Directory UMM :Data Elmu:jurnal:E:Environmental Management and Health:Vol09.Issue5.1998:
Biochemical changes in wheat plants as af fected by
residues of dimethoate and pirimicarb
M .A. Abo-El-Seoud
Ato mic Ene rgy Autho rity, De partme nt o f Plant Re se arc he s, Abo u-Z abal, Egypt
M . Frost
Bio lo gisc he Bunde sanstalt für Land-und Fo rstwirtsc haft, Be rlin, Ge rmany
Wheat plants were grown in
fi eld plots of 3×3m area.
After growth period of two
months, the growing plants
were sprayed with dimethoate
and pirimicarb at the recommended dose. Spraying was
repeated after a further 45
days. Plant samples were
taken at intervals of zero,
three, six, nine, 12 and 15
days after each application. A
gradual and continuous
degradation of the applied
pesticides had taken place in
the treated wheat shoots up
to the end of the experiment.
However, dimethoate showed
more residues and persistence rather than pirimicarb.
The break down and metabolism of the applied pesticides
was correlated with some
biochemical changes in the
sprayed plants. Sampling
dates of three and six days
after application were the
most critical periods to affect
plant metabolism. A decline
was noticed in chlorophyll,
sugars and carbohydrates,
total proteins and RNA content of wheat shoots as a
function of the applied pesticides. Free amino acids were
accumulated in the sprayed
plants, meanwhile the DNA
content did not show observable changes as a consequence of the applied pesticides treatment.
Enviro nme ntal Manage me nt
and He alth
9 / 5 [ 1998] 1 8 8 –1 9 3
© MCB Unive rsity Pre ss
[ ISSN 0956-6163]
[ 188 ]
Introduction
Th e expa n din g u se of pesticides for pr otectin g cr ops a ga in st pests a n d disea se a tta ck is
a n im por ta n t pa r t of th e m oder n a gr icu ltu r e.
Pesticides a r e in ten tion a lly toxic su bsta n ces
beca u se of th eir u tiliza tion pu r poses. Repor ts
em a n a tin g fr om a r ea s in wh ich th ese ch em ica ls a r e u sed h ave sh ow n th a t besides
pa th ogen s a n d pests, m a n y oth er or ga n ism s
h ave fa llen victim to pa r ticu la r a pplica tion .
In th is con n ection , Koem a n (1979) m en tion ed
th a t th e m ost obviou s side effects of th ese
toxica n ts a r e: m or e or less wh olesa le m or ta lity of m a n y a n im a ls a n d pla n t species,
ch a n ges in th e a bu n da n ce of species a n d th e
diver sity of ecosystem s, a n d a r edu ction in
th e pr odu ctive poten tia l of n a tu r a l r esou r ces
a n d n on - ta r get species.
Addition a lly, som e r esea r ch er s r epor ted
th a t th e u tiliza tion of pesticides for cr ops
pr otection w a s a ccom pa n ied by th e a ppea r a n ce of som e toxic a n d in h ibition im pa cts on
pla n t gr ow th . Th ese effects r a n ge fr om a
sligh t gr ow th in h ibition to a deleter iou s m or ph ologica l distu r ba n ce for a ll th e pla n t or
pa r ticu la r or ga n s. Ca r tw r igh t (1976) a n d
Ash ton a n d Cr a fts (1981) m en tion ed th a t
pesticides ca u sed deleter iou s a lter a tion in
cell division , cell en la r gm en t a n d tissu e differ en tia tion . Th ese u n desir a ble effects m igh t
lea d to gr ow th in h ibition s, epin a sty, for m a tive effects, a lbin ism a n d a lso cou ld r edu ce
cu ticle for m a tion a s dem on str a ted by Va n
An del et a l. (1976) a n d An bu du r a l et a l. (1986).
In a ddition , lea f ch lor osis, wh ich is followed
by n ecr osis, a com m on r espon se of pla n ts,
cou ld be tr ea ted w ith th e ph otosyn th esis
in h ibitin g pesticides (Adh ya et a l., 1981;
Moor th y et a l., 1992).
Na tu r a lly, th e a bove m en tion ed m or ph ologica l ch a n ges a n d h a za r dou s im pa cts r esu ltin g
fr om pesticide u tilization sh ou ld be du e to a
distu r a ba n ce in th e ph ysiologica l pr ocesses
a n d m eta bolic pa th w ays in pla n ts. P r eviou s
stu dies in dicated a n in h ih ition in th e syn th esis of ph otosyn th etic pigm en ts, a declin e in
ca r boh ydr a tes a n d su ga r s con ten t a s well a s a
distu r ba n ce in th e m etabolism of pr otein s a n d
n u cleic a cids con ten t of th e pesticides tr ea ted
pla n ts (Moor th y et a l., 1992; Sh a m s E l-Din et
a l., 1995; Won g a n d Ch a n ge, 1988).
Th e pr esen t wor k in vestiga ted th e bioch em ica l r espon se of wh ea t pla n ts to th e a pplica tion of eith er dim eth oa te or pir im ica r b.
Materials and methods
Insecticides
1 Dim eth oa te: O,O-dim eth yl S- (m eth ylca r ba m oyl m eth yl) ph osph or odith ioa te. It
w a s u sed u n der tr a de n a m e of Cygon 4E ,
a n em u lsifia ble con cen tr a te w ith a n a pplica tion r a te of 480g AI/ h a
2 Pir im icab : 2- dim eth yla m in o - 5,6dim eth ylpyr im idin - 4-yl- N,N - dim eth ylca r ba m a te. It w a s u sed u n der tr a de n a m e
of P ir im ior 50, a wetta ble pow der w ith a n
a pplica tion r a te of 200g AI/ h a
Field experiment and pesticides application
Wh ea t seeds (Tr iticu m a estivu m L. cv. Hein es
Koga II) wer e sow n in field plots of 3 × 3m
a r ea . After gr ow th per iod of two m on th s, th e
gr ow in g wh ea t pla n ts wer e tr ea ted w ith th e
in dividu a l in secticides a t th e a bove m en tion ed r a tes. For ea ch pesticide, th r ee plots
wer e u sed a n d distr ibu ted in a com pletely
r a n dom ized design . Spr ayin g w a s r epea ted
on ce m or e a fter 45 days fr om th e fi r st a pplica tion . Repr esen ta tive sa m ples wer e r a n dom ly
collected fr om th e tr ea ted a n d n on -tr ea ted
wh ea t pla n ts on e h ou r a fter a pplica tion (zer o
tim e) a n d th en a t in ter va ls of th r ee, six, n in e,
12 a n d 15 days. Th e obta in ed sa m ples wer e
divided in to sh oots a n d r oots a n d pla ced in a
deep fr ee zer a t 18°C u n til a n a lysis.
Determination of pesticide residues
Pesticide r esidu es wer e extr a cted a ccor din g
to th e pr ocedu r es of Stein w a n dter (1985).
Sa m ples wer e extr a cted by blen din g w ith
a ceton e a n d sa ltin g ou t w ith sodiu m ch lor ide.
M.A. Abo -El-Se o ud and
M. Fro st
Bio c he mic al c hange s in
whe at plants as affe c te d by
re sidue s o f dime tho ate and
pirimic arb
Enviro nme ntal Manage me nt
and He alth
9 / 5 [1 9 9 8 ] 1 8 8 –1 9 3
Th en , n -h exa n e w a s a dded a n d th e m ixtu r e
w a s blen ded a ga in . Th e or ga n ic ph a se w a s
con cen tr a ted u n der va cu u m to 2-3m l. Th e
r edu ced extr a cts wer e clea n ed u p over silica
gel, eva por a ted to dr yn ess a n d th en tr a n sfer r ed qu a n tita tively to 10m l volu m etr ic
fla sk s a n d br ou gh t to volu m e w ith n -h exa n to
be u sed for GC deter m in a tion .
A P YE u n ica m ser ies equ ipped w ith N / P
detector a n d pyr ex gla ss colu m n pa ck ed w ith
OV.17 on 80/ 100 m ech ch r om osor b w a s u sed
for deter m in a tion of pesticides r esidu e. Th e
tem per a tu r e u sed w a s 260, 250 a n d 265°C for
in jection , colu m n a n d detector r espectively.
Determination of chlorophyll content
Ch lor oph yll con ten t of wh ea t sh oots w a s
extr a cted u sin g 96 per cen t eth a n ol on 80°C
a n d estim a ted a ccor din g to th e equ a tion s of
Win ter m a n s a n d Mots (1965).
Carbohydrates and sugars analysis
Tota l ca r bohydr ates wer e deter m in ed followin g hydr olysis u sin g 1 N su lph u r ic a cid in
sea led tu bes in a n electr ic oven at 100°C for 24h .
Tota l solu ble su ga r s wer e extr a cted by 85 per
cen t eth a n ol u sin g soxh elt appa r atu s for 6h .
Tota l hydr olyzable ca r bohydr ates a n d solu ble
su ga r s wer e estim ated u sin g th e m eth od
descr ibed by Du bois et al. (1956). Redu cin g
su ga r s wer e deter m in ed in th e eth a n olic
extr a ct u sin g th e AOAC m eth od (1985).
Determination of total proteins and free
amino acids content
Tota l fr ee a m in o a cids wer e estim a ted in th e
eth a n olic extr a ct u sin g th e m eth od of Dot et
a l. (1981). Tota l N a n d cr u de pr otein s wer e
estim a ted u sin g th e u su a l m icr o-Kjelda h l
m eth od (AOAC, 1985).
Determination of nucleic acids content
RNA a n d DNA wer e extr a cted a ccor din g to th e
m eth od descr ibed by Ogu r a n d Rosen (1950).
Th e UV a bsor ption of both RNA a n d DNA
solu tion s w a s m ea su r ed a t 260 a n d 280n m .
Results and discussion
Pesticides residues
De gr a da tion beh aviou r of both dim eth oa te
a n d pir im ica r b in th e tr ea ted wh ea t sh oots is
illu str a ted in Ta ble I. Dim eth oa te sh owed
in itia l r esidu es of 27.35 a n d 25.34 ppm a fter
th e fir st a n d secon d a pplica tion r espectively.
After th r ee days of a pplica tion , a sh a r p
declin e occu r ed sin ce m or e th a n 50 per cen t of
th e a pplied pa r en t com pou n d w a s de gr a ded.
F u r th er de gr a da tion occu r ed du r in g th e n ext
sa m plin g da tes, h owever, it w a s slower du r in g
th e la ter per iods wh en com pa r ed w ith th e
ea r lier on es. On ly 0.09ppm of th e a pplied
in secticide w a s detected in wh ea t sh oots a fter
15 days of a pplica tion w ith r e ga r d to th e fir st
spr ay, h owever, it w a s u n detecta ble a fter th e
sa m e tim e for th e secon d a pplica tion .
Com pa r in g r a te of dim eth oa te br ea k dow n
a fter th e im posed a pplica tion s, it w a s
a ppa r en t th a t r a te of pesticide de gr a da tion
w a s r ela tively h igh er a fter th e secon d spr ay
a s com pa r ed w ith th e fi r st on e. N a tu r a lly, th is
obser va tion sh ou ld be a ttr ibu ted to th e ph ysiologica l sta tu s a n d th e developm en ta l gr ow th
sta ge of th e tr ea ted pla n ts a fter ea ch spr ay.
On th e oth er h a n d, in itia l a m ou n ts of
pir im ica r b wer e 12.86 a n d 10.86ppm a fter th e
fir st a n d secon d spr ay r espectively. Meta bolic
de gr a da tion of pir im ica r b du r in g th e exper im en t cou r se exh ibited n ea r ly sim ila r tr en ds
a s th ose obser ved for dim eth oa te. F a st de gr a da tion w a s r ecor ded du r in g th e ea r lier
sa m plin g da tes a n d a slower r a te w a s n oticed
for th e la ter in ter va ls. On th e oth er h a n d, th e
ca r ba m a te in secticide u n der in vestiga tion
beca m e u n detecta ble in th e tr ea ted wh ea t
sh oots a fter 15 a n d 12 days of a pplica tion w ith
con cer n to th e fi r st a n d secon d spr ay r espectively. Aga in , r a te of pir im ica r b decom position w a s com pa r a tively h igh er in th e spr ayed
wh ea t sh oots collected a fter th e secon d
a pplica tion r a th er th a n th ose of th e fir st on e.
For both dim eth oate a n d pir im ica r b, n o
r esidu es cou ld be detected in wh eat r oots
du r in g th e stu died per iods a fter application .
Th is in dicates th at th er e wa s n o down wa r d
tr a n slocation fr om th e sh oots a n d a lso n o pen etr ation fr om th e a ccu m u lated r esidu es on soil
su r fa ce to th e gr owin g r oots h a d occu r r ed.
Com pa r in g da tes of both th e stu died pesticides r esidu es in wh ea t sh oots r evea led th a t
dim eth oa te h a s h igh er con cen tr a tion r a th er
th a n th ose of pir im ica r b. In a ddition ,
dim eth oa te sh owed m or e per sisten ce a n d less
degr a da tion a s it cou ld be estim a ted in pla n t
tissu es for lon ger tim e r a th er th a n pir im ica r b.
Resu lts of th e pr esen t wor k a r e in a gr eem en t
w ith r eleva n t stu dies con du cted ea r lier. Th u s,
Szeto et al. (1985) fou n d th a t tota l r esidu es of
dim eth oa te a n d pir im ica r b a pplied to a spa r a gu s wer e decr ea sed by a bou t 90 per cen t a fter
seven days of tr ea tm en t a n d th e declin e
beca m e a t a slower r a te th er ea fter. Ca br a s et
al. (1991) m en tion ed r a pid degr a da tion for
pir im ica r b a pplied to lettu ce a n d it beca m e
detecta ble five days a fter tr ea tm en t. Xia oh on g
et al. (1992) r epor ted a r apid declin e of
dim eth oa te in ea r s a n d leaves of wh ea t a s it
r ecor ded a h a lf life of 1.85 a n d 1.93 days r espectively. Recen tly, F r ost a n d Abo-El-Seou d (1997)
fou n d th a t r a dioa ctive pir im ica r b w a s
depleted to 16.79 per cen t of th e in itia l dose
a fter seven days of a pplica tion to wh eat sh oots.
[ 189 ]
Chlorophyll content
Da ta pr esen ted in Ta ble II dem on str a te th e
im pa ct of stu died pesticides on th e ch lor oph yll con ten t of wh ea t sh oots. Applica tion of
eith er dim eth oa te or pir im ica r b r esu lted in a
declin e in ch lor oph yll “a ”, ch lor oph yll “b”
a n d con sequ en tly tota l ch lor oph yll con ten t.
However, m a gn itu de of th is declin e depen ded
m a in ly on th e la pse of tim e a fter ea ch a pplica tion . In th is con sider a tion , th e lowest va lu es
of ch lor oph yll con ten t wer e r ecor ded in sa m ples ta k en a fter th r ee a n d six days of th e fi r st
a n d secon d a pplica tion r espectively. Th a t
h olds tr u e for eith er dim eth oa te or pir im ica n b. Sa m ples collected a fter n in e a n d 12 days
of spr ay sh owed a sligh t r ecover ed in cr ea se in
th eir ch lor oph yll con ten t r a th er th a n th ose of
M.A. Abo -El-Se o ud and
M. Fro st
Bio c he mic al c hange s in
whe at plants as affe c te d by
re sidue s o f dime tho ate and
pirimic arb
Enviro nme ntal Manage me nt
and He alth
9 / 5 [1 9 9 8 ] 1 8 8 –1 9 3
Table I
Re sidue s o f dime tho ate and pirimic arb in whe at sho o ts at diffe re nt days
afte r applic atio n
Dimethoate
First spray
Second spray
Days after
Percent
Percent of
treatment ppm
of loss
ppm
of loss
0
3
6
9
12
15
27.35
12.36
7.81
2.48
0.93
0.09
0
54.81
71.44
90.93
96.60
99.67
25.34
10.61
2.95
0.84
0.02
ND
0
58.13
88.36
96.69
99.92
–
Pirimicarb
First spray
Second spray
Percent
Percent
ppm of loss
ppm of loss
12.86
5.24
1.95
0.81
0.06
ND
0
59.25
84.84
93.70
99.53
–
10.86
4.08
0.73
0.06
ND
ND
0
62.43
93.28
99.45
–
–
Table II
Chlo ro phyll c o nte nt (mg/ g.d.wt) o f whe at sho o ts as affe c te d by dime tho ate
and pirimic arb applic atio n
Days after
treatment
Control
Chlorophyll “a”
0
15.08
3
14.26
6
15.35
9
15.20
12
16.09
15
15.92
First application
Dimethoate Pirimicarb
Second application
Control
Dimethoate Pirimicarb
16.25
12.35
11.03
14.78
15.30
14.98
15.34
13.16
12.81
13.77
14.83
15.08
12.85
13.65
12.91
12.65
12.75
12.96
13.11
9.45
10.66
12.56
12.93
12.85
12.44
10.52
10.83
12.25
12.16
12.41
3.56
3.11
3.85
3.76
3.24
3.38
3.25
2.81
2.75
2.94
3.11
3.08
3.28
2.80
2.71
2.97
3.11
3.14
2.88
2.79
2.91
2.97
2.80
2.88
2.91
2.12
2.28
2.65
2.61
2.74
2.80
2.35
2.46
2.54
2.48
2.67
Total Chlorophyll
0
18.64
3
17.37
6
19.20
9
18.96
12
19.33
15
19.30
19.53
15.16
13.78
17.72
18.41
18.06
18.62
15.96
15.52
16.74
17.96
18.22
15.73
16.44
15.82
15.62
15.55
15.84
16.02
11.57
12.94
15.21
15.54
15.59
15.24
12.87
13.29
14.79
14.64
15.08
Chlorophyll “b”
0
3
6
9
12
15
[ 190 ]
th e ea r lier in ter va ls, bu t it w a s still sligh tly
less th a n th e u n tr ea ted con tr ol. Ch lor oph yll
con ten t of th e tr ea ted wh ea t sh oots h a r vested
15 days a fter a pplica tion sh owed m or e or less
sim ila r va lu es to th e u n spr ayed pla n ts. Th u s,
it cou ld be con clu ded th a t th e deleter iou s
effect of th e u sed pesticida l ch em ica ls on
ch lor oph yll w a s detected in th e ea r lier sa m plin g da tes a n d sta r ted to disa ppea r gr a du a lly in th e la ter per iods.
On th e oth er h a n d, da ta exh ibit th a t
dim eth oa te h a d m or e pr on ou n ced effect to
declin e th e ch lor oph yll con ten t of th e spr ayed
wh ea t sh oots a s com pa r ed w ith pir im ica r b. In
th is r e ga r d, th e m a gn itu de of declin e a s a
fu n ction of th e u sed a gr och em ica l a fter six
days of spr ay w a s 28.2 a n d 19.2 per cen t for th e
fir st a pplica tion , h owever, it w a s 18.2 a n d 15.9
per cen t for th e secon d a pplica tion w ith
r e ga r d to dim eth oa te a n d pir im ica r b r espectively. Th e obser va ble in h ibition im pa ct of
th e stu died in secticides on ch lor oph yll con ten t of wh ea t sh oots du r in g th e fir st per iods
a fter tr ea tm en t m igh t be du e to a distu r ba n ce
effect on th e pigm en t’s biosyn th esis.
Th e in flu en ce of folia r a pplica tion of
pesticides on th e gr een pigm en ts con ten t of
th e tr ea ted pla n ts w a s discu ssed in som e pr eviou s stu dies. Ha ssa n et a l. (1978) n oticed a
declin e in ch lor oph yll con ten t of cotton pla n t
leaves tr ea ted w ith som e or ga n oph osph or u s
in secticides. Afifi a n d E l-Ba lla l (1982)
m en tion ed th at th e in secticides su m ith ion
a n d du r sba n h a d th e capa city to ca u se m or e
r edu ction in ch lor oph yll con ten t of br oa d
bea n s’ leaves r a th er th a n dim eth oate a n d
ga r don a . In a ddition , Won g a n d Ch a n g (1988)
dem on str a ted th a t dim eth oa te a n d oth er
in secticides in h ibited th e gr ow th a n d ch lor oph yll con ten t of a lga . Recen tly, Sh a m s-E l-Din
et a l. (1995) m en tion ed a declin e in ch lor oph yll
con ten t of ca bba ge pla n ts a s a fu n ction of
som e or ga n oph osph or u s a pplica tion . On th e
oth er h a n d, a n in cr ea se in ch lor oph yll con ten t
r esu lted in som e pla n ts du e to th e applica tion
of som e pesticides a s m en tion ed by Fa is (1988)
on leaves of n ovel or ga n es a s tr ea ted w ith
pr oth iofos, wh ile both m a la th ion a n d pr oth iofos did n ot in du ce a n y sign ifica n t effect on
ba la di or a n ges leaves. Th u s it cou ld be
dedu ced th a t th e effect of pesticides on pla n t
ch lor oph yll con ten t is va r ia ble a n d it depen ds
m a in ly on th e a pplied su bsta n ce, th e tr ea ted
pla n t a s well a s th e pla n t gr ow th sta ge a n d
m eth od of pesticide applica tion .
Carbohydrates and sugars content
E ffects of folia r a pplica tion of th e investiga ted
in secticides on ca r boh ydr a tes a n d su ga r s
con ten t of wh ea t sh oots a r e dem on str a ted in
Ta ble III. Tota l ca r boh ydr a tes wer e depleted in
th e spr ayed wh ea t sh oots in r espon se to th e
u sed pesticides u p to 12 days a fter a pplica tion .
However, th e m a gn itu des of th is declin e
depen ded on h a r vest tim e a fter spr ayin g. In
th is con sider a tion , th e m a xim u m r ecor ded
depr essa n t in tota l ca r boh ydr a tes con ten t w a s
n oticed w ith sa m plin g da te of six days a fter
a pplica tion . Th en , it sta r ted to in cr ea se a ga in
to th e n or m a l level u p to th e en d of th e exper im en t. Th e r edu ction in tota l ca r boh ydr a tes
a fter six days of th e spr ay w a s 12.9 a n d 8.6 per
cen t a fter th e fi r st a pplica tion , a n d 11.1 a n d 8.7
per cen t a fter th e secon d a pplica tion w ith
r ega r d to dim eth oa te a n d pir im ica r b r espectively. Th u s, it cou ld be con clu ded th a t
dim eth oa te w a s m or e effective to depr ess tota l
ca r boh ydr a tes con ten t r a th er th a n pir im ica r b.
Tota l solu ble su ga r s a n d r edu cin g su ga r s
con ten t exh ibit th e sa m e tr en d a n d beh aviou r
du r in g th e design ed sa m plin g dates a fter th e
im posed pesticides applica tion . Sa m plin g date
of six days a fter spr ayin g sh owed th e m ost
pr on ou n ced depletion in solu ble a n d r edu cin g
su ga r s con ten t of wh ea t sh oots tr ea ted w ith
th e tested pesticides. Aga in , th e obta in ed
decr ea se in su ga r s con ten t w a s m or e obser va ble u n der tr ea tm en t of dim eth oate.
Th e n oticea ble decr ea se in ca r boh ydr otes
a n d su ga r s con ten t of wh ea t sh oots in r ela tion to th e a pplied pesticides m igh t be du e to
th e distu r bin g in fl u en ce of su ch toxica n ts on
th e en zym es in volved in th e m eta bolic pa th w ays of th e a bove m en tion ed com pon en ts. A
decr ea se in su ga r s a n d ca r boh ydr a tes in th e
M.A. Abo -El-Se o ud and
M. Fro st
Bio c he mic al c hange s in
whe at plants as affe c te d by
re sidue s o f dime tho ate and
pirimic arb
Enviro nme ntal Manage me nt
and He alth
9 / 5 [1 9 9 8 ] 1 8 8 –1 9 3
Table III
Carbo hydrate s and sugars c o nte nt (mg/ g.d.wt) o f whe at sho o ts as affe c te d
by dime tho ate and pirimic arb applic atio n
Days after
treatment
Control
First application
Dimethoate Pirimicarb
Second application
Control
Dimethoate Pirimicarb
Total carbohydrates
0
245.26
3
239.85
6
241.76
9
243.87
12
239.96
15
240.62
241.08
218.15
210.61
228.56
236.43
238.16
242.25
225.10
221.08
231.86
237.34
241.18
268.31
270.81
272.08
269.39
274.66
271.26
270.18
246.83
241.87
253.16
268.38
269.08
272.35
254.61
248.30
256.47
268.24
274.08
Total soluble sugars
0
28.56
3
30.11
6
29.42
9
29.86
12
30.14
15
32.65
27.41
22.65
20.08
23.51
25.81
28.36
28.87
25.11
23.46
26.38
28.11
28.93
31.46
32.65
32.47
31.91
32.05
32.75
32.46
28.16
25.31
26.75
29.31
31.86
32.85
30.26
28.45
30.11
30.94
32.86
Reducing sugars
0
9.61
3
8.53
6
9.16
9
9.43
12
9.11
15
8.92
8.35
6.11
5.22
7.31
8.96
8.15
8.92
6.24
6.18
6.93
7.25
8.19
11.22
12.38
12.25
11.61
12.41
12.83
11.33
9.25
8.16
10.31
12.46
11.59
12.56
10.11
8.92
9.35
11.86
12.94
pesticides-tr ea ted pla n ts w a s m en tion ed
ea r lier in r eleva n t stu dies. Gom a a et a l. (1976)
r epor ted th a t dim eth oa te h a d r edu ced tota l
ca r boh ydr a tes a n d its fr a ction s in th e
spr ayed pea pla n ts. F a is (1988) dem on str a ted
th a t pr oth iofos a n d m a la th ion sign ifica n tly
r edu ced tota l ca r boh ydr a tes in fr u its of n avel
a n d ba la di or a n ges. F u r th er m or e, Sh a m s-E lDin et a l. (1995) fou n d a depletion in su ga r s
a n d ca r boh ydr a tes con ten t in th e pesticidestr ea ted ca bba ge leaves. Ma la th ion in du ced
th e m a xim u m declin e followed by pr oth iofos
a n d pir im iph os-m eth yl.
Free amino acids and total proteins content
F r ee a m in o a cids sh owed con sider able
a ccu m u lation in wh eat sh oots u n der str ess of
th e im posed pesticides (Table IV). In th is
con cer n , th e obta in ed in cr ea se in fr ee a m in o
a cids wa s clea r ly n oticed th r ee days a fter pesticide application a n d u p to th e en d of th e exper im en t. However, th e m a xim u m fr ee a m in o a cids
a ccu m u lation a s a r esu lt of th e applied in secticides wa s r ecor ded du r in g th e in ter m ediate
sa m plin g dates of six a n d n in e days, a fter th e
fir st a n d secon d application r espectively. In
th is con cer n , per cen t of m a xim u m in cr ea se
wa s 145.6 a n d 128.8 per cen t a fter six days of th e
fir st spr ay, h owever, it wa s 173.9 a n d 157.3 per
cen t a fter n in e days of th e secon d appliction for
dim eth oate a n d pir im ica r b r espectively. No
r egu la r va r iation cou ld be detected between
both dim eth oate a n d pir im ica r b con cer n in g
th eir capa city to a ccu m u late th e fr ee a m in o
a cids in th e tr eated wh eat sh oots.
Sh a m s-El-Din et al. (1995) stu died th e effect of
som e or ga n oph osph or u s in secticides on fr ee
a m in o a cids con ten t of cabba ge pla n ts. No
appa r en t im pa ct cou ld be detected in va lu es of
fr ee a m in o a cids con ten t a s exer ted by
m a lath ion , h owever, a declin e wa s r ecor ded
with both pir im iph os m ethyl a n d pr oth iofos.
On th e oth er h a n d, fr ee a m in o a cids ten d to be
a ccu m lated in pla n ts u n der str ess of
u n favou r able envir on m en ta l con dition s a n d
th is a ccu m u lation cou ld be con sider ed a s a n
a daptor fa ctor for su ch con dition s (Abo-ElSeou d et al.1990; Abo-El-Seou d a n d Ha sh im ,
1994). Th u s, th e obta in ed in cr ea se in fr ee a m in o
a cids con ten t in th e pr esen t wor k m igh t h ave a
ben eficia l effect to fa ce th e toxic a n d u n desir able im pa cts of pesticids on th e tr eated pla n ts.
On th e oth er h a n d, tota l pr otein s con ten t of
wh eat sh oots sh owed som e depletion s a s a
fu n ction of th e im posed in secticides u p to 12
days a fter application . However, th is declin e
wa s m or e pr on ou n ced with a n in ter va l of six
days of eith er dim eth oate or pir im ica r b application . Sa m plin g dates of n in e a n d 12 days a fter
application exh ibited gr a du a l r ecover ed
in cr ea se in tota l pr otein s con ten t of th e tr eated
wh eat sh oots, bu t it wa s still less th a n th at of
[ 191 ]
th e u n tr eated pla n ts. After 15 days of th e
pesticida l ch em ica ls application , n o obser vable
va r iation cou ld be r ecor ded between both th e
spr ayed a n d n on -spr ayed wh eat sh oots r ega r din g th eir pr otein con ten t. Com pa r in g th e effectiven ess of th e applied pesticides to a ffect pr otein con ten t of th e tr eated pla n t, it cou ld be
in fer r ed th at dim eth oate h a s m or e capicity to
decr ea se pr otein con ten t r ath er th a n pir im ica r b. For in sta n ce, th e m a gn itu de of declin e
r ecor ded with th e sa m plin g date of six days
M.A. Abo -El-Se o ud and
M. Fro st
Bio c he mic al c hange s in
whe at plants as affe c te d by
re sidue s o f dime tho ate and
pirimic arb
Enviro nme ntal Manage me nt
and He alth
9 / 5 [1 9 9 8 ] 1 8 8 –1 9 3
Table IV
To tal pro te ins and fre e amino ac ids c o nte nt (mg/ g.d.wt) o f whe at sho o ts as
affe c te d by dime tho ate and pirimic arb applic atio n
Days after
treatment
Control
First application
Dimethoate Pirimicarb
Second application
Control
Dimethoate Pirimicarb
Free amino acids
0
2.35
3
2.26
6
2.15
9
2.47
12
2.51
15
2.31
2.81
3.11
5.28
4.97
5.25
3.16
2.74
4.34
4.92
4.01
3.91
4.81
2.08
2.31
2.26
2.18
2.27
2.36
2.13
4.04
5.11
5.97
4.22
4.27
2.27
3.81
5.23
5.61
5.21
3.14
Total proteins
0
167.31
3
171.35
6
169.65
9
172.31
12
170.31
15
170.98
170.31
153.26
146.11
148.39
156.21
168.45
169.45
158.11
150.31
157.11
163.22
170.14
145.31
142.28
156.11
146.43
144.26
145.15
147.26
132.83
127.16
131.24
140.35
146.81
145.16
140.11
133.06
139.31
143.19
147.15
Table V
Nuc le ic ac ids c o nte nt (mg/ g.d.wt) o f whe at sho o ts as affe c te d by
dime tho ate and pirimic arb applic atio n
Days after
treatment
Control
First application
Dimethoate Pirimicarb
Second application
Control
Dimethoate Pirimicarb
RNA
0
3
6
9
12
15
16.25
16.18
17.31
16.92
17.31
17.28
17.09
15.22
12.26
14.31
14.25
15.69
17.43
14.11
11.28
14.86
15.26
17.08
17.82
16.31
16.28
17.15
16.93
16.26
17.33
13.18
11.06
14.18
15.37
16.93
17.11
14.12
12.25
15.26
15.92
17.23
DNA
0
3
6
9
12
15
2.82
2.76
2.61
2.72
2.85
2.65
2.85
2.74
2.66
2.75
2.81
2.83
2.91
2.76
2.72
2.74
2.86
2.72
2.71
2.70
2.68
2.75
2.69
2.72
2.81
2.76
2.68
2.52
2.63
2.86
2.72
2.51
2.42
2.61
2.65
2.73
RNA/ DNA ratio
0
3
6
9
12
15
5.76
5.86
6.63
6.22
6.07
6.52
5.99
5.55
4.61
5.20
5.07
5.54
5.99
5.11
4.15
5.42
5.33
6.28
6.58
6.04
6.07
6.24
6.29
5.98
6.17
4.78
4.13
5.63
5.87
5.92
6.29
5.63
5.06
5.85
6.01
6.31
[ 192 ]
a fter th e fir st application wa s 13.9 a n d 7.4 per
cen t, m ea n wh ile it wa s 12.6 a n d 8.93 per cen t
a fter th e sa m e in ter va l of th e secon d applica tion for dim eth oate a n d pir im ica r b r espectively. Th e pr esen t depr ession in tota l pr otein
con ten t coin cides with th e fin din gs of Gom a a et
al. (1976) on pea pla n ts tr eated with
dim eth oate. Sim ila r ly, Rozek a n d Ma r ecr ek
(1981) r epor ted th at dim eth oate a n d m a lath ion
declin ed lea f pr otein con ten t of pea pla n ts. In a
r ecen t investigation Sh a m s-El-Din et al. (1995)
stu died th e effect of con sequ en t application s of
pesticides on pr otein con ten t of th e tr eated
cabba ge leaves. Tota l pr otein con ten t sh owed
a n in cr ea se a fter th e fir st application in
r espon se to both m a lath ion a n d pr oth iofos.
However, a ll th e u sed pesticides decr ea sed
pr otein con ten t of th e tr eated cabba ge leaves
a fter th e secon d a n d th ir d application .
Nucleic acids content
RNA a n d DNA con ten t of wh eat sh oots a s
a ffected by dim eth oate a n d pir im ica r b spr ayin g is pr esen ted in Table V. RNA con ten t wa s
decr ea sed du r in g th e in ter m ediate sa m plin g
dates du e to th e u tilization of th e stu died pesticides. Aga in , a sa m plin g date of six days a fter
spr ay wa s th e m ost cr itica l per iod to r edu ce
RNA con ten t of th e tr eated pla n ts. Th e in h ibition im pa ct of th e applied a gr och em ica l on
RNA con ten t of tr eated pla n ts sta r ted to disappea r fr om sa m plin g date of n in e days a n d u p to
th e en d of th e exper im en t. On th e oth er h a n d,
n o detectable va r iation s cou ld be in du ced in
th e DNA con ten t of wh eat sh oots a s fa r a s th e
in flu en ce of th e spr ayed in secticides wa s con sider ed. On ly a sim ple flu ctu ation cou ld be
obser ved. In oth er wor ds, DNA con ten t exh ibited fixed ph en om en on towa r d th e u sed in secticides. RNA/ DNA r atio sh owed a ligh t decr ea se
du r in g th e in ter m ediate in ter va ls a fter application du e to th e depr ession in th e RNA level.
Liter atu r e sh owed th at ver y lim ited wor k wa s
con du cted r ega r din g th e im pa ct of pesticides’
folia r application on n u cleic a cids. Per epelen ko (1987) sh owed th at dim eth oate a ffected
n u cleic m etabolism in cotton seedlin gs via th e
ch a n ge in ch r om osom e aber r ation fr equ en cy.
As a gen er a l con clu sion , it cou ld be
m en tion ed th a t th e a pplied in secticides wer e
gr a du a lly declin ed a n d decom posed du r in g
th e design ed sa m plin g da tes a fter a pplica tion .
Th e degr a da tion of th e spr ayed in secticides
w a s a ccom pa n ied by som e bioch em ica l
ch a n ges in th e tr ea ted wh eat sh oots. Sa m plin g
da tes of th r ee a n d six days a fter a pplica tion
wer e th e m ost cr itica l per iods to in du ce som e
distu r ba n ces in th e pla n t m eta bolism . Th e
la ter sa m plin g da tes sh owed r egu la r ch a n ge of
th e deter m in ed ch em ica l con stitu en ts to th e
n or m a l levels. Th u s, it cou ld be con clu ded th a t
th e im pa ct of th e u sed pesticides on th e
M.A. Abo -El-Se o ud and
M. Fro st
Bio c he mic al c hange s in
whe at plants as affe c te d by
re sidue s o f dime tho ate and
pirimic arb
Enviro nme ntal Manage me nt
and He alth
9 / 5 [1 9 9 8 ] 1 8 8 –1 9 3
m eta bolic ch a n ges is a tem por a r y effect a n d it
h a d n ea r ly disa ppea r ed a t th e en d of th e
exper ipm en t. Th e obta in ed bioch em ica l
ch a n ges du r in g th e in ter m edia te sa m plin g
da tes m igh t be du e to th e toxic a n d in h ibitor y
in flu en ce of th e pesticides’ r esidu es on th e
en zym a tic system s involved in th e m eta bolic
pa th w ays of th e stu died con stitu en ts.
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En viron m en tal Pollu tion, Vol. 55, pp. 179-89.
Xia oh on g, Z., Da di, Z. a n d J ia n pin g, Z. (1992),
“Residu e de gr a da tion of fen va ler a te a n d
dim eth oa te on wh ea t, Br ssica ch in en sis a n d
pea ch ”, J ou r n a l of S h a n gh a i A gr icu ltu ra l
College (Ch in a ), Vol. 10, pp. 181-6.
[ 193 ]
residues of dimethoate and pirimicarb
M .A. Abo-El-Seoud
Ato mic Ene rgy Autho rity, De partme nt o f Plant Re se arc he s, Abo u-Z abal, Egypt
M . Frost
Bio lo gisc he Bunde sanstalt für Land-und Fo rstwirtsc haft, Be rlin, Ge rmany
Wheat plants were grown in
fi eld plots of 3×3m area.
After growth period of two
months, the growing plants
were sprayed with dimethoate
and pirimicarb at the recommended dose. Spraying was
repeated after a further 45
days. Plant samples were
taken at intervals of zero,
three, six, nine, 12 and 15
days after each application. A
gradual and continuous
degradation of the applied
pesticides had taken place in
the treated wheat shoots up
to the end of the experiment.
However, dimethoate showed
more residues and persistence rather than pirimicarb.
The break down and metabolism of the applied pesticides
was correlated with some
biochemical changes in the
sprayed plants. Sampling
dates of three and six days
after application were the
most critical periods to affect
plant metabolism. A decline
was noticed in chlorophyll,
sugars and carbohydrates,
total proteins and RNA content of wheat shoots as a
function of the applied pesticides. Free amino acids were
accumulated in the sprayed
plants, meanwhile the DNA
content did not show observable changes as a consequence of the applied pesticides treatment.
Enviro nme ntal Manage me nt
and He alth
9 / 5 [ 1998] 1 8 8 –1 9 3
© MCB Unive rsity Pre ss
[ ISSN 0956-6163]
[ 188 ]
Introduction
Th e expa n din g u se of pesticides for pr otectin g cr ops a ga in st pests a n d disea se a tta ck is
a n im por ta n t pa r t of th e m oder n a gr icu ltu r e.
Pesticides a r e in ten tion a lly toxic su bsta n ces
beca u se of th eir u tiliza tion pu r poses. Repor ts
em a n a tin g fr om a r ea s in wh ich th ese ch em ica ls a r e u sed h ave sh ow n th a t besides
pa th ogen s a n d pests, m a n y oth er or ga n ism s
h ave fa llen victim to pa r ticu la r a pplica tion .
In th is con n ection , Koem a n (1979) m en tion ed
th a t th e m ost obviou s side effects of th ese
toxica n ts a r e: m or e or less wh olesa le m or ta lity of m a n y a n im a ls a n d pla n t species,
ch a n ges in th e a bu n da n ce of species a n d th e
diver sity of ecosystem s, a n d a r edu ction in
th e pr odu ctive poten tia l of n a tu r a l r esou r ces
a n d n on - ta r get species.
Addition a lly, som e r esea r ch er s r epor ted
th a t th e u tiliza tion of pesticides for cr ops
pr otection w a s a ccom pa n ied by th e a ppea r a n ce of som e toxic a n d in h ibition im pa cts on
pla n t gr ow th . Th ese effects r a n ge fr om a
sligh t gr ow th in h ibition to a deleter iou s m or ph ologica l distu r ba n ce for a ll th e pla n t or
pa r ticu la r or ga n s. Ca r tw r igh t (1976) a n d
Ash ton a n d Cr a fts (1981) m en tion ed th a t
pesticides ca u sed deleter iou s a lter a tion in
cell division , cell en la r gm en t a n d tissu e differ en tia tion . Th ese u n desir a ble effects m igh t
lea d to gr ow th in h ibition s, epin a sty, for m a tive effects, a lbin ism a n d a lso cou ld r edu ce
cu ticle for m a tion a s dem on str a ted by Va n
An del et a l. (1976) a n d An bu du r a l et a l. (1986).
In a ddition , lea f ch lor osis, wh ich is followed
by n ecr osis, a com m on r espon se of pla n ts,
cou ld be tr ea ted w ith th e ph otosyn th esis
in h ibitin g pesticides (Adh ya et a l., 1981;
Moor th y et a l., 1992).
Na tu r a lly, th e a bove m en tion ed m or ph ologica l ch a n ges a n d h a za r dou s im pa cts r esu ltin g
fr om pesticide u tilization sh ou ld be du e to a
distu r a ba n ce in th e ph ysiologica l pr ocesses
a n d m eta bolic pa th w ays in pla n ts. P r eviou s
stu dies in dicated a n in h ih ition in th e syn th esis of ph otosyn th etic pigm en ts, a declin e in
ca r boh ydr a tes a n d su ga r s con ten t a s well a s a
distu r ba n ce in th e m etabolism of pr otein s a n d
n u cleic a cids con ten t of th e pesticides tr ea ted
pla n ts (Moor th y et a l., 1992; Sh a m s E l-Din et
a l., 1995; Won g a n d Ch a n ge, 1988).
Th e pr esen t wor k in vestiga ted th e bioch em ica l r espon se of wh ea t pla n ts to th e a pplica tion of eith er dim eth oa te or pir im ica r b.
Materials and methods
Insecticides
1 Dim eth oa te: O,O-dim eth yl S- (m eth ylca r ba m oyl m eth yl) ph osph or odith ioa te. It
w a s u sed u n der tr a de n a m e of Cygon 4E ,
a n em u lsifia ble con cen tr a te w ith a n a pplica tion r a te of 480g AI/ h a
2 Pir im icab : 2- dim eth yla m in o - 5,6dim eth ylpyr im idin - 4-yl- N,N - dim eth ylca r ba m a te. It w a s u sed u n der tr a de n a m e
of P ir im ior 50, a wetta ble pow der w ith a n
a pplica tion r a te of 200g AI/ h a
Field experiment and pesticides application
Wh ea t seeds (Tr iticu m a estivu m L. cv. Hein es
Koga II) wer e sow n in field plots of 3 × 3m
a r ea . After gr ow th per iod of two m on th s, th e
gr ow in g wh ea t pla n ts wer e tr ea ted w ith th e
in dividu a l in secticides a t th e a bove m en tion ed r a tes. For ea ch pesticide, th r ee plots
wer e u sed a n d distr ibu ted in a com pletely
r a n dom ized design . Spr ayin g w a s r epea ted
on ce m or e a fter 45 days fr om th e fi r st a pplica tion . Repr esen ta tive sa m ples wer e r a n dom ly
collected fr om th e tr ea ted a n d n on -tr ea ted
wh ea t pla n ts on e h ou r a fter a pplica tion (zer o
tim e) a n d th en a t in ter va ls of th r ee, six, n in e,
12 a n d 15 days. Th e obta in ed sa m ples wer e
divided in to sh oots a n d r oots a n d pla ced in a
deep fr ee zer a t 18°C u n til a n a lysis.
Determination of pesticide residues
Pesticide r esidu es wer e extr a cted a ccor din g
to th e pr ocedu r es of Stein w a n dter (1985).
Sa m ples wer e extr a cted by blen din g w ith
a ceton e a n d sa ltin g ou t w ith sodiu m ch lor ide.
M.A. Abo -El-Se o ud and
M. Fro st
Bio c he mic al c hange s in
whe at plants as affe c te d by
re sidue s o f dime tho ate and
pirimic arb
Enviro nme ntal Manage me nt
and He alth
9 / 5 [1 9 9 8 ] 1 8 8 –1 9 3
Th en , n -h exa n e w a s a dded a n d th e m ixtu r e
w a s blen ded a ga in . Th e or ga n ic ph a se w a s
con cen tr a ted u n der va cu u m to 2-3m l. Th e
r edu ced extr a cts wer e clea n ed u p over silica
gel, eva por a ted to dr yn ess a n d th en tr a n sfer r ed qu a n tita tively to 10m l volu m etr ic
fla sk s a n d br ou gh t to volu m e w ith n -h exa n to
be u sed for GC deter m in a tion .
A P YE u n ica m ser ies equ ipped w ith N / P
detector a n d pyr ex gla ss colu m n pa ck ed w ith
OV.17 on 80/ 100 m ech ch r om osor b w a s u sed
for deter m in a tion of pesticides r esidu e. Th e
tem per a tu r e u sed w a s 260, 250 a n d 265°C for
in jection , colu m n a n d detector r espectively.
Determination of chlorophyll content
Ch lor oph yll con ten t of wh ea t sh oots w a s
extr a cted u sin g 96 per cen t eth a n ol on 80°C
a n d estim a ted a ccor din g to th e equ a tion s of
Win ter m a n s a n d Mots (1965).
Carbohydrates and sugars analysis
Tota l ca r bohydr ates wer e deter m in ed followin g hydr olysis u sin g 1 N su lph u r ic a cid in
sea led tu bes in a n electr ic oven at 100°C for 24h .
Tota l solu ble su ga r s wer e extr a cted by 85 per
cen t eth a n ol u sin g soxh elt appa r atu s for 6h .
Tota l hydr olyzable ca r bohydr ates a n d solu ble
su ga r s wer e estim ated u sin g th e m eth od
descr ibed by Du bois et al. (1956). Redu cin g
su ga r s wer e deter m in ed in th e eth a n olic
extr a ct u sin g th e AOAC m eth od (1985).
Determination of total proteins and free
amino acids content
Tota l fr ee a m in o a cids wer e estim a ted in th e
eth a n olic extr a ct u sin g th e m eth od of Dot et
a l. (1981). Tota l N a n d cr u de pr otein s wer e
estim a ted u sin g th e u su a l m icr o-Kjelda h l
m eth od (AOAC, 1985).
Determination of nucleic acids content
RNA a n d DNA wer e extr a cted a ccor din g to th e
m eth od descr ibed by Ogu r a n d Rosen (1950).
Th e UV a bsor ption of both RNA a n d DNA
solu tion s w a s m ea su r ed a t 260 a n d 280n m .
Results and discussion
Pesticides residues
De gr a da tion beh aviou r of both dim eth oa te
a n d pir im ica r b in th e tr ea ted wh ea t sh oots is
illu str a ted in Ta ble I. Dim eth oa te sh owed
in itia l r esidu es of 27.35 a n d 25.34 ppm a fter
th e fir st a n d secon d a pplica tion r espectively.
After th r ee days of a pplica tion , a sh a r p
declin e occu r ed sin ce m or e th a n 50 per cen t of
th e a pplied pa r en t com pou n d w a s de gr a ded.
F u r th er de gr a da tion occu r ed du r in g th e n ext
sa m plin g da tes, h owever, it w a s slower du r in g
th e la ter per iods wh en com pa r ed w ith th e
ea r lier on es. On ly 0.09ppm of th e a pplied
in secticide w a s detected in wh ea t sh oots a fter
15 days of a pplica tion w ith r e ga r d to th e fir st
spr ay, h owever, it w a s u n detecta ble a fter th e
sa m e tim e for th e secon d a pplica tion .
Com pa r in g r a te of dim eth oa te br ea k dow n
a fter th e im posed a pplica tion s, it w a s
a ppa r en t th a t r a te of pesticide de gr a da tion
w a s r ela tively h igh er a fter th e secon d spr ay
a s com pa r ed w ith th e fi r st on e. N a tu r a lly, th is
obser va tion sh ou ld be a ttr ibu ted to th e ph ysiologica l sta tu s a n d th e developm en ta l gr ow th
sta ge of th e tr ea ted pla n ts a fter ea ch spr ay.
On th e oth er h a n d, in itia l a m ou n ts of
pir im ica r b wer e 12.86 a n d 10.86ppm a fter th e
fir st a n d secon d spr ay r espectively. Meta bolic
de gr a da tion of pir im ica r b du r in g th e exper im en t cou r se exh ibited n ea r ly sim ila r tr en ds
a s th ose obser ved for dim eth oa te. F a st de gr a da tion w a s r ecor ded du r in g th e ea r lier
sa m plin g da tes a n d a slower r a te w a s n oticed
for th e la ter in ter va ls. On th e oth er h a n d, th e
ca r ba m a te in secticide u n der in vestiga tion
beca m e u n detecta ble in th e tr ea ted wh ea t
sh oots a fter 15 a n d 12 days of a pplica tion w ith
con cer n to th e fi r st a n d secon d spr ay r espectively. Aga in , r a te of pir im ica r b decom position w a s com pa r a tively h igh er in th e spr ayed
wh ea t sh oots collected a fter th e secon d
a pplica tion r a th er th a n th ose of th e fir st on e.
For both dim eth oate a n d pir im ica r b, n o
r esidu es cou ld be detected in wh eat r oots
du r in g th e stu died per iods a fter application .
Th is in dicates th at th er e wa s n o down wa r d
tr a n slocation fr om th e sh oots a n d a lso n o pen etr ation fr om th e a ccu m u lated r esidu es on soil
su r fa ce to th e gr owin g r oots h a d occu r r ed.
Com pa r in g da tes of both th e stu died pesticides r esidu es in wh ea t sh oots r evea led th a t
dim eth oa te h a s h igh er con cen tr a tion r a th er
th a n th ose of pir im ica r b. In a ddition ,
dim eth oa te sh owed m or e per sisten ce a n d less
degr a da tion a s it cou ld be estim a ted in pla n t
tissu es for lon ger tim e r a th er th a n pir im ica r b.
Resu lts of th e pr esen t wor k a r e in a gr eem en t
w ith r eleva n t stu dies con du cted ea r lier. Th u s,
Szeto et al. (1985) fou n d th a t tota l r esidu es of
dim eth oa te a n d pir im ica r b a pplied to a spa r a gu s wer e decr ea sed by a bou t 90 per cen t a fter
seven days of tr ea tm en t a n d th e declin e
beca m e a t a slower r a te th er ea fter. Ca br a s et
al. (1991) m en tion ed r a pid degr a da tion for
pir im ica r b a pplied to lettu ce a n d it beca m e
detecta ble five days a fter tr ea tm en t. Xia oh on g
et al. (1992) r epor ted a r apid declin e of
dim eth oa te in ea r s a n d leaves of wh ea t a s it
r ecor ded a h a lf life of 1.85 a n d 1.93 days r espectively. Recen tly, F r ost a n d Abo-El-Seou d (1997)
fou n d th a t r a dioa ctive pir im ica r b w a s
depleted to 16.79 per cen t of th e in itia l dose
a fter seven days of a pplica tion to wh eat sh oots.
[ 189 ]
Chlorophyll content
Da ta pr esen ted in Ta ble II dem on str a te th e
im pa ct of stu died pesticides on th e ch lor oph yll con ten t of wh ea t sh oots. Applica tion of
eith er dim eth oa te or pir im ica r b r esu lted in a
declin e in ch lor oph yll “a ”, ch lor oph yll “b”
a n d con sequ en tly tota l ch lor oph yll con ten t.
However, m a gn itu de of th is declin e depen ded
m a in ly on th e la pse of tim e a fter ea ch a pplica tion . In th is con sider a tion , th e lowest va lu es
of ch lor oph yll con ten t wer e r ecor ded in sa m ples ta k en a fter th r ee a n d six days of th e fi r st
a n d secon d a pplica tion r espectively. Th a t
h olds tr u e for eith er dim eth oa te or pir im ica n b. Sa m ples collected a fter n in e a n d 12 days
of spr ay sh owed a sligh t r ecover ed in cr ea se in
th eir ch lor oph yll con ten t r a th er th a n th ose of
M.A. Abo -El-Se o ud and
M. Fro st
Bio c he mic al c hange s in
whe at plants as affe c te d by
re sidue s o f dime tho ate and
pirimic arb
Enviro nme ntal Manage me nt
and He alth
9 / 5 [1 9 9 8 ] 1 8 8 –1 9 3
Table I
Re sidue s o f dime tho ate and pirimic arb in whe at sho o ts at diffe re nt days
afte r applic atio n
Dimethoate
First spray
Second spray
Days after
Percent
Percent of
treatment ppm
of loss
ppm
of loss
0
3
6
9
12
15
27.35
12.36
7.81
2.48
0.93
0.09
0
54.81
71.44
90.93
96.60
99.67
25.34
10.61
2.95
0.84
0.02
ND
0
58.13
88.36
96.69
99.92
–
Pirimicarb
First spray
Second spray
Percent
Percent
ppm of loss
ppm of loss
12.86
5.24
1.95
0.81
0.06
ND
0
59.25
84.84
93.70
99.53
–
10.86
4.08
0.73
0.06
ND
ND
0
62.43
93.28
99.45
–
–
Table II
Chlo ro phyll c o nte nt (mg/ g.d.wt) o f whe at sho o ts as affe c te d by dime tho ate
and pirimic arb applic atio n
Days after
treatment
Control
Chlorophyll “a”
0
15.08
3
14.26
6
15.35
9
15.20
12
16.09
15
15.92
First application
Dimethoate Pirimicarb
Second application
Control
Dimethoate Pirimicarb
16.25
12.35
11.03
14.78
15.30
14.98
15.34
13.16
12.81
13.77
14.83
15.08
12.85
13.65
12.91
12.65
12.75
12.96
13.11
9.45
10.66
12.56
12.93
12.85
12.44
10.52
10.83
12.25
12.16
12.41
3.56
3.11
3.85
3.76
3.24
3.38
3.25
2.81
2.75
2.94
3.11
3.08
3.28
2.80
2.71
2.97
3.11
3.14
2.88
2.79
2.91
2.97
2.80
2.88
2.91
2.12
2.28
2.65
2.61
2.74
2.80
2.35
2.46
2.54
2.48
2.67
Total Chlorophyll
0
18.64
3
17.37
6
19.20
9
18.96
12
19.33
15
19.30
19.53
15.16
13.78
17.72
18.41
18.06
18.62
15.96
15.52
16.74
17.96
18.22
15.73
16.44
15.82
15.62
15.55
15.84
16.02
11.57
12.94
15.21
15.54
15.59
15.24
12.87
13.29
14.79
14.64
15.08
Chlorophyll “b”
0
3
6
9
12
15
[ 190 ]
th e ea r lier in ter va ls, bu t it w a s still sligh tly
less th a n th e u n tr ea ted con tr ol. Ch lor oph yll
con ten t of th e tr ea ted wh ea t sh oots h a r vested
15 days a fter a pplica tion sh owed m or e or less
sim ila r va lu es to th e u n spr ayed pla n ts. Th u s,
it cou ld be con clu ded th a t th e deleter iou s
effect of th e u sed pesticida l ch em ica ls on
ch lor oph yll w a s detected in th e ea r lier sa m plin g da tes a n d sta r ted to disa ppea r gr a du a lly in th e la ter per iods.
On th e oth er h a n d, da ta exh ibit th a t
dim eth oa te h a d m or e pr on ou n ced effect to
declin e th e ch lor oph yll con ten t of th e spr ayed
wh ea t sh oots a s com pa r ed w ith pir im ica r b. In
th is r e ga r d, th e m a gn itu de of declin e a s a
fu n ction of th e u sed a gr och em ica l a fter six
days of spr ay w a s 28.2 a n d 19.2 per cen t for th e
fir st a pplica tion , h owever, it w a s 18.2 a n d 15.9
per cen t for th e secon d a pplica tion w ith
r e ga r d to dim eth oa te a n d pir im ica r b r espectively. Th e obser va ble in h ibition im pa ct of
th e stu died in secticides on ch lor oph yll con ten t of wh ea t sh oots du r in g th e fir st per iods
a fter tr ea tm en t m igh t be du e to a distu r ba n ce
effect on th e pigm en t’s biosyn th esis.
Th e in flu en ce of folia r a pplica tion of
pesticides on th e gr een pigm en ts con ten t of
th e tr ea ted pla n ts w a s discu ssed in som e pr eviou s stu dies. Ha ssa n et a l. (1978) n oticed a
declin e in ch lor oph yll con ten t of cotton pla n t
leaves tr ea ted w ith som e or ga n oph osph or u s
in secticides. Afifi a n d E l-Ba lla l (1982)
m en tion ed th at th e in secticides su m ith ion
a n d du r sba n h a d th e capa city to ca u se m or e
r edu ction in ch lor oph yll con ten t of br oa d
bea n s’ leaves r a th er th a n dim eth oate a n d
ga r don a . In a ddition , Won g a n d Ch a n g (1988)
dem on str a ted th a t dim eth oa te a n d oth er
in secticides in h ibited th e gr ow th a n d ch lor oph yll con ten t of a lga . Recen tly, Sh a m s-E l-Din
et a l. (1995) m en tion ed a declin e in ch lor oph yll
con ten t of ca bba ge pla n ts a s a fu n ction of
som e or ga n oph osph or u s a pplica tion . On th e
oth er h a n d, a n in cr ea se in ch lor oph yll con ten t
r esu lted in som e pla n ts du e to th e applica tion
of som e pesticides a s m en tion ed by Fa is (1988)
on leaves of n ovel or ga n es a s tr ea ted w ith
pr oth iofos, wh ile both m a la th ion a n d pr oth iofos did n ot in du ce a n y sign ifica n t effect on
ba la di or a n ges leaves. Th u s it cou ld be
dedu ced th a t th e effect of pesticides on pla n t
ch lor oph yll con ten t is va r ia ble a n d it depen ds
m a in ly on th e a pplied su bsta n ce, th e tr ea ted
pla n t a s well a s th e pla n t gr ow th sta ge a n d
m eth od of pesticide applica tion .
Carbohydrates and sugars content
E ffects of folia r a pplica tion of th e investiga ted
in secticides on ca r boh ydr a tes a n d su ga r s
con ten t of wh ea t sh oots a r e dem on str a ted in
Ta ble III. Tota l ca r boh ydr a tes wer e depleted in
th e spr ayed wh ea t sh oots in r espon se to th e
u sed pesticides u p to 12 days a fter a pplica tion .
However, th e m a gn itu des of th is declin e
depen ded on h a r vest tim e a fter spr ayin g. In
th is con sider a tion , th e m a xim u m r ecor ded
depr essa n t in tota l ca r boh ydr a tes con ten t w a s
n oticed w ith sa m plin g da te of six days a fter
a pplica tion . Th en , it sta r ted to in cr ea se a ga in
to th e n or m a l level u p to th e en d of th e exper im en t. Th e r edu ction in tota l ca r boh ydr a tes
a fter six days of th e spr ay w a s 12.9 a n d 8.6 per
cen t a fter th e fi r st a pplica tion , a n d 11.1 a n d 8.7
per cen t a fter th e secon d a pplica tion w ith
r ega r d to dim eth oa te a n d pir im ica r b r espectively. Th u s, it cou ld be con clu ded th a t
dim eth oa te w a s m or e effective to depr ess tota l
ca r boh ydr a tes con ten t r a th er th a n pir im ica r b.
Tota l solu ble su ga r s a n d r edu cin g su ga r s
con ten t exh ibit th e sa m e tr en d a n d beh aviou r
du r in g th e design ed sa m plin g dates a fter th e
im posed pesticides applica tion . Sa m plin g date
of six days a fter spr ayin g sh owed th e m ost
pr on ou n ced depletion in solu ble a n d r edu cin g
su ga r s con ten t of wh ea t sh oots tr ea ted w ith
th e tested pesticides. Aga in , th e obta in ed
decr ea se in su ga r s con ten t w a s m or e obser va ble u n der tr ea tm en t of dim eth oate.
Th e n oticea ble decr ea se in ca r boh ydr otes
a n d su ga r s con ten t of wh ea t sh oots in r ela tion to th e a pplied pesticides m igh t be du e to
th e distu r bin g in fl u en ce of su ch toxica n ts on
th e en zym es in volved in th e m eta bolic pa th w ays of th e a bove m en tion ed com pon en ts. A
decr ea se in su ga r s a n d ca r boh ydr a tes in th e
M.A. Abo -El-Se o ud and
M. Fro st
Bio c he mic al c hange s in
whe at plants as affe c te d by
re sidue s o f dime tho ate and
pirimic arb
Enviro nme ntal Manage me nt
and He alth
9 / 5 [1 9 9 8 ] 1 8 8 –1 9 3
Table III
Carbo hydrate s and sugars c o nte nt (mg/ g.d.wt) o f whe at sho o ts as affe c te d
by dime tho ate and pirimic arb applic atio n
Days after
treatment
Control
First application
Dimethoate Pirimicarb
Second application
Control
Dimethoate Pirimicarb
Total carbohydrates
0
245.26
3
239.85
6
241.76
9
243.87
12
239.96
15
240.62
241.08
218.15
210.61
228.56
236.43
238.16
242.25
225.10
221.08
231.86
237.34
241.18
268.31
270.81
272.08
269.39
274.66
271.26
270.18
246.83
241.87
253.16
268.38
269.08
272.35
254.61
248.30
256.47
268.24
274.08
Total soluble sugars
0
28.56
3
30.11
6
29.42
9
29.86
12
30.14
15
32.65
27.41
22.65
20.08
23.51
25.81
28.36
28.87
25.11
23.46
26.38
28.11
28.93
31.46
32.65
32.47
31.91
32.05
32.75
32.46
28.16
25.31
26.75
29.31
31.86
32.85
30.26
28.45
30.11
30.94
32.86
Reducing sugars
0
9.61
3
8.53
6
9.16
9
9.43
12
9.11
15
8.92
8.35
6.11
5.22
7.31
8.96
8.15
8.92
6.24
6.18
6.93
7.25
8.19
11.22
12.38
12.25
11.61
12.41
12.83
11.33
9.25
8.16
10.31
12.46
11.59
12.56
10.11
8.92
9.35
11.86
12.94
pesticides-tr ea ted pla n ts w a s m en tion ed
ea r lier in r eleva n t stu dies. Gom a a et a l. (1976)
r epor ted th a t dim eth oa te h a d r edu ced tota l
ca r boh ydr a tes a n d its fr a ction s in th e
spr ayed pea pla n ts. F a is (1988) dem on str a ted
th a t pr oth iofos a n d m a la th ion sign ifica n tly
r edu ced tota l ca r boh ydr a tes in fr u its of n avel
a n d ba la di or a n ges. F u r th er m or e, Sh a m s-E lDin et a l. (1995) fou n d a depletion in su ga r s
a n d ca r boh ydr a tes con ten t in th e pesticidestr ea ted ca bba ge leaves. Ma la th ion in du ced
th e m a xim u m declin e followed by pr oth iofos
a n d pir im iph os-m eth yl.
Free amino acids and total proteins content
F r ee a m in o a cids sh owed con sider able
a ccu m u lation in wh eat sh oots u n der str ess of
th e im posed pesticides (Table IV). In th is
con cer n , th e obta in ed in cr ea se in fr ee a m in o
a cids wa s clea r ly n oticed th r ee days a fter pesticide application a n d u p to th e en d of th e exper im en t. However, th e m a xim u m fr ee a m in o a cids
a ccu m u lation a s a r esu lt of th e applied in secticides wa s r ecor ded du r in g th e in ter m ediate
sa m plin g dates of six a n d n in e days, a fter th e
fir st a n d secon d application r espectively. In
th is con cer n , per cen t of m a xim u m in cr ea se
wa s 145.6 a n d 128.8 per cen t a fter six days of th e
fir st spr ay, h owever, it wa s 173.9 a n d 157.3 per
cen t a fter n in e days of th e secon d appliction for
dim eth oate a n d pir im ica r b r espectively. No
r egu la r va r iation cou ld be detected between
both dim eth oate a n d pir im ica r b con cer n in g
th eir capa city to a ccu m u late th e fr ee a m in o
a cids in th e tr eated wh eat sh oots.
Sh a m s-El-Din et al. (1995) stu died th e effect of
som e or ga n oph osph or u s in secticides on fr ee
a m in o a cids con ten t of cabba ge pla n ts. No
appa r en t im pa ct cou ld be detected in va lu es of
fr ee a m in o a cids con ten t a s exer ted by
m a lath ion , h owever, a declin e wa s r ecor ded
with both pir im iph os m ethyl a n d pr oth iofos.
On th e oth er h a n d, fr ee a m in o a cids ten d to be
a ccu m lated in pla n ts u n der str ess of
u n favou r able envir on m en ta l con dition s a n d
th is a ccu m u lation cou ld be con sider ed a s a n
a daptor fa ctor for su ch con dition s (Abo-ElSeou d et al.1990; Abo-El-Seou d a n d Ha sh im ,
1994). Th u s, th e obta in ed in cr ea se in fr ee a m in o
a cids con ten t in th e pr esen t wor k m igh t h ave a
ben eficia l effect to fa ce th e toxic a n d u n desir able im pa cts of pesticids on th e tr eated pla n ts.
On th e oth er h a n d, tota l pr otein s con ten t of
wh eat sh oots sh owed som e depletion s a s a
fu n ction of th e im posed in secticides u p to 12
days a fter application . However, th is declin e
wa s m or e pr on ou n ced with a n in ter va l of six
days of eith er dim eth oate or pir im ica r b application . Sa m plin g dates of n in e a n d 12 days a fter
application exh ibited gr a du a l r ecover ed
in cr ea se in tota l pr otein s con ten t of th e tr eated
wh eat sh oots, bu t it wa s still less th a n th at of
[ 191 ]
th e u n tr eated pla n ts. After 15 days of th e
pesticida l ch em ica ls application , n o obser vable
va r iation cou ld be r ecor ded between both th e
spr ayed a n d n on -spr ayed wh eat sh oots r ega r din g th eir pr otein con ten t. Com pa r in g th e effectiven ess of th e applied pesticides to a ffect pr otein con ten t of th e tr eated pla n t, it cou ld be
in fer r ed th at dim eth oate h a s m or e capicity to
decr ea se pr otein con ten t r ath er th a n pir im ica r b. For in sta n ce, th e m a gn itu de of declin e
r ecor ded with th e sa m plin g date of six days
M.A. Abo -El-Se o ud and
M. Fro st
Bio c he mic al c hange s in
whe at plants as affe c te d by
re sidue s o f dime tho ate and
pirimic arb
Enviro nme ntal Manage me nt
and He alth
9 / 5 [1 9 9 8 ] 1 8 8 –1 9 3
Table IV
To tal pro te ins and fre e amino ac ids c o nte nt (mg/ g.d.wt) o f whe at sho o ts as
affe c te d by dime tho ate and pirimic arb applic atio n
Days after
treatment
Control
First application
Dimethoate Pirimicarb
Second application
Control
Dimethoate Pirimicarb
Free amino acids
0
2.35
3
2.26
6
2.15
9
2.47
12
2.51
15
2.31
2.81
3.11
5.28
4.97
5.25
3.16
2.74
4.34
4.92
4.01
3.91
4.81
2.08
2.31
2.26
2.18
2.27
2.36
2.13
4.04
5.11
5.97
4.22
4.27
2.27
3.81
5.23
5.61
5.21
3.14
Total proteins
0
167.31
3
171.35
6
169.65
9
172.31
12
170.31
15
170.98
170.31
153.26
146.11
148.39
156.21
168.45
169.45
158.11
150.31
157.11
163.22
170.14
145.31
142.28
156.11
146.43
144.26
145.15
147.26
132.83
127.16
131.24
140.35
146.81
145.16
140.11
133.06
139.31
143.19
147.15
Table V
Nuc le ic ac ids c o nte nt (mg/ g.d.wt) o f whe at sho o ts as affe c te d by
dime tho ate and pirimic arb applic atio n
Days after
treatment
Control
First application
Dimethoate Pirimicarb
Second application
Control
Dimethoate Pirimicarb
RNA
0
3
6
9
12
15
16.25
16.18
17.31
16.92
17.31
17.28
17.09
15.22
12.26
14.31
14.25
15.69
17.43
14.11
11.28
14.86
15.26
17.08
17.82
16.31
16.28
17.15
16.93
16.26
17.33
13.18
11.06
14.18
15.37
16.93
17.11
14.12
12.25
15.26
15.92
17.23
DNA
0
3
6
9
12
15
2.82
2.76
2.61
2.72
2.85
2.65
2.85
2.74
2.66
2.75
2.81
2.83
2.91
2.76
2.72
2.74
2.86
2.72
2.71
2.70
2.68
2.75
2.69
2.72
2.81
2.76
2.68
2.52
2.63
2.86
2.72
2.51
2.42
2.61
2.65
2.73
RNA/ DNA ratio
0
3
6
9
12
15
5.76
5.86
6.63
6.22
6.07
6.52
5.99
5.55
4.61
5.20
5.07
5.54
5.99
5.11
4.15
5.42
5.33
6.28
6.58
6.04
6.07
6.24
6.29
5.98
6.17
4.78
4.13
5.63
5.87
5.92
6.29
5.63
5.06
5.85
6.01
6.31
[ 192 ]
a fter th e fir st application wa s 13.9 a n d 7.4 per
cen t, m ea n wh ile it wa s 12.6 a n d 8.93 per cen t
a fter th e sa m e in ter va l of th e secon d applica tion for dim eth oate a n d pir im ica r b r espectively. Th e pr esen t depr ession in tota l pr otein
con ten t coin cides with th e fin din gs of Gom a a et
al. (1976) on pea pla n ts tr eated with
dim eth oate. Sim ila r ly, Rozek a n d Ma r ecr ek
(1981) r epor ted th at dim eth oate a n d m a lath ion
declin ed lea f pr otein con ten t of pea pla n ts. In a
r ecen t investigation Sh a m s-El-Din et al. (1995)
stu died th e effect of con sequ en t application s of
pesticides on pr otein con ten t of th e tr eated
cabba ge leaves. Tota l pr otein con ten t sh owed
a n in cr ea se a fter th e fir st application in
r espon se to both m a lath ion a n d pr oth iofos.
However, a ll th e u sed pesticides decr ea sed
pr otein con ten t of th e tr eated cabba ge leaves
a fter th e secon d a n d th ir d application .
Nucleic acids content
RNA a n d DNA con ten t of wh eat sh oots a s
a ffected by dim eth oate a n d pir im ica r b spr ayin g is pr esen ted in Table V. RNA con ten t wa s
decr ea sed du r in g th e in ter m ediate sa m plin g
dates du e to th e u tilization of th e stu died pesticides. Aga in , a sa m plin g date of six days a fter
spr ay wa s th e m ost cr itica l per iod to r edu ce
RNA con ten t of th e tr eated pla n ts. Th e in h ibition im pa ct of th e applied a gr och em ica l on
RNA con ten t of tr eated pla n ts sta r ted to disappea r fr om sa m plin g date of n in e days a n d u p to
th e en d of th e exper im en t. On th e oth er h a n d,
n o detectable va r iation s cou ld be in du ced in
th e DNA con ten t of wh eat sh oots a s fa r a s th e
in flu en ce of th e spr ayed in secticides wa s con sider ed. On ly a sim ple flu ctu ation cou ld be
obser ved. In oth er wor ds, DNA con ten t exh ibited fixed ph en om en on towa r d th e u sed in secticides. RNA/ DNA r atio sh owed a ligh t decr ea se
du r in g th e in ter m ediate in ter va ls a fter application du e to th e depr ession in th e RNA level.
Liter atu r e sh owed th at ver y lim ited wor k wa s
con du cted r ega r din g th e im pa ct of pesticides’
folia r application on n u cleic a cids. Per epelen ko (1987) sh owed th at dim eth oate a ffected
n u cleic m etabolism in cotton seedlin gs via th e
ch a n ge in ch r om osom e aber r ation fr equ en cy.
As a gen er a l con clu sion , it cou ld be
m en tion ed th a t th e a pplied in secticides wer e
gr a du a lly declin ed a n d decom posed du r in g
th e design ed sa m plin g da tes a fter a pplica tion .
Th e degr a da tion of th e spr ayed in secticides
w a s a ccom pa n ied by som e bioch em ica l
ch a n ges in th e tr ea ted wh eat sh oots. Sa m plin g
da tes of th r ee a n d six days a fter a pplica tion
wer e th e m ost cr itica l per iods to in du ce som e
distu r ba n ces in th e pla n t m eta bolism . Th e
la ter sa m plin g da tes sh owed r egu la r ch a n ge of
th e deter m in ed ch em ica l con stitu en ts to th e
n or m a l levels. Th u s, it cou ld be con clu ded th a t
th e im pa ct of th e u sed pesticides on th e
M.A. Abo -El-Se o ud and
M. Fro st
Bio c he mic al c hange s in
whe at plants as affe c te d by
re sidue s o f dime tho ate and
pirimic arb
Enviro nme ntal Manage me nt
and He alth
9 / 5 [1 9 9 8 ] 1 8 8 –1 9 3
m eta bolic ch a n ges is a tem por a r y effect a n d it
h a d n ea r ly disa ppea r ed a t th e en d of th e
exper ipm en t. Th e obta in ed bioch em ica l
ch a n ges du r in g th e in ter m edia te sa m plin g
da tes m igh t be du e to th e toxic a n d in h ibitor y
in flu en ce of th e pesticides’ r esidu es on th e
en zym a tic system s involved in th e m eta bolic
pa th w ays of th e stu died con stitu en ts.
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