C.S.I.R.O. lrtigation Research Laboratory, Griffith, N.S.W., Australia.

      Experiments with rooted cuttings of Washington Navel orange, grown in
      sand culture and carrying 0, I, 2 or 3 fruits, showed that increased number
      of oranges resulted in reduced vegetative development, smaller fruit, thinner
      skin and higher juice content. Partial defoliation reduced fruit grOwth
      relatively less than vegetative growth, resulting in high fruit weight ratios.
      This dominance of fruit over vegetative growth has obvious relevance to
      alternate bearing in field-grown trees, but the process is studied more easily
      and more completely on the cuttings. The balance between vegetative and
      fruit growth affected fruit quality and such effects should always be taken
      into account when interpreting environmental effects on fruit quality.

     wo major problems in citrus growing are alternate bearing and fruit qUalit
   Alterna:e bearing is one aspect of. fluctuation in the balance between vegetative ~
 ,generative growth. These fluctuatlOns are presumably mduced by climate, nutritional
   status, etc. (Bouma and McIntyre, 1963). The alternate beanng 's accompanied b
"changes in fruit quality, for example smaller fruit during heavy cropping (Sham~
   et at., 1933; Shamel and Pomeroy, 1934).
         The effects of leaf area on the weight and volume of fruits have been demo
   strated by defoliation and shading experiments with grapes (Coombe, 1959; lirova~­
   1958; May and Antcliff, 1963) and with pome and stone fruit (Haller and Magues '
   1925; Chandler, 1957). On the other hand fruiting reduces vegetative grOwth s,
   indicated by negative correlations between shoot and fruit growth in Washin:' as
 . Navel orange cuttings (Gates et at., 196rb). This has been demonstrated more direct!
   by Maggs (1963) who deblossomed and defruited two-year-old apple trees. On the oth;
   hand, Rogers and Booth (1964) found no correlation between yield and the curren~
   year's shoot growth in field-grown apple trees, but a significant negative correlatio
   between yield and the following year's shoot growth.                                  n
         The present experiments with Washington Navel orange cuttings studied the

     t Present address: Institut fiir Obstbau,   I   Berlin 33, Kiebitzweg   18-20.
32                Growth of Washington Navel Orange Cuttings

eHecis of yield, defoliation and deblossoming on the development of fruit and
vegetative parts as \ve11 as on fruit quality.

                                 lvlater£al and 1ncthods
Raising of cuttings
     One \Vasllington Navel orange tree was selected and cuttings \vere taken from
the tips of spring flush shoots according to Gates et al. (rg6ra). The cuttings \\'cre
rooted in a mist propagator covered with plastic sheeting so that the temperature
was goO F. (320 C.) and the relative humidity about roo %. uniform cuttings seledcd
from this initial propagation were tmnsplantcd during June 1963 into 22' 5 em.
plastic pots filled with cleaned COa.fSC river s

ev(']opment of fruit and                 ~~:~~.~~~~ ~ :;r~,~~~~~'I~i~:~"~:~~I~;:;r;t~'i:~':h.~;:~~
                                         :.;' f. L["

cuttings \vere taken from
:96ra). The cuttings Were
: so that the temperature
 L'nifonn cuttings selected
fune 1963 into 22' 5 em.
nd \vas regularly leached
                                                                                                            1'L \TE I
    -~   -,4'0; K   ~,   5'0;   ~a-
    I                        GROWTH                                                  DRY WEIGHT AT 176 DAYS

                                              LSD P
34                       Growth of Washington :Kave! Orange Cuttings

                                           Defoliation fxp(rimcnls                                                 the orangl~5 in the defo1iat(
       The effects of different degrees of defoliation on fruit development and quality                            of the controb.
were   exalllilH~
,5                                                                                                                  F. LENZ                                                                       35
                                      the oranges in the defoliated treatment \vere \vell developed though smaller than those
)pment and quality                    of the umtrol::;.
or a long period, all
Growth and gcne:ral                                                                                                 T'SLE       II
lie II.                                                           r.jfect of defoliation on mean quatity chtl}'acteristics per frllit

                                                                                                                    Fresh            Vrj]umc        c        c        c              TSS             Skin
OAYS                                                                                                                                                                  ,. u
                                                        Treatment                                                   weight            (ml.)          '"
                                                                                                                                                   JUIce     "
                                                                                                                                                            add      'ISS            acid­        tlllckness
                                                                                                                     (gm.)                                                                         (mm.)
                                _-\11 leaves except new growth removed                                              "5 9             25 8 3        41 - 0   o-S,~     8'3        IO'13               0'2
                                Control                                                                             3 .,.,, 5        399 S         37'0     0'9 1     9'9        I   r . 26          "2
                    140         LS.D. P < 0'05··                            ..        ..            ..       "j      64 h             78 4         ;-15     NS        , '0
                                                                                                                                                                                 .:\.5.              , .2

                                All leaves removed, except behind fruit                                              144' I          1°7 -2
Growth of Washington Navel Orange Cuttings
                                                                                                                                                               "n,                GF
     Defolt'atl:on excluding fruit-bearing shoots
         \Vhen only the leaves of the fruit-bearing shoots were left, there was reduction
    in fruit growth. At the end of the experiment the severity of the treatment was
    demonstrated by the very small1eaf weight of the plants so treated. Considering this,
    fruit growth was remarkably good (Fig. 5).

             em.                                                                                                                                                 6 '12·63
                                             GROWTH                                                 DRY W£lGHT AT 222 DAYS
                                                                                   ________ CONTROL
                                                                                                                                                      W    7
                                                                        /              LSD. P

 ~ttings                                                                             F. LENZ                                              37
                                                  ,m.              GROWTH                                    DRY WEIGHT AT 222 DAYS

 left, there was reduction
ty of the treatment Was                                                                         COI.,TP.OL
tre3.ted. Considering this,

                                                   6 '12·63
                            140                                                         167·64         ~;-


             l-    FPJJIT   100 Z

                                  ~                                ,           ,
                            60                                50   100        ISO     200             Do         Dn    CONTROL

                                                                       DAYS                                    TREATMENTS
             I - LEAVES
                                                                                      FIG. 6
                                              Fruit size development and dry matter of plant parts in cuttings with only old cycle
                                                                   leaves (Do) and young cycle leaves (Dn).
             I - S1EMS      20
             J -   flOOTS                     It might be that the type of leaves could have influenced the results, but one
                                          would expect less photosynthesis in the old than in the young cycle leaves. Hence the
                                          very high fruit/plant weight ratio in the "old cycle" cuttings was all the more

oats, on fruit developmeniand             Efficts of defoliation on fruit quality
                                               These aIe shown in Table II. FollO\ving dcfolLation the skin thickne::;s decreased
                                          with concurrent increases in juice %. This occurred even in the experiment illustrated
                                          in Fig. 6, where fruit growth \vas not greatly r0'clucec1. Effects on other quality
ut 6 to 8 weeks intervals,                characteristics were variable. \Vhen fruit growth was reduced there were also
:l until fruit set are called             decreases in aciel antI T55, but in the experiment of Fig. 6 acid and TSS were highest
young growth cycles. The                  in severely defoliated plants.
  of old and young growth
 reatment differences were                                                          DlSCUSSIOK
 with only old cycle leaves
 ments. ~evertheless, fruit                                                    Fruit quality
.veights \\'ere similar in all                  Increase in the number of oranges per cutting increased sugar and acid contents,
1\\'th was strongly reduced               and decreased skin thickness (Table I). These changes are similar to those occurring
                                          in field-grown trees during heavy bearing.
Growth of Washington Nave! Orange Cuttings
                                                                                                      CH,"I-NDLER,   \V. H.
     That the balance between vegetative and gf:n~rative growth can affect fruit
                                                                                                      CoOME.E, B. G. (1
quality was also shov,rn by the defoliation experimf'nts (Table II). Large e[[ec\:s on
                                                                                                            aficcted by ,
frUtl qUJlity due to different l1l:.trient regimes have been reported for apples
                                                                                                            Fitic., 10, K;
(Bunelllann, 19(4) and for citrus (Parker and Jones, 195T), but whether these were
                                                                                                      GATl'S, C. T., Bor!»
all direct effects O~ were partly due to changes 1:1 the balance hehvee-:-t vegetative allll
                                                                                                             of the \Vasb
generative growth is not kr:own. Thus interpretation of s'tlch stud~es would be
                                                                                                              of the rootf'.(
facilitated if plants Wit11 equal numbers of fruits were used.
                                                                                                      GATES, C. T., BOl
                                                                                                              cntti'!.1gs of
                                  Fruit and vegetat1've growth
                                                                                                                 frliting cu:1
      A strong dominance of frnit over vegetative development was shown ill th2                           H ALl.ER, :'it H., ar
preseut experiments with \Vashington Navel orange::;. Tncreased number of (rnit~                                 and compos
reduced vegetative devdopment. :Moreovcr reduction in le;:d area, due to GckliaLiou                       HOAGLAND, D. R.,
4 weeks after fruit set, had a stronger depressing effect on Vf~getative than on fruit                            plants with(
developmcnt, the latter not being reduced in one instance c1('spite a reduction iE                         KInD, F., and WE'
foliage to one-fJ!th of the control (Fig. 6). Thus suggestions that the fmit is dominant                          fruits after
in t11C developmcnt of citrus (Gates et al., 196Ib) as it is in other :::pecies (\Vi1cox, 1937;            LEONAR", E. R. (­
Leonard, 1962) were confirmed. The strong fruit developner.t, even in plants with a                                special refel
very small leaf area (Fig. 5) suggests high net assimilation rates, which would be                         MAGGS, D. H. (I<
similar to increases in photosynthetic efficiency in fruit-bearing trees of peach ~nd                              fruiting. J.
apple (Ryugo and Davis, "959; Mochizuki, J962; J\lagg3, 1063).                                              MAY, P., and AN~
      Apart from the eompetiLiu!l between vegetative organs and the fruit then'. \.\/;1.S.                          in the Sult'
also competition between indiviuual fruits on the same plant lFig. I).                                      MOCHIZUKI, T. (I'
      Dominance of the fruit is presumably res?onsible for the induction of altrrnate                                apI)le tree \
bearing in fielrl-grmvn trees. F::uiting leads to depletion of reserves, as is demon­                                ~, 4 0 - 124 .
strated by the red11ced de\.cclopmcnt of root and ste,n in heavily bearing plants                            NOVAK, ].(195 8',.
(Fig. I), and partic.nlarly after defoliation (Fig, 3).                                                           of gral)cs, ,
      It is not kno'Nn ,,,,hich metabolites or Illinc-:'"al nutrients become limiting, nor how               PAHRER, E. R., a­
tlw successful compf'.tition of the fruit over the vegetative organs comes about.                                    and    lJu(lJil~
Future \vark on this shnl1kl be initiated on cutCngs, where all plant parts can be                            RUGEKS, VI/T.S., a
quantitatively studied, rather than on ficld-growll trees.                                                            apple.J. h,
                                                                                                              RVL:Go, I{., and I
       I wish to thank 11r. E. Hoare, Officer i'l Cha::ge C.S.I.1\.. O. IrngaTion Research            ,             rate of pea
Laboratory, Griffith, N.S.\V., for his kind support of Lllis work and 1 gladly acknO\v­                                PrOG.   A 11;0
ledge my indebtedness to lIdr, G, 'kIntyre for :::..tatistical treatment of the data, to                       SI1A~1EL, A. D., ~
.\liss ~\i. Stokes, 11r. H. Gilliard and ~'IL T. l'IIitchel for able ter.Jwical assistance, ar.d to                    size in Val
Dr. H. Greenway and Mr. R. de Fossard for critical suggestions wltile pre?aringthe paper.                      SHAME:", A. D., I
                                                                                                      \              size in \\1::;
                                        EEFEHENCES                                                              "hecox,   J. C. (,
                                                                                                                        between f
BOl'MA, D., and. :l\lcINTYRE, G. .i\.. (1963). A factorial field       exp~riment    with citrl1S.    I
      j. hort. Sci., 38, I75-98.
B(~.\"EM . \NN, G. (I90.1). Die Fruchtqualitat bc:m Apfel in Abhangigkeit yon der
        i\Tabrstofizu:uhr. f. Litera:ur-Dbersicbt (Samrr:elrde:-atl. GartenbaU1o£ss., 29,             \
        :f- Sr-5!6.
""o,L',~"',=0_.- - - - - - - - - - - -                                                                0"

tings                                                               F. LENZ                                      39

rO\vth can affect fruit      CH.-\~DLER, \V. H. (1957). Deciduous orchards. H, Eimpton, London, 3rd edition.
c II), Large effects on      COO;,[BE, B. G. (1959). Fruit set and development in seeded grape yariettes as
1 reported for apples                affected by defoliation, topping, girdling and other treatments. Am. j. Enol.
ut whether these were                Vitie., 10, 85-IOO.
lehveen vegetative and       G_\TES, C. T., BOL"}lA, D., and GROE:K'E\VEGEK, H. (I96Ia). The development of cuttings
uch studies would be                 of the "\Vashington :Kavel orange to the stage of fruit set. 1. The development
                                    of the rooted cutting. Aust. j. agric. Res., 12, 1050-65.
                             GATES. C. T., BOU}lA, D., and GROEKEWEGE~, H. (rg6rb). The development of
                                    cuttings of the \Vashington Navel orange to the stage of fruit set. III. The
                                    fruiting cutting. Aust. j. agric. Res., 12, IOS1-8.
ent was shovm in the
                             HALLER, M. R, and MAGNESS, J R. (1925). The relation of leaf area to the growth
ased number of fruits
                                    and composition of apples. Froc. Amer. Soc. hort. Sci., 22, 189---g6.
lrea, due to defoliation
                             HOAGLAND, D. R. and ARKON, D. I. (1950). The water-culture method for growing
2getative than on fruit
                                    plants without soiL Cire. CatiI agrie. Exp. Stn., No. 347.
despite a reduction in
                             KIDD, F., and WEST, C. (1947i. A note on the assimilation of carbon dioxide by apple
it the fruit is dominant
                                    fruits after gathering. Nc'''' Phytol., 46, 274-5.
r species (Wilcox, 1937;
.J even in plants with a
                             LEONARD, E. R. (1962). Inter-relations of vegetative and reproductive growth, with
rates, which would be               special reference to indeterminate plants. Bot. Rev., 28, 353-410.
                             MAGGS, D. R (1963). The reduction in growth of apple trees brought about by
ing trc('~ of peach and
                                    fruiting. I IIort. Sci., 38, II9-28.
md the fruit there was       MAY, P., and ANTCLlFF, A. J (1963). The effect of shading on fruitfulness and yield
 (Fig, 1),                          in the Sultana. J- hort. Sci., 38, 85-94­
                             ivloCHIZGKI, T. (I962). Studies on the elucidation of factors affecting the decline in
; induction of alternate
                                    apple tree vigour as induced by fruit load. Bull. Fac. Agric. Hirosaki Univ. No.
reserves, as is demon­
                                    8, 40-I24.
heavily bearing plants
                             NOV,\K, J. (1958). The effect of reduced leaf surface of vines on quantity and quality
                                    of grapes. Arh. poljopr. Nauk., 11. 82-92; Hort. Abstr., 29, 2242, 1959.
~come  limiting, nor how
                             PARKER, E. R, and Jo,ms, W. W. (1951). Effects of fertilizers upon the yields, size
e organs comes about.
                                    and quality of orange fruits. Bull. Calif. agr. Exp. Stn., No. 722.
 all plant parts can be
                             ROGERS, \V. S., and BOOTH, G. A. (1964). Relationship of crop and shoot growth in
                                    apple. I hort. Sci., 39, 61-5.
                             RVUGo, K., and DAVIS, L. D. (1959). The comparison behveen the net assimilation
 .0. Irrigation Research
                                    rate of peach leaves and the rate of accumulation of dry weight by the crop.
'k and I gladly acknow­
,atment of the data, to             Proc. Amer. Soc. hort. Sci., 74, 134-43.
                             SHAMEL, A. D., and POMEROY, C. S. (1934). Relation of amount of foliage to fruit
mical assistance, and to
'hile preparing the paper.          size in Valencia oranges. Calif Citrog., 19, 140-1.
                             SHAMEL, A. D., POMEROY, C. S., and CARYL, R E. (1933). Relation of foliage to fruit
                                    size in \Vashington Navel oranges. Calif. Citrog., 1S, 296.
                             WILCOX, J C. (1937). Field studies of apple tree growth and fruiting. II. Correlations
experiment \vith citrus.            between growth and fruiting. Scient. Agric., 17, 573-86.

 Abhangigkeit von cler
·at). GarteHbauwiss., 29,
You can also read
NEXT SLIDES ... Cancel