Abstract
I. Forcing test
1. 21-24g. bulbs of William Pitt variety, produced by supplying different amounts of nitrogen, phosphate and potassium fertilizers, as mentioned in the previous report, were selected. The bulbs were treated at 10-15°C. for 30 days starting on July 20th, then at 0-3°C. for 50 days, and were immediately planted in wooden boxes in the plastic film house. The growing conditions for all bulbs were the same. The growth and blooming responses of the tulips were examined.
2. It was observed that the greater the amount of each of the 3 elements supplied to the previous generation, the sooner the blooming and the smaller the rate of blind in the forcing culture. The tendency was observed especially with nitrogen fertilizer, but the effects were smaller with potassium fertilizer.
3 The earliness of blooming and the smallness of rate of blind were highly correlated with the earliness of flower bud differentiation in the seed bulbs.
4. The characteristics concerning with the quality of cut flowers, such as plant height, leaf area, plant weight, flower size, etc. were superior in those tulips that were raised from the bulbs produced by supplying much fertilizers. The after-effects of nitrogen and potassium supply to the previous generation were remarkable in the lower production of the following year.
II. Field culture test
1. In order to clarify the after-effects of fertilizer supply to the previous generation upon the next-generation large (17-19g.) and small bulbs (2.5-3.0g.), which were selected from the plots supplied with different amounts of fertilizers as in the first test, were planted in a field in the usual manner, and the growth, and yield of bulbs were examined.
2. Generally speaking, the tulips produced by parent bulbs to which much fertilizer was supplied were superior in their growth to those produced by parent bulbs given less fertilizer. Especially this after-effect was conspicuous in nitrogen fertili-zer plots, i.e. the less the amount of nitrogen supplied in the previous generation, the later the leaf emer-gence, the slower the plant growth, and the lower the plant height in the next generation.
3. In the large seed bulb plots, the yield of bulbs, i.e. the number and the weight of bulbs, was varied depending on the amount of nitrogen fertilizer supplied to the previous generation. Within the limit of the present study, as the amount of nitrogen fertilizer supplied to the preceding gener-ation was increased, the following generation ex-hibited higher yield of bulbs. Potassium fertilizer supplied to the preceding generation produced a similar tendency though in _??_ smaller scale. The amount of phosphate fertilizer supplied seemed to be of little effect. In the small seed bulb plots, however, it was hard to recognize such an after-effect of the fertilizer condition in the preceding generation as was seen in the large seed bulb plots mentioned above.
4. The content of dry matter in the harvested bulbs tended to increase where increased amounts of fertilizer were supplied to the preceding genera-tion, but seldom were found correlations between the number of split coat bulbs or the formation of dropper of small bulbs, and the amount of fertilizer supplied to the preceding generation.
