ArticlePDF Available

Herbicidal effects of Datura stramonium (L.) leaf extracts on Amaranthus hybridus (L.) and Tagetes minuta (L.)

Authors:
  • Manicaland State University of Applied Sciences
  • Bndura University of Science Educaton
Vol. 13(34), pp. 1754-1760, 23 August, 2018
DOI: 10.5897/AJAR2018.13225
Article Number: BCEF47558212
ISSN: 1991-637X
Copyright ©2018
Author(s) retain the copyright of this article
http://www.academicjournals.org/AJAR
African Journal of Agricultural
Research
Full Length Research Paper
Herbicidal effects of Datura stramonium (L.) leaf
extracts on Amaranthus hybridus (L.) and
Tagetes minuta (L.)
Nyasha Sakadzo1*, Innocent Pahla1, Simbarashe Muzemu1, Ronald Mandumbu2
and Kasirayi Makaza3
1Department of Horticulture, Faculty of Natural Resources Management and Agriculture, Midlands State University,
Gweru, Zimbabwe.
2Department of Crop Science, Faculty of Agriculture and Environmental Science, Bindura University of Science
Education, Bindura, Zimbabwe.
3Department of Soil and Plant Sciences. Faculty of Agricultural and Natural Sciences, Great Zimbabwe University,
Masvingo, Zimbabwe.
Received 5 May, 2018; Accepted 11 June, 2018
Evolution of weeds resistant to herbicides demands new solutions to cope with the problem since
economic losses generated by weeds can be higher than those caused by insect pests. Bioactive
compounds known as allelochemicals have the potential to act as natural herbicides in weed
management in agro-ecosystems. Laboratory, pot and greenhouse experiments were carried out to
investigate the herbicidal effects of Datura stramonium aqueous leaf extracts on the germination and
early growth of Tagetes minuta and Amaranthus hybridus. The laboratory and greenhouse experiments
were arranged as completely randomised design, and the open field pot experiment was arranged as a
randomised complete block design. Four concentrations of 2, 4, 6 and 8%, respectively of D.
stramonium aqueous leaf extracts were used. Distilled water was the control. Data for germination,
radicle and plumule length was collected within the first 10 days for the laboratory experiment. Root
length, shoot length and biomass yield was collected 30 days after germination for both the greenhouse
and field experiments. Results indicated that germination percentage, radicle length, plumule length
and dry matter significantly decreased (P<0.001) as concentration of D. stramonium leaf extracts
increased in all the experiments. This implies that D. stramonium has pre-emergence and early post
emergence herbicidal effects on the two weeds. This study revealed that allelopathic sprays of D.
stramonium can be used by resource poor small scale farmers or organic farmers for the control of
Amaranthus hybridus and T. minuta in Zimbabwe.
Key words: Allelopathy, aqueous leaf extract, D. stramonium, Amaranthus hybridus, Tagetes ereca, herbicidal
effects, germination, early growth.
INTRODUCTION
Allelopathy is defined as any process involving secondary metabolites produced by plants, algae, bacteria and fungi
that influence the growth and development of agricultural
or biological systems (Macías et al., 2007; Thi et al.,
2015). Allelopathy involves synthesis of bioactive
compounds known as allelochemicals which are capable
of acting as natural pesticides. Plants produce these
compounds as a mechanism to defend themselves in the
course of co-evolution. The fact that allelopathy is a
crucial defense and attack weapon of the plant to gain a
foothold on the community can not be ignored (Marcias et
al., 2007).
According to Asaduzzaman et al. (2014), Casimiro et
al. (2017) and Farooq et al. (2011), the wise exploitation
of allelopathy in the cropping systems may be an
effective, economical and natural method of weed
management. These compounds are usually degraded
easily in the environment due to their short half life as
they contain fewer halogen constituents in their
structures. Due to their impure nature, they usually
contain a number of active compounds which can act on
more than one site like a mixture of herbicides and may
control a wider spectrum of weeds (Solts et al., 2013).
This discourages the development of resistance.
Abandoning of chemical control with current agriculture is
rather impossible, it is therefore necessary to create new
classes of herbicides with new mechanism of action and
target site not previously exploited. Natural compounds
pose as a potential source for the discovery of eco-
friendly herbicides, so called bio herbicides (Solts et al.,
2013).
The herb, D. stramonium is an annual upland weed that
is widely distributed throughout the world. In Mexico, the
plant inhabits open, cultivated and disturbed sites where
they attain an average height of 1 m (Valverde et al.,
2002). According to Fatoba et al. (2001), the plant is
characterised by solitary white trumpet shaped flowers.
Weed surveys done in Zimbabwe by Thomas (1971) and
Chivinge (1983, 1988) classified the weed as aggressive
and difficult to control. The plant has been increasing in
the cropping systems and farmers cut it and use the
leaves as mulch.
Currently, the weed has turned invasive, thereby
making available its leaves for mulch placement in
gardens and agronomic fields. Other farmers have
reported that it reduces weed germination. It has been
said that several chemicals have been identified and
phytochemical investigators believe that there are still
many other chemicals in D. stramonium which have not
been identified to be exploited as bioherbicides (Elisante
et al., 2014). Allelochemicals found in D. stramonium
have allelopathic effects on survival of native plants. D.
stramonium contains a series of allelochemical in form of
Sakadzo et al. 1755
alkaloids, atropine, hiosciamine and scopolamine
(Butnariu, 2012), which inhibits the growth and
development of root and shoots of Trigonella and
Lepidium in a concentration dependent manner (EL-
Shora and Abd EL-Gawad, 2014; 2015a; An et al., 1996).
Currently, there is no basic information of the allelopathic
effects of D. stramonium on A. hybridus and T. minuta
which are seriously problematic arable weeds in
Zimbabwe. The objective of this current study was to
determine the multi-herbicidal effects or mode of actions
of D. stramonium leaf extracts on the germination and
early establishment of the A. hybridus and T. minuta.
MATERIALS AND METHODS
Experiment 1: Effect of D. stramonium concentration on the
germination and early establishment of two weeds in the laboratory
experiment.
Study site
The laboratory experiment was carried out at Midlands State
University, located in Midlands province of Zimbabwe. The
geographical location is 19˚45’ S (line of latitude) and 29˚85’ E (line
of longitude). It experiences mean annual temperature of 18°C. The
site is in agro-ecological region III, at an altitude of 1428 m (Vincent
and Thomas, 1960; Mugandani et al., 2012).
Experimental design
The experiment was arranged as a complete randomised design
with five treatments replicated three times. Treatments were 20 ml
of distilled water (control) and aqueous D. stramonium leaf extracts
applied at 2, 4, 6 and 8% concentration as a ratio of plant extract
powder to 100 ml distilled water. 2 g of extract powder was added
to 100 ml of distilled water to give 2% concentration of aqueous and
the same was done for 4, 6 and 8% concentrations.
Preparation of D. stramonium aqueous leaf concentrations for
the three experiments
Leaves of fully grown plants collected from the wild were washed to
remove soil particles. The material was then cut into pieces and
shed dried for one month. After drying, the material was crushed
into powder form manually using a traditional mortar and pistil.
Further grinding was done by using an electric mortar. The material
(powder and distilled water) was mixed and poured into a conical
flask with its mouth closed and kept for 24 h in the dark at room
temperature according to the method used by Dhawan and Narwal
(1994). The four flasks were marked with stickers according to the
D. stramonium concentrations (2,4 ,6 and 8%, respectively). This
was followed by filtration process in two steps. In the first step,
muslin cloth was used, and later the filtrate was allowed to pass
*Corresponding author. E-mail: nsakadzo87@gmail.com. Tel: +263 775 985 724.
Author(s) agree that this article remain permanently open access under the terms of the Creative Commons Attribution
License 4.0 International License
1756 Afr. J. Agric. Res.
through Whatman filter paper no.1. The prepared aqueous
concentrations were kept in a refrigerator for the duration of the
experiment to prevent conversions of some of the compounds upon
exposure to light and high temperature.
Experimental procedure
Two hundred and twenty five seeds of the selected weeds were
surface sterilized with 0.1 % mercuric chloride solution for two
minutes and washed twice with distilled water. The petri dishes
were labelled with a permanent marker in relation to concentration
level. Fifteen seeds of each weed were placed in petri dishes on
Whatman filter paper no.1. Twenty millilitres of each D. stramonium
aqueous concentration (2, 4, 6 and 8%, respectively) was added to
each petri dish. The same amount of distilled water was used as a
control. Watering was done after every three days, and the petri
dishes were kept in an incubator at 24°C room temperature for 10
days.
Experiment 2: Pot experiment: Effects of different D.
stramonium aqueous concentrations on germination and early
seedling growth of weeds in the field.
Study site
The field experiment was carried out at Midlands State University,
located in Midlands province of Zimbabwe. The geographical
location is 19˚45’ S (line of latitude) and 29˚85’ E (line of longitude).
It experiences mean annual temperature of 18°C. The site is in
agro-ecological region III, at an altitude of 1428 m.
Experimental design
The experiment was arranged as a complete randomised design
with five treatments replicated three times and two weeds were
tested.
Experimental procedure for field and green house experiments
Two hundred and twenty five seeds of the selected crops were
surface sterilized with 0.1% mercuric chloride solution for two
minutes, and washed twice with distilled water. Five litre pots were
used and they were filled with mixtures of soil (loamy sand). Fifteen
seeds of each of the tested weeds were sown in each pot at 0.5
cm, and then irrigated with various solutions to field capacity every
three days.
Data collection for field and green house experiments
Data on seed emergence, shoot, and root length; seedling fresh
and dry weight was recorded. Seed emergence was determined by
physically counting the number of seedlings on the 8th day after
planting. During the experiment period (after 30 days after planting),
shoot and root length was also measured using a 30 cm ruler. The
dry weight was determined by placing the tested samples in the
oven to a temperature of 110°C for 48 h until a constant weight was
realised.
Experiment 3: Effects of different D. stramonium aqueous
concentrations on germination and early seedling growth of
weeds in the greenhouse.
Study site
The greenhouse experiment was carried out during the 15/16
summer season at Morningside suburb in Masvingo Province of
Zimbabwe at a geographical location of latitude 20˚ 7’ 17S and
longitude 30˚ 49’ 58 E. The site is in agro-ecological zone 4, at an
altitude of 1034 m above the sea level. It receives an average of
600 mm of rain annually with a mean annual temperature of 28°C.
Experimental design
The experiment was arranged as a complete randomised design
with five treatments replicated three times.
Data analysis
Collected data was subjected to Analysis of Variance at 5%
significance level using Genstat 4.0 version 2013. Fishers protected
least significance test at 5% was used to separate the means
where significant differences were noted.
RESULTS
Germination and emergence
The results showed that the germination percentage as
affected by D. stramonium aqueous leaf extracts was
significantly (P<0.001) lower than the control at all levels
in the laboratory percentage compared to the rest of the
treatment (Figure 1) in the laboratory. As concentrations
increased, germination percentage decreased. The
highest germination (100%) was recorded where distilled
water was applied in all tested species whilst 8%
concentration significantly (p<0.001) decreased
germination. The same trend was observed in the field
(Figure 2) and in the greenhouse (Figure 3) where the
emergence percentage decreased with increase in the
concentration.
Radicle and root length
Results indicated that as the concentration decreased
from 8 to 0%, the radicle and root length increased with a
decrease in the concentration of D. stramonium. Results
showed highly significant effects (p<0.001) of D.
stramonium on A. hybridus and T. minuta as shown on
Table 1 across all the environments.
Plumule and shoot length
Results indicated that aqueous concentrations of thorn
Sakadzo et al. 1757
0
20
40
60
80
100
120
0
2
4
6
8
D. stramonium concentration (%)
T. minuta
A. hybridus
Figure 1. Effect of Datura stramonium concentration on the germination of the two weeds in the
laboratory.
Figure 2. Effect of D. stramonium concentrations on the emergence percentage of the
two weeds in the pot experiment in the field.
apple on plumule and shoot length was highly significant
(P<0.001). Distilled water recorded the highest plumule
length and shoot length when all treatments were
compared on all tested species. It was observed that the
rate of percentage decrease in plumule and shoot length
was concentration dependent across all the tested
species. Shoot length decreased as the concentration of
D stramonium increased from 0 to 8% as presented on
Table 2.
Dry matter traits
Results indicated that the effects of aqueous
concentrations of thorn apple on seedling dry weight was
significant (P<0.001). There was a general percentage
1758 Afr. J. Agric. Res.
Figure 3. Effect of D. stramonium concentrations on the emergence of the two weeds in the greenhouse.
Table 1. Effect of the D.stramonium concentration on radicle and root length of T. minuta. and A. hybridus in laboratory, field
and greenhouse conditions.
Concentrations
Laboratory
Field
Greenhouse
T. minuta
A. hybridus
T. minuta
A. hybridus
A. hybridus
T. minuta
0
26.97±0.14a
28.67±0.491a
44.17±2.09a
80.4±1.21a
80.13±1.07a
44.17±2.09a
2
25.1±0.14b
24.97±0.491b
38.37±2.09b
75.2±1.21b
74.50±1.07b
38.37±2.09b
4
22.1±0.14c
22.83±0.491c
34.3±2.09c
64.9±1.21c
64.43±1.07c
34.30±2.09bc
6
20.93±0.14d
21.35±0.491d
31.7±2.09d
54.47±1.21d
54.27±1.07d
31.70±2.09c
8
19.37±0.14e
19.67±0.491e
26.8±2.09e
44.6±1.21e
44.27±1.07e
26.80±2.09d
P-value
<0.001
<0.001
<0.001
<0.001
0.001
<0.001
CV (%)
0.7
2.3
6.6
2.1
1.8
6.6
*Means followed by the same letter in the same column are not significantly different.
Table 2. Effect of the D. stramonium concentration on plumule and shoot length of T. minuta and A. hybridus in laboratory, field
and greenhouse conditions.
Concentration (%)
Laboratory
Field
Green house
T. minuta
A. hybridus
T. minuta
A. hybridus
T. minuta
A. hybridus
0
16.5±0.09a
20.07±0.705a
65.47 ±2.85a
80.13±1.07a
65.03±0.27a
80.40±1.22a
2
14.83±0.09b
18.40±0.705b
63.17±2.85b
74.50±1.07b
62.37±0.27b
75.20±1.22b
4
12.90±0.09c
16.30±0.705c
60.13±2.85ab
64.43±1.07c
55.43±0.27c
64.90±1.22c
6
11.53±0.09d
15.40±0.705cd
55.50±2.85bc
54.27±1.07d
50.93±0.27d
54.47±1.22d
8
10.17±0.09e
14.60±0.705d
50.27±2.85c
44.27±1.07e
49.90±0.27e
44.60±1.22e
P value
<0.001
<0.001
<0.001
<0.001
<0.001
<0.001
CV (%)
0.8
4.6
5.3
1.8
0.5
2.1
*Means followed by the same letter in the same column are not significantly different.
Sakadzo et al. 1759
Table 3. Effects of the various Datura stramoniium concentrations on the dry matter properties of the Targetis minuta and
Amaranthus hybridus in the greenhouse and the field experiments.
Concentration (%)
Field
Greenhouse
T. minuta
A. hybridus
T. minuta
A. hybridus
0
0.786±0.06a
2.013±0.069a
0.803±0.051a
2.037±0.076a
2
0.736±0.06a
1.86±0.069b
0.723±0.051a
1.887±0.076a
4
0.413±0.06b
1.673±0.069c
0.406±0.051b
1.697±0.076b
6
0.266±0.06c
1.49±0.069d
0.273±0.051c
1.513±0.076c
8
0.116±0.06d
1.26±0.069e
0.123±0.051d
1.28±0.076d
P value
<0.001
<0.001
<0.001
<0.001
CV (%)
14.3
4.6
12.4
5
*Means followed by the same letter in the same column are not significantly different.
decrease in seedling dry weight as aqueous concentration
increased from 0 to 8% on all tested species. Tagetes
minuta recorded the highest decrease of 54.8% whilst
wheat and A. hybridus recorded seedling dry weight
decreases of 22 and 15.3% respectively as concentration
increased from 6 to 8%. The concentration of 2 % was
not significantly different from the treatment watered by
distilled water except for A. hybridus in the field (Table 3).
DISCUSSION
The results showed a reduced germination percentage
with increasing concentration of allelochemicals from
D.stramonium across all the measured weeds. These
results concur with the findings of many authors
(Hassannejad and Ghafarbi, 2013; Yu et al., 2003;
Elisante et al., 2013; Levitt et al., 1984; Oyun, 2006; Alam
and Islam, 2002). D. stramonium allelochemicals contains
chemicals that retard the metabolism of food reserves in
the seed (Levit et al., 1984) and the secondary effects of
these processes include reduced germination and early
growth of radicles (Levitt and Lovetti, 1984).
Altikat et al. (2013), Ullah et al. (2015) and Alam and
Islam (2002) concur with these findings and reported that
allelochemicals disturb the activities of the peroxidase
alpha amylase enzyme and acid phosphatases which aid
the breaking down of starch for successful germination to
occur. Another assertion by EL-Shora et al. (2015a) and
Oyun (2006) posits that allelochemicals inhibit water
absorption which is a precursor for physiological
processes that should occur before germination is
triggered. All this help to support the assertion that D.
stramonium has pre-emergence herbicidal effects.
Both shoot and root lengths of the two weeds were
reduced by leaf extracts and the level of decrease
depended on the concentration of the allelochemicals.
Hussain and Reigosa (2011) found similar results on D.
glomerata, L. perenne and R. acetosa. Gholami et al.
(2011) concluded that D. stramonium alkaloids
(hiosciamine and scopolamine) can reduce cell division
or interferes with the auxin that induces growth of shoots
and roots. Findings by EL-shora et al. (2015a) found that
D. stramonium inhibit cell division. This can serve as a
confirmation of the existence of the early post emergence
effects of the allelochemicals. This further confirms the
existence of more than one mode of action of herbicide
which is critical in developing herbicides that are not
prone to resistance development.
Total dry matter for all the weeds was reduced as
concentration increased. Total dry matter is the function
of the ability of the whole plant to obtain edaphic
resources (minerals and water). Whilst all parameters
were analysed individually, the cumulative contributions
of the small differences has bigger effects on the
metabolism of the whole plant (Robeiro, 2011). Any
inhibition at each stage in the growth of the plant
contributes towards reduced ability of the plant to capture
resources for its survival. The various concentrations are
therefore able to reduce dry mass of both weeds which
indicated the presence of herbicidal effects.
Conclusion
We conclude that D.stramonium leaf extracts have both
pre-emergence and early post emergence herbicidal
effects towards the weeds studied. This study therefore
recommends the use of D. stramonium leaf extracts at
high concentrations as cheap bio herbicides to control T.
minuta and A. hybridus in Zimbabwe. However, there is
need for further research on the efficacy of other plant
parts like the roots and fruits and solvent extraction
method (ethanol and aqueous) of D. stramonium.
CONFLICT OF INTERESTS
The authors have not declared any conflict of interests.
1760 Afr. J. Agric. Res.
ACKNOWLEDGEMENTS
The Midlands State University Zimbabwe is thanked for
providing experimental site and equipment for this study.
REFERENCES
Alam SM, Islam EU (2002). Effects of aqueous extracts of leaf, stem,
roots of nettle leaf goose foot and NACL on germination and seedling
growth of rice. Pakistan Journal of Science and Technology 1(2):47-
52.
Altikat S, Terzi L, Kuru HL, Kocacaliskan L (2013). Allelopathic effects
of juglone on growth of cucumber and muskmelon seedlinghs with
respect to anti oxidant enzyme activities and lipid peroxidation.
Journal of Environmental Protection and Ecology 14(3):1244-1253.
An M, Pratley JE, Haig T (1996). Allelopathy: from concerpt to reality.
Environmental and analytical laboratories and Ferrer centre for
conservation farming. Charles University, Wagga Wagga.
Asaduzzaman M, Luckett DJ, Cowley RB, An M, Prately JE, Lemerle D
(2014). Canola cultivar performance in weed infested field plots
confirms allelopathy ranking from in vitro testing. Biocontrol Science
and Technology 24(12):1394-1411.
Casimiro GS, Mansur E, Pachelo G, Garcia R, Leal ICR, Simas NK
(2017). Allelopathic activity of extracts from different Brazilian peanut
(Arachis hypogeal L.) cultivars on lettuce (Lactuca sativa) and weed
plants. Science World Journal 17: 1-8.
Chivinge OA (1983). A weed survey of arable lands in the commercial
sector of Zimbabwe. Zimbabwe Agriculture Journal 80:39-41.
Chivinge OA (1988). A survey of weeds in arable lands in small scale
farming sector of Zimbabwe. Zambezia 15:167-178.
Dhawan SR, Narwal SS (1994). Critical assessment of allellopathy
bioassays in India: proceedings of the International Symposium on
Allellopathy in sustainable agriculture, forestry and environment. New
Delhi. Indian Society of allellopathy. Indian Agricultural Research
Institute (IARI).
Elisante F, Ndakidemi PA (2014). Allelopathic effects of Datura
stramonum on the survival of grass and legume species in the
conservation areas. American Journal of Research Communication
29(1):27-43.
Elisante F, Tarimo MT, Ndikademi PA (2013). Allelopathic effects of
seed and leaf aqueous extracts of Datura stramonium on leaf
chlorophyll content shoot and root elongation of Cencrus ciliaris and
Neonotonia wightii. American Journal of Plant Sciences 4:2332-2339.
EL-Shora HM, A EL-Gawad AM (2014). Evaluation of allelopathic effect
of white (Lupinus termis L) leaf extract on the biochemical dynamics
of common purslane (Portulaca oleracea L.) Egyptian Journal of Bat
54:317-332.
EL-Shora HM, EL-Farrash AH, Kamal H, Abdelzarek A (2015a).
Enhancement of antioxidant defense system by UV-Radiation in
fenugreek as a medicinal plant. International Journal of Advance
Research 3:529-535.
Farooq M, Khawar J, Cheema ZA, Wahid A, Kadambot H, Siddique M
(2011). The role of allelopathy in agricultural pest management. Pest
Management Science 67:493-506.
Fatoba TA, Saladoye OA (2011). Response of subcutaneous
administration of different doses of aqueous extracts of Datura
stramonium Linn seeds on liver enzymes. Journal of Environmental
Issues and Agriculture in Developing Countries 3(3):140-143.
Gholami BA, Faravani M, Kashki MT (2011). Allelopathic effects of
aqueous extract from Artemisiakopetdaghensis and Satureja
hortensison growth and seed germination of weeds. Journal of
Applied Environmental and Biologival Sciences 1(9):283-290.
Hassannejad S, Ghafarbi SP (2013). Allelopathic effects of some
Lamiacea on seed germination and seedling growth of dodder
(Cuscuta campestris Yunck.). International Journal of Bioscience 3:9-
14.
Hussain IM, Reigosa MJ (2011). Allelochemical stresses inhibit growth,
leaf water relations, PSII photochemistry, non photochemical
fluorescence quenching and heat energy dissipation in three C3
perennial spp. Journal of Experimental Botany 62(13):4533-4545.
Levitt J, Lovett JV (1984). Activity of allelochemicals of Datura
stramonium L in contrasting soil types. Plant and Soil 79:181-189.
Levitt J, Lovett JV, Garlick PR (1984). Datura stramonium
allelochemicals: longevity in soils and ultra structural effects on root
tip cells of Helinthus annuus L. New Phytologist 97:213-218.
Macías FA, Molinillo JMG, Varela RM, Galindo JCG (2007). Allelopathy-
a natural alternative to weed control. Pest Management Science
63:327-348.
Mugandani R, Wuta M, Makarau A, Chipindu B (2012). Re-classification
of agro-ecological regions of Zimbabwe in conformity with climate
variability and change. African Crop Science Journal 20(2):361-369.
Robeiro JPN (2011). Global effect index, a new approach to analysing
allelopathy survey data. Weed science 59:113-118.
Solts D, Krasuska U, Bogatek R, Gniazdowska A (2013).
Allelochemicals as Bioherbicides-Present and Perspectives:
http://dx.doi.orgl10.5772/56185.
Thi HL, Hyuk P, Ji PY (2015). Allelopathy in Sorghum bicolor L. Moenoa
a review on environmentally friendly solution for weed control.
Research of Crops 16(4):657-662.
Thomas PEL (1970). A survey of weeds of arable lands in Rhodesia.
Rhodesia Agricultural Journal 67:3-4.
Ullah N, Haq IU, Safdar N, Mirza B (2015). Physiological and
biochemical mechanisms of allelopathy mediated by the
allelochemical extracts of Phytolacca latbenia (Morq.) H. Walter.
Toxicology and Industrial Health 31(10):931-937.
Valverde PL, Fornoni J, Nunez-farfan J (2002). Evolutionary ecology of
Datura stramonium: equal plant fitness benefits of growth and
resistance against herbivory. Journal of Evolutionary Biology 16:127-
137.
Vincent V, Thomas RG (1960). An Agro-ecological Survey of Southern
Rhodesia Part 1: Agro-ecological survey: Government Printers.
Salisbury pp. 1-217.
Yu JQ, Ye SF, Zhang FM, Hu WH (2003). Effects of root exudates and
aqueous root extracts of cucumber (Cucumis sativus) and
allelochemicals on photosynthesis and antioxidant enzymes in
cucumber. Biochemical Systematics and Ecology 31(2):129-139.
... Four concentrations were made on the basis of weight and volume (extract powder: distilled water); 2 grams of extract powder was added to 100ml of distilled water to give 2% concentration of aqueous, 4 grams of extract powder was added to 100ml of distilled water to give 4% concentration of aqueous, 6 grams of extract powder was added to 100ml of distilled water to give 6% concentration of aqueous. The material (powder and distilled water) was mixed and poured into a conical flask with its mouth closed and kept for 24 hours in the dark at room temperature according to the method used [10]. The four flask were marked with stickers according to the T. minuta concentrations ( 0,2,4 and 6%). ...
... The fourth conical flask was filled with distilled water which acted as the control. The prepared aqueous concentrations were kept in a fridge for convenient use during the experiment [10]. Soap solution was added to each of the four solutions to act as a sticking agent [11]. ...
Article
Aphids (Brevicoryne brassicae) pose a threat to production of most vegetables including rape by sap sucking and transmitting viral diseases. A trial was carried out at the Jichidza High School, Masvingo Zimbabwe (2019) to evaluate the repellent properties of Mexican marigold (Tagetes minuta) aqueous extracts on aphid population in rape (Brassica napus). The experiment was laid out as a randomised complete block design (RCBD) with four treatments (0%, 2%, 4% and 6%) concentration of Mexican marigold extracts on rape replicated five times. Application of these concentrations was done at fortnight interval from week one after planting to week six of age. Data on growth rate, aphid counts, and cumulative leaf weight was collected from week three to week six after planting. The results showed that, the effects of Mexican marigold on growth rate, aphid population and cumulative leaf weight were significantly different (p < 0.05). Using 6% concentration of Mexican marigold aqueous extracts recorded the highest growth rate, lowest aphid population and highest leaf weight as compared to all other treatments. However, results from using 2% concentration of Mexican marigold aqueous extracts were not significantly different (p > 0.05) from the use of 4% concentration of Mexican marigold aqueous extracts in rape. From the results, it can be concluded that the use of 6% concentration of Mexican marigold in rape is an effective control method for aphids. From this study, it is recommended that poor smallholder farmers can utilise the repellent properties of Mexican marigold to reduce aphid yield losses in rape. Keywords: Repellent; Brassica napus; Tagetes minuta; Aqueous; Brevicoryne brassicae
... Four concentrations were made on the basis of weight and volume (extract powder: distilled water); 2 grams of extract powder was added to 100ml of distilled water to give 2% concentration of aqueous, 4 grams of extract powder was added to 100ml of distilled water to give 4% concentration of aqueous, 6 grams of extract powder was added to 100ml of distilled water to give 6% concentration of aqueous. The material (powder and distilled water) was mixed and poured into a conical flask with its mouth closed and kept for 24 hours in the dark at room temperature according to the method used [10]. The four flask were marked with stickers according to the T. minuta concentrations ( 0,2,4 and 6%). ...
... The fourth conical flask was filled with distilled water which acted as the control. The prepared aqueous concentrations were kept in a fridge for convenient use during the experiment [10]. Soap solution was added to each of the four solutions to act as a sticking agent [11]. ...
Article
Full-text available
Aphids (Brevicoryne brassicae) pose a threat to production of most vegetables including rape by sap sucking and transmitting viral diseases. A trial was carried out at the Jichidza High School, Masvingo Zimbabwe (2019) to evaluate the repellent properties of Mexican marigold (Tagetes minuta) aqueous extracts on aphid population in rape (Brassica napus). The experiment was laid out as a randomised complete block design (RCBD) with four treatments (0%, 2%, 4% and 6%) concentration of Mexican marigold extracts on rape replicated five times. Application of these concentrations was done at fortnight interval from week one after planting to week six of age. Data on growth rate, aphid counts, and cumulative leaf weight was collected from week three to week six after planting. The results showed that, the effects of Mexican marigold on growth rate, aphid population and cumulative leaf weight were significantly different (p<0.05). Using 6% concentration of Mexican marigold aqueous extracts recorded the highest growth rate, lowest aphid population and highest leaf weight as compared to all other treatments. However, results from using 2% concentration of Mexican marigold aqueous extracts were not significantly different (p>0.05) from the use of 4% concentration of Mexican marigold aqueous extracts in rape. From the results, it can be concluded that the use of 6% concentration of Mexican marigold in rape is an effective control method for aphids. From this study, it is recommended that poor smallholder farmers can utilise the repellent properties of Mexican marigold to reduce aphid yield losses in rape. Key words: Repellent, Brassica napus, Tagetes minuta, Aqueous, Brevicoryne brassicae.
... Sakadzo et al. [40] found that an aqueous extract of D. stramonium inhibited root development, plumule length, and dry matter amount in Amaranthus hybridus and Tegetes minuta, with herbicidal effects both pre-and post-emergence. ...
Article
Full-text available
Datura stramonium is one of the most intriguing, in part because of its well-known therapeutic and psychoactive properties in the treatment of many diseases. Datura species have been found to exhibit a variety of biological activity. Insecticide, fungicide, antioxidant, antibacterial, hypoglycemic, and immune response boosting properties have been linked to the genus' species. These effects are linked to the existence of secondary metabolites such as terpenoids, flavonoids, with anolides, tannins, phenolic compounds, and tropane alkaloids, which are the most prevalent atropine and scopolamine in the genus Datura. Ingestion of jimson weed produces the toxidrome of anticholinergic intoxication. Understanding and recognizing the classic signs and symptoms of anticholinergic intoxication can help clinicians evaluate persons presenting with jimson weed poisoning. Moreover, this review is to identify the most important phytochemical substances extracted from the jimsonweed and to characterize their biological activity for health effect and biopesticide application. This is because bio-pesticides are less harmful than chemical pesticides because they do not leave harmful residues, generally target one specific pest or a small number of related pests versus broad spectrum chemical pesticides that affect, in addition to the pest, other beneficial insects, birds, mammals, or non-target species, are effective in smaller quantities, decompose quickly and do not cause environmental problems, and are often cheaper than chemical pesticides. In conclusion, Datura stramonium, beside its medicinal value, can applicable for biopesticide application and for post-harvest loss control of insects such as weevil.
... Otros autores también destacan la sensibilidad de esta variable al efecto alelopático inhibitorio con diferentes extractos acuosos en S. lycopersicum, Amaranthus spp. (Amaranthaceae), Tagetes minuta (Asteraceae) y Euphorbia heterophylla L. (Euphorbiaceae) (González et al., 2015;Sakadzo et al., 2018;Alonso et al., 2020). ...
Article
Full-text available
Los extractos vegetales constituyen una alternativa promisoria en el manejo de plagas, pero con frecuencia se subestima su influencia sobre el crecimiento de las plantas. En la presente investigación se determinó el efecto alelopático de extractos acuosos de Azadirachta indica A. Juss. (nim) sobre semillas certificadas de Solanum lycopersicum L. cv. Pingüino (tomate), en condiciones de laboratorio. Los extractos se prepararon al 5 % m/v empleando por separado hojas y semillas y por dilución, las concentraciones utilizadas en el ensayo fueron: 0,0 % (control), 0,5 %, 1,0 %, 1,5 % y 2,0 % v/v. La siembra de semillas se realizó en placas de Petri sobre papel de filtro, distribuidas en un diseño completamente al azar con arreglo factorial y cuatro réplicas por concentración. Los resultados mostraron un estímulo en la germinación con extracto acuoso de semillas de A. indica al 0,5 % y una reducción con el extracto de hoja al 2,0 %. La longitud del hipocótilo aumentó en todas las concentraciones respecto al control y la longitud de la radícula disminuyó con el incremento de la concentración de los extractos, alcanzando una reducción superior al 20 % respecto al control. La masa fresca total de las plántulas no arrojó diferencias entre las concentraciones de los extractos y el control, y se concluyó que existe un efecto alelopático diferenciado de A. indica en la germinación de S. lycopersicum que podría aprovecharse en el contexto de una agricultura sostenible, aunque se sugiere la evaluación de los extractos en especies de arvenses.
... Sakadzo et al. [42] found that an aqueous extract of D. stramonium inhibited root development, plumule length, and dry matter amount in Amaranthus hybridus and Tegetes minuta, with herbicidal effects both pre-and post-emergence. ...
Chapter
Full-text available
Datura stramonium is one of the most intriguing, in part because of its well-known therapeutic and psychoactive properties in the treatment of many diseases. Datura species have been found to exhibit a variety of biological activity. Insecticide, fungicide , antioxidant, antibacterial, hypoglycemic, and immune response boosting properties have been linked to the genus' species. These effects are linked to the existence of secondary metabolites such as terpenoids, flavonoids, with anolides, tannins, phenolic compounds, and tropane alkaloids, which are the most prevalent atropine and scopolamine in the genus Datura. Ingestion of Jimson weed produces the toxi-drome of anticholinergic intoxication. Understanding and recognizing the classic signs and symptoms of anticholinergic intoxication can help clinicians evaluate persons presenting with Jimson weed poisoning. Moreover, this review is to identify the most important phytochemical substances extracted from the Jimsonweed and to characterize their biological activity for health effect and biopesticide application. Biopesticides are less harmful than chemical pesticides because they do not leave harmful residues, generally target one specific pest or a small number of related pests rather than broad spectrum chemical pesticides that affect other beneficial insects, birds, mammals, or non-target species, are effective in smaller quantities, decompose quickly and do not cause environmental problems, and are often cheaper. In conclusion, Datura stramo-nium, beside its medicinal value, can applicable for biopesticide application and for postharvest loss control of insects such as weevil.
... Sakadzo, et al. [80] reported the significative effect of aqueous extract of D. stramonium in inhibiting root development, plumule length, and dry matter amount against Amaranthus hybridus and Tegetes minuta with pre-and postemergence herbicidal effects. ...
Article
Full-text available
Solanaceae is an important family of plants where many species of this family are source for food, industrial products, ornamental and medicinal uses. Within the family of Solanaceae, the genus Datura is one of the most interesting, in principle for its known medicinal and psychotropic uses against different pathologies. Multiple biological activities of Datura species have been documented. The species of the genus are attributed with insecticide, fungicide, antioxidant, antimicrobial, hypoglycemic, and immune response enhancing activity against cancer cells. These activities are related to the presence of different secondary metabolites such us: terpenoids, flavonoids, withanolides, tannins, phenolic compounds and tropane alkaloids, the main secondary metabolite of the genus Datura , being the most abundant atropine and scopolamine. The propose of this review is to identify the main phytochemical compounds isolated from the genus Datura and describe their biological activities associated to different secondary metabolites.
... Two, six and ten grams of crushed powder were mixed with 100ml of water to produce 2%, 6% and 10% Aloe-vera solutions respectively.. This is in line with the protocol used by Sakadzo., et al [8]. ...
Article
Full-text available
LLELOPATHY has become a much more important phenomenon in biological control method of weeds in any kind of agricultural practices. So, the present study has been carried out to evaluate the allelopathic influence of the Lupinus leaf extract on biochemical constituents and enzymatic activities of the Portulaca oleracea L. plant. The obtained results indicate that induction of calmodulin (CaM), abscisic acid (ABA) and indole acetic acid (IAA) levels in the P. oleracea plant under the effect of Lupinus leaf extract. Also, seed germination, total soluble sugars, total lipids, total amino acids and total protein contents were reduced in P. oleracea under treatment with Lupinus leaf extract. The extract induced the activities of both α-amylase and IAA oxidase but inhibited the activities of nitrate reductase (EC, 1.7.1.3), glutamine synthetase (EC, 6.3.1.2) and pyruvate dehydrogenase (EC, 1.2.4.1). Thus, allelopathic extract of the L. termis may be used as eco-friendly natural herbicide for management of the P. oleracea.
Article
Full-text available
Peanut ( Arachis hypogaea L.) is the fourth most consumed oleaginous plant in the world, producing seeds with high contents of lipids, proteins, vitamins, and carbohydrates. Biological activities of different extracts of this species have already been evaluated by many researchers, including antioxidant, antitumoral, and antibacterial. In this work, the allelopathic activity of extracts from different Brazilian peanut cultivars against lettuce (Lactuca sativa) and two weed plants ( Commelina benghalensis and Ipomoea nil ) was studied. Aerial parts, roots, seeds, and seed coats were used for the preparation of crude extracts. Seed extract partitioning was performed with n -hexane, dichloromethane, ethyl acetate, n -butanol, and aqueous residue. Germination and growth of hypocotyls and rootlets were evaluated after one and five days of incubation with plant extracts, respectively. Crude seed extract and its dichloromethanic partition displayed highest allelopathic activity. These results contribute for the study of new potential natural herbicides.
Article
Full-text available
The effects of juglone, which exists in walnut and has allelopathic effect, on seedling growth and biochemical stress parameters were researched in this study. While a significant decrease was observed in the growth parameters (seedling elongation, fresh and dry weights) of cucumber (Cucumis sativus cv. Beith Alpha) and muskmelon (Ananas) (Cucumis melo cv. Ananas), an increase was observed in muskmelon (Kis Kavunu) (Cucumis melo cv. Kis Kavunu) by the effect of juglone. On the other hand, juglone increased malonyldialdehyde (MDA) levels of cucumber and muskmelon (Ananas) significantly, whereas it decreased MDA level of muskmelon (Kis Kavunu). However, juglone decreased catalase (CAT) and superoxide dismutase (SOD) enzyme activities of cucumber and muskmelon (Ananas), but it was contrary to those of muskmelon (Kis Kavunu). As a result of juglone effect, a positive correlation was observed between seedling growth and antioxidant enzyme (CAT, SOD) activities, but a negative correlation with lipid peroxidation (MDA) levels was seen.
Article
The agricultural industry has tried to develop effective herbicides, especially biological herbicides, with less impact on our agricultural environment. Recently, allelopathy has emerged as a potential alternative to chemical herbicides for weed management. Allelopathy is defined as "any direct or indirect, harmful or beneficial effects of one plant on another through the production of chemical compounds that are released into the environment."Sorghum bicolor (L.) Moench, a species that originates from Africa and is widely cultivated in both tropical and sub-tropical regions, is considered as a rich source of allelochemicals with biological weed control ability. Chemical constituents of sorghum include tannins, phenolic acids, anthocyanins, phytosterols and policosanols. Investigations on underground parts of sorghum indicate that sorgoleone is in charge of the weed control activity, while phenolic compounds play a vital role in its herbicidal activity on aerial parts of weeds. This review aims at providing up-to-date and comprehensive information about allelopathy in sorghum and further application of sorghum extract in weed control.
Article
Crop competition and allelopathy are two cultural control options for possible inclusion in cropping systems. This research aimed to identify superior allelopathic canola genotypes through a two-year field study. First year screening results of 312 diverse Brassica genotypes showed genotypes differed significantly in their ability to suppress weed infestations. Crop plant height was correlated with the competitive ability of several genotypes, while other genotypes showed good weed-suppressive ability despite being short. Thirty-six of the genotypes grown in the field had been previously assessed for their allelopathic ability to inhibit the growth of annual ryegrass (Lolium rigidum) seedlings using an in vitro technique. The highly allelopathic genotypes: Av-opal, Sardi603, Rivette and Atr-beacon performed well against annual ryegrass in the laboratory and also against other species, including Capsella bursa-pastoris, Sisymbrium orientale and Hordeum leporinum in the field. The weakly allelopathic Barossa and X-06-6-3725 genotypes performed poorly both in the laboratory studies and in the field. The following year, field testing of selected genotypes at two sowing dates further suggested that the most allelopathic genotypes in the laboratory bioassay were generally those that suppressed weed numbers and their biomass in the field. The late sowing time increased the natural weed pressure leading to a decrease in both canola grain yield and quality. Many of the highly allelopathic canola genotypes, which caused low weed populations in the field, had relatively low grain yield. This suggests that the allelopathic trait is independent of local adaptation and yields potential under weed-free conditions. Ideally, cultivars with both high allelopathy and high competitive ability would be most useful to help farmers maximise yield and control weeds. Selection for allelopathy in canola shows potential as a future non-chemical weed control option and requires further investigation.