الفهرس 
effect of drought at different stages of plant age o growth
materials and methodsOnly 14 pages are availabe for public view
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Abstract
E.xpt. St a, in Xalubia Governorate, A,R. of Egypt
to investigate the effect of soil moisture stress (SMS)
as well as skipping one irrigation at different stages of
plant age on growth, yield, yield components and grain
quality characters of tne local wheat cultivar (Bakha 8).
The first and second experiments were conducted
in 1978 I 19 season and the third and fourth in 1979/80
season. The first and third experiments were performed
to study the effect of SMS, while the second and fourth
to study the effect of skipping one irrigation at different
stages of plant age.
The experimental design of each experiment was
randomised complete block desigen in four replications.
The treatments were as fallowa:-
I, The effect of soil moisture stress (first and third
e.rpt.):
1. Irrigation after 40% depletion of available soil
moisture, i.e. AMD = 40%.
2. Irrigation after 60% depletion of available soi3. Irrigation after 80% depletion of available soil
moisture i.e. AMD = 80%.
4. Irr:l.gction after 100% depletiGn of available soil
moisture for a week i.e. afte~ one week of 100 %
AJJD.
All the treatments started at tillering stage,
II. The effect of drough at different stages of plant age
(second and fourth expt.):
A: Sb: irrigations ~the first at planting, the second
at tillering, the third at the beginning of spike
initiation, tl;e Lmrth at heading, the fifth at
flowering and the sLI:t\1 at Dough stage,
B: Fi .,, irrigations: the s,n~ as ”A” except slcil-YPing
an .. ·c·rigation at tille:dng .ltq;e.
io::t stage.
” ,,, r: s ”A” except skipping
’, __ iii:g of spikes initiat-
D: Five irrigatiOll’: the same as ”A” except skipping
~~ ir~igation at heading stage.
E: Pive irrigations: the aa::e as ”J..” e::::e;:-t st;:i;:;:~ ~,;
an irrigation at flowering stage.lh Five irrigations: the sa.Illl!l as ”A.” except skipping
a.n irrigation at dougl:t stage.
The planting dates were 30/11/1978 and 1/12/1979
for the first and second season, respectively. Irrigation
water was measured by portable water meter. Soil samples
were taken Just before ae well as 48 hr. after every irrigation
to determine the water consumptive use. The quantity
of irrigation water was added to rais the soil moisture
content to the field capacity.
The most important results for this investigation
could be summarized as follows:
I. Effect of soil moisture a tress (SMS) ”first and third
e.xpt.”;
1. Exposing wheat plants to high moisture stress ranging
from irrigation after 40% depletion of available
soil moisture to after a week of lOo% depletion
of’ available soil moisture depressed flag leaf
area, plant length and spike length.
2. The relationship between soil moisture content and
each of flag leaf area, plant length, spike length
and number of tillers without spikes was ourvilinJ. Exposing wheat plants to tb.e :f’.:J:rtner -;;~ntoa c.epressed
yield and yield components characters i.e.
number of spikes per plant, number of spikelets
per spike. number of grains per spike, number of
uafertile florets per spike. total number of florets
per spike, fertility percentage. 1000 kernlea
weight • grain yield and straw yield.
4. The combined data revealed that the differences between
irrigating the plants at 40% AMD and 60% AMD
were not significant for the number of spikes per
plant, the number of spikelets per spike, the number
of grains per spike and the 1000 kernels weight.
In addition, the differences between irrigating the
plants at 40% AYD, 60% AMD and 80% AMD were not significant
for the number of spikes per plant and
number of spikelets per spike.
I 5. The r>,lationships between soil moisture content at
the irrigation time and each of number o:f’ spike per
plant, number of spikelets per spike, number of grains
per spike• number of unfertile florets per
spike, total number of florets per spike, 1000 kernels
weight, grain yield and straw yield were6. Increasing depletion of available soil moisture before
irrigation ranging from 40% to after one week
of 100% depletion of AK depressed some grain qualit1
ob.aracters, i.e. the hectol.i:ier 110igttt,. fi:al t: r>ar
percentage and ash percentage. On the contrar.r,
other grain quality cBaracters i.e. fine middlings
percentage, middlings percentage (Bran% ), crude
protein peroe~t~ge, sedimentation value, wet gluten
~~ ~
percentage, dry gluten percentage and do11gll properties
( dough energy. dough extensibility, dough elasticity
and tBe ratio of elasticity ,to extensibility
) increased with increasing depletion of A.M.
before irrigation.
7. ’!’he relationships between each of th.e grain quality
characters ( excluding dough properties ) and soil
moisture content at the irrigation time were curvilinear.
ll
a. Irrigation requirements ( IR ) tended to decrease
wi tb. increase in soil moisture stress from the low
moisture stress up to tb.e bigll stress i.e. :f’rom irrigating
after 40% depletion of A.M. up to irrigating
one week after 100% depletion of A.M. ~verage
values of !R of the two seasons were 4087, )259 ,
)J21 and 2421 m’/faddan when the plants wer~ ..irrigated after 40~, 60%, 80% and 100% ( for one
week ) depletion of the available soil moisture,
9. Average consumptive use of the two seasons tended
to decrease with increase in SMS before irrigation.
Average seasonal oonaumpti ve use values were 78.4 •
63.4, 66,8 and 52,1 ems when the plants were irrigated
after 40%, 60%, 80% and 100% for a week depletion
of A.M. respectively.
10. Maximum consumptive use ( c.u. ) ae well as coll£1umptive
use coefficient (K) of,wheat plants were obtained
duri:og March.
11. Averages of water use efficiency ( 1lUE ) i.n kg.
grains/m> water were o.65).o.ns. 0.0# a.Qd O.i.ll
for the irrigation treatments after 40%, 60%, 80%
and after one week of 100% depletion of AM, respectively;
II, Effect of drought conditions at different stages of
plant age:-
1. Exposing wneat plants to drought at tillering stage
or at the beginning of spike initiation reduced
flag leaf are~ compared with the other treatments.
Minimum value of flag leaf area was obtained by
irrigating Wheat plants 5 times skipping one at the2. Exposing wheat plants to drought at tillering stage
or the beginning of spike initiation stage or heading
stage had a significant reduction effect on
plant length. Delaying wheat plant expo sure to
drought i.e.” at flowering stage or dough stage
had no significant effect on plant length.
3. Exposing wheat plants to drought at the beginning
of spike initiation stage as well as at heading
stage reduced significantly the spike length. Minimum
spike length was obh.ined by cposi.Jlg wi:l.eaX
plant to drought at heading stage_
4. Number of tillers without heads increased sig.nificanlty
by exposing wheat plants to drought at the
beginnjng of spike initiation or at heading stage.
5. H. i.nimum. number of tillers per plant was obtained
by exposing wheat plants to drought at tillering
stage; lj’
I
6. Exposing wheat: plants to drought at tile tilleri.ng
stage (B) or at the beginning of spike initiation
(C) or at heading stage (D) reduced significantly
the number of spikes per plant, the number of spikelet
a per spike and tile number of grains per spike
compared w itb. the control (A). Minimum number ofspikes per plant was obtained~ Tre&~ (el.
w~ile minimum number o~ t~e spikelete perspike and
grains per spike were obtained from treatment (D).
7. Number o~ un:fertile florets per spike was decrea-•
sed significantly by exposing wheat plants to drought
at the beginning of apike initiation where
as it increased significantly by exposing the plants
to drought at heading stage.
s. Exposing wheat plants to drought at tillering stage
(E), or at the beginning of spike initiation
stage (C) resulted in a significant reduction on
tb.e total number of florets per spike. Minimum
number of florets per spike was obtained by treat ....
ment (C)~
9. Fertility percentage was reduced clearly with exposing
wheat plant to drought at heading stage (D).
’I
10. Erposing wheat plants to drought at flowerillg stage
(E) or dough stage (F} reduced significantly
the l.OOO kernels weight. Minimum value was scored
with treatment (F).
11. Grain yield was reduced significantly with ski¥ping
one irrigation during one of the plant lifestages i.e. treatments 13, o, D, E and F• Minimu.m
reduction was oocured with skipping an irrigation
at heading stage.
12. Straw yield was reduced significantly wit~ exposing
wheat plants to drought at the ’tillering stage
or at the beginning of spike initiation stage (0).
Minimum value was obtained with treatment (O).
13. The hectoliter weight decreased significantly with
skipping an irrigation at dougl:l stage (D).
14. Exp9sing wheat plants to drought at B.llY’ stage ( B,
0, D, E or F ) reduced significantly the fine flour
pe:t’oentage • MaximQI!I value was oocured with skipping
an irrigation at dough stage (D).
15. Exposing wheat plants to drought at an,y stage of
plant age ( B, 0, D, E or J.i’ ) increased siga1fioant11’
the :f’ine 11!Liddli.tlgs percentage. Var!m•mr increase
oocu.red ~th ek1pp:f.ns: an :i.rJ:oj,p:t::f..aA at; u._
stage~
16. Skipp~g an irrigation at the tillering stage (B)
or the beginning of spike initiation (0) or the
heading stage (D) or the dough stage (F) increased
significantly the bran percentage. Maximum increase
oocured with treatment (F).17, Skipping an irrigation at the heading (D) or the
dough stage (F) increased significanlty the crude
protein. Maximum increase occured with treatment
( D )~
lti. Exposing Wheat plants to drought at the beginning
of spike initiation stage (C) or heading stage (D)
or floweriAg stage (E) or dough stage {P) increased
s:l.gnificanl ty the sedimentation value, Maximum
value obtained with treatment (F).
19. Exposing wheat plants to drought at the heading
stage (D) or dough stage (F) increased significantly
the wet gluten percentage. Maximum increase
occured with treatment (D).
20, Dry gluten percentage increased significantly
with skipping an irrigation at the heading stage
(D) or the dough stage (F). While skipping an
irrigation at the tillering stage (B) decreased
’Signi:ficantly the d:r7 gluten perc~~Uttage. K•x:imum
increase ooca.red with treable.nt (D).
21. Exposing wlleat plants to @ought at the heading
stage increased significantly the ash percet~tage
while it decreased significantly with skipping an
irrigation at flowering stage (E).22. Irrigation requirements (IR) of wheat plants which
were iJ:’l.”igated si% ti.mes {J.) e.:.c.eeai! Umae :u:::igated
:N.ve ti-mes b,r skippi-ng one :f.1’riga;Uon ai: 11-
llering stage (B) or the beginning of spike initiation
stage (C) or the heading stage (D) or the
flowering stage (E) or at the dough stage (P).
Average values of IR of the two seasons were 2568.6•
2337;0, 2204.6, 2268.2 1 2356.4 and 1970.4 m3/faddan
for treatments A. ( control ) , :B, C, D, I and P,
respectively.
23. Consumptive use of water (ou) for the plants which
were irrigated sir times (A) exceeded those irrigated
five times by skipping one irrigation at the
~illering stage (B) or the beginning of spike initiation
stage (C) or the heading stage (D) or the
flowering stage ( E) or at dough stage (F}. Average
seasonal ( cu ) values were 52.4, 4J.s. 4J.O,
39.5, 42.8 an~!J7,8 ems for treatments A (control),
. ’
B1 . C,D, E and ’P respeotivel,v< ·
24. The period of maximum water use values corresponding
closely to the heading, flowering and dough
stages of all treatments. J.finimum eu was obtained
with irrigating wheat plants five times ezoluding
an irrigation at the dough stage {l!’). lfarliiWDc.u. as well as consumptive use coefficient (K)
of wheat plants for all treatments were obtained
during March.
25. Consumptive use coefficient (K) of wheat plants
which irrigated six times exceeded those irrigated
five times. It was 0,875, 0.721• 0.6~7, 0,629,
0.714 and 0.652 .ror treatments A(control), B, C,
D, E and F, respectively.
26. Jverages of water use efficie::~cy ( WUE )• in kg,
er”.ns/mJ \~’ter were 0.744. 0.806, 0.703; o •. 655;
0.797 and O.o02 for the treatments A (control),
B, C, D, E and F, respectively~