Abstract
Cucumber plant, 'Kagafuto' kyuri is mainly cultivated in the Utsugi district of Kanaza- wa City, Ishikawa Prefecture of Japan. The cucumbers are harvested when they weigh about 800 g and cooked in salads or dishes with a liquid starch dressing. The frequently bitter and unmarketable fruit harvested from April to May prompted this study.
1. In the semi-forcing culture practiced in Ishikawa Pefecture, more fruits harvested on April 22 were bitter, especially those borne on the first lateral shoot than were those on the secondary lateral. The cucumbers on the first lateral shoot were harvested 19 days earlier than were those on the secondary lateral.
2. High occurrence of bitter fruit was observed on the first lateral shoot whether the main shoot was kept as the leader or pruned back to the first lateral shoot. Whether the leader was headed or not, harvesting of the first lateral shoot began 17 days earlier than were those on the secondary.
3. Regardless of the own-rooted plant and the grafted plant, the bitterness in the leaf intensified according to the leaf height on the plant, with the highest leaves being the most bitter.
4. The bitterness was strong in young fruit, but it decreased with age and size.
5. Shoots in which stems were longer and leaves were heavier (bitter line) bore bitter fruits at higher frequencies than did short shoots with smaller leaves (non-bitter line).
6. 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.
From these results, I postulate that in young, vigorous plants, a large amount of cucur- bitacin C, the bitter constituent, is synthesized, compared with older, less vigorous plants.
