Effects of drought and moist soil conditions of various periods from summer to autumn on fruit quality of satsuma mandarin [Citrus unshiu] cv. 'Aoshima Unshiu'
2002
Sasaki, T. (Shizuoka-ken. Citrus Experiment Station, Shimizu (Japan))
Effects of soil drought at various periods from flowering time to harvesting time on fruit quality of satsuma mandarin cv. 'Aoshima Unshiu' were studied. The results obtained were as fellows. 1.Fruit diameter was decreased in plots kept drought during the period from early May to mid July and from late August to mid September. 2.Coloring of fruit was later and worse in plots kept drought during the period from late July to mid August, but it was earlier and better in plots kept drought during the period from late September to mid October. Especially, it became earliest in the combination of moist treatment during the period from late July to mid August and drought treatment during the period from late September to early October. 3.Sugar content of the juice at harvest time increased in plots kept drought during the period from late August to mid October. 4.Citric acid content in fruit juice was higher in plots kept drought during the period from early May to mid July and from late August to mid October. 5.Sugar and content of the juice at harvest time increased in plots kept drought during the period of a month from late August to mid September, but citric acid content was similar to that of well-watered controls. 6. In conclusion, sugar and acid concentrations of fruits were affected greatly by the variation of soil moisture in summer and autumn. Especially, higher sugar content of the juice may be expected by the exposure to water stress during the period from late August to mid October. Even in such a case, when if the soils were kept drought for a month, citric acid content became similar to that of well-watered controls.
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