Influence of irrigation, crop thinning and canopy manipulation on composition and aroma of riesling grapes

WAII'E INSTruTE

INFLUENCE 0F IRRIGATI$.1, CRoP THIÌ$.IING

AT.ID CAI.IOPY MANIPULATIÍIN S,¡ CÍ},IPOSITI (N fl.ID AR$4A OF RIESLING 6RAPES.

by

Mi

chael G.

HcCan

thy

B.Ag. Sc .

Department

of Plant Physiologl [,l¿ite Agricul tural Reseacch Institute

Univensity

o+ Adelaide South Austral i¿

Thesie gubmitted

{on thc

^Degnee

of

^l{asten

o{

Agricul

tunal

Science.

,'ì' ^-'¡'{-o

J

)i)¡rr _iáb

Aprit,

^198ó

TABLE 0F CfI.fTtfTS

SUMMARY.

STATEI',IENT.

ACKN(xdLED6EHENTS ^.

LIST OF TABLES.

LIST OF ^FIGURES.

I ^.

f}

INTRODUSTI ^{fT.I .}

I ^.

I

l'le¡sures

of

Frui

t

^{0uel i}

ty

^f on l,li ne.

I .

l. t oBrix r pH, acidi tv and natios.

I

.t ,2 t,li ne col our .

I ^. I

.3

^{Ju i ce and wi ne ånqlìâ .}

I .

L3.I

Anqn¿

and {lavour quanti{i cation.

1.1.3.2

^The

role o{ monotenpenes in grape and wine ånoma.

2.0

I.hTERIALS & ^T.IETHODS.

2.1

Location

o{ {ield cxperiment.

?,2 Planting naterial .

2.3

Expenimental si

te histony.

2.4

Trcatments and Expenirrenteì Design.

2,4.1

^{I nr i gat i on tneatmen}

ts.

2.4.2.

^Cnop

thinning

^treatment _'

2,4.3.

^Canopr månegement treatment.

2.5

Pruning

lcvels.

2.ê E¡tinrtion ol vinr lrr{ ærr.

2.7 Fruit

^ranrpl

ing procrdune rnd iuicr pnrp*rtion.

2,8

Torpenc

¡n¡ly¡i¡.

2,9

}le¡euncmcnt

rnd c¿lculrtion o{ tcnpen:

concentnetion.

2.10

Juicc prGp¡r¡tion for penrl

¡sgessment.

2.ll

P¿ncl

¡r¡r¡¡ncnt.

2.12

ânalysi¡ o{ rlrult¡.

Page no.

t 3 4 5 6

I I I I

t1

t2 t2

IB IB

l8

l9 l7

20 22 2?

24 24 24 2?

2?

3t 32 32

3.0

RESULTS.

3.

t

^I 984 harvest ^.

3.1.1 Fnuit yield and its cornponents.

3.1.2 Vine Lea{ Area.

3.1.3

^Changes

in

^oBrix.

?.1

.4

^Ti

tratabl e

^{ac i} di

tr

^and PH.

3. t

.5

Fnee tenpenes ^{(FVT) .}

3.1.ó Potential terPenes (ruT).

3.1.7

^FVT

+

^PVT

content per vine.

3.1.8

^Panel

iuice

^scones.

3.1.9

Regression analyses

of

^åro{nå scoPe Versug ^tenpenes.

3.1.9.1

Score and Free tenpenes (FVT).

3.1.9.2

Scone

and Potential terpenes (FJT) . 3,2 t982 llanve¡t .

3.2,1 Fnuit yield and its cunponents'

3.2.2

^Changes

in oBrix, titratable acidity

^{and pH.}

3,2,3

^{Free terPenes ( FW) .}

3.2.4

^{Poten t}

ial

^{tenPenes ( PVT) .}

3.2.5

^FW

+

^{RIT con ten}

t per v i ne .

4.0

^qlgqEglQN.

4.1 Yicld ¡nd itr caEPonents.

4.2 Incrcard

crop

r{f rcts on nipening.

4.3

Thinning

r{frct¡

^{on riPening.}

4.4 Fr:e

end

potrntial

tcrPencs.

4.5 Potcntf¡l uolrtilr tmpcnGß vcPrur oBrix.

4.ó

FVT

+

PIIT

cont¡nt

pen vine

4.7 Orgrnolrptic tss?s¡ncnt o{ arqr¡.

4,8 .Iuict

Bconr end tenpenc

contcnt.

4.9 ll¡nurrt cmponrnts at 'winernrking ' lHturity.

34 34 34 34 34 37 39 39 39 43 52 53 54 55 55 5ó 5ó 5ó 57 64 64 é4 6é é8 70

7l 7t

74 75

5

.0

cfNcLust ü.1 .

ó.0

REFERENCES.

APPENDIX

I.

APPENDIX 2.

78 79 84 8ó

WAITE INSTITUTE

LIBRAR Y

I

sl,.ht'IARY

Variations in

^{the anoma}

o{

expenimentaì

lots o{ Riesling

^grape

juice

wene

investigated br subjective and obiective means'

^TheEe

methods

wece used to åssess the effect o{

^vi

ticul tunal

^pnactices¡

innigation

and I

ighten pnuning, crop load, and shoot directioning which åre suspected ol a{{ecting

wine

qualitl.

Tt¡o years data ^are pnesented on

the e{{ect o{ these

^vi

ticul tunal pnactices on {nuit yiel d, vegetative

^{gnor,,lth and {nui}

t

composi

tion

^duning

nipening.

^0ne

seasons data on

iuice

^ånomå àssessment ane pnesented.

Irnigation and

^I

ighter pnuning

^nesul

ted in ån

åPPFoximate

doubling

o{ {ruit yield

^pen

vine r¡ith only a småll delav in

nipening.

Crop thinning o{

irniqrated and

lighten

^pnuned

vines

^caused

a

^halving

ot yield

and

a

hastening

o{ ripening

^cønpaned

with irnigatedi

^such

{nuit

ripened

eanlier

than uninnigated

but with the

same

vield.

^Shoot

directioning on innigated and lighten

^pruned

vines

^had

only

^minon

effec

ts.

Monotenpenes,

å

ccrnponent

o{ årtrner

^{u,ere extnacted {rorn the}

juice

_and measuned by

colour neaction' The concentnation o{

'{nee

volati

^I

e terpenes' (FW) in the iuice wåE not

af

lected bv

^the

experimentel

tneatments but significant treatment e{{ects on

the

concentnation o{ 'potential volati

^I

e terpenes' (ruT)

wene observed.

Inrigetion and lighten pnuning caused a signi{icant neduction

ⁱⁿ

while

^cnop

thinning o{ inrigeted

vineE

nesulted in a signi{icant

enhancernen

t

cønpared wi

th

i rn i gated al one ⁱ

n

season two.

The

concentration o{

^F\rT incneased

å5

^{gråPes ripened.}

Subiective

åssessment

o{ iuice

^arsna wås cåFnied

out

b}'

å

^panel

ol six

winemakers

with

experience

in iuice

assessrnent. Although ^thene were

difficul ties in data interpnetation,

^panel

ists wene able

^to

discenn dif{erences in årqîå intensity

associated

with {nuit

^nipening

and fou¡

^mernberE

of the paneì detected di{fenences

^between

2

expenimental tneatments.

Multiple linear negression analysis of

^anoma score end FW of al

I

sampl

ings

sholed

a negative connelation fon {our of the

^six

rnembers

o{ the panel. Regression analysis o{

anomå ecore and ^P\IT concentnation shoued

å

^posi

tive connelation {or two of the six

rnernbers¡

there urås no correlation lor the othen {our

^members.

Howeven, when

the

data {nom

the {oun

tneatments wene cunpaned

at

the såme

stage o{ cqnnencial harveEt Ql oBnix), the

two lot¡¡-yielding tneatments

(unirrigated

_and

innignted plus crop thinned) had

^highen

P\/T and ånüîå scores than

the high-rietding

treatments.

The significance and

^impl

ications o{ these {indings

^a¡e

di Ecussed.

3

STATEI.IENT

I

^{heneby declane}

that the thesis

hene presented

is

my

*Jn

wonk,

that it contains

^no

m¿terial

^pneviouslv

published,

except whene due ne{enence

is

^måde

in

^the

text,

and

that

^no

part of it has been suHnitted {on

an)¡

other

degree.

I

consent

to thie thesiE being rnade available {on

photocopling and

loan i{ accepted {on the award of

the

^degnee.

(tl. _G.l'lcCar thy)

4

ACKNq¡LEDGE},IENTS

I wish to

^expness m)'sincene thanks

to

Dr'B'G'Coqnbe

{or his

encoupågerîent

to

undentake

thiE

work and

fon his guidance

duning

{he

course

o{ this

^{pnogram, and}

in the pnepanation o{

thiE

^{thesi s.}

I

^thank Dn.P.J.l¡JilliemE

o{ the Austnalian tline Reseanch

Institute

^{t¡ho ès my second} supenvisen pnovided advice and

whose

initial

^{wonk made}

this project possible.

Thanks

are

due

to

J.lessns. R.Chapman, R.Day, D.Gnoonr A.Hoeyt

c. lbtchen and D.t¡lardlaw {on being wi I I ing membens of the

åssessnent panel.

I

acknq¡ledge

the specialist assistance o{

Mn.P.l.McCloud ^{on

help in the etatistical interpretation o{ the

voluminouE

d¡ta.

Finencial assistance

^{was pnovided}

by the S.A. Oepartment

o{ Agnicuìture

^which

is

ackn*¡ledged.

5

List of

^Tabìes

Tabl

e

^{2. I}

Tabl

e

2.4

.l

Tabl

e

2.7.

T¡ble

3,1.1

Tabl

e

3.1 .2

Selected cl

imatic data {on

Nuniootpa.

Selected

climatic

data and volumes

o{

waten

applied

duning

the l?93/84

ÉeåEon.

Sarnpl

ing

dates and eìapsed davs

fnqn

Zóth Januan ), ^.

Yield

and

its

components

{on

1984 (average

o{ all

sampl

ing

times except bennz

weight

and number o{

benries

per

bunch which was detenmined

at time 4 ) '

Lea{ uaniables

o{ unirrigeted and irrigated vines

(Treatments A and

B)

estimated

at

sample

time six'

Juice

ertrnå scone

for

^each

panelist

^{on each}

essessnent dåy

fon all tneatments end sampl ing times.

Analysis o{ iuice

^{anorna rnean scone}

{or

day one

and day two

o{

assessment.

Juice

enqnå scone

of

each tneatment

fon

al I

sampling times and

Panelists.

Test of non-onthogonalitv bv modification to the rnodel fon those panel iEts {or u¡hqn rnodel (t)

could be used

{on

FVT vensus

iuice

ånqnå score.

Surn¡ry o{ nultiple ìinear

negneesion analysis

of iuice scone with fnee and potential tenpenes' Yield and its cønponents {on 1982 (evenage

o{

al

I

^sarnpl

ing

timeE).

PlrT

x

100./oBrix

{or

treatments

A,

^{B and C {on}

henvest yeårs 1982 and 1984.

Analyser

of fruit

on dåv 40 (l'lerch

óth

¹⁹⁸⁴⁾

Anelyses

of fnuit at 2l oBrix ({ound bv

i ⁿ tæpolat i on

at the dates i ndi catcd)

An :xemple

of the linear

negneesion

¡n¡lysie ured to

^detenmine

the

regnession equation {oc tenpene

disti

^I

lates.

Paqe no.

l8

2t

Tabl

e

3.1 .3 Summany

o{ quadratic

^{cunve model I}

ing

^of

oBrix

_versus

time {or

^{1984 vintage.}

Table 3.1.8.1

Canplete

set of iuice anorna scones'

Table

3.1.8.2 Analysis of

^vaniance

table for

each

paneìist {or test o{

hunogeneity

o{

variance'

Table

3.1.8.3 Analvsis of scones o{ all panelists.

23

36

3ó

37 45

43 4é

48

4B

4?

53

54 55

70

76

77

88 Tabl e

Tabì e

Tabl e

Tabl e

Tabl e

3. l .8.4

3.1.9.5

3.1.8.ó

3.1 .8.7

3.1.9

Tabl

e

3.2.1

Table

4.5

Table 4.9.1 Tebl

e

4.?,2

Tabl e A,2

é

List of

Fioures Fioune numben

FIGURE

1.1.3.2

A

classi{ication o{ the

monoterPene cmPounds

o{

^gnaPes.

Paoe no.

14

FI6URE 2.4 .3

FIGURE 2.7,1

FI GURE 2,7 ,2

FIGURE 2.8

FTGURE 2,IO

FIGURE 3.1.3

Ventical tneìlis used in Tnt.D

sholing docmant shootE tnained between paired {ol iage wires.

Zambcl I

i

gråpe crushen-destenmer used ^{on crushing and destenrning

{nuit

samples.

tlaten-bag pcess

in the open position used

{or

expnessing

iuice {nqn the gnåPe pulp.

Blass¡¡ane used

to

prepåne terpene

distillates

^{shw¡ing steam}

{laskr

^thnee

necked

{lask,

^{condenson and}

electronic

balance.

l,lineny

tasting rosn

uEed

{or juice

åssessnent shot,ing two membens

o{

the panel assesEing

juices.

Change

in oBrix with time durinq 1984

vintage.

23

26

28

30

33

35

38

40

4l

42

44

47

50 FIGURE

3.1.4.1

Change

in titnatable acid with

^time

during

^{l9B4 vintage.}

FIGURE

3.1.4.2

^Change

in

must ^pH

with time duning 1984

vintage.

FI6URE

3.1.5

^Change

in {ree tenpenes with time duning 1984 vintage.

FIGURE

3.1.ó

^Change

in potential tenpenes with time

duning 1984 uintage.

F¡ 6URE 3.1 .7 Change

in

^FVT

+

PVT peP

vine with time duning 1984 vintage'

FIGURE

3.1,B.l Plot ol residuel

^veFsui

fitted

^{0¿lues {on}

the cqnbined analysie o{ iuice

^{anoma econe}

fon

^al

I

Panel

ists.

FIGURE

3.1.8.2

l'lean

iuice

^scoPe

{or

each treatment {on each

panelist {on all sampling times.

7

FIGURE

3.1.8.3

Mean

juice

_scone

{on

each tneatment

at

each sampling

time {on all panelists'

FIGURE

3,2.2.1

Change

in

^{oBnix with}

vintage.

time

duning 1982

FIGURE

3.2.2.2

Change

in titratable acid t¡rith time during 1982 vintage.

FI6URE

3.2.2.3

Change

in

^{must pH}

with time duning 1982

vintage.

FI6URE 3.2.3 Change

in

{nee tenpenes

with time during 1982 vintage.

5t

58

59

ó0

ót

é?

64

85

87 FI CURE 3.2,4

FIGURE 3.2.3

FIGURE

A.I

FIGURE 4.2

Change

in potential tenpenes with time

duning t982 vintage.

Change in'FVT

+ F\/T

content

with

^time

duning 1982 vintage.

Concentration

o{

^{{nee and}

potential

terpenes

in

senial

lv

col

lected distil lates.

The

relationEhip

between micnognams terpenes

as linalool and absorbance neading.