Influence of Seeded Fruit on Seedless Fruit Set in Japanese Persimmon Cv

J.Japan.Soc.Hort.Sci.61(3): 499-506.1992.

Influence of Seeded Fruit on Seedless Fruit Set in Japanese Persimmon cv. Fuyu (Diospyros kaki L. f.)

Akira Kitajima, Hidehiko Akuta, Terutaka Yoshioka, Tetsuyuki Entani, Mikio Nakano and Masashi Ishida Faculty of Agriculture, Kyoto Prefectural University, Kyoto 606

summary

The influence of seeded Japanese persimmon cv. Fuyu (Diospyros kaki L. f.) fruit on the

setting of seedless ones achieved by 1) hand-pollination; 2) open-pollination; 3) non-pollination; 4) ringing of the bearing shoot; and 5) gibberellin-3 (GA3) application was investigated to

clarify the factors affecting seedless fruit set and the inconsistency of GA-treated fruit set. The number of seeds per fruit and the degree to which seedless fruit abscised on the same

tree were significantly different among trees. However, a highly significant, positive linear relationship (r= 0.77) existed between the two parameters. No abscission of seedless fruits on ringed shoots occurred until the girdle region had healed.

On non-pollinated trees, seedless fruit set increased as the concentration of GA3 was increased. However, more seedless fruit dropped from pollinated trees than from non-pollinated trees, although seedless fruits of both plots were treated with the same concentration. This

induction of abscission is ascribed to the competition between seedless fruit and seeded fruit

on the same tree. A major factor to fruit set was the competition among fruits; the competi- tive advantage of seeded fruit over parthenocarpic ones is the decisive factor whether or not GA-treated •eFuyu' fruits abscise.

fruits destined to abscise the rate of accumulation Introduction of dry matter decreased about one week prior to

Premature fruit drop has been a serious problem abscission, and that in a few instances fruit abscis- in the production of Japanese persimmon (Diospyros sion was induced by competition for photosyn- kaki L. f.). Studies of the phenomenon indicate that thates between fruit and shoot. fruit drop appears to be influenced by such factors The capacity for a cultivar to set seeded and as pollination (Kajiura, 1941; Nagasawa et al., parthenocarpic kaki fruits is considered to be a 1968; Sobajima and Takagi, 1968; Sobajima et al., hereditary characteristic. Hence, Tuyu' is classi-

1969), shoot growth (Kajiura, 1942c), solar radia- fied as a cv. which sets more seeded and less par- tion (Kajiura, 1942a; Kaneko, 1977), shading thenocarpic fruits than does •eHiratanenashi'

(Fujimura and Nakagawa, 1955; Takahashi et al., (Kajiura, 1941). Recently, it was reported that the 1971), fruit density (Kajiura, 1942b; Kaneko et al., seedless fruit set of Tuyu' varied from season to

1979), and endogenous plant hormones (Sobajima season, whereas it was categorized into a group et al., 1969; Suzuki et al., 1989). Kajiura (1941, which sets a low percentage of parthenocarpic

1942a, 1942b, 1942c) suggested that fruit drop was fruits (Yamada et al., 1987). GA promote seeded induced by a deficiency of photosynthates because and seedless fruit set; the promotive effect is of competition among fruits or between fruit and usually stronger in •eHiratanenashi' than it is in shoot. uyu', but the effect is not consistent (Nagasawa •eF

We reported (Kitajima et al., 1987, 1990) that in et al., 1968; Sobajima et al., 1969; Yamamura

et al., 1989). Received for publication 16 July 1991. A part of this This investigation was undertaken to 1) clarify paper was presented at the 1989 and 1992 Autumn Meeting of Japan. Soc. Hort. Sci. the factors which influence premature fruit drop

499 500 A. KITAJIMA, H. AKUTA, T. YOSHIOKA, T. ENTANI, M. NAKANO AND M. ISHIDA and seedless fruit set, and 2) determine the basis 2. Effect of GA3 on seedless fruit set for the inconsistent set of GA-treated seedless Fuyu' fruit. •e This experiment was carried out in 1989 using four 20-year-old Tuyu' trees (#1 to # 4) growing Materials and Methods in the experimental farm of Kyoto Prefectural University. Flowers on all trees were thinned to 1. Factors affecting fruit drop one flower per shoot; all flowers on trees # 1 and Experiments were carried out in 1988 using 24 # 2 and 100 flowers on trees #3 and #4 were Fuyu' trees (trees A to X) which were growing •ein bagged before anthesis to prevent pollination. the experimental farm of Kyoto University. They GA3 was applied with a brush at 0, 100, 300 were about 54 years old. Three to five days before and 500 mg¥liter-1 in 50% EtOH to bagged flow- anthesis, 10 bearing shoots, 15 and 35 cm long, ers on trees # 1 and #2; GA3 was applied either and 20 bearing shoots, 25 cm long, were selected once at anthesis or at anthesis and again 3 weeks on each tree. The flower buds on these bearing later. Bagged flowers on trees # 3 and # 4 were shoots were thinned to one per shoot and bagged treated with 300 m•liter-1 GA3 at anthesis. The to prevent pollination. On half of the 25 cm shoots, remaining flowers on tree #3 were hand-pollinated a ring of bark, 5 mm wide, was removed near the with pollen from •eZenjimaru'; whereas those of base at anthesis. The bagged flowers on 12 trees, tree # 4 were open-pollinated. The number of A to L, were hand-pollinated at anthesis with 'Zen- fruits which set following GA-treatment was deter- jimaru' pollen, whereas those flowers on trees M mined weekly after anthesis, and the numbers of to X were not pollinated. All non-bagged flowers seeds in hand-pollinated and open-pollinated fruits were open-pollinated. Full bloom lasted from 29 were counted on 3 August. May to 1 June. At weekly intervals beginning at anthesis, the Results number of fruit which dropped from the labelled 1. Factors affecting fruit drop shoots was counted and the shoot length mea- sured. On 20 July, about 100 open-pollinated fruits Fruit count for 7 weeks in succession after were collected from 10 trees, M to V, to deter- anthesis revealed that a high proportion of seedless mine the number of seeds per fruit. All fruits on fruits in the non-pollinated group dropped, whereas labelled shoots were harvested on 1 August and only 20% of them on girdled shoot abscised (Fig. the number of seeds per fruit was counted. 1). The length of the bearing shoots caused non-

Fig. 1. Percentage cumulative drop of fruits resulting from hand-pollinated (seeded) and non-pollinated (seedless) on shoots of different lengths and ringed ones 7 weeks after anthesis. J.Japan.Soc.Hort.Sci.61(3):499-506.1992. 501 pollinated fruits to drop at different times after (non-pollinated) ranged from 13.5 to 100.0% among anthesis (Fig. 2). On the shortest shoots, more these 10 trees. Furthermore, the percentage drop fruits dropped during the early period of June of seedless fruit increased with increasing numbers drop, but on the longest shoots, more fruits of seeds per open-pollinated fruit on the. same tree; dropped 4 weeks after anthesis. Seedless fruits on ringed shoots began to drop 5 weeks after Table 1. Number of seeds in hand-pollinated fruit on the anthesis. different length shoots with or without ringing treatment. The number of seeds in hand-pollinated fruits was unaffected by shoot length and ringing, but there were differences in the number of seeds per fruit among the test trees (Tables 1 and 2). The number of seeds per open-pollinated fruit collected from the 10 trees, M to V, varied significantly. The percentage drop of seedless fruit

Fig. 2. Percent drop of seedless fruit occurring after anthesis from shoots of different lengths with or without the ringing treatment.

Table 2. Number of seeds per fruits on different trees on which flowers were hand-pollinated and open-pollinated. 502 A. KITAJIMA, H. AKUTA, T. YOSHIOKA, T. ENTANI, M. NAKANO AND M. ISHIDA

Fig. 3. Relationship between percent drop of seedless fruit Fig. 4. Relationship between number of seeds per •eFuyu' fruit

and the number of seeds per fruit resulting from open pol- resulting from open-pollination and the distance between the

lination on trees, M to V. uyu' trees and their pollinizer, 'Kubo'. •eF

Fig. 5. Fruit set (%) of seedless fruit treated with 300 mg¥liter-1 GA3 from

hand-pollinated (•œ-•œ), open-pollinated (•£-•£) and non-pollinated

(•¡-•¡) trees after anthesis.

a positive linear coefficient of correlation (r=0.77) trees #1 and #2 (non-pollinated), intermediate on existed between the two phenomena (Fig. 3). tree # 4 and lowest on tree #3.

However, there was no relationship between the On non-pollinated trees #1 and #2, the set of number of seeds per open-pollinated fruit on a seedless fruit increased with an increase in GA3 given tree and its distance from the pollinizer tree concentration. A coefficient of correlation of 0.993 (Fig. 4). existed between the percent of parthenocarpic fruit set and the logarithmic concentration of GA3 (Fig. 2. Effect of GA3 on fruit set 6). For all concentrations of GA3, there was no

The numbers of seed per fruit on tree # 3 (hand- difference in parthenocarpic fruit set between sin- pollinated) and tree # 4 (open-pollinated) were 3.3 gle and double applications (Fig. 7). and 1.7, respectively. The drop of seedless fruits Discussion treated with 300 mg¥liter-1 GA3 was greatest between 3 to 4 weeks after anthesis in all treatments Although •eFuyu' is considered to have a tenden- (Fig. 5). The set of seedless fruits was highest on cy to set many seeded fruits and few parthenocar- J.Japan.Soc.Hort.Sci.61(3):499-506.1992. 503

pic ones, in our experiments, the percentage of among fruits due to an insufficient supply of as- seedless fruit drop from 10 •eFuyu' trees ranged similates. Three weeks after anthesis, fruit began from 13.5 to 100.0%. Moreover, a strong relation- to enlarge rapidly and to be a main sink organ for ship was observed between the dropping of seed- assimilates (Kitajima et al., 1987). Fruit abscission less fruits and the number of seeds in adjacent has already been triggered several days before fruits on the same tree. The physiological influence fruit drop actually occurs (Kitajima et al., 1990). of seeded fruit on the same tree seems to be an The heavy drop of seedless fruit 4 weeks after important factor in fruit drop. anthesis is probably the result of severe competi- As for the relationship between fruit drop and tion among fruits. shoot growth, the dropping of pollinated fruit was Ringing inhibits fruit abscission, a finding previ- consistently low, regardless of the length of the ously reported (Kajiura, 1941), but the effect is shoot. The abscission of seedless fruit from long temporary lasting a few weeks (Nagasawa et al., shoots was comparatively low until 3 weeks after 1968). Likewise, in our experiment, the treatment anthesis, but that on short shoots was higher and initially promoted the setting of seedless fruit, but began earlier. As shoot growth has ceased by their abscission began 5 weeks after anthesis. The anthesis, fruit drop of •eFuyu' may be seldom ringing region began to heal about 4 weeks after caused by competition between fruit and shoot. anthesis, and this was accompanied by onset of

The higher level of seedless fruit drop from short seedless fruit abscission. The treatment results in shoots seems to be the result of competition an accumulation of assimilate (Kajiura, 1942b) or acidic GA above the girdle (Goren et al., 1971). But, we believe that ringing blocked the flow of assimilates, reducing competition among fruits. Hence, seedless fruit set initially improved, but seedless fruit drop began when the bark callused over. Plant hormones are required for the normal fruit development (Crane, 1964); grape and citrus culti- vars which tend to set fruits parthenocarpically possess higher concentrations of endogenous auxin and/or gibberellins than do those cvs. which set seeded fruits (Nitsch, 1970). GAs are the most ac- Fig. 6. Relationship between fruit set (%) on non-pollinated tive hormones used to induce parthenocarpic fruits trees and logarithmic concentrations of GA3. as in apple, peach, pear, citrus, grape (Monselise,

Fig. 7. Fruit drop (%) of seedless fruit on non-pollinated trees

given single (•œ) or double (•›) applications of different concentrations of GA3. 504 A. KITAJIMA, H. AKUTA, T. YOSHIOKA, T. ENTANI, M. NAKANO AND M. ISHIDA

1986), and kaki (Nagasawa et al., 1968; Sobajima Acknowledgement et al., 1969; Yamamura et al., 1989). Although

auxins are less effective in setting fruit than are This work was partly supported by a Grant-in-

GAs (Crane, 1964), they prevent fruit abscission Aid for Scientific Research No.63760037 from the

(Kotob, 1971). Furthermore, endogenous auxin is Ministry of Education. We are grateful to the Ex-

induced by high levels of GAs in fruit (Jackson, perimental Farm of Kyoto Univ. for providing 1962); the GAs appear to enhance the sink many samples of •eFuyu' fruits.

strength of the fruit either directly or indirectly Literature Cited (Priestley, 1987; Stutte and Gage, 1990). For ex-

ample, GA enhanced the movement of 14C- Crane, J. C. 1964. Growth substances in fruit setting

metabolites to citrus fruit (Powell and Krezdorn, and development. Ann. Rev. Plant Physiol.

1977). 15 : 303-326. Goldwin, K. G. and W. W. Schwabe. 1975. Partheno- GA-treatment effectively increased seedless carpic fruit in Cox's Orange Pippin apples, obtained Fuyu' fruit set, especially at higher concentrations.•e without hormones. J. Hort. Sci. 50: 175-178. However, at 300 mg¥liter-1 GA, the drop of seed- Goldwin, K. G. 1983. Factors affecting hormone- less fruit was highest on trees on which flowers assisted setting of Cox's apple. Acta Hort. were hand-pollinated, intermediate on open- 149 : 161-171.

pollinated one, and lowest on trees from the non- Goren, R., E. E. Goldschmidt and S. P. Monselise

pollinated plot. Thus, the reduction of seedless 1971. Hormonal balance in bark and leaves of fruit drop was probably an indirect effect because Shamouti orange trees (Citrus sinensis (L.) Osbeck)

the drop depended more on the numbers of seed in relation to ringing. J. Hort. Sci. 46 : 443-451. Fujimura, J. and T. Nakagawa. 1955. Effect of light in- per fruit in the remaining fruits on the same tree terception on June drop of some fruit trees. Bull. than on GA concentration; the drop of seedless Fac. Agr. Mie Univ. 10: 1-14. (In Japanese with fruit followed the same pattern in untreated trees. English summary). Thus, the endogenous gibberellin in `Fuyu' fruit is Jackson, D. I. 1962. Gibberellin and growth in stone not directly related to fruit abscission even if the fruit : Induction of parthenocarpy in plum. Aust. J. endogenous auxin level is increased by exogenous Biol. Sci. 21 : 1103-1106.

GA application. Consequently, auxin may, likewise, Kajiura, M. 1941. Studies on the physiological fruit drop of Japanese persimmon. II. J. Japan. Soc. not directly control fruit abscission. Goldwin (1975, Hort. Sci. 12 : 247-283. (In Japanese). 1983) reported that in apple, competition from Kajiura, M. 1942a. Studies on the physiological fruit seeded fruit was the most important factor deter- drop of Japanese persimmon. III. J. Japan. Soc. mining the incidence of parthenocarpy, since par- Hort. Sci. 13 : 1-14. (In Japanese). thenocarpic fruits were obtained when there was Kajiura, M. 1942b. Studies on the physiological fruit minimal cross-pollination. This agrees with our drop of Japanese persimmon. IV. J. Japan. Soc. finding. We consider the set of seedless fruit in- Hort. Sci. 13 : 89-96. (In Japanese).

creased when their sink strength was higher than Kajiura, M. 1942c. Studies on the physiological fruit

or nearly equal to that of competing fruits. GA drop of Japanese persimmon. V. J. Japan. Soc.

likely promoted the set of fruits by increasing their Hort. Sci. 13 : 97-101. (In Japanese). Kaneko, M. 1977. Relation between yields of Japanese sink strength, but because the sink strength of the persimmon and hours of sunshine. Res. Bull. Aichi competing seeded fruit was stronger, the seedless Agric. Res. Centr. B9 : 131-136. (In Japanese with ones abscised. English summary). We conclude that 1) this balance between sink Kaneko, M., Y. Yamamoto, G. Suzuki and H. Imagawa. strengths or internal competition varies consider- 1979. Investigation on the physiological fruit drop

ably among •eFuyu' fruits and probably accounts for of Jiro Kaki (Diospyros Kaki Linn. f.) in Higashi-

the inconsistent effect of GA on seedless fruit set Mikawa district. Res. Bull. Aichi Agric. Res. Centr.

and 2) although •eFuyu' fruits tend to be seeded, 11 : 94-102. (In Japanese with English summary). Kitajima, A., T. Fujiwara, T. Kukizaki, M. Ishida and Y. nevertheless, parthenocarpic ones can be produced Sobajima. 1987. Relationship between early fruit without hormone treatments provided minimal drop and dry matter accumulation on bearing shoot competition exists among fruits. in Japanese persimmon (Diospyros kaki Thunb.). J.Japan.Soc.Hort.Sci.61(3):499-506.1992. 505

Sci. Rep. Kyoto Pref. Univ., Agr. 39 : 1-11. (In English summary). Japanese with English summary). Sobajima, Y., M. Ishida, K. Kiyokawa and M. Sakiyama. Kitajima, A., T. Matsumoto, M. Ishida and Y. Sobajima. 1969. Investigations on the cause and control of 1990. Relationship between dry matter production physiological dropping in the Japanese persimmon of bearing shoots and physiological fruit drop of fruit. II. Effects of pollination and gibberellin treat- Japanese persimmon, by shading treatment. J. ment on the physiological dropping of fruits and Japan. Soc. Hort. Sci. 59 : 75-81. (In Japanese with changes of auxin in the fruits. Sci. Rep. Kyoto Pref. English summary). Univ., Agr. 21 : 12-23. (In Japanese with English Kotob, A. M. and W. W. Schwabe. 1971. Induction of summary). parthenocarpic fruit in Cox's Orange Pippin apples. Stutte, G. W. and J. Gage. 1990. Gibberellin inhibits J. Hort. Sci. 46 : 89-93. fruit abscission following seed abortion in peach. Monselise, P. S. 1986. Handbook of fruit set and de- J. Amer. Soc. Hort. Sci. 115: 107-110. velopment. CRC Press Inc., Florida. Suzuki, A., T. Sugiura, Y. Murakami and T. Maotani. Nagasawa, K., E. Takahashi and M. Nozaki. 1989. Physiological studies on physiological fruit 1968. Physiological studies on fruit drop of drop of Japanese persimmon, Diospyros kaki Thunb. Diospyros kaki L. I. Effects of Gibberellin sprays on V. Relationship between auxin in fruit and physio- fruit drop prevention of Hiratanenashi and Fuyu logical fruit drop of Japanaese persimmon, cv. varieties. Tec. Bull. Fac. Hort. Chiba Univ. Hiratanenashi. Bull. Fruit Tree Res. Stn. A16: 16: 9-16. (In Japanese with English summary). 31-37. (In Japanese with English summary). Nitsch, J. C. 1970. Hormone factors in growth and de- Takahashi, E., Y. Inoue and K. Nagasawa. velopment. p.427-472. In : A. C. Hulme (ed.). The 1971. Physiological studies on fruit drop of biochemistry of fruit and their products. Academic Diospyros kaki L. II. Effect of shading and ringing Press, London and New York. on physiological dropping of Hiratanenashi cultivar Powell, A. A. and A. H. Krezdorn. 1977. Influence of during June drop period. Tec. Bull. Fac. Hort. Chi- fruit-setting treatment on translocation of 14C- ba Univ. 19 : 13-21. (In Japanese with English metabolites in citrus during flowering and fruiting. summary). J. Amer. Soc. Hort. Sci. 102 : 709-714. Yamada, M., A. Kurihara and T. Sumi. 1987. Varietal Priestley, C. A. 1987. Source-sink relationship of fruit differences in fruit bearing in Japanese persimmon trees. p.81-97. In : M. R. Sethuraj and A. S. (Diospyros kaki Thunb.) and their yearly fluctuation. Raghavendra (eds.). The crop physiology. Elsevier, J. Japan. Soc. Hort. Sci. 56 : 293-299. (In Japanese Amsterdam. with English summary). Sobajima, Y. and M. Takagi. 1968. Investigations on Yamamura, H., K. Matsui and T. Matsumoto. the cause and control of physiological dropping in 1989. Effects of gibberellins on fruit set and the Japanese persimmon fruit. I. The time of fruits flower-bud formation in unpollinated persimmons. dropping and abscission layer formation. Sci. Rep. Scientia Hortic. 38 : 77-86. Kyoto Pref. Univ., Agr. 20 : 1-11. (In Japanese with 506 A. KITAJIMA, H. AKUTA, T. YOSHIOKA, T. ENTANI, M. NAKANO AND M. ISHIDA

カキ‘富有'の無核果実の結実に及ぼす有核果の影響

北島宣・芥田英彦・吉岡照高・圓谷徹之・中野幹夫・石田雅士

京都府立大学農学部 606 京都市左京区

摘要

カキ‘富有'の落果発生および無核果実の結実やジベレベレリン濃度にもかかわらず,ジベレリン処理した無リン処理による結実促進が不安定な要因を明らかにす核果実の結実は他の果実が無核であれば優れ,他の果るために,受粉,花粉遮断,環状剥皮およびジベレリ実の種子数が多いと劣った. ン処理を行った. ・これらのことから,カキ‘富有'の無核果実の結実は,

樹体の違いにより無核果実の結実や種子形成は大き他の果実の種子数に強く影響を受けることが明らかとく異なった.無核果実の落果は同一樹体における他のなり,おもに果実間の競合により落果が生じるものと果実の種子数が少ないほど抑えられ,両者には高い相考えられた.また,ジベレリン処理による不安定な結関(r=0.77)が認められた.また,環状剥皮処理によ実促進効果は有核果実からもたらされるため,ジベレり剥皮部の癒合時期までは落果は認められず,多くのリン処理による無核果実の結実安定には,花粉遮断処無核果実が結実した. 理などによる有核果実の除去が重要であることが明らすべての花を花粉遮断した樹体では,ジベレリン処かとなった. 理濃度の高い果実ほど結実が優れた.しかし,同じジ