| 摘要： 番石榴果實呈現雙S型生長曲線，其果實之呼吸型式因品種而異:有些品種屬於更年型，如''梨仔拔''、''大蒂''、''中山月拔''、''白拔''等種；有些則表現非更年型果實特性，如''珍珠拔''、''世紀拔''、 ''泰國拔''、''無子拔''等。更年型之品種在各發育階段採下，果實均表現更年型特性；而屬於非更年型品種除幼果表現擬更年性外其於發育階段則表現非更年型果實特性。非更年型果實具較長之櫥架壽命，且不易軟化，而與更年型品種在後熟特性之差異，可能主要在於合成ACC之能力，前者合成能力低，所以無法生成乙烯以促進後熟。RAPD是鑑別品種及建立親緣關係之有效技術，本文試驗結果顯示，其中4組引子(O3, Q19, S14, R18)可區分番石榴栽培種之差異，出現不同型式之條帶圖譜(多型性)，其中具有更年型及非更年型番石榴品種的RAPD條帶之相似性很低，可將兩群組區分出，同時與園藝性狀外表型親緣圖譜比對，亦大致吻合。因此，技術亦具有區別更年型及非更年型果實之能力；另外，利用Kinetin可誘發原本不產生乙烯之番石榴葉片合成乙烯，在此種情況下合成乙烯之能力，因品種不同而異，其能力之高低和其後熟行為有關。更年型果實之品種此合成乙烯能力較高，而屬非更年型果實之品種則較低，所以此技術可在幼苗期即以Kinetin處理葉片，得知其乙烯合成之能力，進而辨別其果實後熟特性，以供早期選拔之參考。由於番石榴原產於熱帶美洲，其果實有不耐低溫之特性，在低溫下所顯現的寒害症狀計有果實褐化、果心水浸狀、易腐及不正常後熟等，而在本試驗所調查品種(''梨仔拔''、''泰國拔''、''世紀拔''及''珍珠拔'')中，所表現寒害症狀及嚴重性不一，整體而言，以''珍珠拔''較耐低溫，為具外銷潛力之品種。''梨仔拔''屬於更年性品種具濃郁之香氣，果實採下後易軟化後熟速度快及櫥架壽命較短，利用低氧及酒精處理可抑制及延緩果實後熟作用；酒精作用之主要機制為抑制ACC合成，使乙烯生成速率降低而達延緩果實黃化及軟化等後熟變化。The growth curves of guava (Psidium guajava L.) fruit was found to be double sigmoid. Depending on the individual cultivar, both climacteric and non-climac teric types of respiratory patterns were found in guava fruits. Culitivars of ''Li-Tzy Bar'', ''Dar Dih'', ''Jong-Shan Yuen Bar'', and ''Pei Bar'' were climacteric , and ''Jen-Ju Bar'', ''Shyh-Jii Bar'', and ''Tai-Kuo Bar'' were found to be non-cli macteric.An abrupt rise in respiratory rate and subsequent ethylene production were observed in climacteric type fruits harvested at various periods during fruit ontogeny. Similar phenomena were observed in non-climacteric type fruit s only at very immature stage of development, but not at mature stage. Shelf life of non-climacteric guava fruits was relatively longer than that of climac teric. The difference in ripening behavior between climacteric and non-climac teric type fruit was in the capability of synthesis of 1-aminocyclopropane-1-c arboxylic acid (ACC). Non-climacteric fruit lack the ability of synthesizing ACC when fruit reached mature stage.Randomly amplified polymorphic DNA (RAPD) markers were used to study the identification and discrimination of guava. Th e results showed that RAPD technique was fairly dependable for identifying a R APD marker linked to respiratory pattern. It was also found that kinetin grea tly increased the ethylene production of guava leaf discs excised from climact eric cultivars, but had negligible effect on non-climacteric cultivars. A clo se and positive correlation was found between kinetin-induced ethylene biosynt hesis in the leaf and the climacteric behavior of the fruit. This finding sugg ests that kinetin-induced ethylene production by guava leaf discs could be use d as an indication of the respiratory behavior of the fruit, and this techniqu e could be used in early prediction of fruit ripening behavior in future breed ing programs.Guava are chilling sensitive and the symptoms of chilling injury include abnormal ripening, peel and pulp browning, water-soaking core and deca y of fruits. Among the different cultivars, ''Jen-Ju Bar'' was the most chillin g resistant, and ''Shy-Jii Bar'' and ''Li-Tzy Bar'' were most sensitive to low tem perature.Exposure of guava fruit (cv. Li-Tzy Bar) to ethanol vapor or low oxyg en resulted in delaying fruit ripening. A reduction in ACC synthesis was main ly responsible for the inhibition of ethylene production in guava fruits by et hanol. Postharvest application of ethanol vapor to retard ripening may be an useful technique to extend the market life of guava fruits. |
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