嘉義地區葡萄柚之礦物營養狀況研究

An Investigation on the Status of Mineral Nutrition of Grapefruit (Citrus paradisi) in Chia Yih Area

民國七十、七十一年間，先後調查嘉義地區較具規模葡萄柚果園三處，基於果樹營養觀點，採取葉片、果實及土壤等試機拱作化學分析，同時誕查各園施肥、收穫量、根砧、病蟲害防治以至品種等狀況，套熙研判、論證。從果實之內在品質判之，其維生素丙、可熔性固形物、果汁中枸構酸、以及果汁等之含量乃至糖酸比等，均不及美國產之品質水準；考其主要導因不外選用根砧及果樹營養問題，前者欲求革新非一蹴可即，但營養控制之改進應不難達成。另從葉片採樣研判，認其氮素含量高達2.6-2.7%，而鉀素含量亦高達1.7%甚至2.1%，乃導致果實內在品質之低下，如維生素丙含量低，果河中含酸量高，可熔性固形物含量低，循而降低其糖酸比等情形，而葉片中含過高量氮、鉀，則可歸咎於施肥不當（過多）之故。至其收穫量遠較美國相當樹齡生產者為多，使對調查資料存疑，蓋氮肥施量過高，不但無益於果實內在品質，亦無助於收穫量。

Sizable grapefruit groves in Chia Yih area were investigated during 1981 to 1982 in view of fruit nutrition status. Aside from collecting leaf, fruit and soil samples for chemical analysis, investigations involving fertilization programme, yield, root stocks, varieties as well as pest control were all performed to make reference to the judgement. To judge by internal quality of the grapefruits indicated that either its content of fruit juice, ascorbic acid, soluble solids, citric acid in fruit juice or soluble solids: acid ratio was far lower than the standard of American products which may be attributed to root stock selection and fruit nutritional problems. The former innovative work needs a long way to get through while quality improvement by means of nutritional control may not be difficult to approach. Interpretation from leaf samples revealed that its high nitrogen (2.6-2.7%) and high potassium content (1.7 and even up to 2.1%) may be the attribution of inferior quality, in which lower ascorbic acid and juice content. high citric acid in the fruit juice following by lower soluble solids content, therefore, resulted in lower soluble solids: acid ratio. The excessive content of nitrogen and potassium in leaf tissue can be ascribed to unsuitable fertilization (over application). As for the yield, the investigation showed doubtful due to its high annual production in reference to American yield of relative tree age, Since under an over application of nitrogen which will neither be helpful to fruit quality nor its yield.