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Variation of sweet potatoes with respect to source potentials and sink capacities

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(1)

Variation of sweet potatoes with respect to source potentials and

sink capacities

L . Li' & C .H . Kao 2

1 Department of Horticulture, Chinese Culture University, Taipei, Taiwan, Republic of China;

2

Department of Agronomy, National Taiwan University, Taipei, Taiwan, Republic of China

Received 11 July 1988 ; accepted in revised form 8 August 1989

Key words : Ipomoea batatas, sweet potato, grafting, sink capacity, source potential

Summary

By using four tester clones either as scions or stocks, source potentials and sink capacities of two groups of 13

and 20 sweet potato clones were measured in 1986 and 1987, respectively . Results obtained in the 1986 trial

were generally consistent with those in the 1987 trial, though different clones were used in both trials . There

were significant differences in source potentials and in sink capacities among tested clones . Responses of

source to sink and of sink to source were also estimated using a regression method . No significant correlation

was observed between source potential and response of source to sink . However, sink capacity showed

significant relationship with response of sink to source .

Introduction

Hozyo (1970) and Wilson (1967) suggested that

yield of sweet potato was determined primarily by

sink capacity rather than source potential . Hahn

(1977), on the other hand, has inferred that both

source potential and sink capacity can be rate

limit-ing to yield with the latter more important than the

former . In our previous work using reciprocal

grafts, we concluded that the source potential was

more

limiting

than sink in the first four months, but

they are equally important in determining tuberous

root yield at 6 months (Li & Kao, 1985a) .

Bouw-kamp & Hassam (1988) recently reported that

cul-tivars showing strong sink' effects were generally

low-yielding .

In a breeding program, it is much easier to

eval-uate and select for

sink

capacity (yield) than for

source potential (photosynthetic capacity) .

How-ever, evaluation for source potentials of sweet

po-tatoes is possible because source and sink can be

easily exchanged by reciprocal grafting for this

pur-pose . In the present investigation, four tester

clones were used as source and sink, respectively,

to evaluate source potentials and sink capacities of

various experimental sweet potato clones .

Materials and methods

All experiments were conducted in 1986 and 1987

in an experimental field of Chiayi Agricultural

Ex-periment Station, Chiayi, Taiwan, Republic of

China . The

soil

type was sandy loam .

Th four t st r clon s w r

C70-245, C70-200,

C70-311 and C70-105 which w r

us d in

our pr

vi-ous work (Li &

Kao,

1985a) . Thirt

n and tw nty

xp rim ntal clon s w r chos n for th 1986 and

1987 trials, r sp ctiv ly, to d t rmin th ir sourc

pot ntials and sink capaciti s . For th

1986 trial, 16

slips of

ach

xp rim ntal clon

w r

graft d to

ach of th four t st r clon s, and 16 slips of

ach

(2)

13 2

Z

N

F

1 .5

1 .3

0

1 .1

D

0

N

0.9

U

.

0

W

N

O .7

Z

0

W

0.5

0

.3

Y = 0 .5235 + 0 .0041 x

r = 0 .242

n = 13

13

12

11

10

8

9

-1/

1 I I I I I 1 1

75

85

95

105

115

125 135 145

7

6

4

5

SOURCE POTENTIAL (g/ plant)

Fig. 1 . R lation b tw n sourc pot ntial (x) and r spons of sourc to sink (y) for 13 xp rim ntal sw t potato clon s (1986 trial) . Th numb rs by points r f r to clon s ranking in Tabl 1 .

Tabl 1. Dry tub rous root yi lds (g/plant) of th 13 xp rim ntal clon s graft d to th four t st r sw t potato clon s (1986 trial)

2

1

*, ** M ans having sam l tt rs ar not significantly diff r nt at 5% and 1% l v l, r sp ctiv ly, by Duncan's Multipl Rang T st .

Ranking Clon t st d Stock M an scion

ff ct R spons of sourc to sink C70-245 C70-200 C70-311 C70-105 1 C68-220 177 .0 171 .1 162 .5 73 .1 145 .9a* 1 .10 2 C72-769 109.7 147 .9 230 .1 87 .7 143 .9a 1 .16 3 C69-27 146.3 160 .5 188 .1 44 .1 134 .8ab 1 .50 4 C66-51 133.0 120 .4 184 .1 54 .8 123 .1abc 1 .36 5 C66-24 152.1 170 .6 119 .1 50 .3 123 .Oabc 0.86 6 C70-244 150.2 141 .8 119 .2 77 .9 122 .3abc 0.60 7 C69-29 154.4 110 .9 120 .1 83 .8 117 .3abc 0.65 8 C67-249 145 .7 44 .6 166 .6 83 .9 110 .2abc 1 .15 9 C70-220 144.5 89 .8 108 .3 97.0 109 .9abc 0 .39 10 C67-59 152.9 78 .8 126 .7 68 .8 106 .8abc 0.95 11 C66-18 142.3 39 .4 166 .9 62 .7 102 .8abc 1 .39 12 C69-61 116.4 56 .9 139 .0 48 .0 90 .lbc 1 .13 13 C72-637 94.6 39 .3 119 .3 57 .9 77 .8c 0.77

M an stock ff ct 139 .9a** 105.5b 150 .Oa 68 .5c 116 .0

(3)

Y = - 0 .3035 + 0.0136 x

r = 0 .648 *

n=13

13

11

12

10

8

7

6

4

3

2

.

1

65

75

85

95

105

115

125

135

SINK CAPACITY

(g/plant )

Fig. 2 .

R lation b tw n sink capacity (x) and r spons of sink to sourc (y) for 13 xp rim ntal sw t potato clon s (1986 trial) . Th

numb rs by points r f r to clon s ranking in Tabl 2.

t st r clon w r

graft d to ach of th

13 xp

ri-m ntal clon s . In th

trial of 1987, 12 slips of ach

xp rim ntal clon w r graft d to ach of th four

t st r clon s as stock, and 12 slips of

ach t st r

clon us d as a scion w r graft d to ach of th

20

xp rim ntal clon s . About a month aft r grafting,

th grafts w r

plant d in th fi ld at a spacing of

100 cm b tw

n rows and 25 cm within rows in

August 1986 and August 1987 . A randomiz d

com-pl t block d sign was us d with four r com-plications .

Each plot consist d of four and thr

plants for th

1986 and 1987 trials, r sp ctiv ly . F rtiliz r was

appli d prior to planting (40 kg N, 40 kg P and 80 kg

K p r ha) and at 30 days aft r planting (40 kg N and

80 kg K p r ha) . Plants w r

harv st d 150 days

aft r planting and dri d in th

ov n at 90° C for 2

days . Data of dry tub rous root yi ld w r

ana-lyz d . Th

d gr

s of r spons s of sourc

to sink

and of sink to sourc

w r

d t rmin d by th

r

-gr ssion m thod propos d by Hahn (1977) .

In 1987, yi ld trial of 20

xp rim ntal clon s

without grafting w r

also conduct d simultan

-ously . All th

xp rim ntal conditions' and d sign

w r

similar to thos

of grafting

xp rim nt

con-duct d in 1987 .

1.55

w

1 .35

N

1 .15

O

Y

0.95

Z

U)

0

0,75

W

0

0

Q55

a

w

cc

0.35

0 .15

(4)

134

Tabl 2 .

Dry tub rous root yi lds (g/plant) of th four t st r clon s graft d to th 13 xp rim ntal sw t potato clon s (1986 trial)

* M ans having sam l tt rs ar not significantly diff r nt at 1% l v l by Duncan's Multipl Rang T st .

R sults

r spons of sourc to sink m asur d by r gr ssion

co ffici nts for th

13

xp rim ntal clon s ar

1986 trial

shown in Tabl

1 . Th r

w r

significant diff

r-nc s at th 5% l v l among th sourc pot ntials

Th

sourc

pot ntial of a clon

is d fin d as its

of th 13 clon s . Th r w r significant diff r nc s

m an scion ff ct and th sink capacity is its m an

at th

1% l v l among th

sink capaciti s of th

stock

ff ct . Th sourc pot ntials and d gr

s of

four t st r clon s . Th r sults pr s nt d in Tabl 1

Tabl 3. Dry

tub rous root yi lds (g/plant) of th 20 xp rim ntal clon s graft d to th four t st r sw t potato clon s (1987 trials)

* M ans having sam l tt rs ar not significantly diff r nt at 1% l v l by Duncan's Multipl Rang T st .

Ranking Clon t st d Stock M an scion

ff ct R spons of sourc to sink C70-245 C70-200 C70-311 C70-150 1 TN 64 268 .3 136 .3 84 .0 148 .3 159 .2a* 0 .11 2 C72-130 237 .1 163 .6 140 .6 86 .9 157 .1a 1 .29 3 C72-324 172 .4 132 .4 216 .9 101 .4 155 .8a 1 .53 4 C72-738 226.1 94 .5 240 .3 45 .9 151 .7ab 2 .95 5 C72-38 152.8 92 .8 221 .8 129 .4 149.2ab 1 .15 6 C72-769 105 .0 115 .8 178 .7 137 .4 134 .2abc 0 .27 7 C70-141 103 .6 193 .2 190.8 22 .9 127 .6abc 1 .81 8 TN 67 120 .7 138 .1 144.8 82 .7 121 .6abcd 0 .73 9 TN 66 156 .0 110 .5 125 .9 90.9 120 .8abcd 0 .71 10 TN 68 132 .9 112 .2 152 .5 62.6 115 .lbcd 1 .22 11 C68-106 87.1 155 .2 172 .2 40.7 113 .8bcd 1 .35 12 C68-220 122.2 73 .9 134 .7 106.9 109 .4cd f 0 .45 13 C72-554 106 .4 203 .0 81 .7 46.5 109 .4cd f 0 .38 14 C70-244 127 .8 80 .3 114 .9 32.7 88.9d f 1 .30 15 IN 57 99.3 54 .2 126 .7 60.4 85 .2d f 0 .92 16 C67-222 91 .3 26 .5 144 .4 54.8 79.3 f 1 .19 17 C72-277 113.1 66 .3 87 .5 24 .9 73 .Of 1 .08 18 C70-203 72.4 81 .2 84 .7 49 .0 71 .8f 0 .43 19 C71-66 66.6 45 .7 118 .2 55 .0 71 .4f 033 20 C70-220 64.7 60 .3 100 .0 59 .7 71 .2f 0 .43

M an stock ff ct 131 .3a* 106 .8b 143 .1a 72 .Oc 113 .3

R spons of sink to sourc 1 .46 0 .93 0 .91 0 .70

Ranking Clon t st d Scion M an stock

ff ct R spons of sink to sourc C70-245 C70-200 C70-311 C70-105 1 C69-27 188 .6 147 .3 129 .4 43 .1 127 .1a* 1 .56 2 C70-220 175 .3 177 .6 68 .2 76 .5 124 .4a 1 .54 3 C66-18 137 .8 126.8 137 .4 77 .3 119 .8ab 0.59 4 C70-244 129 .8 185.4 78 .8 46 .2 110 .1abc 1 .52 5 C67-59 119 .0 140.2 88 .3 71 .7 104 .8abcd 0.80 6 C72-637 174 .6 109.4 79 .8 44 .0 102 .Oabcd 1 .37 7 C69-29 144 .2 132.5 76 .4 45 .8 99 .7abcd 1 .28 8 C69-61 122 .6 112 .9 80 .5 23 .4 84 .9bcd 1 .20 9 C67-249 146 .0 75 .3 44 .5 61 .0 81 .7bcd 0.85 10 C68-220 79 .9 101 .7 112 .1 32 .5 81 .6bcd 0.55 11 C66-24 95 .3 99 .9 56 .3 40 .0 72 .9cd 0 .80 12 C66-51 71 .0 81 .9 53 .9 67 .9 68 .7d 0 .18 13 C72-769 75 .8 114 .4 31 .5 47 .8 67 .4 0.76

M an scion ff ct 127 .7a* 123 .5a 79.8b 52 .1c 95 .8

(5)

confirm d our arly finding (Li & Kao, 1985a), that

C70-311 and C70-105 had high and low sink

capac-iti s, r sp ctiv ly . No significant corr lation was

obs rv d b tw

n th

sourc

pot ntials and th

r spons s of sourc s to sinks (Fig . 1) .

Tabl

5 . Av rag dry tub rous root yi lds of 12 plants for 20 sw t potato clon s without grafting (1987 trial)

* M ans having sam l tt rs ar not significantly diff r nt at 1% l v l by Duncan's Multipl Rang T st .

Th

sink capaciti s and d gr

s of r spons

of

sink to sourc

of th

13

xp rim ntal clon s ar

summariz d in Tabl 2 . Th r w r significant

dif-f r nc s at th

1% l v l among th sink capaciti s

of th 13 clon s t st d, and also among th sourc

pot ntials of th

four t st r clon s . C70-245 was

d monstrat d to b

a good sourc , wh r as

C70-105 a poor sourc . Th s r sults ar

in agr

m nt

with our

arly work (Li & Kao, 1985a) . Th

d

-gr

s of r spons s of sink to sourc w r plott d

against r sp ctiv sink capaciti s (Fig . 2) . In g n

r-al, clon s with high sink capaciti s show d high

r spons s of sinks to sourc s .

1987 trial

Th r sults of 1987 trial ar , in g n ral, consist nt

with thos

of 1986 trial, though diff r nt clon s

w r us d . Both sourc pot ntials and sink

capac-iti s w r significantly diff r nt among th

20

x-p rim ntal clon s at th 1% l v l (Tabl s 3 and 4) .

R sults also d monstrat d that C70-245 was a good

sourc wh r as C70-311 was a good sink . C70-105

1 C70-141 129 .8 253 .0 116 .6 93 .1 148.la* 1 .52 2 C70-203 208 .9 180 .9 58 .3 95 .1 135.8ab 1 .50 3 C72-738 108 .0 230 .5 118 .7 65 .8 130.8abc 1 .43 4 C68-106 216 .1 141 .6 80 .5 74 .2 128.labcd 1 .21 5 C70-244 117 .2 229 .3 94 .7 68 .4 127.4abcd 1 .57 6 TN 66 168 .6 169 .8 67 .9 99 .4 126.4abcd 1 .13 7 TN 67 147 .1 168 .4 90 .1 88 .8 123 .6abcd 0 .99 8 C72-554 144 .5 186.9 72 .0 89 .6 123 .3abcd 1 .24 9 C72-38 113 .8 160.0 147 .4 63 .4 121 .2abcd 0 .66 10 C72-277 176 .1 136.7 58 .4 82 .2 113 .4abcd 1 .05 11 C72-324 102 .1 160.7 83 .9 77 .3 106.Oabcd 0 .85 12 C71-66 133 .9 112.3 108 .4 67 .8 105 .6bcd 0 .48 13 TN 57 116 .2 154.8 75 .1 52 .1 99.6bcd 1 .11 14 C72-769 128 .9 108.3 92 .6 51 .8 95 .4bcd 0 .64 15 C70-220 116 .3 172.6 48 .4 39 .8 94.3bcd 1 .52 16 TN 64 109 .2 111 .1 107 .6 35 .5 90.9cd 0 .63 17 C72-130 127 .0 107.0 51 .4 72 .3 89.4cd 0 .68 18 C67-222 117 .5 79.4 100 .4 50 .8 87.Od 0 .28 19 C68-220 99 .5 138.4 59 .9 46 .2 86.Od 1 .02 20 TN 68 63 .2 137.7 38 .9 101 .5 85 .3d 0 .52 M an scion ff ct 132 .2b* 157.Oa 83 .6c 70 .8c 110.9

R spons of sourc to sink 1 .07 1 .82 0 .52 0 .60

Clon t st d Yi ld (g/plant) TN 64 245 .1 C70-141 235 .3 C72-130 233 .4 C72-738 218 .6 C68-106 203 .1 C72-769 196.0 C72-554 195 .3 C72-324 193 .5 C68-220 190.1 TN 68 181 .9 TN 66 181 .3 C72-38 172.6 TN 67 168 .5 C72-277 142.1 C71-66 136 .0 C70-244 129 .4 TN 57 115 .6 C70-220 113 .7 C70-203 93 .4 C67-222 72.4

(6)

3.0

z

0.5

07

2.0

Y = 0.3044 + 0 .0062x

r = 0 .30

n= 20

19

20

18

16

15

0

-//

i ' 1

70

85

100

115

was found to b poor in both sourc pot ntial and sink capacity . As in 1986 trial, no corr lation was obs rv d b tw n th sourc pot ntials and r -spons s of sourc s to sinks (Fig . 3) . How v r, sink capaciti s w r highly corr lat d with r spons s of sinks to sourc s (Fig . 4) . In ord r to d t rmin th r lativ contribution of sourc pot ntial and sink capacity to th tub rous root yi ld, a yi ld trial of th 20 xp rim ntal clon s without grafting was conduct d simultan ously . Th r sults w r pr -s nt d in Tabl 5 .

12

13

Discussion

Grafting proc dur s, though t dious and labo-rious, p rmit us to scr n th sourc pot ntials and sink capaciti s of sw t potato s . Our pr s nt study cl arly confirm d th arly r ports by Hahn (1977, 1982) that sourc pot ntials and sink capac-iti s vari d among clon s or cultivars .

Th dry tub rous root yi ld of sw t potato is d p nd nt on sourc pot ntial and sink capacity . R c ntly, Bouwkamp & Hassam (1988) d

mon-0

8

9

7

6

SOURCE

POTENTIAL (g/plant

Fig. 3.

R lation b tw n sourc pot ntial (x) and r spons of sourc to sink (y) for 20 xp rim ntal sw t potato clon s (1987 trial) . Th

numb rs by points r f r to clon s ranking in Tabl 3 .

4

3

2

1

I i 1

130

145

160

(7)

0

1 .0

0.8

0.6

0.2

20 18 16 12

80 90

100

110

120

130

140

150

SINK

CAPACITY

(9/plant )

Fig. 4. R lation b tw n sink capacity (x) and r spons of sink to sourc (y) for 20 xp rim ntal sw t potato clon s (1987 trial) . Th numb rs by points r f r to clon s ranking in Tabl 4.

strat d that th r lativ importanc s of sourc po-t npo-tial and sink capacipo-ty chang d during th grow-ing s ason and diff r d among cultivars . Und r th ir conditions, sourc pot ntials pr dominat d ov r sink capaciti s in t rms of ff cts on dry tub r-ous root yi ld . In our pr vir-ous work, w also r -port d that th r lativ contribution of sourc po-t npo-tial and sink capacipo-ty po-to dry po-tub rous roopo-t yi ld was d p nd nt upon growth p riod (Li & Kao, 1985b) . Sourc pot ntial was mor limiting than sink capacity wh n growth p riod was '4 months, but th y ar qually important wh n growth p riod was 6 months . In th pr s nt study, th growth

p riod was 5 months . TN 64 and C72-130 had th high st yi lds among th 20 xp rim ntal clon s (Tabl 5) . Th s two clon s had good sourc po-t npo-tials bupo-t poor sink capacipo-ti s . Oth r high-yi ld-ing clon s such as C70-141, C72-738, C68-106 and C72-769 show d both high sourc pot ntials and sink capaciti s . Low-yi lding clon s such as C67-222 and C70-220 w r obs rv d to b poor in both sourc and sink . Anoth r low-yi lding clon was C70-203, show d high sink capacity but low sourc pot ntial . Thus, sourc pot ntial app ars to b mor important than sink capacity wh n growth p riod was 5 months .

(8)

Assimilat

translocation is d t rmin d by th

photosynth tic capacity of sourc , and sink

activ-ity . Sink activactiv-ity alt rs th photosynth tic capacactiv-ity

through aff cting assimilat

translocation which is

r gard d as r spons of sourc to sink . By contrast

r spons of sink to sourc

r f rs to th

chang s in

sink capacity wh n photosynth tic capacity

chang-s . Hahn (1982) d monchang-strat d that chang-sourc pot

n-tial show d significant r lationship with r spons

of sourc to sink, which contradicts what w

pr

-s nt d h r . Our r -sult-s -s

m to sugg st that th

clon s with high sourc , pot ntials do not n c

ssar-ily hav

high r spons of sourc

to sink . It m ans

that photosynth tic capacity of a clon

with high

sourc

pot ntial is unlik ly to b

alt r d by th

chang of sink capacity . Th discr pancy b tw

n

Hahn's r sults and ours is possibly du to diff r nt

growth p riod us d . Th growth p riod of Hahn's

xp rim nt was 3 months, wh r as that of ours was

5 months .

Although TN 64 had th high st yi ld and sourc

pot ntial of th

xp rim ntal clon s, this clon had

th low st r spons of sourc to sink (Tabl 3 and

5) . It is lik ly that th

assimilat

translocation of

TN 64 is l ss s nsitiv to th chang s of sink

activ-ity .

It has b

n shown that high-yi lding g notyp s

g n rally partition d mor photosynthat to tub

r-ous roots than low-yi lding g notyp s (Bhagsari &

Harmon, 1982 ; Hu tt, 1976 ; Li & Kao, 1985b) . In

th pr s nt inv stigation, a significant r lationship

was found b tw

n sink capacity and r spons

of

sink to sourc . Accordingly, s l ction of clon s

with high sink capaciti s and id al d gr

s of r

-spons of sink to sourc is possibl . In oth r words,

s l ction for larg sink will, to a c rtain xt nt, l ad

to improv m nt of translocation capacity .

Acknowl dg m nt

This r s arch was support d by th

Council of

Agricultur , R public of China .

R f r nc s

Bhagsari, A.S . & S .A . Harmon,1982. Photosynth sis and pho-tosynthat partitioning in sw t potato g notyp s . J . Am r . Soc. Hort . Sci . 107 : 506-510 .

Bouwkamp, J .C . & M .N.N. Hassam, 1988 . Sourc -sink r la-tionships in sw t potato . J. Am r. Soc. Hort . Sci . 113 : 627-629 .

Hahn, S .K ., 1977. A quantitativ approach to sourc pot ntials and sink capaciti s among r ciprocal grafts of sw t potato vari ti s . Crop Sci . 17: 559-562 .

Hahn, S . K . ,1982 . Scr ning sw t potato for sourc pot ntials . Euphytica 31 : 13-18 .

Hozyo, Y., 1970 . Growth and d v lopm nt of tub rous root in sw t potato . Proc . Intl . Symp . Trop . Root Crops 2 : 22-23 . Hu tt, D .O ., 1976 . Evaluation of yi ld variability quality of

sw t potato cultivars in subtropical Australia . Expl . Agric. 12: 9-16.

Li, L . & C .H . Kao, 1985a. Inv stigation of sourc -sink r lation-ship in sw t potato by r ciprocal grafts . Bot . Bull . Acad mia Sinica 26 : 31-38 .

Li, L . & C . H . Kao,1985b . Dry matt r production and partition of six sw t potato (Ipomo a batatas L .) cultivars . J . Agric. Assoc. China (N w s ri s) 131 : 10-23 .

Wilson, L. A . ,1967 . Th us of root d l av s and graft plants for th study of carbohydrat m tabolism in sw t potato . Proc. Intl . Symp . Trop . Root Crops 1 : 46-57 .

數據

Tabl 1. Dry tub rous root yi lds (g/plant) of th 13 xp rim ntal clon s graft d to th four t st r sw t potato clon s (1986 trial)
Fig. 2 . R lation b tw n sink capacity (x) and r spons of sink to sourc (y) for 13 xp rim ntal sw t potato clon s (1986 trial)
Tabl 2 . Dry tub rous root yi lds (g/plant) of th four t st r clon s graft d to th 13 xp rim ntal sw t potato clon s (1986 trial)
Tabl 5 . Av rag dry tub rous root yi lds of 12 plants for 20 sw t potato clon s without grafting (1987 trial)
+3

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