Adaptability of chrysanthemum to protected culture in the reclaimed land of the Isahaya Bay [Nagasaki, Japan] and its cultivation method

1) The center reclaimed land of the Isahaya Bay has the following climatic characters: a large annual range of temperature, high temperatures in the summer, and low temperatures from the autumn to early in the spring. The climatic characters are not necessarily favorable for protected culture of chrysanthemum. On the other hand, the reclaimed land has favorable conditions for the protected culture of chrysanthemum, such as long sunshine hours and abundant solar radiation in the winter. 2) An analysis of reclaimed land soil in the Isahaya Bay before planting showed a pH of 7.04 and a high base saturation percentage of 111%, which may affect chrysanthemum growth adversely. To improve the soil in favor of chrysanthemum growth, nitrogen alone should be applied for the time being and results of soil analyses need to be watched carefully to judge a proper timing for starting to apply other nutrients. 3) Chrysanthemum summer cropping characteristically grows slowly during the initial growth stage before pinching, after which the growth is as good in the reclaimed land as in non-reclaimed land used for the protected culture of chrysanthemum. Also, because the internodes tend to be short and the leaf development tends to be slow, leaves tend to develop more abundantly for the same grass height in the reclaimed land as that in the non-reclaimed land. Although chrysanthemum summer cropping has such problems as slow initial growth and requirement for measures to cope with high temperatures, the growth is as good in the reclaimed land as in the non-polder land after pinching and early fix planting can secure as good a yield from the reclaimed land as that from the non-reclaimed land. Thus, chrysanthemum summer cropping can be judged as adaptable to protected culture in the reclaimed land as to that in the non-reclaimed land. 4) As for chrysanthemum winter cropping, a pinching cropping type for fix planting around August 20th and shipment in the latter half of December is believed to yield as good a harvest from the reclaimed land as from the non-reclaimed land. Thus, chrysanthemum winter cropping can be judged as adaptable to protected culture in the reclaimed land as to that in the non-reclaimed land. 5) With regard to fertilizer application from the viewpoints of securing yield and conserving environment, basal dressing nitrogen needs to be applied at a level of 30 kg/10a up to the third crop. Basal dressing nitrogen may continue to be applied at the level of 20 kg/10a, a baseline level, to the fourth crop and subsequent crops. 6) A growth survey showed no need for potassium application. Soil analyses showed potassium deposition in a fertilizer-applied plot and also potassium deposition resulting from manure application. Therefore, the reclaimed land needs no potassium application for the protected culture of chrysanthemum and needs to be given a reduced level of cattle manure, which is high in potassium, around 3 t/10a per crop.