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

甜瓜叶片和果实中苦味的发育。1.1995年调查结果(1)。苦果发生在第一次侧枝上，而不是在第二次侧枝上。苦味在幼叶和果实中较强，但随着年龄的增长苦味逐渐减弱。苦味品系的叶片全氮含量与非苦味品系相当，但其叶片硝酸根离子含量低于非苦味品系的一半。苦味品系的苦果数明显多于非苦味品系(2)。苦味品系叶片全氮和氨基酸氮含量均高于非苦味品系。果实上部(或苦果)全氮和氨基酸氮含量高于下部(或非苦果)。与生长后期相比，生长前期苦果发生率较高。生长前期总氮、硝酸根离子和氨基酸态氮含量均高于生长后期。与晚播相比，早播苦果发生率较高。总氮、硝酸根离子和氨基酸态氮的含量早播高于晚播，说明苦品系叶片、苦叶或苦果的氨基酸态氮含量较高，导致蛋白质大量产生，导致与葫芦素C合成途径有关的酶活性合成，造成强烈苦味。

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.