Pak. J. Weed Sci. Res. 9(1-2):89-97, 2003

 

RESPONSE OF WHEAT AND WINTER WEEDS TO FOLIAR APPLICATION OF DIFFERENT PLANT WATER EXTRACTS OF SORGHUM (S. bicolor)

 

Z.A. Cheema, A. Khaliq and M. Mubeen[1]

 

ABSTRACT

                Allelopathy has been explored recently as a substitute for chemical herbicides to reduce environmental pollution. Various plant water extracts alone and in combinations with each other may exert their influence differently on weeds and crop plants. Response of wheat and its weeds to foliar application of sorghum (Sorghum bicolor), sunflower (Helianthus annuus) and eucalyptus (Eucalyptus camaldulensis) water extracts individually and in combinations with each other at different doses were tested under field conditions. Concentrated sunflower water extract @ 12 L ha-1 sprayed at 30 and 40 days after sowing gave consistently better weed control and increased wheat yield by 5.5% over control. A combination of water extracts of sorghum, sunflower and eucalyptus each @ 12 L ha-1 and 8 L ha-1 were also  economical. However, conventional methods like hand weeding and herbicides, though effective in weed control, were uneconomical due to higher costs.

 

Key words:  Allelopathy, plant water extracts, wheat, weed control, net income.

 

INTRODUCTION

Allelopathy is being utilized in agriculture in various ways i.e. allelopathic stubble mulches, allelopathic crops in rotation and inter/mixed cropping systems (Fortney and Foy, 1985; Cheema, 1988; Narwal, 2000). A relatively new approach is to use foliar sprays of different allelopathic water extracts for inhibiting weeds in field crops (Iqbal, 1997; Cheema and Ahmad, 1992; Dur-e-Shahwar, 1996). Reduction in weed biomass by 33-53% and increase in wheat yield (7-14%) by application of sorghum (Sorghum bicolor) and sunflower (Helianthus annuus) water extracts was reported (Cheema et al., 1997). Similar observations were made in other crops (Bhatti et al., 2000; Khaliq et al., 1999). The allelochemicals present in one plant water extract might act synergistically with the allelochemicals of another plant water extract. Mixture of vanillic and p-hydroxybenzoic acids reduced radish seed germination by 48% whereas individually they reduced seed germination by 29% and 5%, respectively (Einhellig and Rasmussen, 1978). Equimolar concentration of 3.3 mM of each of ferulic, p-coumaric and vanillic acids exerted a synergistic inhibition of sorghum seed germination; however this concentration did not have synergistic effect on seedling growth which might have resulted from the stimulatory effect exhibited by the 3.3 mM concentration of vanillic acid on seedling growth (Rasmussen and Einhellig, 1979). Similarly there was little effect of any phenolic compound at 10-5 M. At 10-3 M, coumarin, hydrocinnamic acid, juglone and pyrocatechol strongly inhibited seed germination of test crop and weed species. The combination of coumarin and p-hydroxybenzaldehyde had an additive effect on germination of two weed species, inhibiting germination to a greater extent than either compound alone (Williams and Hoagland, 1982).

 

The objectives of the instant studies were to evaluate the effect of aqueous extracts of allelopathic plants such as sorghum (Sorghum bicolor), sunflower (Helianthus annuus) and eucalyptus (Eucalyptus camaldulensis) on wheat weeds and to evaluate any possible synergistic effect by combining these extracts on growth of wheat and its weeds under field conditions.

 

MATERIALS AND METHODS

The experiment was conducted at agronomic research area, University of Agriculture, Faisalabad during 2001-2002. Sorghum (S. bicolor) and sunflower (H. annuus) herbage and eucalyptus (E. camaldulensis) leaves were harvested at maturity and dried. Sorghum and sunflower herbage was chaffed (into 2 cm pieces) and eucalyptus leaves were ground. Chaffed herbage and ground leaves were soaked in distilled water in the ratio of 1:10 (w/v) for 24 hrs and then filtered to collect the respective water extracts. The extracts were concentrated to 20 times by boiling at 100°C on a gas burner. Wheat variety Uqab-2000 was sown in 25 cm spaced rows with single row hand drill after maize crop on November 1, 2001. Treatments were arranged in randomized complete block design with four replications. Recommended cultural practices were followed for all the treatments except weed control measures. The three aqueous extracts alone and in combinations with each other and the herbicide were sprayed on the standing wheat and weeds with knapsack hand sprayer fitted with flat fan nozzle, calibrated to 357 liters per hectare. The plant water extracts used were two sprays of concentrated sorgaab (SorWE), concentrated sunflower water extract (SunWE) and concentrated eucalyptus water extract (EuWE) each @ 12 L ha-1 at 30 and 40 days after sowing (DAS) and combined spray of these concentrated water extracts each @ 6, 8 and 16 L ha-1 one spray at 30 DAS; isoproturon was applied @ 1 kg a.i. ha-1 and one hand weeding was done at 30 DAS. A weedy check was maintained as control treatment. Data on weed density and biomass were recorded at 45 DAS and 60 DAS from randomly selected two quadrates (50 x 50 cm2) from each experimental plot. The dry weight of weeds was taken after drying in an oven at 80°C till the weight was constant. Data on various wheat growth parameters were recorded from randomly selected samples using standard procedures and grain yield per plot was obtained by threshing and then converted to t ha-1.

Data collected were analyzed by using Fisher’s analysis of variance technique (Steel and Torrie, 1984). Economic analysis of the treatments was done to determine the most economical treatment (Byerlee, 1988).

RESULTS AND DISCUSSION

Major weeds at the experimental site were canary grass (Phalaris minor) and wild oat (Avena fatua) while sweet clover (Melilotus parviflora) and broad-leaved dock (Rumex dentatus) were present in relatively lesser number.

 

Total weed density was reduced upto 78 and 72% by isoproturon and hand weeding, respectively (Table  1). Among plant water extracts, combinations of SorWE + SunWE + EuWE each @ 8 L ha-1 and 16 L ha-1 were consistently effective, followed by SunWE (two sprays) which although was not promising at 45 DAS, yet reduced total weed density by 34% at 60 DAS. Isoproturon, hand weeding and combination of water extracts each @ 6 L ha-1 were effective treatments in suppressing density of canary grass by 87, 73 and 41% suppressions, respectively. Wild oat density was suppressed more by hand weeding. SorWE (two sprays), though promoting at 45 DAS, was inhibitory up to 47% at 60 DAS. Control of wild oat density by SorWE confirm the findings of Iqbal (1997) and Qadir (2000) who reported good control of wild oat density by application of sorgaab (SorWE). Density of sweet clover was checked effectively by isoproturon and hand weeding. Most water extract treatments were suppressive at 45 DAS but a slightly stimulating at 60 DAS. Broad-leaved dock was greatly suppressed by isoproturon and hand weeding, followed by combination of SorWE + SunWE + EuWE each @ 6 L ha-1 (causing 58% reduction at 60 DAS).

 

Total weed dry weight was inhibited greatly by hand weeding and isoproturon by 67-75% and 50-71%, respectively. Combination of water extracts each @ 16 L ha-1 was the next best treatment causing up to 34% reduction in total weed dry weight (Table 2). Dry weight of canary grass was greatly controlled by isoproturon and hand weeding (63-100% and 75-91%, respectively) followed by combination of water extracts each @ 12 L ha-1 causing up to 30% reduction. Certain water extracts as EuWE (two sprays), a combination of water extracts each @ 6 L ha-1, 8 and 16 L ha-1 and isoproturon were statistically similar to hand weeding (which gave maximum control) in controlling dry weight of wild oat at 60 DAS. Inhibition of wild oat by mixture applications is in lines with findings of Rice et al. (1981) and Einhellig et al. (1982) who concluded that combinations of allelochemicals have synergistic effects. Dry weight of sweet clover was controlled effectively by isoproturon (100%) and hand weeding (55-87%). Combination of water extracts each @ 16 L ha-1 gave 34-48%.

 

Table 1. Effect of various plant water extracts on density of different weed species

Treatments

 

Density (number per 50 cm2)

Total weeds

Canary grass

Wild oats

Sweet clover

Broad-leaved dock

45 DAS

60 DAS

45DAS

60 DAS

45 DAS

60 DAS

45 DAS

60 DAS

45 DAS

60 DAS

Control (weedy check)

80.381 ab

 

89.25 a

26.13 a

24.38 bc

15.75 b

27.0 a

18.88 a

10.63 abc

6.38ns

5.63 a

SorWE @ 12 L ha-1 at 30 & 40 DAS

83.38 a

(+4.35) 2

74.5 ab

(-16.53)

28.0 a

(+7.16)

30.0 a

(+23.05)

22.38 a

(+42.09)

14.38 bc

(-46.74)

16.88 ab

(-10.59)

7.25 bc

(-31.8)

5.88

3.75 ab

(-33.39)

SunWE @ 12 L ha-1 at 30 & 40 DAS

53.38 c

(-33.59)

89.88 a

(0)

16.13 bcd

(-38.27)

27.5 ab

(+12.8)

14.13 b

(-10.29)

25.13 ab

(-6.92)

13.0 bcd

(-31.14)

11.13 abc

(+4.7)

3.38

5.75 a

(+2.13)

EuWE @ 12 L ha-1 at 30 & 40 DAS

67.63 bc

(-15.86)

81.63 ab

(-8.54)

25.63 ab

(-1.91)

23.5 cd

(-3.6)

14.13 b

(-10.29)

21.63 ab

(-19.89)

13.75 bcd

(-27.17)

13.88 a

(+30.57)

6.25

3.88 ab

(-31.08)

SorWE + SunWE + EuWE each @ 6 L ha-1 at 30 DAS

58.25 c

(-27.53)

75.0 ab

(-15.97)

15.5 cd

(-40.68)

22.5 cd

(-7.7)

17.25 ab

(+9.52)

21.13 ab

(-21.74)

14.63 abc

(-22.51)

11.13 abc

(+4.7)

4.63

2.38 bc

(-57.73)

SorWE + SunWE + EuWE each @ 8 L ha-1 at 30 DAS

64.25 c

(-20.07)

70.63 b

(-20.86)

24.5 abc

(-6.24)

21.5 cd

(-11.81)

13.13 b

(-16.63)

18.88 abc

(-30.07)

12.25 cd

(-35.12)

10.5 abc

(-1.22)

7.0

3.75 ab

(-33.39)

SorWE + SunWE + EuWE each @ 12 L ha-1 at 30 DAS

59.88 c

(-25.5)

81.5 ab

(-8.68)

19.38 abc

(-25.83)

20.63 d

(-15.38)

14.88 b

(-5.52)

23.38 ab

(-13.41)

12.38 bcd

(-34.43)

11.88 ab

(+11.76)

6.38

3.88 ab

(-31.08)

SorWE + SunWE + EuWE each @ 16 L ha-1 at 30 DAS

64.75 c

(-19.45)

72.25 b

(-19.05)

27.0 a

(+3.3)

22.63 cd

(-7.18)

14.0 b

(-11.11)

21.13 ab

(-21.74)

9.38 d

(-50.32)

10.5 abc

(-1.22)

4.75

5.25 a

(-6.74)

Isoproturon @ 1 kg a.i. ha-1 at 30 DAS

31.63 d

(-60.65)

19.75 d

(-77.87)

9.13 d

(-65.08)

3.25 f

(-86.67)

15.38 b

(-2.35)

9.5 c

(-64.81)

1.13 c

(-94.01)

1.38 d

(-87.02)

0.00

0.00 c

(-100)

Hand weeding at 30 DAS

22.5 d

(-72.0)

41.13 c

(-53.92)

7.0 d

(-73.21)

15.75 e

(-35.40)

6.0 c

(-61.9)

8.5 c

(-68.52)

2.5 e

(-86.76)

6.13 cd

(-42.33)

4.38

1.63 bc

(-71.05)

L.S.D. (5%)

15.19

16.68

9.789

3.30

6.24

11.24

4.54

5.44

-

2.73

1 Means with different letters differ significantly at 5%; 2 in parenthesis % increase or decrease over control is shown; SorWE = Sorghum water extract conc.; SunWE = Sunflower water extract conc.; EuWE = Eucalyptus water extract conc.; DAS = Days after sowing; n.s. = non-significant.


 

reduction in sweet clover dry weight. Dry weight of broad-leaved dock was suppressed upto 100 and 86% by isoproturon and hand weeding, respectively followed by combination of water extracts each @ 12 L ha-1 and SunWE (two sprays) giving upto 72 and 65% control, respectively. Water extracts exhibited differential effects on wheat growth (Table 3). Isoproturon, SunWE (two sprays) and hand weeding were statistically similar treatments causing 31, 23 and 20% increase in leaf area index over control. This may be either due to better weed control by the three treatments and/or promoting effect by SunWE on wheat crop. Ghafar et al. (2000) also reported stimulatory and inhibitory effect of SunWE on wheat at different concentrations. Similarly higher number of grains per spike was obtained in isoproturon, combination of SorWE + SunWE + EuWE each @ 12 L ha-1 and SunWE (two sprays) treated plots (statistically similar treatments) giving 6, 4 and 3% increase over control. The other treatments were statistically similar to control; this may be due to concentration dependent and synergistic effects of various allelochemicals as described by Nandal et al. (1992), Rice et al. (1981) and Einhellig et al. (1982). Treatments yielding higher number of grains per spike yielded less 1000-grain weight e.g. it decreased very much in treatments like isoproturon, combination of water extracts each @ 12 L ha-1 and SunWE (two sprays). This is in accordance with the findings of Frederick and Camberato (1995) and Slafer and Andrade (1993) describing inverse relationship between grain number per spike and grain weight.

 

Isoproturon, SunWE (two sprays), hand weeding, combinations of SorWE + SunWE +EuWE each @ 16 and 12 L ha-1 were among the higher grain yield giving treatments. The maximum increase was achieved in isoproturon treated plot (6.4%) followed by SunWE (5.5%) confirming the results of Cheema et al. (1997) and Cheema and Khaliq (2000). Economic and marginal analyses (Table 4&5) show that SunWE concentrated applied @ 12 L ha-1 (two sprays at 30 and 40 DAS) was the most economical and best treatment with higher net benefits (Rs. 28395 ha-1) and maximum marginal rate of return (7797.5%). Combinations of SorWE + SunWE + EuWE each @ 8 and 12 L ha-1 were also economical treatments due to 6.6 and 523% marginal return, respectively. The other extracts were uneconomical and it is worthwhile to state here that EuWE @ 12 L ha-1 (two sprays) caused 19.8% reduction in wheat yield due to suppressive allelopathic effect. This is in accordance with findings of Bansal et al. (1992) reporting concentration dependent activity of eucalyptus against wheat. On the basis of present study it is suggested that using crop water extracts for controlling weeds is economical and environment friendly and combining water extracts at appropriate dose exerts positive influence on wheat.

 

Table 2: Effect of various plant water extracts on dry weight of different weed species.

Treatments

 

Dry weight (g 50 cm-2)

Total weeds

Canary grass

Wild oats

Sweet clover

Broad-leaved dock

45 DAS

60 DAS

45DAS

60 DAS

45 DAS

60 DAS

45 DAS

60 DAS

45 DAS

60 DAS

Control (weedy check)

0.4061 bcd

 

1.728 a

0.081 abc

0.548 a

0.225 a

0.718 abc

0.063 a

0.116 ab

0.018ns

0.091ns

SorWE @ 12 L ha-1 at 30 & 40 DAS

0.552 ab

(+ 35.96)2

1.881 a

(+8.85)

0.119 a

(+46.91)

0.608 a

(+10.95)

0.229 a

(+1.78)

0.95 a

(+32.31)

0.066 a

(+4.76)

0.085ab

(-26.72)

0.025

0.097

SunWE @ 12 L ha-1 at 30 & 40 DAS

0.397 bcd

(- 2.22)

1.799 a

(+4.1)

0.079 abc

(-2.47)

0.514 a

(-6.20)

0.186 ab

(-17.33)

0.748 ab

(+4.18)

0.04 ab

(-36.51)

0.138ab

(+18.96)

0.0063

0.069

EuWE @ 12 L ha-1 at 30 & 40 DAS

0.584 ab

(+43.84)

1.335 a

(-22.74)

0.113 a

(+39.51)

0.37 ab

(-32.48)

0.33 a

(+46.67)

0.445 cd

(-38.02)

0.066 a

(+4.76)

0.139 a

(+19.83)

0.023

0.073

SorWE + SunWE + EuWE each @ 6 L ha-1 at 30 DAS

0.722 a

(+77.83)

1.385 a

(-19.85)

0.113 a

(+39.51)

0.514 a

(-6.2)

0.206 a

(-8.44)

0.491 bcd

(-31.62)

0.053 a

(-15.87)

0.104ab

(-10.34)

0.011

0.056

SorWE + SunWE + EuWE each @ 8 L ha-1 at 30 DAS

0.349 bcd

(-14.04)

1.629 a

(-5.73)

0.091 ab

(+12.34)

0.589 a

(+7.48)

0.179 ab

(-20.44)

0.531 bcd

(-26.04)

0.066 a

(+4.76)

0.103ab

(-11.21)

0.013

0.051

SorWE + SunWE + EuWE each @ 12 L ha-1 at 30 DAS

0.431 bc

(+6.16)

1.504 a

(-12.96)

0.057 abc

(-29.63)

0.466 a

(-14.96)

0.158 ab

(-29.78)

0.733 abc

(+2.09)

0.049 a

(-22.22)

0.081ab

(-30.17)

0.005

0.06

SorWE + SunWE + EuWE each @ 16 L ha-1 at 30 DAS

0.424 bc

(+4.43)

1.136 ab

(-34.26)

0.114 a

(+40.74)

0.506 a

(-7.66)

0.216 a

(-4.0)

0.494 bcd

(-31.19)

0.033 abc

(-47.62)

0.076 b

(-34.48)

0.021

0.049

Isoproturon @ 1 kg a.i. ha-1 at 30 DAS

0.201 cd

(-50.49)

0.508 b

(-70.6)

0.03 bc

(-62.96)

0.0       C

(-100)

0.118 ab

(-47.56)

0.505 bcd

(-29.67)

0.0       C

(-100)

0.0       C

(-100)

0.0075

0.00

Hand weeding at 30 DAS

0.132 d

(-67.49)

0.44 b

(-74.54)

0.02 c

(-75.31)

0.049 bc

(-91.06)

0.058 b

(-74.22)

0.325 d

(-54.73)

0.008 bc

(-87.3)

0.01 C

(-91.38)

0.0038

0.013

L.S.D. (5%)

0.283

0.77

0.068

0.367

0.142

0.297

0.034

0.063

-

-

1 Means with different letters differ significantly at 5%; 2 in parenthesis % increase or decrease over control is shown; SorWE = Sorghum

water extract conc.; SunWE = Sunflower water extract conc.; EuWE = Eucalyptus water extract conc.; DAS = Days after sowing; n.s. = non-significant.

 

Table 3. Effect of various plant water extracts on growth parameters and yield of wheat.

Treatments

Leaf Area Index

No. of grains per spike

1000-grain weight (g)

Grain yield (t ha-1)

Control (weedy check)

2.571 b

51.53 cd

37.01 ab

4.038 c

SorWE @ 12 L ha-1 at 30 & 40 DAS

2.19 cd

(-14.75)2

52.0 cd

(+0.91)

36.81 abc

(-0.54)

4.102 bc

(+1.58)

SunWE @ 12 L ha-1 at 30 & 40 DAS

3.15 a

(+22.61)

53.25 ab

(+3.34)

34.81 d

(-5.94)

4.26 ab

(+5.50)

EuWE @ 12 L ha-1 at 30 & 40 DAS

2.60 b

(+1.10)

51.64 cd

(+0.21)

32.44 e

(-12.35)

3.24 d

(-19.76)

SorWE + SunWE + EuWE each @ 6 L ha-1 at 30 DAS

1.91 d

(-25.88)

52.66 bc

(+2.19)

35.74 bcd

(-3.43)

4.074 c

(+0.89)

SorWE + SunWE + EuWE each @ 8 L ha-1 at 30 DAS

2.20 c

(-14.51)

51.58 cd

(+0.10)

36.27 abcd

(-2.00)

4.083 c

(+1.11)

SorWE + SunWE + EuWE each @ 12 L ha-1 at 30 DAS

2.11 cd

(-18.09)

53.76 ab

(+4.33)

35.51 cd

(-4.05)

4.143 abc

(+2.60)

SorWE + SunWE + EuWE each @ 16 L ha-1 at 30 DAS

2.75 b

(+6.96)

50.31 d

(-2.37)

36.99 ab

(-0.05)

4.178 abc

(+3.47)

Isoproturon @ 1 kg a.i. ha-1 at 30 DAS

3.37 a

(+31.17)

54.58 a

(+5.92)

35.08 d

(-5.21)

4.298 a

(+6.44)

Hand weeding at 30 DAS

3.08 a

(+19.92)

50.56 d

(-1.88)

37.52 a

(+1.38)

4.205 abc

(+4.14)

L.S.D0.05

0.29

1.73

1.46

0.172

1 Means with different letters differ significantly at 5%; 2 in parenthesis % increase or decrease over control is shown; SorWE = Sorghum water extract conc.; SunWE = Sunflower water extract conc.; EuWE = Eucalyptus water extract conc.; DAS = Days after sowing; n.s. = non-significant.

 

Table 4. Economic analysis of different weed control methods in wheat.

 

T1

T2

T3

T4

T5

T6

T7

T8

T9

T10

Remarks

Total grain yield

4038

 

4102

4260

3240

4074

4083

4143

4178

4298

4205

kg ha-1

Adjusted yield

3634.2

 

3691.8

3834.0

2916.0

3666.6

3674.7

3728.7

3752.7

3868.2

3784.5

kg ha-1(10% reduction)

Gross income

(ha-1)

27256.5

27688.5

28755

21870

27499.5

27560.25

27965.25

28145.25

29011.5

28383.75

Wheat grain price

@ Rs. 750/100 kg

Cost of SorWE

-

100

-

-

-

-

-

-

-

-

Rs. 40/40 kg Sorghum herbage+ SorWE preparation

Cost of SunWE

-

-

100

-

-

-

-

-

-

-

Rs. 40/40 kg Sunflower herbage+ SunWE preparation

Cost of EuWE

-

-

-

80

-

-

-

-

-

-

Rs. 40/40 kg Eucalyptus leaves + EuWE preparation

Cost of mixture

-

-

-

-

125

155

220

250

-

-

combining respective doses of water extracts

Cost of

Herbicide

-

-

-

-

-

-

-

-

840

-

Rs. 840/1kg a.i.

Spray application cost

-

160

160

160

80

80

80

80

80

-

Rs. 80/man (one man /day/ha)

Spray rent

-

100

100

100

50

50

50

50

50

-

Rs. 50/spray

Cost of Hand weeding

-

-

-

-

-

-

-

-

-

800

Rs. 80/man and 10 men/ha

Cost that vary

-

360

360

340

255

285

350

380

970

800

Rs. ha-1

Net benefit

27256.5

27328.5

28395

21530

27244.5

27275.25

27615.25

27765.25

28041.5

27583.75

Rs. ha-1

T1 = Control (weedy check); T2 = SorWE @ 12 L ha-1 at 30 & 40 DAS; T3 =SunWE @ 12 L ha-1 at 30 & 40 DAS;T4 = EuWE @ 12 L ha-1 at 30 & 40 DAS; T5 = SorWE +SunWE + EuWE each @ 6 L ha1 at 30 DAS; T6 = SorWE +SunWE + EuWE each @ 8 L ha-1 at 30 DAS; T7 = SorWE + SunWE + EuWE each @ 12 L ha-1 at 30 DAS; T8 = SorWE + SunWE + +EuWE each @ 16 L ha-1 at 30 DAS; T9 = Isoproturon @ 1kg a.i. ha-1 at 30 DAS; T10 = Hand weeding at 30 DAS

 

Table 5: Marginal analysis of different weed control methods in wheat.

Treatments

Varying Costs

(Rs. Ha-1)

Net benefit

(Rs. ha-1)

Marginal rate of return (%)

Control

0

27256.5

 

SorWE + SunWE + EuWE each @ 6 L ha-1

255

27244.5

D

SorWE+ SunWE+ EuWE each @ 8 L ha-1

285

27275.25

6.58

EuWE two sprays

340

21530

D

SorWE + SunWE + EuWE each @ 12 L ha-1

350

27615.25

523.08

SunWE two sprays

360

28395.0

7797.5

SorWE two sprays

360

27328.5

D

SorWE + SunWE + EuWE each @ 16 L ha-1

380

27765.25

D

Hand weeding

800

27583.75

D

Isoproturon

970

28041.5

D

D = Dominated;Marginal rate of return (MRR) % = Change in net benefits/Change in cost x 100; Cost that vary = The cost that is incurred on the variable inputs (weed control measures) in the production of a particular commodity (wheat);.SorWE= Sorghum water extract conc.; SunWE = Sunflower water extract conc.;EuWE = Eucalyptus water extract conc.; DAS = Days after sowing.

 

REFERENCES CITED

 

Bansal, G.L., H. Nayyar and Y.S. Bedi. 1992. Allelopathic effect of Eucalyptus macrorrhyncha and E. youmanii  on seedling growth of wheat (Triticum aestivum)  and radish (Raphanus sastivus). Indian J. Agric. Sci. 62 (11): 771-772. [W.B.T.A., 11(6): 758; 1994].

 

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[1] Department of Agronomy, University of Agriculture, Faisalabad, Pakistan. E-mail: zachemma@pakwatan.com.

 

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Department of Weed Science
NWFP Agricultural University Peshawar, 25130 Pakistan