الفهرس 
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Abstract
Baxley is one of the important cereal crops in
the world. Helminthosporium diseases ale considered
as most destructive diseases which etta.ck this crop •.
In this respect spot blotch became one of the main
cause,ls of yield reduction of baIley in Egypt
specie,1ly in warm,. wet weather in coestal regions.
The causal organism was isola.ted from different
localities in Egypt., identified end the pathogenicity
wa.s det e.rmined.. The host range and viability of
the pathogen were studied together with the activities
of pectolytiC, cellulolytic and.oxidative enzymes
for both the paghogen and extracts of baxley plants.
The relationship between resistance and chemical
components of baIley plants i.e. aminO acidS, sugars
and phenolic c0mpounds and the toxic effect of culture
filtrates of the fungus were evaluated. The susceptibility
and resistance of different bal:ley variet ies to
the disease was studied. The effect of different
fungicides on linear growth of the pathogen in l~boratory
and in the greenhouse end the field was studied
also. Results obtained could be summarized as follows:
(1) spot blotch of barley in Egypt during seasons
1979-81 indicated that the disease was found in
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coastal legions, Delta. and the Middle Governora.tes
of Upper Egypt. The highest percentages of infection
were observed at Kefr El-Sheikh, Alexandria,
De.m.iett a and deer eased gradually south-waI ds.
(2) Twelve isola.t es of !!.el~inthosporj.-ill!! sat ivum were
isolated from diseased leaves showing typica.l spot
blotch sympt ems. The pathogenicity test revee.led
thet the se i sola.t es vexied great 1y in t heir pathogenicity
together with differences in morphologica.l
characteristics and isolate No.4 was the most
virulent isolate, whezeas, isolate No. 12 was the
least virulent one.
(3) Results of the host range of Hel~intho~ori~~
sativum indicated t hat the fungus has a wide host
lange in EgypL, as it was found to infect Avena.
futua, Cynodon dactyl~L .~~ Lotundus,
Echinochloa colonum, ~chi~2.h.1:2J!’£!’1!§.&slli,
Horde~ vulgare, Loliu@ temule~~, ~olium ~erena,
Oryza sa.t iVJ!, Polypogen monspelienais, Set ax ia.
viridi~, Sorghum v~lgar~, Triticum vulgare and
~ maize.
(4) The severity of the fungus increased gradually and
zeached the maximum after 1 month, then gxadually
decreased by ageing t i~l the 18th month.
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(5) The highest activities of polygalacturonase (PG),
Cellulolytio (ex) and pectinmethylestrese (PME)
enzymes were found in the fungal filtra.tes of
isola.te No.4 (the most viru1ent)~whereas the
lowest activities were in isolate No. 12 filtrate
(the less virulent).
(6) As regards the effect of fungicides on enzymes
activities studies indicated that PG and ex
activities were reduced with the increase in the
concentration of the tested fungicides specially
in case of l?lant avax and ba.yleton, whe reas ,
Wolfen-thiram and Dithane M22 had little effect
on PG and ex enzymes activities.
(7) polyphenoloxidase, Pero~ida.se, Catalase and
Ascorbic acid oxidase activities were relativ&ly
higher in the mycelial matrix than in the filtrate
of each of the tested isolates. Also these activities
were higher in the highly pathogenic isOlates
(isolate No.4) than the least pathogenic
one (isolate No. 12). These activities incYeased
alsO by increasing the incubation periods in both
mycelial matYix and fungal filtrate.
(8) Adult plants showed high levels of polyphenol-
!xidase activity as compared with the seedlings.
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In this .respect infection with H. !!.ativJ!!!lcaused
gr adual, Lncr ease in enzyme act ivity specially in
the .resistant varieties specie.llY in the seedling
stage.
(9) A~ult plants and seedlings of resistant vaxieties
exhibited higher levels of peroxidase a.ctivity e.s
compared with the susceptible cnes. In this
regar d the Lncr ease of per 0:: idase eC t i vi t y was
slight in susceptible varieties and higher in
resistant ones specially in adult plants.
(10) Catalase activity was higher in seedling and adult
leaves of the tested varieties specially in resistant
ones. Also, infection with the pathogen
exhibited higher catalase activity in the resistant
cultivars than in susceptible ones.
(11) Healthy leaves from seedlings and a.dult plants of
the resistant varieties exhibited higher activity
of ascorbic acid oxidase enzyme then that in the
suscept i ble onea , Inoculat i on wi t h g. .~ti.Y”..’!m
result ad an increase in aScor bic acid oxide.se
enzyme activity speciallY in the leaves of resistant
varieties than in that of susceptible ones and
in adult plants than 1n seedling stage.
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(12) Concerning phenol Lc compounds, reSI.11 t s indicated
that total, free, conjugated and ortho-dihydroxyphenols
were fCQlld in higher amounts in the
resistant varieties than in susceptible ones.
However, it was found clearly that phenolic
compounds eccumulat ed fast er in resist ant var ieties
then in susceptible ones as a result of infection
end also by long incubation period
spec ially aft ex 10 days fr om inOcLllat ion and in
re$istent plants.
(13) Total and reducing sugars contents were higher in
leaves of susceptible varieties than in the
resist ant ones. Adult plant s conta.ined higher
amounts of total and reducing sugars then the
seedlings. Inoculation with li. ~~~Jv~ caused
pronounced decrease in both total and reducing
sugars in seedlings or adult plants of susceptible
vaxieties, whereas, inoculation induced an increase
in the resistant ones.
(14) Paper chIomatogrsphic analysis showed the presence
of Maltose, Sucrose, Glucose, Ga~actose and
Fr ac t 0 se in inoculat e4 and uninoc uLat ed leaves of
all the tested varieties in both seedlings and
adult plants. However, no ·clear correlation was
found between resistance or susceptibi1ity of
the tested barley varieties and any of the
above-mentioned sugasSt
(15) Concernj~g of total free amino acids, their
content increased as a result of inoculation with
Helm1~~hosporium sati~ in both resistant and
susceptible vaxieties in the seedlings as well as
in adult plents. In this regard, susceptible
varieties contained higher levels of total free
amino acids than the resist ant ones in both Eeedling
end adult plant stages. However, e.dult
plants contained higher amounts of amino acids
than seedlings.
(16) Qualitative analysis indicated the presence of
seventeen amino a.cids namely Cystine, Lycine.
Histidine, Arginine, Aspazatic acid, Glycine,
Serine, Glutamic, Therionine, Alanine, Proline,
Tyrosine, Methionine, Valine, phenylalanine,
Leucine and Iso-leucine in seedlings as well as
adult plents of resistant and susceptible varieties.
(17) The amounts of total amine acids inczeased as
8 xesult of infection in both the susceptible and
zesistent varieties as compared with the uninoculated
contrcl.
(18) ’rhe quantities of carta.in amino acids as Lycine,
Histidine and Arginine were higher in the susceptible
vazieties then resistant ones, wheree.s the
contrast we.s noticed as regards Tyrosine end
phenylalanine. On the other hend, Proline
appeeIed with higher concentrations in the susceptible
vezieties than the resistant ones in both
seedlings and adult stages and its concentrations
were higher in healthy plants as compared with
inocule.t ed ones.
(19) In response to inoculation with Ii· s§;.liV:~.mTylcsine
and Phenylalanine quantities increased in the
resistant vaIieties and decreased in the susceptible
ones. In this respect, Methionine and Valine increased
as a result of infection in resistant varieties
in the seedlings. The highest amoants of
Lyeine, Histidine and Arginine were obtained in the
infected susceptible varieties. As for, the other
amino acids no general trend was noticed in either
resistant 01 susceptible varieties.
(20) The elude culture filtrate of two isolates of
H-. sativum (one virulent and the other avirulent) .--,-.””.......--._’----
induced inhibitory effect on the percentage of seed
germineti(n, lengths of cole~ptile and roots on ell
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the testlj-d varieties.. HpweveI, the high concent-
Iation of crude culture filtrate W8.S the most
effective in this I espect. This effect decreased
proporticne.llY with the dilution of crude filtrate.
In this regard the most effective flitrete
was take:n from 30 daYS eLd cultures end was that
of the most virulent isolate No.4.
(21) One to:x:_c fraction waS isola.ted in crystaline f cr m
(rod cz:,stals), according to the method adopted by
Lindberg (1971), and Turner (1971) and was identified
as Helminthospcral. In this regard the virulent
iselete No.4 produced 4.633 go/liter of
eultuI€ medium of toxin; while the less virulent
isola.te NO. 12 p:r:oduced 2.461 g./liter of cut t ure
medium. The toxin gave simileI symptoms on seedlings
and adult plants and effects as mentioned
before. However, the phytoxic effect of the toxin
decreased proportionallY by decresing its concentration.
(22) Sczeening of 37 selected baxley varieties under
greenhouse conditions in the seedlings, indicated
that 16 vexieties weze highly resistant and 5
varieties were moderately susceptible, while !6
vazieties were susceptible. (n the other hand,
under field conditions in adult stage results
indicated that from 44 varieties, 19 were resistant,
4 modeIately susceptible, 13 susceptible and
8 were very susceptible.
(23) As regards the correla.tion between the beha.vioUI
of 45 v8xieties in both seedling and adult ,stages,
it was fClxod that these vaIieties could be put in
two gr~ups as follows:
A- Thefrist group in which there was no effect
of plant age on the vaxietel resistance or
susceptibility as follows:
1. Seven vBxieties were resistent in both
seedlings and adult stages.
2. Fourteen varieties were susceptible in
both seedlings and adult plants.
B- The second group in which there waS an important
effect of plant age on the varietal resistance
or susceptibility as folloWS:
1. Eleven varieties showed increasing
resistance with age.
2. Six varieties were susceptible in the
seedling stage end became resistant
with age.3. Seven varieties showed increasing susceptibility
with age.
(24) Soreening fungicides !a vitro showed that the
tested fungicides varied in their effect on
fungal gIowtn. However, all the fungicides
except Bevistin and Spergon almost stopped the
linear growth of ~. ~~tivumat relatively low
eoncentr a.tions of 100 ppm. This effect in •.
creased with the increase in concentrations.
The fungicides Wolfen thiram, Dexon, Plsntevax
~d Dithane M
completely inhibited the fungal
growth at the concentrations of 50, 200, 400
and 400 ppm respectively.
(25) Using these fungicides as seed dressings under
greenhOuse increased the percentage of seed germination,
the number of ears per pot, the weight
of grains in gm per pot and 100 grains weight.
On the other hand, the severity of infection was
xeduced as the fungicides were applied. However,
wo].fsn *hiram, Dexon and Spergon were super ior in
this respect while Vitavax and Brassteol followed
the afolementioned fungicides in tneir effect,
whereaS, Bavistin was almost uneffective.
(26) Using these fungicides as foliage spraY under
greenhOuse conditions (after artificial infection
by splaying with a spore suspension at the concentration
of 80,ouO - 100,000 conidia/ml. of
Belminthoephorium sativum), the severity of infection
was reduced while the weight of grains per
pot and $be 100 gxains weight significantly increased
Plantevax end Dithane M.45 (Mancozeb) were •
supezior in this respect while Dlthane M22 (Mane~
and Bayleton followed them.
(27) Using these fungicides as seed dressings under
field conditions showed tha,t all the tested fungicides
reduced the severity of infection and significantly
increased the yield and weight of 1000
grains. In this respect, Wolten thiram, Dero.n and
Vitavax were superior to the other tested fungir
cides. Un the other ~aad, by using fungicides for
oliage spray under field conditions after artiicial
infection by spraYing spore suspension of
elmlnthos Ottum Bativum, the severity of infection
was reduced as the fungicides were applied whereas
significant increase in the yield for each plot and
the weight of 1000 grains was noticed. Dithane M45
end Plentavax were super io.r in this respect to the
other tested fungicides.