya et al

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143

with cowpea enhanced the plant height and growth attributes
of cassava as the quantity of N fixed from the atmosphere
by cowpea through microbial symbiosis would have met
at least a part of the requirement of cassava which agreed
with the results of Sheela and Mohammed Kunju
(1988). Cassava intercropped with cowpea produced
higher DMP, which was comparable to sole cassava.
This effect could be attributed to the complementarity of
companion crop of cowpea and the better utilization of
biologically fixed N by cassava base crop during latter
part of its growth. The work of Chittapur et al (1994) on
maize-legume-intercropping system extends support to the
present finding.

The application of herbicides viz., fluchloralin
combined with hand weeding caused significant
improvement of yield attributes. This may be due to their
effect on reducing crop-weed competition and hence better
utilization by crop plants. The treatment fluchloralin (0.75
kg/ha) +1HW increased tuber length (31.5 cm), tuber
circumference (25.7 cm) and mean tuber weight (447.9 g)
(Table 2). Regarding the different intercrops studied,
vegetable cowpea increased tuber length, tuber
circumference and mean tuber weight. Kaushik and Gautam
(1984) and Verma and Kumar (1985) also reported
improvement in yield components due to elimination of
severe crop-weed competition.

Table 2. Effect of intercropping and weed management practices on agronomic traits of cassava

Treatments Plant height DM Tuber length Tuber Mean tuber Tuber
(cm) P(t/ha) (cm) circumference (cm) weight/ plant (g) yield(t/ha)

Intercropping
Groundnut 258.30 13.45 28.7 22.4 434.6 22.8
Cowpea 264.95 13.55 30.5 23.7 434.1 23.7
Blackgram 254.00 13.30 29.6 20.3 434.1 18.4
Groundnut fb Blackgram 238.80 13.40 26.2 20.7 431.2 18.6

 
Cowpea fb Blackgram 262.55 13.40 29.6 22.6 435.7 23.6
Pure crop 262.00 13.80 29.9 24.9 444.1 24.4
CD (P=0.05) 5.40 0.05 0.6 0.5 9.5 0.3

Weed management
Pendi.(0.75kg/ha)+1HW 257.45 14.75 30.2 23.7 438.5 23.8
Ala.(1.5kg/ha)+1HW 256.55 14.15 30.1 22.8 439.1 22.4
Flu.(0.75kg/ha)+1HW 267.25 15.25 31.5 25.7 447.9 25.4
HW twice 228.85 11.35 26.0 19.4 424.6 18.4
HW thrice 239.85 11.90 27.3 21.0 431.5 20.0
HW four times 248.00 13.45 29.3 22.0 432.1 21.0
CD (P=0.05) 6.20 0.35 0.7 0.6 10.7 0.2

Table 1.  Effect of intercropping and weed management practices on weed density, weed  dry matter production and weed control
efficiency at 60 days

Treatments Weed density ( / m2) Total weed Weed control
DMP(g/m2) efficiency (%)

Grasses Sedges Broad leaved weeds Grasses Sedges
Intercropping

Groundnut 11.75(3.50) 16.58(4.13) 7.75(2.87) 27.37(5.28) 40.1
Vegetable Cowpea 9.58(3.18) 13.59(3.75) 10.25(3.28) 24.80(5.03) 44.5
Blackgram 11.59(3.48) 17.00(4.18) 10.00(3.24) 28.85(5.42) 35.9
Groundnut fb Blackgram 11.58(3.48) 16.92(4.17) 9.25(3.12) 28.00(5.34) 37.3
Veg. Cowpea fb Blackgram 9.63(3.19) 13.75(3.78) 10.33(3.29) 25.07(5.06) 43.9
Pure crop 18.83(4.40) 19.83(4.51) 13.09(3.69) 39.20(6.30) 14.0
CD (P=0.05) 0.05 0.05 0.21 0.10 0.1

Weed management
Pendi.(0.75kg/ha) + 1HW 11.00(3.39) 13.75(3.77) 8.08(2.93) 23.29(4.88) 39.1
Ala.(1.5kg/ha)+1HW 10.67(3.34) 11.75(3.50) 7.50(2.83) 22.45(4.79) 44.1
Flu.(0.75kg/ha) +1HW 8.25(2.96) 14.67(3.90) 7.09(2.76) 23.32(4.88) 44.6
HW twice 13.92(3.80) 20.34(4.57) 12.42(3.60) 34.17(5.89) 13.5
HW thrice 14.92(3.93) 19.84(4.51) 12.92(3.66) 36.10(6.05) 11.7
HW four times 13.92(3.80) 17.34(4.22) 12.67(3.63) 33.96(5.87) 18.8
CD (P=0.05) 0.07 0.05 0.17 0.12 0.1
Transformed values (square root) are within parentheses

Weed management in cassava

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144

There was a significant influence of weed
management and intercropping practices on the tuber yield.
The tuber yield per plant ranged from 18.4 to 25.4 t/ha.
The highest tuber yield was recorded in sole cassava (24.4
t/ha) followed by cassava intercropped with cowpea, which
was comparable with sole cassava. In sole cassava, there
was no competition for resources except intra-species
competition, which explains the increase in growth and yield
parameters and yield. Savithri and Alexander (1995)
reported that there was no significant difference in yield of
cassava when intercropped with cowpea which is in
agreement with the present findings. Pre-emergence
application of fluchloralin @ 0.75 kg/ ha + one hand
weeding at 4 WAP increased the tuber yield of cassava (25.4
t/ha) compared to other weed management practices (Table
2). The results are in accordance with the findings of
Sankaran and Balasubramanian (1981) who reported that
the pre-emergence application of fluchloralin reduced the
weed population leading to reduced crop-weed competition
ultimately increasing the crop yield.

Intercrop yield

Cassava is usually wide spaced and has slow initial
development. Hence, intercropping at early stages of crop
growth is feasible and usually results in higher total income
and reduces soil erosion. The different weed management
practices markedly improved the yield of intercrops.
Increased yield (0.82 t/ha) of groundnut was recorded in
the treatment fluchloralin @ 0.75 kg/ha+ one hand weeding
at 4 WAP (I

1
W

3
). Similarly, in cowpea and blackgram, the

same weed management practice resulted in the highest
yield of 4.78 t/ha (I

2
W

3
) and 0.73 t/ha (I

3
W

3
), respectively

(Table 3).  Intercropping with groundnut or cowpea has been
used as smother crop in cassava + maize mixture to give
good weed control, high mixture yield and land equivalent
ratio. (Abate, 1992).

Economics

Among the different intercropping and weed
management treatments, the highest net income (Rs.62,165)
and benefit cost ratio (3.31) was recorded with cowpea as
intercrop combined with spraying of pre emergence
application of fluchloralin @ 0.75 kg/ha + one hand weeding
at 4 WAP (I

2
W

3
)

 
(Table.3). This was closely followed by

the treatment I
5
W

3
 with a net income of Rs.57,765 and a

benefit cost ratio of 3.08. The lowest benefit cost ratio (1.58)
was recorded in the pure cropping of cassava with hand
weeding thrice on 4, 12 and 20 WAP (I

6
W

5
).

Hence, it could be concluded that among the
different intercropping and weed management practices,
growing vegetable cowpea along with pre-emergence
herbicide application of fluchloralin @ 0.75 kg/ha + one
hand weeding at 4 weeks after planting significantly reduced
the weed growth, increased the crop growth, yield attributes,
yield and economic returns of cassava with high benefit
cost ratio.

REFERENCES

Abate, 1992. Effects of groundnut, cowpea and melon on
weed control and yields of intercropped cassava and
maize. Field Crops Res., 28:309-314

Chittapur, B.M., Hiremath, S.M. and Meli, S.S. 1994.
Performance of maize and green forage yield of

Table 3. Economics of intercropping and weed management
practices in cassava

Treatments Intercrop Net income Cost benefit
yield (t/ha)  (Rs.) ratio

I
1
W

1
0.77 36143 2.21

I
1
W

2
0.72 30462 2.01

I
1
W

3
0.82 41060 2.38

I
1
W

4
0.58 21427 1.70

I
1
W

5
0.54 23188 1.74

I
1
W

6
0.62 22023 1.68

I
2
W

1
4.66 49214 2.82

I
2
W

2
4.54 45465 2.67

I
2
W

3
4.78 62165 3.31

I
2
W

4
3.80 33167 2.20

I
2
W

5
3.56 33330 2.16

I
2
W

6
4.21 34775 2.17

I
3
W

1
0.73 26604 1.97

I
3
W

2
0.61 26738 1.97

I
3
W

3
0.73 33033 2.21

I
3
W

4
0.49 19047 1.68

I
3
W

5
0.45 17301 1.60

I
3
W

6
0.55 19650 1.65

I
4
W

1
0.71 26561 1.87

I
4
W

2
0.68 28271 1.91

I
4
W

3
0.75 38807 2.27

I
4
W

4
0.54 21914 1.70

I
4
W

5
0.49 18894 1.59

I
4
W

6
0.59 20462 1.61

I
5
W

1
4.67 54874 2.97

I
5
W

2
4.51 46382 2.65

I
5
W

3
4.73 57765 3.08

I
5
W

4
3.78 37871 2.34

I
5
W

5
3.39 33519 2.13

I
5
W

6
4.17 36548 2.20

I
6
W

1
- 30566 2.23

I
6
W

2
- 28205 2.12

I
6
W

3
- 42055 2.69

I
6
W

4
- 19747 1.77

I
6
W

5
- 15371 1.58

I
6
W

6
- 21863 1.79

Padmapriya et al

J. Hortl. Sci.
Vol. 3 (2): 141-145, 2008



145

legumes in maize + forage legume intercropping
system in Northern transitional tract of Karnataka.
Fmg. Systems, 10:11-15

Kaushik, S.K. and Gautam, R.C. 1987. Effect of nitrogen
and phosphorus on the production potential of pearl
millet-cowpea on green gram intercropping systems
under rainfed conditions. J. Agril. Sci., Cambridge,
108: 361-364

Matsunaka, S. 1979. Mode of action and selectivity
mechanism of herbicides. Sixth Asian Pacific Weed
Sci. Soc. Conf., Jarkarta, 2. pp.525-536

Panwar, R.S, Bhanand, V.M. and Malik, R.K. 1985. Weed
management studies in summer moong. Ind. Soc.
Weed Sci., Annual Conference held at Hissar, p.53

Sankaran, S and Balasubramanian, N. 1981. Weed control
in pulses. Ind. Soc. Weed Sci.,Weed Science
Conference held at Bangalore, pp. 27-28

Savithri, K.E. and Alexander, D. 1995. Performance of
cowpea varieties in cassava-cowpea intercropping
system. Legume Res., 18: 59-60

Sheela, K.R. and Kunju, U.M. 1988. Growth and yield of
cassava as influenced by intercropping with cowpea
and groundnut under different nutrient levels. J. Root
Crops, 14: 67-69

Verma, R.S. and Kumar, V. 1985. Effect of different tillage
practices and weed control measures on growth, yield
and weed flora in bajra (Pennisetum americanum L.).
Abstract of paper, Annual Conference of Indian
Society of Weed Science. p.31

Wilson, G.F and Adeniran, M.O. 1976. Intercropping of
cassava with vegetables. In: Intercropping in semi-
arid areas. Monyo, J.H., Ker, A.D.R. and Campbell,
M. (Eds.) IDRC076 e., Int’l. Dev. Res. Centre,
Ottawa, Canada

(MS Received 25 September 2008, Revised 19 November 2008)

J. Hortl. Sci.
Vol. 3 (2): 141-145, 2008

Weed management in cassava