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

葡萄叶片和果实苦味的发展。Kagafutokyuri接受了调查。1995年结果(1)。苦果在第一侧枝上产生，而在第二侧枝上不产生。幼叶和果实的苦味较强，但随着年龄的增长而减弱。苦系叶片总氮含量与非苦系相当，但叶片硝酸盐离子含量不到后者的一半。1996年的结果(1)。在苦系中观察到的苦果数量比在非苦系中观察到的多(2)。苦系叶片中总氮和氨基酸氮含量均高于非苦系。总氮和氨基酸氮含量上叶（或苦果）高于下叶（或无苦果）。1997年的结果(1)。与生育后期相比，生育前期苦果发生率高。生长前期总氮、硝态氮和氨基酸氮含量均高于生长后期。早播期苦果发生率高于晚播期。全氮、硝态氮和氨基酸氮含量均在播前高于播后。从这些结果可以认为，苦系叶片、苦叶或苦果中氨基酸氮含量较高，导致大量蛋白质产生，导致葫芦素C合成途径相关酶合成活跃，产生强烈的苦味。

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.