Stable production of high quality fruits and application of 'Hiryu' rootstock to nucellar varieties of satsuma mandarin [Citrus unshiu] bred at Kumamoto prefecture [Japan]
2008
Fujita, K.(Kumamoto-ken. Agricultural Research Center, Koshi (Japan)) | Miyata, R. | Sakaki, H. | Kitazono, K. | Fukunaga, Y. | Sakamoto, H. | Mitsuta, M.
Using satsuma mandarin nucellar varieties, under sheet-multi cultivation of 'Hinoakebono' which is early maturing type mandarin was investigated by water stress. Secondary, the effects of the shoot control and the application of growth regulators on successive stable fruits production was tested on 'Sirakawa' which is late maturing type mandarin. Furthermore, the graft on 'Hiryu' rootstock was discussed under the production of several varieties. The results obtained were as follows. 1) The correlation of 'Hinoakebono' fruits quality between harvest time and fruits growing season was so high with sugar content at August First, while that of citric acid was at August 21th. Water stress effected for sugar and citric acid content, that is lower water stress at the middle August to first of September for low citric acid but sugar content was not cleared. 2) 'Sirakawa', known for its tendency to display biennial bearing as well as vigorous tree, sprayed Ethychlozate in summer was controlled in extension of current shoots and feeder roots. Superior bearing shoots were 10cm degree in length and under level at shoot angle at off year, so shoot control methods for promotion of bearing was leaving the weeping shoots at pruning and bud picking in physiological fruit drop season. Promotion of flower bud differentiation was increased by paclobutrazol treatment in winter. 3) Comparing 'Toyohuku-wase', 'Hinoakebono' and 'Sirakawa' on 'Hiryu' with that on trifoliate orange, growth of trees was lower and yield per unit canopy volume was higher. Fruit quality of that on 'Hiryu' was generally higher in size and Brix. 'Sirakawa' sprayed Gibberellin reduced the number of flowers and stimulate vegetative growth. Adequate fruit load of 'Sirakawa' at first bearing year was 30 fruits per unit canopy volume.
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