169
Agrichemicals
FLUORESCENCE DECLINE RATIO: COMPARISON WITH
QUANTUM YIELD RATIO FOR PLANT PHYSIOLOGICAL
STATUS AND HERBICIDE TREATMENT RESPONSES
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Plant Protection ChemistryNZ, PO Box 6282, Rotorua, New Zealand
Corresponding author: [email protected]
ABSTRACT
3ODQWÁXRUHVFHQFHLVQRUPDOO\PHDVXUHGXVLQJWKHUDWLR)Y)PTXDQWXP
\LHOG$QDOWHUQDWLYHPHDVXUHPHQWÁXRUHVFHQFHGHFOLQHUDWLR5fd), can
EHXVHGLQVWHDGRI)Y)P7KHXVHIXOQHVVRIWKH5fd ratio in comparison to
)Y)P ZDV WHVWHG ZLWK WKUHH SODQW VSHFLHV RI GLIIHULQJ OHDI FKDUDFWHU
Diurnal trends were measured after treatment with two herbicides, diuron, a
lipophilic photosynthesis inhibiting herbicide and dalapon, a less-lipophilic
non-photosynthesis inhibiting herbicide. In wheat, both herbicides
were tested with three non-ionic surfactants of differing hydrophileOLSRSKLOHEDODQFH+/%7KH5fd ratio was a more sensitive numerical
indicator of plant responses and provides an alternative approach to
monitoring and measuring the effect of stress factors in plants.
Keywords:FKORURSK\OOÁXRUHVFHQFHTXDQWXP\LHOGÁXRUHVFHQFHGHFOLQH
ratio, herbicide effects.
INTRODUCTION
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SKRWRV\QWKHWLFDFWLYLW\&KORURSK\OOÁXRUHVFHQFH&)LVXVHGWRORRNDWSKRWRV\QWKHWLF
DFWLYLW\0D[ZHOO-RKQVRQDQGFDQUHÁHFWWKH¶KHDOWK·RIDSODQW&)PHDVXUHPHQW
is rapid, non-invasive and can measure a number of parameters linked to the physiological
status of the plant. The most common CF parameter used is the quantum yield
)Y)PZKLFKLVDPHDVXUHRIPD[LPXPSKRWRFKHPLFDOHIÀFLHQF\RISKRWRV\VWHP,,
Another parameter that can show the physiological status of a plant under stress is the
ÁXRUHVFHQFHGHFOLQHUDWLR5fd), which is obtained from the Kautsky curve (Lichtenhaler
&RPSDUHGWR)Y)PWKH5fd ratio is more sensitive to a variety of stress factors
ZKLOH)Y)PFKDQJHVRFFXUPDLQO\XQGHUH[WUHPHFRQGLWLRQV6D\HG
This paper investigated the applicability of RfdDVDQDOWHUQDWLYHWR)Y)PPHDVXUHPHQWV
for species responses, diurnal effects and the effect of herbicides with or without added
surfactants.
METHODS
Plant material
The species used were fathen (Chenopodium album), wheat (Triticum aestivum) and
Madagascar jasmine (6WHSKDQRWLV ÁRULEXQGD). Each has a different cuticle thickness
(fathen and wheat have a thin cuticle while Madagascar jasmine has a thick cuticle)
DQGWKH\GLIIHULQWKHLUUHVSRQVHWR[HQRELRWLFV)RUVWHUHWDO7KHIDWKHQ and
ZKHDWSODQWVZHUHJURZQIURPVHHGLQLQGLYLGXDOSRWV%ORRPSRWWLQJPL[<DWHV/WG
DQGZHUHUDLVHGXQGHUFRQWUROOHGHQYLURQPHQWFRQGLWLRQVž&ž&DQGž&žGD\
QLJKW WHPSHUDWXUH UHVSHFWLYHO\ KRXU SKRWRSHULRG 5+ DQG OLJKW LQWHQVLW\ FD
ƫPROP2VDQGXVHGZHHNVDIWHUVRZLQJ7KHMDVPLQHSODQWVZHUHJODVVKRXVHJURZQ
DQGDSSUR[LPDWHO\\HDUVROGEXWWUDQVIHUUHGWRFRQWUROOHGHQYLURQPHQWFRQGLWLRQVIRU
at least 2 weeks prior to being used.
New Zealand Plant Protection 61:169-173 (2008)
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Chemicals and treatments
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ðƫOGURSOHWVSHUOHDIDWDSSUR[LPDWHO\KDIWHUWKHVWDUWRIWKHSKRWRSHULRG
/HDIUHSOLFDWLRQYDULHGIURPOHDYHVSHUWUHDWPHQWRQHIXOO\H[SDQGHGOHDISHUSODQW
These herbicides were also used with three alcohol ethoxylate adjuvants (triethylene
glycol monododecyl ether, C12EO KH[DHWK\OHQH JO\FRO PRQRGRGHF\O HWKHU &12EO6
decaethylene glycol monododecyl ether C12EODOOIURP)OXNDDOODWYY
Instrumentation and analysis
&KORURSK\OOÁXRUHVFHQFHZDVPHDVXUHGXVLQJD3KRWRQ6\VWHP,QVWUXPHQWV&ORVHG
)OXRU&DP0)8VLQJ)OXRUFDPYHUVLRQVRIWZDUHDQGSURWRFROÁXRUHVFHQFH
YDOXHVIRUPLQLPDOÁXRUHVFHQFH)RPD[LPDOÁXRUHVFHQFH)PÁXRUHVFHQFHSHDN
)SDQGVWHDG\VWDWHÁXRUHVFHQFH)WZHUHREWDLQHGIRUWKHWUHDWHGOHDIDUHDV)RZDV
taken in the dark using dark adapted plant material prior to irradiating with a white light
saturating pulse (of 1.6 s) to obtain Fm. Forty seconds after the end of the saturating pulse,
FRQWLQXRXVDFWLQLFOLJKWQRQVDWXUDWLQJUHGUDGLDWLRQZDVVZLWFKHGRQIRUVSURGXFLQJ
a Kautsky response. Fp was measured at the initial phase of the Kautsky curve and Ft
DWDFRQVWDQWWLPHVDIWHU)S)Y)P>)P)R)P@DQG5fd>)S)W)S@SDUDPHWHUV
were derived from these measurements and these values used for comparison of effects.
Readings were taken before the start of treatments (2 h after start of photoperiod), then
DWUHJXODULQWHUYDOVDQGKDIWHUWKHLQLWLDOUHDGLQJ3ODQWVZHUHGDUNDGDSWHG
DWOHDVWPLQXWHVSULRUWRPHDVXUHPHQWVEHLQJWDNHQ2EVHUYDWLRQVLQYLVLEOHOLJKWZHUH
also made over several days after treatment.
The statistical software package Statistix was used to analyse the wheat treatment
UHVXOWV /HDVW VLJQLÀFDQW GLIIHUHQFH /6' WHVWV 3 ZHUH XVHG WR FRPSDUH WKH
YDULDEOHVWLPHDQGWUHDWPHQW7KHVHZHUHERWKKLJKO\VLJQLÀFDQWDVZDVWKHLQWHUDFWLRQ
EHWZHHQ WUHDWPHQW DQG WLPH 3 IRU )Y)P DQDO\VLV DQG 3 IRU 5fd
analysis). The interaction between treatment and time has been used to illustrate the
trends found.
RESULTS AND DISCUSSION
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MDVPLQHZKHDWDQGIDWKHQZKLFKVWD\HGWKHVDPHWKURXJKRXWWKH
24 h measuring period (data not shown). However, the RfdYDOXHVUHVSHFWLYHO\
DQGDWWLPH]HURGLGFKDQJHGXULQJWKHGD\7KLVYDULDWLRQZDVPRVWHYLGHQW
in fathen, where RfdYDOXHVGURSSHGWRIURPDWPLGGD\EHIRUHUHFRYHULQJ
The other two species did not show a regular diurnal trend. The trends are virtually
identical to those shown in Figure 1 after dalapon treatments. Diurnal variation was
REVHUYHGE\5RKDFHN%DUWDNZKHQPRQLWRULQJVSUXFHVHHGOLQJVXVLQJ5fd.
A diurnal effect may be present with some species or conditions and needs to be
considered when using the RfdSDUDPHWHU7KLVFRQWUDVWVZLWKWKH)Y)PUDWLRZKLFKLV
insensitive to such effects.
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HIIHFWRQSKRWRV\QWKHVLV/HDVXUH7KHUHVHHPHGWREHQRHIIHFWRQWKHSODQWV
DIWHUWUHDWPHQWZLWKGDODSRQ)LJ7KHUHZDVOLWWOHYDULDWLRQLQ)Y)PRU5fd for any
species other than due to diurnal variation. This may be due to lack of uptake of dalapon
into the leaves, or, since dalapon does not have a direct effect on photosynthesis, it takes
longer than 24 h for stress effects to show using CF. Visible damage to the leaves was
REVHUYHGDIWHUDERXWGD\VZLWKZKHDWDQGIDWKHQEXWQRWZLWKWKHMDVPLQHUHÁHFWLQJ
the different cuticle permeabilities.
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FIGURE 1: Mean Fv/Fm and RfdYDOXHVIRUIDWKHQZKHDWDQG0DGDJDVFDUMDVPLQH
plants treated with dalapon over 24 h. Error bars are ± SEM.
Diuron is a lipophilic (log Kow 2.6) photosynthesis-inhibiting herbicide. The diuron
did have an effect on CF for wheat and fathen plants (Fig. 2). There was a slight reduction
LQ)Y)PYDOXHVRYHUWLPHEXWODUJHFKDQJHVLQ5fd values for both species. Diuron had
little effect on jasmine, with RfdDQG)Y)PYDOXHVVWD\LQJUHODWLYHO\FRQVWDQW7KLVPD\
be due to the inability of diuron to penetrate the very thick and waxy jasmine cuticle.
The lipophilic character of the diuron allows it to be taken up rapidly by some species
but not by others, making the CF technique a rapid screening method for susceptibility
or tolerance.
FIGURE 2: Mean Fv/Fm and RfdYDOXHVIRUIDWKHQZKHDWDQG0DGDJDVFDUMDVPLQH
plants treated with diuron over 24 h. Error bars are ± SEM.
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species. The addition of alcohol ethoxylate surfactants to dalapon did not cause any
changes in CF responses (data not shown), indicating these are inappropriate or that
again a longer measurement interval is required for this type of herbicide.
In contrast, the addition of these surfactants to diuron produced a greater stress
UHVSRQVHLQZKHDW$OOWKHGLXURQWUHDWPHQWVVKRZDGHFOLQHLQERWK)Y)PDQG5fd values,
with Rfd showing a much greater decrease within 4 h (Tables 1, 2). The most lipophilic
surfactant, C12EODSSHDUHGWRKDYHWKHJUHDWHVWLQÁXHQFH$VWDWLVWLFDOFRPSDULVRQRI
ERWK)Y)P7DEOHDQG5fd (Table 2) values over the 24 h period showed that there
ZHUHVLJQLÀFDQWGLIIHUHQFHV7KHVHGLIIHUHQFHVZHUHPRVWHYLGHQWXVLQJWKH5fd values.
7KHUHZHUHVLJQLÀFDQWGLIIHUHQFHVLQ5fd values between the diuron treatment and the
WUHDWPHQWV ZLWK DGGHG VXUIDFWDQWV 7KHUH ZDV DOVR D VLJQLÀFDQW GLIIHUHQFH EHWZHHQ
surfactants at the 4 hour time period with C12EO being different to C12EO (Table 2).
This shows that the Rfd ratio was more responsive to the stress changes compared to
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TABLE 1:
Fv/Fm values of wheat plants treated with diuron and various
surfactants over 24 h.
Treatment
Control
Diuron
'LXURQ&12EO
'LXURQ&12EO6
'LXURQ&12EO
1
a
a
a
a
a
Time (hours)1
4
a
ab
cd
cde
bc
24
a
de
cde
de
e
7UHDWPHQWVZLWKQROHWWHULQFRPPRQDUHVLJQLÀFDQWO\GLIIHUHQW3 TABLE 2:
Rfd values of wheat plants treated with diuron and various surfactants
over 24 h.
Treatment
Control
Diuron
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'LXURQ&12EO6
'LXURQ&12EO
1
a
bc
de
de
de
a
a
a
a
a
Time (hours)1
4
ab
bc
efg
def
d
ab
c
gh
fgh
efg
24
ab
de
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(a few seconds) than those for calculation of Rfd (approximately 1 min) it would be the
preferred operational option. However, it may be less useful since Rfd measurements
FDQVKRZGLIIHUHQFHVZLWKLQDIHZKRXUVFRPSDUHGWRRQHRUPRUHGD\VIRUWKH)Y)P
measurements.
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CONCLUSIONS
The results obtained demonstrate that CF measurement can measure a number of
different stress effects, including diurnal variation, different responses among species
to herbicide treatment and the effect of different herbicide formulations.
The use of RfdLQVWHDGRI)Y)PIRUFKORURSK\OOÁXRUHVFHQFHPHDVXUHPHQWVSURYLGHV
an alternative approach to monitoring and measuring the effect of stress factors in plants.
Rfd is a more sensitive indicator for numerical comparisons, although due to diurnal
effects, caution may be required when using this parameter.
ACKNOWLEDGEMENTS
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7HFKQRORJ\&RQWUDFW1R&;7KDQNVDUHGXHWR.'6WHHOHIRUPDLQWDLQLQJ
the controlled environment facility.
REFERENCES
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[HQRELRWLFV LQWR OLYLQJ SODQWV ,QÁXHQFH RI [HQRELRWLF GRVH RQ WKH XSWDNH
of three model compounds applied in the absence and presence of surfactants
into Chenopodium album, Hedera helix and 6WHSKDQRWLVÁRULEXQGD leaves. Pest
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/LFKWHQWKDOHU+.In vivoFKORURSK\OOÁXRUHVFHQFHDVDWRROIRUVWUHVVGHWHFWLRQ
LQSODQWV,Q/LFKWHQWKDOHU+.HG$SSOLFDWLRQVRI&KORURSK\OO)OXRUHVFHQFHLQ
Photosynthesis Research, Stress Physiology, Hydrobiology and Remote Sensing.
Kluwer Academic, Dordrecht, the Netherlands. Pp. 129-142.
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