栽培イチゴ(Fragaria×ananassa Duch.)の四季成り現象に関する研究 : とくに温度及び日長の影響について
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概要
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In spite of advance in the current cropping systems used for strawberry culivation, few strawberries are harvested from mid summer to autumn in Japan. So far as is known, there exist two production possibilities during this period, 1) utilization of everbearing cultivar and 2) application of the everbearing behavior of June-bearing cultivars. The purpose of this study is to demonstrate the difference in flower-bud formation between everbearing and June-bearing cultivars, and to elucidate the everbearing behavior based on physiological and ecological aspects. 1. Seasonal changes in growth, flowering, and fruiting of a 'Hokowase' June-bearer and five 'Arapahoe', 'Kletter Erdbeere Hummi (Kletter)', 'Ostara', 'Rabunda' and 'Revada' everbearers were investigated. Harvest of all the plants began in May, and that of 'Arapahoe', 'Ostara', 'Rabunda' and 'Revada' continued until September, but 'Hokowase' and 'Kletter' ceased flowering by early summer. 'Rabunda' initiated flower bud in spring, but neither 'Hokowase' nor 'Kletter' did during that season. 2. Non-and pre-chilled plants of twenty cultivated and wild strawberries were examined in inflorescence production (IP) under 24-hr long-day conditions (24-LD). Based differences in their IP, the tested materials were classified into five types as follows: 1) everbearers ('Arapahoe', 'Ostara', 'Rabunda' and 'Revada') insensitive to the 24-LD and pre-chilling. 2) June-bearer ('Golerra', 'Lassen', 'Senga Sengana', 'Fukuba', 'Hokowase', 'Morioka 16', 'Reiko', 'chiloensis 1' and 'virginiana 2') inhibited by 24-LD and pre-chilling. 3) intermediate types ('Aiko', 'Kletter', 'Tioga', and 'virginiana 1') insensitive to the 24-LD, but inhibited by pre-chilling. 4) 'Redgauntlet' insensitive to pre-chilling, but inhibited by the 24-LD. 5) 'chiloensis 2' was observed only under the 24-LD. 3. 'Ostara' and 'Rabunda' everbearers, a 'Hokowase' June-bearer, and intermediate type of 'Kletter' were examined for the effect of pre-chilling on their IP. There was no effect of pre-chilling on the IP of the everbearers, but IP numbers of the June-bearer and intermediate decreased with the increment of pre-chilled duration. 4. The three types of strawberries were investigated for the effect of pre-chilling and daylength conditions [a 16 hours day length (LD) and a 8 hours day length (SD)] on their floral intiation. The non-chilled plants of the everbearer and intermediate type intiated flower buds under the LD and SD, but the LD inhibited the floral initiation of the June-bearers. The fully pre-chilled plants of the everbearer initiated flower buds when grown at 20℃ whether under the LD or SD, but the floral initiation of the intermediate type did not occur under the LD for at least two months when given full pre-chilling. 5. Non- and pre-chilled everbearers ('Ostara' and 'Rabunda'), June-bearers ('Hokowase' and 'Reiko'), and intermediate types ('Aiko' and 'Kletter') were grown in a high temperature area, an intermediate temperature area and a cool temperature zone during summer, and their IP was periodically counted. Both non-and pre-chilled everbearers successively produced inflorescences throughout the summer at the three sites. In June-bearers, pre-chilled plants produced few inflorescences at all the sites, while the IP of the non-chilled plants could be observed until mid summer and then gradually decreased. The non-chilled 'Aiko' and 'Kletter' plants successively produced inflorescences throughout the summer only in the cool temperature zone. 6. The above results can be simmarized as follews: 1) No floral intiation of June-bearers occurs in spring because of the effect of chilling in winter and long-day conditions in spring, and this is the reason why the June-bearers did not show everbearing behavior. 2) Everbearers suffer from the either of the above effects, and begin floral initiation in spring, hence show everbearing behavior. 3) Although almost all June-bearers are regarded as SD plants, the existence of intermediate types between June-and everbearers was indicated by this study. This type shows everbearing behavior when grown in warm conditions in winter because the flower-bud differentiation is inhibited by winter chilling. Consequently, there may be everbearing cultivars that could be used for summer and autumn strawberry production in temperate zones such as Japan because of their stable production of inflorescence.
- 大阪府立大学の論文
- 1992-03-31