Study on the development of bitterness in the fruit of cv. Kagafutokyuri

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The development of bitterness in the leaf and fruit of cv. Kagafutokyuri was investigated.Results in 1995(1). Bitter fruits were borne on the first lateral shoot, but not on the secondary lateral one.(2). The bitterness was strong in young leaf and fruit, but it decreased with age.(3). The total leaf nitrogen content of the bitter line was equal to that of the non-bitter line but the leaf nitrate ion content of the former was less than half of the latter.Results in 1996(1). A larger number of bitter fruit was observed in the bitter line than in the non-bitter line(2). The content of total nitrogen and amino acid-nitrogen in the leaf were higher in the bitter line than in the non-bitter line.(3). The content of total nitrogen and amino acid-nitrogen was higher in the upper leaf (or the bitter fruit) than in the lower(or non-bitter) one.Results in 1997(1). The occurrence of bitter fruit was high in the early growth stage, as compared with the late growth stage. The content of total nitrogen, nitrate ions and amino acid nitrogen was higher in the early growth stage than in the late growth stage.(2). The occurrence of bitter fruit was high in the early planting, as compared with the late planting. The content of total nitrogen, nitrate ions and amino acid nitrogen was higher in the early planting than in the late planting.From these results, it can be considered that the higher content of amino acid-nitrogen in the leaf of the bitter line, of bitter leaf, or of the bitter fruit results in a large quantity of protein production, which causes active synthesis of enzymes related to the synthetic pathway of cucurbitacin C,causing intense bitterness.