チューリップの茎葉早期枯死について

Investigations on the effect of bulb yield against the living period of leaves were carried out 10 days, 20days, 30days, 40days and 47days after the flowering stage of tulip plant.
In these experiments, "William Pitt" was employed as test variety. The results obtained were summarized as follows :
1.When tulip leaves were killed in early stage after flowering, the bulb yield was worse than those killed in later stage.
2.The plants which were killed in early stages showed higher moisture content than those killed in later stage.
3.The plants which were killed in later stage had high starch content than those killed in early stage, but the plot of 47 days after flowering stage showed lower content than 40days plot. The same tendency was observed in the case of total ash of tulip bulbs.
4.The development of nose, flower bud and inmost vegetation point was worse in the case of killing in early stages than in later stage.