Masuda Jun-Ichiro, Urakawa Toshihiro, Ozaki Yukio, Okubo Hiroshi
Laboratory of Horticultural Science, Faculty of Agriculture, Kyushu University, 812-8581 Fukuoka, Japan.
Ann Bot. 2006 Jan;97(1):39-45. doi: 10.1093/aob/mcj008. Epub 2005 Nov 15.
Lotus (Nelumbo nucifera) has been cultivated as an ornamental and food plant in Japan for more than 1000 years. As large areas are required for its cultivation (approximately 2 m2 per plant), physiological research, such as into the effect of environmental factors on dormancy, has not been well studied until recently. In this paper, seedlings were used to examine environmental factors affecting dormancy induction.
In a first experiment, seeds were sown from 6 April to 6 October at 2-month intervals, and cultivated for 2 months in an unheated greenhouse. In a second experiment, seeds were prepared for germination on 16 November and 16 May and the seedlings were grown at 25 or 30 degrees C under natural daylength in phytotron growth rooms. After 1 month, the seedlings were cultivated at 20, 25 or 30 degrees C for a further month. The number of leaves and rhizome branches on the main stem were counted, and growth of rhizomes on the main stem was calculated using a rhizome enlargement index (= maximum internode diameter/internode length) after 2 months of culture in both experiments.
Rhizomes elongated without enlargement when the seeds were sown in April and June. Sowing the seeds in August and October resulted in rhizome enlargement from the tenth and fifth internodes, respectively. Rhizomes enlarged in the November-sowing but elongated in the May-sowing irrespective of temperature treatments under natural daylength in the phytotron rooms. The seedlings cultivated from May at 25-30 degrees C for 2 months had more leaves, and more rhizome branches and nodes than those cultivated from November.
Short days led to induced dormancy in lotus.
莲花（Nelumbo nucifera）在日本作为观赏植物和食用植物已种植了1000多年。由于其种植需要大面积土地（每株植物约2平方米），直到最近，关于环境因素对休眠影响等生理研究还未得到充分开展。本文利用幼苗研究影响休眠诱导的环境因素。
在第一个实验中，于4月6日至10月6日每隔2个月播种种子，并在未加热的温室中培养2个月。在第二个实验中，于11月16日和5月16日准备种子进行发芽，幼苗在人工气候箱生长室中于自然日长条件下25或30摄氏度培养。1个月后，幼苗在20、25或30摄氏度下再培养1个月。在两个实验中，培养2个月后，统计主茎上的叶片数量和根茎分支数量，并使用根茎增大指数（=最大节间直径/节间长度）计算主茎上根茎的生长情况。
4月和6月播种种子时，根茎伸长但未增粗。8月和10月播种种子分别导致根茎从第十和第五节间开始增粗。在人工气候箱自然日长条件下，无论温度处理如何，11月播种的根茎增粗，5月播种的根茎伸长。5月开始在25 - 30摄氏度下培养2个月的幼苗比11月培养的幼苗有更多的叶片、更多的根茎分支和节。
短日照导致莲花诱导休眠。
