Abstract
Experiments were carried out to analyse the effect of the time of nitrogen application on the growth and flowering of Phalaenopsis plants.
The leaf blade area expanded for one month from July to August, 1990, when nitrogen was applied from April, while such an expansion of the leaf blade area occurred from August to September, when nitrogen was applied from June onward.
The emergence of inflorescences was accelerated when nitrogen application was discontinued before August as in the case of the application between April and May, between April and July or between June and July. When the application was continued until September as in the case of the application between April and September, between June and September or between August and September, the emergence of inflorescences was delayed by about ten days as compared with the cases in which the application was discontinued before August.
These results suggest that for the optimum growth of the plant the nitrogen should be applied from April with about 1.5% increase of the total amount of nitrogen applied in the plants during the summer. Moreover, it was suggested that nitrogen application should be discontinued in September or that the concentration of nitrogen applied in September should be reduced to avoid the delay in the emergence of the inflorescences.
