الفهرس 
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Abstract
Rice is one of the most important oereal orops in
Egypt. It is the seoond export orop after ootton and
important food orop. Rice blast incited by Pyricularia
oryzae avara., is considered, one of the most des tructive
disease of rioe allover the rioe growing areas in
Egypt. It oauses considerable losses of the orop yearly.
Results obtained from this investigati.on could be l!IUIDIIlarized
•• followSl
1- During 1980 rice growing season. eleven physiologio raoes
of ~. oryzae designated as: IA28 IAS7’ IBl, IBS’ ~C19’
.IC
26
, ID
2
~ IEI’ IE.-r,IGI and Illl were identified from
94 speoimens oollected from different rice growing
governorates in ARE using the set of international differential
rice vari.eties.
2- Twosubraoes of ~. oryzae were identified under each of
raoes IAs7’ IE.-rand Ill1 by the use of 12 local and foreign
rioevarieties. g,uring season 1980..s..
3- Eighteen physiologio raoes of ~. oryzae were identified
from 103 speoimens of infeoted~leaves and necks of rioe
plants col1eoted from different localities of the rioe
grOWing area during 1981 season. These raoes were designated
as: IA17, IAs7’ 1A64, I~21’ IB32, IB34• IBS7’ IB59,
IB
62
• IC
14
, 1°
27
, 1030’ ID5, IFl, IFi’ IF), 1Gi and 1G2•
-- --- - - -_.---_ .. - -_.- --
- 1}6 -
4- Using 33 local and for eign rice varie ties two subraces
of Pyricularia oryzae were identified under each race
of IFl and IG2 and three eLilracesunder race IF2 during
1981 growing rice aeason.
s- Using the set of international differential rice varietie.
s. fifteen races of!.. oryzae were identified from
107 specimens of infected leaf and necks collected from
different localities of the rice growing areas in ARE
during 1982 rice growing season. These races were
designated as IA116• IB54• ICl, IC17, IC20, ID1, ID
9
,
IE1, IE2• IES’ IE6, IF1• IFi. IG1 and IH1•
During 1982 rice growing seson, three subraces of
!.. otyzae were identified under each of races IEl and
lEi also two subraces under each of races IES’ IFl and
IF2, using 12 Japanese rice varieties and 4 local ~nes
7-All races and subraces of !.. otyzae identified during
the period from 1980 to 1982 varied in their virulene on
all the tested varieties.
8- Race groups IA. IB and IC are more common each year during
the period 1980-1982 and there is f1.uctuation between
races groups namely ID, IE, IF and IG from year to other.
9- Horizontal resistance occurred in five rice varieties i.e.
• ~aby. Giza 180, CO 34. Sakha 2 and IR 36 and ten rice
varieties showed vertical resistance, these varieties are,
i.e ,Nahda, SalJieni, Agamiml, Yabani 15, Giza 14, Giza
159, Giza 1’70, Giza 171, Giza 172 and IR 8.
10- No stable races were found from.the first asexual generation
to the last one ’(after 36 months)~ HoweverSOme
races showedstability during the 24 generations as IGl
and IFlthen cllangedto other races, also their virulence
changed as race cllanged. However,someraces changed but
their virulence was not changed such ~ race I026 (with
disease index 14) which cllanged to race I027 with the same
disease iIJdex (14).
11- Bacterial and fungal spp were isolated from leaf surfaces
of both susceptiblo or resistalllLrice varieties ..lfueir
numbersincreased with the increase of age of the plant and
also on the resistant varieties more than. sueceptible ones~
12- ~o bacterial spp. showedant~onistic reaction against
E. aryza.e. These isolates wereidenti:fied as: Bacillus
cerious var~ lD,ycoidss and the aecond sp, have
two isolates which were identified as Bacillus sUbtilis •
.B1ocer1ne,antibiotic, was isolated and identified frolll
culture filtrate of Bacillus cerious var m,ycoidAlS and
Myoosubtiline from culture filtrate of the two isolates
of 12. subtililll. ’fhese compoundswere effective in decreasing
the infection of rice plants with E~oryzae especially
Bioceren. Also the crude filtrate of the obovementioned
Bacilli Walileffective in controlling E~oryzae eapecially
that of 12~cereus v ; lll,ycoidlS_
13- Total free amino acids showedsignificant differences at
the seedling stage between susceptible and resistant
varieties. Higher amounts were noticed in susceptible
varieties. Yabani 15 found in leaf of healthy resistant
Araby variety. However these amounts increased greatly
in the infected plants whethe~’ susceptible or resistant
than healthy ones. Proline was fouhd in higher amounts
in infeoted Giza 180 resistant rice variety while therionine.
arginine and glutanine were found in higher amounts
in both in fected Giza 180 (R) and Nahda (3) rice varieties.
In this respect leucine + isoleucine and aspara-
. tic acids were found in hi~;Aer amounts in infected Yabani
15 (3’ varie ty.
14- At tillering stage althou~l total free amino acids was
equal for the two susceptD~le varieties, Yabani 15 and
Nahda but general decrease in all amino acids except
therionine + glutamine was noticed in both susceptible
anllresistant varieties. Higher amounts of alanine, serine
and glycine werb present in infected Nahda (3) rice variety.
However the lowest.amounts of total amino acids were found
in healthy Araby (R) variety. Although proline amount,
were reduced in all varieties but it was noticed in higher
amounts in infected Giza 180 (R) rice variety.
15- At the adult stage of growth general increase in all the
amounts of total amino acids was noticed in both infected
susceptible and resistant varieties except incase of alonine
in Nahda(S), Giza l80(R) and Araby (R) rice varieties.
AlSO, proline amounts increased in Giza 180 infected
plants only and do,creased in all the other treatnents.
As far leucine + isoleucine their amounts increased
except that oftherionine + glutamine in case of Nahda
healthy. ’plints. However,it could be noticed that the
total amounts of free amino acids were higher in infected
plants than in heal thy ones and the highest amounts were
noticed in Yabani 15 susceptible variety.
l6~ In four tested varieties, Araby and Giza 180 re ’lstant rice
varieties and Nahdaand Yabani 15 susceptible ones,
, total sugars increased by ageing of the plants
whether infected or not. However, the total sugar’contents
were higher in infected plants than heaJtby one.
specially the SLlSCep tible ones at tillering and adult
stages of growth.
11- Reducing sugars were generally higher in infected rice
plants than heal thy ones speciaUy at tillering stage.
However,a general decrease in the reducing sugar contents
Wasnotioed by the increase in plant age in all tested
varieties.
18~ Healthy su.soeptible rice varie ties showhigher amounts
of suorose than the resistant ones. Infected susceptible
varie ties contain higher amounts of sucrose than resistant
ones. Howeversucrose contents decreased at tillering
and adult stages in all tested varieties. Also 1:he same
trend was noticed as regards glucose and galactose exce~t
that.their amounts decreased in case of Araby (R) variety
in infeoted plants than in uninfeoted ones at the seedling
and adult stages only.
19- Fruotose is found inhigner peroentages in infected plants
and in susceptible varieties than ~ninfected plants as well
as resistant varieties in different stages of plant growth.
There was signifioant difference in fr~otose amounts between
infected and uninfeoted plants in oase of Giza 180
(R) rioe varie ty at the adu.lt..ztage~
20- The oontents of mannose were higher in susceptiLle variety
either infected or not than the resistant one specially at
the seedling stage. This inorease was noticed in Yabani
15 (3) variety and at the tillering stage mile no ’signifioant
differenoes were noticed in the adult stage.
21- The amounts of total phenols were higner in infected plants
in all teBted varieties.’ Also their amounts were higher in
resistant varieties than susceptible ones. It is olearly
notioed that these amounts increased also by the inorease
in plant age speoially in reBistant infeoted and uninfeoted
plants •
. 22- Resistant varieties contain higher amounts of free phenols
than susoeptible ones specially •.t seedling and til1eming
stages, whereas their amounts were almost similar exoept
in oese Q~ Araby (R) infected plants.
•
23- As for conjugated phenols their amounts were higher in
all infected varieties than healthy ones speoially at
tillering and adult stages. Also their amounts were
higher in susceptible infected and lminfected plants
than resistant varieties specially at seedling and adult
stages, whereas the contrast was noticed at the tillering
stage.
24- The highest amounts of 0 dihydroxyphenol were detected
in infected and uninfected resistant varieties in all
stages of the growth. As regards the tested susceptible
varieties, the infected plants showed higher amounts of
O. dihydroxyphenols than uninfected plants. It could be
noticed also that it’s amounts decreased by ageing of the
plants, speoially at the adult stage of growth.
25- Four organio acids, i.e. citric, malic, succinic and
fUmarie acids were detected in rice varieties i.e. ~by
and Giza 180, resistant varieties; Nahda and Yabani 15;
susceptible -onea,
26- The infection with r. oryzae caused little decl~ase in
citric aoid contents in seedling stage while in the tillering
and adult stages it’s amounts increased oonsiderably
speoially in resistant varieties.
27- The amounts of malic acid increased by infection except
in case of Yebani 15 in seedling stage. These amount s
decreased in infected plants in tillering stage except in
case of Giza 180 resis tant varie ty. As for the adult
stage malic acid amounts increased in infected plants
except in Hahda susceptible rice variety.
28- The amounts of succinic and fumaric acids decreased in
susceptible varieties due to infeotion, whereas contrast
results were noticed as regards the resistant varieties
in all stages of growth except Araby resistant variety in
the tillering stage of growth.
29- The isolated races differed in there virulence and also
in their contents of total free amino acids. Race I~7
w’hichhave the highest disease index (22) produced lC1Ner
amounts of amino acids both in culture filtrate and
mycelial mat, except asparatic, valine, phenylalanine and
leuoine + isoleucine in culture filtrate whereas it
produoed lower amounts of all amino acids in mycelial mat.
In this respeot the secord race in virulence IB5 ahowed
lower amounts of total free amino acids either in the
filtrate or mycelial mat. The fifth race in virulence
gave the highest amounts of amino acids whereas the least
amol.uitswere obtained by race IB5 which ranks the second
in it’s virulence, whereas the highest amounts j,a obtained
by race I~21 which ranb the fourth in its virulence (16)
both in the filtrate or mycelial mat. Thus it could be
conoluded that there is no oorrelation between the virulenoe
of the race and the amounts of free amino acids both
in filtrate or myoelial mat•
30~ Also, results indicated that there is no correlation
between the ra.ce virulence of l~or,y;zaeand the amounts
·of total and reducing sugars in both the culture filtrate
or the mycelial mat, of each race.
31- As regards sucrose amounts, the h~hly pathogenic race
-
IA17(22) produced moderate amounts of it, while races
IA(l21) (16), IB5(20) and IBi5 (15) differed in their
virulence but produced low amounts of Blorose whereas
race 1Fi(12) and IG2(10) the least virulent races pro’l(’
duced high amounts of sucrose. As before a reversble
correlation ooeficient was obtained between ra.ces
virulence and different sugar contents.
32- Nooorrelation was obtained between amino acids contents
and. different contents of sugars and race virulence with
Yabani 15 rice variety.
:.n- The infection with the eight races ot l. or,y;zaeon Yabani
15; susceptible rioe variety, decreased the amounts of
all organio acids, i.e. oitric, malio. auccini.o and tamaric
aoids. Generaly no correlation was obtained between ra.ce
virulence and all tested organic aoids.
34- Results showed clearly that there is no oorrelation between
the race virulence end its ability of produc:U1g
toxins.
,,5- Total, free and conjugatedphenols increased as a result
of infection of the susceptible variety Iabani 15. As
regards the interaction betweenrace virulence and
phenolic compoundsa negative c~rrelation could b.
noticed.