Abstract
The authors undertook to investigate the ability of fruit development in cucumber plants to which were applied different amounts of nirogen. A heterozygous female line derived from the commercial variety"Kaga-Fushinari"was used. An outline of the results is as follows;
1. When the whole amounts of nitrogen were applied before planting, early growth of leaf area and stem length was slower in higher nitrogen levels than in lower ones. This may be due to the excess of soluble nitrogen in soil.
2. The numbers of pistillates and those that opened per plant were not altered by the level of nitrogen applied. Length of the ovary at flowering time and fruit set in higher nodes were increased as nitrogen level was increased.
3. There were inverse relationship between nitrogen level and the average weight of harvested fruits up to the 20th node in the first experiment, whereas such a relation ship was not noticed in the second experiment. In higher nodes above the 21st one, the average weight and the number of fruits were in direct proportion to nitrogen level irrespective of application procedures.
4. Top weight and total yields were also proportional to nitrogen level in both experiments (r=0.5964** and 0.4652*, respectively).
5. Pistillate flowers around the 18th node could not bloom or enlarge even when they flowered. Such nodal zones where flowers were abortive occurred at the time when total weight of developing fruits was at their first peak in all nitrogen levels. This suggests that developing fruits on lower nodes monopolized available nutrients of the cucumber plants till they were harvested and then the vigor of plants restored. Thus periodical changes in fruit production seem to occur mostly as a result of inter actions among fruit development, the rate of fruit set and flowering, and plant growth which was influenced by nutritional conditions.
