الفهرس 
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Abstract
The present investigation was carried out at the Research
Experimental Station of Ioshtohor, Faculty of Agriculture,
Zagazig Univ., (Benha Branch) during three successive growing
seasons (M” M2 and M3) of 1998 1999 and 2000.
The main objective of this study was to investigate the
mutagenic effect of garruna- rays (10, 20, 30 and 40 KR),
soudium Azide (SA) (1.0 x 10-3 m, 1.5 10-3 m and 2.0 10-3 m)
and Cyanno Gudinin (CQ) (0.001 M 0.01 M and 0.1 M)
treatments on the obtained mutagenic variability in the yield,
yield components. chemical constitution, hyrocyanic acid
contents and downy mildew infection of Tifton and Quna
sorghum under study. Also, the induced promising and
favourable mutagenic characteristics were identified and
selected.
The experimental design used in this investigation was
Randomized Complete Block Design (ReBD) with four
replications. The obtained results could be summarized as
follow’s:
- Vegetative characteristics:
• Fresh forage yield:
- Gamma radiation levels of ]0 KR and 3a KR produced
plants of higher fresh yield in the M3 of both sorghum
va.rieties (Tifton and Quna). The heaviest dose (40 KR)
showed similar effect on M2 and M3 of Tifton and M) of
Quna sorghum.Sodium Azid (SA) at 1.5 x 10-J and 2.0 x 10-’\ m levels
induced significant variation on fresh forage yield in
the MJ generation of Quna sorghum. This result was not
true for Tifton sorghum at any generation.
The lower level of Cyanno Gudinin (CG) of 0.00 I M in
M] and M2 generation was responsible of generating
plants of heaviest forage production in Tifton and Quna
sorghum.
• Forge dry yield:
- The 20 and 30 KR levels of gamma radiation were more
effective ill producing higher forage dry yield for Quna
and Tifton sorghum, respectively Il1 their MJ
generations.
- The same abo c response was detected at the lowest (1.0
x 10’) m) and medium (1.5 x 10-3 111) levels of the SA in
the M3 generation for both Tifton and Quna sorghum.
- Highest concentration of CG O. I M produced plants of
higher dry forage yield in the MJ generation for either
sorghum varieties under study.
• Number of tillers! plant :
- It is generally noticed that either of the two medium
levels of gamma radiation (20 and 30 KR) produced
significantly higher number of tillers/ plant for the two
sorghum varieties in the MJ generations.
- The lower concentration of Sodium Azide (1.0 x 10-3 m)
increased the number of tellering I plant of sorghum as
compared with an y of the applied higher concentration.
- Cyanno Gudinin concentration rates (0.001 M or 0.01 M)
significantly produced the largest number of tillers/
plant of both sorghum at t he M2 and M]generations.
• Plant height:
Heights of plants of the two sorghum varieties were
significantly affected by the applied two doses of 10 and
20 KR of gamma radiation. In other words, mutations of
tallest plants were produced when 10 KR treatments was
applied. Moreover no significant effect was obtained on
plant height of sorghum up to 40 KR for both varieties.
- No appreciated significant effect on sorghum plant
heights ”vas detected due to any of t he applied SA
mutagenic treatments on Tifton sorghum.
- Tallest plants were produced when using the higher
level (0.1 MO of CG rather than the lower one (0.001
M) in Quna sorghum at both of M2 and M) generations.
• Stem diameter:
Using 20 KR gamma radiation could be satisfactory for
inducing mutations of larger stem diameter for either
Tifton or Quna sorghum in the MJ generation.
- The applied level of Sodium Azide (I.S x io’ m) induced
thicker stemmed plants in the M( and M3 generations of
Tifton as well as in M, and M3 generations of Quna
sorghum.
- The applied lower of Cyanno Gudinin (0.001 M)
increased stem diameter in plants of the M2 and M)
generations for Quna sorghum. But Tifton sorghum was
SUil1lVIARY - 92 -
not that sensitive to any of the applied levels of CO
regarding its ffeet on tem diameter.
• Number of leavesl plant:
- In spite of the slight significant differences the number
of leaves per plant as affected by the applied mutagenic
treatments, the differences in this trait were not that
wide or clear. Such results were not much information.
• Leafarea of third top leaf:
- The leaf area of Tifton sorghum was not much affected
by any of the applied physical chemical mutagen
treatments. Lowest level (10 KR) of gamma radiation
significantly produced the largest leaf area in M2
whereas, the extra higher rates (20 30 and 40 KR)
induced similar significant effect for Quna sorghum ill
the M3.
- When using the highest level of CG (0.1 M) and SA (1.5
x 10-3 111) induced plants of larger leaves in M2 and MJ
Quna sorghum.
• Downy mildew infection:
- Downy mildew resistance of Tifton sorghum in MJ
generation was obtained in the control compared to using
the mutagenic treatments of gamma radiation at 20 30
and 40 KR; odium Azide at all of the applied levels;
and Cyanno Gudinin at 0.0 I M and 0.1 M concentration.