الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
Abstract
SUMMARY
The novel plant protectants based on natural products especially which
prepared from allelopathic plants is one of the most important approaches
to find alternatives of chemical herbicides. Such approach is expected to
play an important role in preventing the adverse effects of the chemical
herbicides. So, the aim of the present study is to evaluate the herbicidal
activity allelopathic plant extracts namely Sorghum bicolor L and Oryza
sativa L on wheat and wheat weeds (wild oat, canary grass) under local
conditions. The biocidal activity of the tested extracts was compared with
two of the most common herbicides i.e. diclofop- methyl and clodinafoppropargyl
used on wheat. Also, residues of the tested herbicides in wheat
plant and soil were determined. Evaluation the herbicidal and phytotoxic
effects of the tested materials were carried out under laboratory, green
house and semi field conditions, and the following parameters were
measured:
1- Germination percentage of wheat
2- Seedling shoots and root length
3- Dry weight of treated wheat, wild oat and canary grass
4- Chlorophyll content
5- Plant height
6- Plant numbers in experimental plots
7- Spike length and spike weight of treated wheat
The obtained results could be summarized as follows:
I-Herbicidal activity and phytotoxic effects of the prepared extracts
and conventional herbicides on wheat and associated weeds
1- Germination percentage
Aqueous and methanolic extracts of sorghum and rice straw at 10&20%
were completely suppressed germination of wild oat and canary grass.
However, the concentration of 5% from both indicated less inhibition in
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SUMMARY
Amira, S. Mahmoud, M.Sc., 2016
germination of the two tested weeds, wheat the germination percentage
ranged 5± 0.8 – 51.3 ±1.73. On the other hand, the effect of all extracts
on wheat as compared with control and the two chemical herbicides was
variable based on the concentration. Some concentrations such as
sorghum methanolic extract at concentration of 10 and 20% showed 0%
germination percentage. On the contrary sorghum aqueous extract at
concentration 20% caused an increase in germination percentage 75
±1.4 in control to 90 ±2.6.
2-Seedling shoots and root length
All tested aqueous extracts of both sorghum and rice straw had no
negative effect on seedling shoot and root length of wheat. However, the
tested methanolic extracts as well as chemical herbicides significantly
decreased seedling shoot and root length. On the other hand all tested
treatments completely suppressed seedling shoot and root length of wild
oat and canary grass compared with the control. With exception of 5%
aqueous extract of sorghum showed (1.94 ±0.8 and 1.54 ±0.9 cm) and
(4.94 ±0.8 and 3 ±0.4 cm) for wild oat and canary grass, whereas they
were (2.38 ±0.8 and 1.75 ±1.3) and (6.04 ±0.3 and 2.7 ±0.5) in control,
respectively.
3-Dry weight (under laboratory, green house and semi field
conditions)
3.1- In Laboratory.
The maximum reductions in dry weight (100%) of wheat were obtained
with 20% aqueous and methanolic extract of sorghum. Whereas, the
reduction caused by each of diclofop- methyl and clodinafop- propargyl
were 4.1 and 16.6 %, respectively. Regarding wild oat all tested extracts
significantly reduced the dry weight of the weed. The heights reductions
(100%) were observed for all concentrations of the methanolic extracts,
10 and 20% aqueous extracts. whereas, maximum inhibition in the dry
weight of canary grass (100%) was obtained for concentrations of 10&
20% rice straw extracts and 20% methanolic extract of sorghum.
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SUMMARY
Amira, S. Mahmoud, M.Sc., 2016
3.2- In Green House
All treatments including tested extracts had no significant different
effect on dry weight of wheat than control. Regarding wild oat the
highly reductions of dry weight were observed with diclofop- methyl
then clodinafop- propargyl by 43 and 27.2 %, respectively. Lower %
reductions were recorded by tested extracts. However, the highest %
reduction was recorded against canary grass by the two tested herbicides
as well as the highly concentrated extracts at 10 and 20 %.
3.3-In Semi Field
The two tested herbicides caused an increase in dry weight of wheat
ranged 12.39- 36.32 %. Extracts of sorghum and rice straw at
concentrations of 10 and 20 % caused the same trend or lightly
reduction ranged 1.28- 11.54%. The concentration at 5% caused higher
reduction of the dry weight ranged 7.69- 22.22%. Reduction in dry
weight of wild oat was observed with all treatments. The maximum
reduction was recorded with sorghum methanolic extract at 20% (31.42
%) and diclofop-methyl treatment (30.97%). Other extracts caused
variable percentage of reduction based on the concentration. Dry weight
of canary grass was reduced in all treatments. Diclofop-methyl gave
maximum reduction (53.85%) and was followed by clodinafoppropargyl
(37.12%) and 20% aqueous extract of sorghum (37.46%).
4- Chlorophyll percentage
4.1- In Green House
All tested extracts and herbicides have no negative effect on chlorophyll
contents of wheat leaves compared to the untreated plants (control).
Regarding wild oat all treatments caused observed reduction in
chlorophyll content based on type of treatment. Methanolic extracts at
20% indicated decrease in such content reach to 31.8 and 31.4,
respectively. Whereas, diclofop- methyl and clodinafop-propargyl
showed reduction at 28.2 and 30. The same trend of the effect of the
tested herbicides and extracts on the chlorophyll content was observed on
canary grass.
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SUMMARY
Amira, S. Mahmoud, M.Sc., 2016
4.2-In Semi Field
All tested extracts and herbicides have no negative effect on chlorophyll
contents of wheat leaves after three successive applications. However the
chlorophyll content of wild oat after the 3 application was reduced to
reach 24.5 as a result of treatment with diclofop –methyl and was
followed by clodinafop- propargyl and 20% of tested extracts. On the
other hand chlorophyll content of canary grass was significantly
decreased by all treatments as compared to control.
5- Plant height
5.1- In Green House
All tested extracts had no negative effect on plant height of wheat
compared to the untreated plants. However, plant height of wild oat was
significantly affected by all treatments. There is reduce in plant height
depending on the type of herbicide and concentration of the tested
extracts. Regarding canary grass of plant height showed non- significant
effect between concentrations of tested extracts at 5 and 10%. However,
treatments at 20% concentration as well as the two tested herbicides
caused similar results in reduction the plant height.
5.2-In Semi field
All tested extracts and herbicides have no negative effect on chlorophyll
contents of wheat leaves compared to the untreated plants. However,
aqueous extract of sorghum recorded similar results which obtained with
the diclofop- methyl and clodinafop- propargyl on reduction plant height.
Aqueous extract of rice straw with the two tested herbicides showed the
same trend against canary grass.
6- Plant Number (under Semi Field Conditions)
All extracts at the different concentrations as well as the two tested
herbicides caused reduction in plant number of wild oat. Some of
extracts recorded similar effect of diclofop- methyl and clodinafoppropargyl
such as the methanolic extracts of rice straw at 5and 20%.
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SUMMARY
Amira, S. Mahmoud, M.Sc., 2016
Regarding the canary grass, only the methanolic rice straw at 20%
caused similar results of the two tested herbicides.
7- Spike length and spike weight of treated in wheat
Data concerning spike length and spike weight of treated wheat with the
two tested herbicides and extracts especially at 20% concentration
showed now negative effect on the two parameters of crop productively
under green house or in semi field conditions.
II- Herbicides residues in wheat plants and soil
1. The dissipation of diclofop-methyl residues on wheat leaves and
soil
The initial residues of diclofop-methyl on leaves were 5.24 μg a.i/ gm and
reached 3.95 μg a.i/ gm at 7 days after application. However, no residues
were detected after 14 days of application on wheat leaves. On the other
hand, the higher level of residues was recorded in soil samples at two
week and four week of spraying, showing 0.44 and 0.14 μg a.i/ gm
respectively.
2. The dissipation of clodinafop-propargyl residues on wheat leaves
and soil
The clodinafop-propargyl was rapidly degraded in the wheat leaves and
soil samples. Where, the residues of the treated herbicide were not
detected in all successive intervals of soil and leaves samples except
after 3 h of application on leaves which reached 0.078 μg a.i/ gm.