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https://doi.org/10.26651/allelo.j/2021-53-1-1327 0971-4693/94 Euro 20.00
Allelopathy Journal 53 (1): 53-68 (May, 2021) International Allelopathy Foundation 2021
Tables: 6, Figs : 5
*Correspondence author, 2Department of Land Management, 3Department of Plant Protection,
Universiti Putra Malaysia (UPM), Serdang, Selangor, Malaysia, 4Department of Agronomy,
Bangladesh Agricultural University (BAU), Mymensingh-2202, Bangladesh.
Allelopathic potential of Malaysian invasive weed species on
Weedy rice (Oryza sativa f. spontanea Roshev)
Mst. Motmainna1, Abdul Shukor B Juraimi1*, Md. Kamal Uddin2,
Norhayu Binti Asib3, A. K. M. Mominul Islam4 and Mahmudul Hasan1
Department of Crop Science, Universiti Putra Malaysia (UPM),
Serdang, Selangor, Malaysia
E. Mail: ashukur@upm.edu.my; motmainnamou4@gmail.com
(Received in revised form: December 14, 2020)
ABSTRACT
In laboratory bioassay, we studied the effects of methanolic extracts of 30-Malaysian
invasive weed species (9 families) on the seeds survival rate and seedlings growth of Weedy rice
(Oryza sativa f. spontanea Roshev). Five concentrations [6.25, 12.5, 25, 50, 100 (g L-1)] of
methanolic extracts were used and control was distilled water. The Weedy rice seeds survival
rate and seedlings growth (radicle and hypocotyl length) of 7-day-old seedlings were reduced by
the increasing concentrations of extracts than control. Probit analysis and the concentrations
required for 50% inhibition (EC50) showed that radicle growth was more suppressed than seeds
survival rate and hypocotyl growth. Among the tested weed species, Parthenium hysterophorus
L., Cleome rutidosperma DC. and Borrreria alata (Aubl.) DC. proved strongly allelopathic and
thus, could be used to develop eco-friendly herbicides.
Keywords: Allelopathy, Borrreria alata, Cleome rutidosperma, eco-friendly, herbicidal
potential, invasive weeds, methanolic extracts, Oryza sativa f. spontanea,
Parthenium hysterophorus, weed management, Weedy rice.
INTRODUCTION
Invasive weed species are threat to the biodiversity. Several mechanism including
life history, physiological nature and rapid genetic changes are responsible for the plant
invasion (16). The allelopathy is potential mechanism behind the success of non-native
invasive weeds by producing new chemicals (24,37). Invasive weed species secrete
allelochemicals which may have negative effect on associated species.
Weedy rice (Oryza sativa f. spontanea) is most troublesome weed in rice fields
(21) and reduces rice yields from 5-100 % depending on the infestation in many countries
including Malaysia (6,10,22,45). Its first infestation was recorded in 1988 in Malaysia
(24). It is also known as red rice (genus Oryza) which competes with cultivated rice and
other crops. Weedy rice and cultivated rice possess similar characteristics and is most
harmful in direct seeded rice (10).
Recently, allelopathy has received much attention for managing weeds.
Allelopathic interactions can be used either directly or indirectly by using the
allelochemicals based herbicides (13). Allelopathy is the positive or negative impact of
one plant on the germination and development of associated plants (42,51). The plants
54 Motmainna et al
release allelochemicals in environment through volatilization, leachate, root exudates and
decompo-
Figure 1. Donor plant Oryza sativa f. spontanea Roshev
sing biomass (1,54). Allelochemicals have short half-life than synthetic herbicides and
thus are considered safe for environmental toxicology (38). Yousaf et al. (56) reported that
several allelopathic plants have herbicidal effects on weeds. Aslani et al. (4) reported that
the application of Tinospora tuberculata extracts significantly inhibited the germination,
hypocotyl and radicle length of weedy rice but also slightly inhibited the rice growth.
Decomposed tissue extract of Scirpus grossus at higher concentrations inhibited seedling
growth of Weedy rice (28).
Figure 2. Invasive weeds with highest herbicidal activity to weedy rice.
However, the studies on invasive weeds to identify their possible allelopathic
effects are inadequate. In Malaysian agro-ecosystems, there are 100 invasive weed species
(7). Hence, this study aimed to evaluate the herbicidal effects of selected invasive weed
species on the growth and development of Weedy rice.
MATERIALS AND METHODS
Location of the experiment
The experiment was conducted during January to March 2019 in growth chamber,
Department of Crop Science, Faculty of Agriculture, Universiti Putra Malaysia (3° 02' N,
101°42' E, 31 m elevation), Selangor, Malaysia.
Collection of plant materials: Whole plants of 30 invasive weed species [(broadleaves,
sedges and grasses from 9- families (Table 1)] were collected during the vegetative stage
from Universiti Putra Malaysia and Ladang Infoternak, Sungai Siput, Perak, Malaysia.
Allelopathic potential of Malaysian invasive weed spp on weedy rice 55
Seeds collection: Weedy rice seeds were collected from the rice field of Sekinchan, Kuala
Selangor, Selangor, Malaysia. After collection, the seeds were cleaned, dried and stored at
4°C in refrigerator. To break cold dormancy, before sowing seeds were kept for 1 h each in
sun and shade.
Test plant: Seeds of Weedy rice were used as test plant owing to its quick germination and
high sensitivity to phytochemicals at lower concentration.
Extraction procedure: The collected weeds were washed carefully with running tap water
to remove the dust particles and air dried for 3 weeks. Then each species was chopped and
powdered by grinder. One-hundred g powder of each species was soaked in 1000 mL of
80 % aqueous methanol into a conical flask and paraffin was used to wrap the flask. The
flask was shaken in an orbital shaker for 48 h at room temperature (24-26 ℃). The solution
was filtered through four layers of cheese cloth to remove debris and centrifuged for 1 h at
3,000 rpm then re-filtered using a 0.2-μ, 15-mm syringe filters (Phenex, Non-sterile,
Luer/Slip, LT Resources, Malaysia). The collected supernatant was evaporated by rotary
evaporator at 40 ℃. The dried residue were weighed and converted to % as under:
Extraction (%) = [Extract weight (g)/ powder weight (g)] × 100
Each stock extract was diluted with sterile distilled water to get 6.25, 12.5, 25, 50,100 g L-1
concentrations of extract for bioassay. All extracts were stored in the dark at 4 oC in
refrigerator until used. The methanol extracts were prepared as per Aslani et al. (4).
Laboratory bioassays
Healthy and uniform seeds of Weedy rice were sterilized by immersing for 24 h in
0.2 % potassium nitrate (KNO3) and then rinsed thrice with distilled water. Twenty
uniform pre-germinated seeds of Weedy rice per sterilized Petri dish (90×15 mm) were
sown equidistant on two layers of filter paper. Each Petri dish was moistened with 10 mL
extracts (6.25, 12.5, 25, 50 and 100 g L-1) as per treatments and distilled water was used as
control. The treatments were replicated 5- times in completely randomized design. The
Petri dishes were kept in growth chamber (fluorescent light (8500 lux), 12h/12h (day/night
cycle), temp: 30/20℃ (day/night) and Relative humidity: 30 to 50 %. The lids of the Petri
dishes were not sealed to allow gas exchange and to avoid the anaerobic condition. The
petri plates were incubated until 1 mm long radicle emerged from the seed coat.
Survival rate (%), radicles and hypocotyls length were measured after 7 days. The
hypocotyl and radicle length of Weedy rice were photographed and measured using Image
J software (35) and the inhibitory effects of selected 30-invasive weed species on weedy
rice radicles and hypocotyls lengths were measured as under (4):
I=100 (C-A)/C
Where, I: Inhibition (%), C: radicles and hypocotyls lengths in control and A:
radicles and hypocotyls lengths in methanol extracts.
56 Motmainna et al
Table 1. List of 30- invasive weeds used in this study
No.
Botanical name
Family
Crop
Yield
reduction (%)
References
Broadleaf weeds
1
Amaranthus lividus L.
Amaranthaceae
Cucumber
10 %
9
2
Asystasia gangetica L.
Acanthaceae
Oil palm
25 %
3
3
Borrreria alata (Aubl.)
DC.
Asteraceae
Maize
70 to 97 %
8
4
Cleome rutidosperma DC.
Cleomaceae
Sugarcane
15 % to 55 %
20
5
Croton hirtus L'Her.
Euphorbiaceae
Cassava
90 %
17
6
Euphorbia hirta L.
Euphorbiaceae
Field
crops
4-85 %
53
7
Hyptis capitata Jacq.
Lamiaceae
Maize
60-81 %
23
8
Lindernia crustacea (L.)
F.Muell.
Linderniaceae
Field
crops
51 %
27
9
Parthenium hysterophorus L.
Asteraceae
Maize
21 to 50 %
48
10
Xanthium indicum DC.
Asteraceae
Cotton
6 to 27 %
47
Sedge weeds
11
Cyperus difformis L.
Cyperaceae
Rice
12−50 %
40
12
Cyperus digitatus Roxb.
Cyperaceae
Rice
86% to 93 %
52
13
Cyperus esculentus L.
Cyperaceae
Rice
41 %
29
14
Cyperus pilosus Vahl
Cyperaceae
Rice
50 to 91 %
52
15
Fimbristylis globulosa
(Retz.) Kunth
Cyperaceae
Rice
25 %
34
16
Fimbristylis miliaceae (L.)
Vahl
Cyperaceae
Rice
44 to 96 %
34
17
Rhynchospora corymbosa
(L.) Britton
Cyperaceae
Rice
28–74 %
46
18
Scirpus grossus L.f.
Cyperaceae
Rice
33 %
42
19
Scirpus mucronatus L.
Cyperaceae
Rice
10 to 35 %
42
20
Scleria sumatrensis Retz.
Cyperaceae
Rice
15 to 23 %
12
Grass weeds
21
Brachiaria mutica (Forssk.)
Stapf
Poaceae
Sugarcane
65.3 %
50
22
Digitaria ciliaris (Retz.)
Koeler
Poaceae
Corn
99 %
27
23
Ischaemum rugosum
Salisb.
Poaceae
Rice
50 to 60 %.
42
24
Leersia hexandra Sw.
Poaceae
Rice
30-40 %
2
25
Leptochloa chinensis (L.)
Ness
Poaceae
Rice
10-35 %
19
26
Ottochloa nodosa (Kunth)
Dandy
Poaceae
Oil palm
6 to 20 %
49
27
Panicum repens L.
Poaceae
Sugarcane
50 %
43
28
Paspalum conjugatum P.J.
Bergius
Poaceae
Oil palm
6 to 20 %
49
29
Paspalum distichum L.
Poaceae
Rice
80 %
44
30
Parapholis incurve L.
Poaceae
Rice
30 to 40 %
41
Allelopathic potential of Malaysian invasive weed spp on weedy rice 57
Statistical analysis
A two-way analysis of variance (ANOVA) was carried out to determine any
significant difference between each treatment and the control, the differences among the
treatment means were grouped using the Tukey test at 0.05 probability level. The software
SAS (statistical analysis system) (version 9.4) was used to conduct the analysis. ECs50,
ECr50, and ECh50 are the effective doses which inhibited 50% of seeds germination, radicle
and hypocotyl length respectively. Probit analysis based on inhibition (%) of survival rate,
radicle and hypocotyl length was used to measure the ECs50, ECr50, and ECh50. The most
active extracts Rank (Re) was calculated using the equation given below (4):
Rank (Re) = ECs50n (Survival rate) + ECr50n (Radicle) + ECh50n (Hypocotyl)
The extracts with the lowest Re values were the most phytotoxic.
RESULTS AND DISCUSSION
Seeds survival rate of Weedy rice
The methanol extracts of 30 invasive weed species significantly inhibited the
survival rate of Weedy rice (Table 2). The inhibitory effect of P. hysterophorus, C.
rutidosperma and B. alata extracts were significantly higher than other invasive weed
species (Figure 3). The lowest survival rate of weedy rice was at the maximum
concentration of extract (100 g L-1) and the highest survival rate was in control (distilled
water). The extracts concentrations were responsible to inhibit the survival rate of Weedy
rice. The invasive weeds confirmed allelopathic potential with significant variation
between themselves. The highest concentration (100 g L-1) of P. hysterophorus and C.
rutidosperma extracts prevented the survival rate of Weedy rice seed (100 % inhibition),
while, B. alata caused 83 % inhibition (Table 3). While the lowest conc (6.25 g L-1) of all
extracts except P. hysterophorus did not inhibit the seed germination of Weedy rice. The
maximum mean inhibition of Weedy rice seed survival rate caused by the extracts
followed the order: P. hysterophorus (56.17 %) > C. rutidosperma (45.17 %) > B. alata
(40.17 %) > L. chinensis (7.83 %). In contrast, the C. pilosa and L. hexandra extracts
at 100 g L-1 caused only 35 % inhibition in seed germination of Weedy rice.
Experimental results showed that out of thirty invasive weed species P.
hysterophorus, C. rutidosperma and B. alata strongly influenced germination ability of
Weedy rice by more than 90%.P. hysterophorus and C. rutidosperma completely inhibited
(100%) the germination at higher concentration. The extracts of P. hysterophorus residues
were rich in allelochemicals and exhibited phytotoxicity to the crops (30). Ladhari et al.
(32) reported that 11-α-acetylbrachy-carpone-22(23)-ene was the most phytotoxic
compound of Cleome arabica could be used for controlling different weeds on crop.
According to Azairak and Karaman (5), extracts effectiveness against seed germination
was active only at high concentration and not at low concentrations.
58 Motmainna et al
Table 2. Analysis of Variance (ANOVA) of inhibition (%) of methanol extracts of 30- invasive weed
species on weedy rice
Germination
Hypocotyl length
Radicle length
Source
df
F
p
F
p
F
p
Plant species
29
193.36
<.0001
190.92
<.0001
91.57
<.0001
Concentrations
5
3913.36
<.0001
6080.86
<.0001
3263.78
<.0001
Plant species x
Concentrations
145
26.32
<.0001
18.49
<.0001
7.39
<.0001
Seedlings growth of Weedy rice
Hypocotyl length: The hypocotyl length inhibition of Weedy rice seeds varied
significantly in their response to examine extracts (Table 2). All methanol extracts resulted
in remarkable reduction in hypocotyl growth of Weedy rice and the degree of reduction
increase as the extract concentration increase (Table 4). Highly significant difference was
obtained by using methanol extracts of P. hysterophorus, C. rutidosperma and B. alata on
the hypocotyl length of Weedy rice. Hypocotyl length of Weedy rice was most negatively
affected by P. hysterophorus extracts, followed by C. rutidosperma and B.
alata(Fig. 4).The inhibitory effects ranged between 4.53% (C. hirtus) to 33.90% (P.
hysterophorus) at lowest concentration (6.25 g L-1) and 47.05% (P. conjugatum) and 100%
(P. hysterophorus) at highest concentration (100 g L-1). By increasing the concentration to
100 g L-1, extracts of P. hysterophorus and C. rutidosperma werecompletely inhibited
hypocotyl length of Weedy rice. For each extract, shorter hypocotyl length was observed
at higher concentration (100 g L-1).
The highest concentration (100 g L-1) of P. hysterophorus and C. rutidosperma
extracts prevented the germination of Weedy rice seed (100 % inhibition), hence, there
was no hypocotyl growth. But B. alata caused 90 % reduction (Table 4). On the other
hand, growth inhibition by extracts at high concentration and stimulation at very low
concentration could be due to hormesis (11). Hormesis is the stimulatory activity of any
compound at low doses (15). Some plant hormones increase the hypocotyl and radicle
lengths at lower doses, but were inhibitory at higher doses (15), however, these hormones
could be affected by some allelochemicals.
Radicle length: The methanolic extracts of 30-Malaysian invasive weeds significantly
influenced the radicle length of Weedy rice (Table 2). The highest concentration of
P. hysterophorus (100 %), C. rutidosperma (100 %) and B. alata (94.35 %) methanol
extracts significant decreased the radicle length of Weedy rice (Table 5). At lowest
concentration (6.25 g L-1), the inhibitory effects followed the order: 62.37 %
(P. hysterophorus)> 51.61 % (C. rutidosperma) >49.43 % (B. alata) >0.25 % (X. indicum).
The inhibition in radicle length was increased with the increased concentration of extracts.
The methanolic extracts of invasive weeds species were most inhibitory to radicle length
than hypocotyl length. At the highest concentration (100 g L-1) the P. hysterophorus and
C. rutidosperma methanolic extracts completely inhibited the hypocotyl and radicle
lengths of Weedy rice seedlings. Because these both weeds at 100 g L-1 concentration
prevented the seeds survival rate of Weedy rice. However, the S. mucronatus extracts at
the highest concentration (100 g L-1) caused radicle length inhibition of only 55.55 %.
Allelopathic potential of Malaysian invasive weed spp on weedy rice 59
60 Motmainna et al
Table 3. Inhibitory effects of methanol extracts of 30- invasive weed species on survival rate
inhibition (%) of Weedy rice
Sl.
No.
Donor Weed
Inhibition (%) at various concentrations of methanol extracts
6.25g L-1
12.5 g L-1
25 g L-1
50 g L-1
100 g L-1
1
P. hysterophorus (B)
13.00a
51.00a
80.00a
93.00a
100.00a
2
C. rutidosperma (B)
4.00b
26.00b
56.00b
85.00ab
100.00a
3
B. alata (B)
3.00bc
19.00bc
49.00b
77.00bc
93.00ab
4
F. miliacea (S)
0.00c
14.00cd
36.00c
54.00de
77.00cd
5
P. distichum (G)
1.00bc
10.00cde
24.00de
62.00cd
80.00bcd
6
C. hirtus (B)
0.00c
7.00def
25.00cde
41.00ef
79.00bcd
7
C. difformis (S)
0.00c
9.00def
25.00cde
44.00ef
67.00de
8
A. gangetica (B)
0.00c
1.00ef
11.00f-j
45.00ef
86.00abc
9
A. lividus(B)
0.00c
9.00def
12.00f-j
32.00f-j
77.00cd
10
L. crustacean (B)
0.00c
8.00def
26.00cd
41.00ef
53.00e-i
11
F. globulosa (S)
0.00c
4.00ef
17.00d-h
35.00fgh
60.00ef
12
S. grossus (S)
0.00c
3.00ef
21.00def
37.00fg
48.00f-k
13
O. nodosa (G)
0.00c
4.00ef
14.00e-i
32.00f-j
58.00efg
14
D. ciliaris (G)
1.00bc
8.00def
12.00f-j
19.00i-m
60.00ef
15
R. corymbosa (S)
0.00c
5.00def
18.00d-g
34.00f-i
43.00g-k
16
P. incurve (G)
0.00c
3.00ef
10.00f-j
31.00f-k
55.00e-h
17
P. repenes (G)
0.00c
5.00def
11.00f-j
23.00g-l
54.00e-i
18
S. mucronatus (S)
0.00c
4.00ef
12.00f-j
24.00g-l
46.00f-k
19
I. rugosum (G)
0.00c
2.00ef
5.00ij
31.00f-k
46.00f-k
20
C. esculentus (S)
0.00c
1.00ef
6.00hij
23.00g-l
50.00f-k
21
H. capitata (B)
0.00c
6.00def
9.00g-j
22.00g-l
39.00ijk
22
P. conjugatum (G)
0.00c
4.00ef
9.00g-j
12.00lm
51.00f-j
23
C. digitatus (S)
0.00c
1.00ef
4.00ij
18.00j-m
49.00f-k
24
B. mutica (G)
0.00c
0.00f
6.00hij
16.00klm
47.00f-k
25
X. indicum (B)
0.00c
2.00ef
9.00g-j
17.00klm
41.00h-k
26
S. sumatensis (S)
0.00c
0.00ef
5.00ij
20.00h-m
37.00jk
27
L. hexandra (G)
0.00c
2.00ef
5.00ij
17.00j-m
35.00k
28
E. hirta (B)
0.00c
1.00ef
4.00ij
9.00lm
40.00h-k
29
C. pilosus (S)
0.00c
1.00ef
2.00j
11.00lm
35.00k
30
L. chinensis (G)
0.00c
2.00ef
3.00ij
6.00m
36.00jk
Mean inhibition
0.73e
7.07d
17.53c
33.70b
58.07a
Data are expressed as mean inhibition. Means with same letters in the column for each concentration
of invasive weed extract is not significantly different at p < 0.05. A value with same letter in the row
for concentrations mean inhibition is not significantly different. Here,
B: Broadleaf weed, G: Grass weed, S: Sedge weeds. 6.25: 0.625%, 12.5: 1.25%, 25: 2.5%, 50: 5.0%,
100: 10.0%
Allelopathic potential of Malaysian invasive weed spp on weedy rice 61
Table 4. Inhibitory effects of methanol extracts of 30-invasive weed species on hypocotyl length
inhibition (%) of Weedy rice
Sl.
No.
Donor Weed
Inhibition (%) at various concentrations of methanol extracts
6.25 g L-1
12.5 g L-1
25 g L-1
50 g L-1
100 g L-1
1
P. hysterophorus (B)
33.90a
69.63a
84.57a
95.08a
100a
2
C. rutidosperma (B)
27.55ab
53.28b
80.11a
84.58ab
100a
3
B. alata (B)
18.64bcd
43.77c
58.62b
76.71bc
90.59b
4
P. distichum (G)
19.60bc
39.55cd
53.99b
60.69de
77.18c
5
F. miliacea (S)
19.08bc
29.26e-h
51.42bc
68.44cd
80.02c
6
A. lividus (B)
17.74b-e
32.04de
53.78b
62.93de
81.07c
7
C. hirtus (B)
4.53g
39.40cd
54.70b
64.66cde
81.55c
8
C. difformis (S)
16.69b-f
22.39g-k
55.76b
67.97cd
78.06c
9
A. gangetica (B)
15.57b-g
31.68def
40.14d
71.70bcd
81.57c
10
F. globulosa (S)
17.67b-e
26.80e-j
40.67cd
69.22cd
76.95c
11
C. pilosus (S)
8.07c-g
20.57i-l
40.44d
61.86de
77.53c
12
L. crustacean (B)
6.68d-g
30.30efg
41.17cd
54.27ef
59.79d-g
13
C. digitatus (S)
11.01c-g
27.24e-j
34.94def
53.74ef
64.11d
14
L. hexandra (G)
17.00b-f
28.27e-i
36.89def
44.75fgh
55.70ghi
15
H. capitata (B)
17.39b-e
21.17h-l
32.38d-g
42.50fgh
62.92de
16
E hirta (B)
5.05fg
19.67jkl
38.52de
52.39efg
58.70d-g
17
B. mutica (G)
10.60c-g
23.09f-l
38.29de
41.87fgh
58.95d-g
18
X. indicum (B)
12.87c-g
20.28i-l
33.92def
41.16fgh
62.88def
19
L. chinensis (G)
17.34b-e
21.58h-l
32.74d-g
45.03fgh
52.23hij
20
I. rugosum (G)
9.14c-g
18.79jkl
36.62def
46.04fgh
57.47e-i
21
S. mucronatus (S)
10.61c-g
21.60h-l
38.47de
40.31gh
54.72ghi
22
S. sumatensis (S)
18.29bcd
21.23h-l
27.22fg
44.13fgh
54.69ghi
23
P. repenes (G)
12.45c-g
19.48jkl
35.03def
39.10h
57.39f-i
24
O. nodosa (G)
11.14c-g
19.09jkl
28.09efg
41.54fgh
57.71e-h
25
P. conjugatum (G)
13.89c-g
21.44h-l
36.41def
37.95h
47.05j
26
P. incurve (G)
6.57d-g
20.79h-l
30.94d-g
42.45fgh
55.91ghi
27
S. grossus (S)
16.52b-g
24.72e-j
28.54efg
34.12h
47.79j
28
R. corymbosa (S)
8.34c-g
20.37i-l
28.20efg
36.44h
56.05ghi
29
D. ciliaris (G)
11.06c-g
17.16kl
27.21fg
39.84gh
52.16ij
30
C. esculentus (S)
5.77efg
14.98l
22.86g
42.54fgh
56.15ghi
Mean inhibition
14.03e
27.32d
41.42c
53.45b
66.56a
Data are expressed as mean inhibition. Means with same letters in the column for each concentration
of invasive weed extract is not significantly different at p < 0.05. A value with same letter in the row
for concentrations mean inhibition is not significantly different. Here,
B: Broadleaf weed, G: Grass weed, S: Sedge weeds. 6.25: 0.625%, 12.5: 1.25%, 25: 2.5 %, 50:
5.0%, 100: 10.0% .
62 Motmainna et al
Table 5. Inhibitory effects of methanol extracts of thirty invasive weed species on radicle length
inhibition (%) of Weedy rice
Sl.
No.
Donor Weed
Inhibition (%) at various concentrations of methanol extracts
6.25 g L-1
12.5 g L-1
25 g L-1
50 g L-1
100 g L-1
1
P. hysterophorus (B)
62.37a
71.84a
88.76a
92.28a
100.00a
2
C. rutidosperma (B)
51.61ab
67.09ab
79.62a
88.30a
100.00a
3
B. alata (B)
49.43abc
52.51bcd
56.24bc
83.89ab
94.35ab
4
C. difformis (S)
35.00b-f
50.63bcd
61.08b
72.68bc
84.81bc
5
C. hirtus (B)
40.15bcd
53.45abc
56.95b
64.61c-f
71.21d-g
6
F. miliacea (S)
28.79c-h
46.48c-g
55.16bcd
68.73cde
83.86c
7
F. globulosa (S)
26.27d-i
51.79bcd
55.63bcd
71.60c
76.97cd
8
P. distichum (G)
28.85c-g
47.85cde
55.59bcd
63.12c-g
85.40bc
9
A. gangetica (B)
37.09b-e
46.46c-g
52.51b-e
64.00c-g
75.15cde
10
C. digitatus (S)
27.29d-h
46.69c-g
56.04bcd
64.84c-f
78.03cd
11
C. esculentus (S)
15.95e-j
49.68b-e
57.79b
67.98cde
76.34cd
12
A. lividus (B)
25.36d-i
39.10cd-j
57.51b
64.48c-g
72.51def
13
B. mutica (G)
19.72d-j
47.41c-f
53.73bcd
64.20c-g
70.90d-g
14
L. crustacea (B)
26.97d-h
48.95b-e
54.16bcd
58.54e-j
65.10e-i
15
L. chinensis (G)
18.61d-j
41.30c-i
44.08c-f
61.62c-i
78.34cd
16
I. rugosum (G)
10.65g-c
26.35h-k
56.36bc
71.31cd
77.18cd
17
C. pilosus (S)
12.81g-j
40.83c-i
56.27bc
59.79d-i
71.48d-g
18
E. hirta (B)
26.40d-i
29.31f-k
54.72bcd
63.36c-i
68.06d-h
19
P. incurve (G)
8.29g-j
42.82c-h
54.68bcd
62.90c-h
70.46d-g
20
P. repenes (G)
11.40g-j
34.99c-k
55.04bcd
62.39c-h
70.86d-g
21
P. conjugatum (G)
13.28g-j
28.46g-k
38.60fg
54.92f-j
68.42d-g
22
X. indicum (B)
0.251j
31.46e-k
52.46b-e
55.98f-j
61.75ghi
23
O. nodosa (G)
8.53g-j
34.30d-k
40.97efg
54.92f-j
62.90f-i
24
S. grossus (S)
13.34f-j
31.30e-k
40.80efg
55.42f-j
64.57fi
25
R. corymbosa (S)
4.72ij
26.48h-k
43.81def
50.03g-k
62.55f-i
26
H. capitata (B)
13.23g-j
21.10jkl
34.22fgh
54.19f-k
63.15f-i
27
S. sumatensis (S)
7.11hij
19.35kl
35.27fgh
50.95ijk
59.71hi
28
S. mucronatus (S)
8.46g-j
20.04kl
36.75fg
51.49h-k
55.55i
29
L. hexandra (G)
8.17g-j
24.14i-l
23.71h
43.22k
63.82f-i
30
D. ciliaris (G)
2.89j
5.82l
30.77gh
48.01jk
65.33e-i
Mean inhibition
21.43e
39.27d
51.31c
63.06b
73.29a
Data are expressed as mean inhibition. Means with same letters in the column for each concentration
of invasive weed extract is not significantly different at p < 0.05. A value with same letter in the row
for concentrations mean inhibition is not significantly different. Here,
B: Broadleaf weed, G: Grass weed, S: Sedge weeds. 6.25: 0.625%, 12.5: 1.25%, 25: 2.5 %, 50:
5.0%, 100: 10.0%
Allelopathic potential of Malaysian invasive weed spp on weedy rice 63
The radicle length of Weedy rice was inhibited more than 90% at the
concentration of 50 g L-1. At 100 g L-1 concentration, out of thirty invasive weed species P.
hysterophorus and C. rutidosperma showed complete inhabitation while B. alata exhibited
more than 90% inhibition of radicle length of Weedy rice (Figure 5). The results
confirmed that radicle length inhibition was more significant than hypocotyl length
inhibition of Weedy rice. Generally, radicle is more sensitive compare to hypocotyl
because as a first organ radicle absorb phytotoxic compounds from extract concentration
and also these phytotoxic compounds exhibit higher permeability into radicle tissue
compare to hypocotyl (25). The stronger harmful effects of invasive weed species extract
on radicle growth could be
Table 6. Comparison of allelopathic activity of 30 invasive weed species extract
Sl.
No.
Invasive weed extract
ECs50
ECh50
ECr50
Allelopathic
activity Rank
Values in g L-1
1
P. hysterophorus (B)
13.47
8.72
4.43
I
2
C. rutidosperma (B)
21.88
11.67
6.38
II
3
B. alata(B)
27.55
17.90
7.94
III
4
P. distichum(G)
43.05
24.80
17.62
I V
5
F. miliaceae (S)
42.97
25.35
17.23
V
6
C. hirtus (B)
51.93
26.47
12.70
VI
7
A. gangetica (B)
52.92
27.00
17.06
VII
8
C. difformis (S)
58.48
27.13
13.20
VIII
9
A. lividus (B)
62.84
25.42
22.48
IX
10
F. globulosa (S)
74.23
29.59
16.96
X
11
P. incurve(G)
85.62
70.06
28.17
XI
12
L. crustacea (B)
74.98
46.76
21.81
XII
13
C. digitatus (S)
103.97
47.05
18.62
XIII
14
I. rugosum (G)
100.03
61.25
27.03
XIV
15
B. mutica (G)
107.82
62.20
22.96
XV
16
C. esculentus (S)
98.60
74.74
20.15
XVI
17
O. nodosa (G)
80.01
72.26
42.85
XVII
18
P. repens (G)
96.33
71.50
29.37
XVIII
19
C. pilosus(S)
146.44
35.49
26.36
XIX
20
E. hirta (B)
135.39
52.99
25.35
XX
21
R. corymbosa (S)
104.32
80.80
45.52
XXI
22
X. indicum(B)
132.58
59.61
40.00
XXII
23
D. ciliaris (G)
93.84
89.10
55.97
XXIII
24
S. mucronatus (S)
111.66
71.50
58.43
XXIV
25
S. sumatrensis (S)
128.50
71.23
54.69
XXV
26
H. capitata (B)
145.40
61.20
48.76
XXVI
27
P. conjugatum (G)
115.32
106.46
40.24
XXVII
28
L. chinensis (G)
162.79
80.39
26.60
XXVIII
29
S. grossus (S)
87.51
145.12
40.68
XXIX
30
L. hexandra (G)
153.45
66.24
60.87
XXX
Rank (Re)
2713.88
1650
874.83
64 Motmainna et al
ECs50, ECh50 and ECr50 are the concentration of extracts that inhibits 50 % of survival rate, hypocotyl
and radicle respectively.
described by the higher absorption of allelopathic substances through radicle in close
contact with the extracts. Allelochemicals reduce radicle development by disturbing genes
which are responsible for cellular characterization of ground tissue and endoderm (12). On
the other hand many researchers found low mitotic divisions were responsible for higher
root inhibition (26,31,39).
Allelopathic activity of 30 invasive weed species extracts
The half effective concentrations of each tested extract for Weedy rice have been
given in Table 6. The extracts derived from different invasive weeds exhibited variable
inhibitory effects on the seed survival rate and seedling growth of Weedy rice. The
differences were evident from the rank values of extracts. P. hysterophorus,
C. rutidosperma and B. alata showed highest inhibitory effects. Weedy rice proved most
sensitive to the methanol extract of P. hysterophorus, C. rutidosperma and B. alata.
Thereafter, the rank values of L. hexandra are 10 times more than P. hysterophorus. From
30 invasive weed species P. hysterophorus had the lowest EC50, indicating P.
hysterophorus had the highest allelopathic potential.
The comparison of rank values (Re) of all extracts on survival rate, hypocotyl and
radicle growth indicated that radicles were more sensitive than other growth parameters.
The tested extracts significantly inhibited the radicle development of Weedy rice. The
Weedy rice calculated value of ECr50 (Radicle length) was 4.43 g L-1 for P. hysterophorus
extract, while, the ECh50 (Hypocotyl length) value was 8.72 g L-1. The inhibitory effects of
extracts indicate that the absorption of allelochemicals through radicles was higher than
the hypocotyl. Similar result was also reported by Aslani et al. (4) and found that the ECr50
value was 19.80 g L-1 while the ECh50 value was 49.10 g L-1 for rice seeds when treated
with methanol extract of Tinospora tuberculata. Stronger allelopathic effects of extracts on
radicle have been reported by Meksawat and pornprom (33). Therefore, the herbicidal
potential of extracts can be evaluated through root index. Theranking for most sensitive
extracts according to Re value was P. hysterophorus< C. rutidosperma < B. alata.
Therefore, Weedy rice is most sensitive to P. hysterophorus and C. rutidosperma extract
than other extracts for all measured parameters.
The results confirmed the allelopathic effects of 30-invasive weed species on the
survival rate and seedlings growth of Weedy rice. The present findings are similar to
Valcheva et al. (55) who reported that extracts of 10 invasive weed species applied to
Lactuca sativa and showed higher suppressive effects on germination and initial growth.
Germination and initial development of E. crus-galli was suppressed effectively by the
application of methanol extracts of T. tuberculata (4). Pannacci et al. (39) found that
mugwort extract inhibited the germination, hypocotyl and radicle lengths of Sinapsis alba
and may be considered as potent inhibitor of germination and growth of Lolium
multiflorum. Belchim Crop Protection USA, has launched ‘Beloukha herbicide’, sunflower
bio-based, non-selective, contact, broad-spectrum, foliar-applied herbicide that destroys
the cell membranes of plant epidermis causing rapid tissue dehydration of both annual and
Allelopathic potential of Malaysian invasive weed spp on weedy rice 65
perennial broadleaf and grass weeds (14). It contains 98% pelargonic acid a naturally
occurring allelochemicals present in sunflower (14).
CONCLUSIONS
All 30-test Malaysian invasive weed species allelopathically inhibited the seeds
germination and seedlings growth of Weedy rice (Oryza sativa f. spontanea). The
allelopathic effects of these weed species varied and depended on the extract
concentrations. The P. hysterophorus, C. rutidosperma and B. alata weeds were most
inbitory to survival rate and seedlings growth of Weedy rice. Hence, these weeds species
chemical components needs to be isolated and identified to develop natural products based
eco-friendly bioherbicide to control Weedy rice in sustainable agriculture.
ACKNOWLEDGEMENTS
The authors sincerely acknowledge the Fundamental Research Grant Scheme
(FRGS) project and University Putra Malaysia for providing all required facilities. This
research received funding from the FRGS, Malaysia (FRGS/1/2017/WAB01/UPM/01/2)
and Putra Grant UPM (GP-IPB/2017/9523400).
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