PROPAGATION, GROWTH AND FLOWERING PHYSIOLOGY OF ENDANGERED SPECEIS ARISAEMA SIKOKIANUM.

紫花杉的枝条合轴生长，生长周期为两年。花序发生于5月下部叶腋芽的顶端。顶端相继启动佛焰苞和佛焰柄。花原基在9~10月出现在穗轴上。为了验证四倍体的自交亲和性，从几个雄株上采集了超低温保存一年的花粉，当这些雄株的有性表达转化为雌株时，用花粉给相同的植株授粉。自花授粉和异花授粉都能产生种子，表明四倍体是自交亲和的。到12月中旬，球茎在自然低温下休眠解除。解除休眠的有效温度为5℃。营养球茎在5℃的低温下生长的时间较长，而在20℃下生长的球茎发芽的天数较短。5℃处理的生殖球茎开花天数较短。盆栽四倍子植株在28…下生长在试验田中，将14%和4%的光强转化为全日照(100%)。对发育良好的叶片进行了饱和光强附近的净CO2同化速率(A&lt；sat&gt；)以及黎明前和白天的叶绿素荧光特性的测定。开花初期，雌株的吸光度和中午电子传递速率(ETR)均大于雄株。无论是雄株还是雌株，随着生长光强的增加，中午光能利用率(ΔF/Fm‘)降低，光能利用率(ETR)增大。雄株ETR没有午休部分归因于较大的非光化学猝灭(NPQ)，即过剩光能的成功消散。ΔF/Fm‘在中午的下降一直持续到晚上，这表明即使在光合作用能力较小的雄株中也可以避免慢性光抑制。开花后，夜间ΔF/Fm‘没有恢复，At；Sat和ETr下降。但在弱光下(4%和14%)，雄株和雌株之间表现出相似的光合作用特性和/或光强。这些结果表明，生长在弱光下的马尾松具有维持光合作用生产力的机制，而与性别表达和光照强度无关。从枝条膨大和开花开始，叶片水平上较强的光合作用能力将支持雌性植株的生产力。较少

A.sikokianum has a sympodial shoot with a two-year growth cycle. Inflorescence initiation occurred on the apex of the axillary shoot of the lower leaf in May. The apex initiated the spathe and spadix in succession. Floral primodia appeared on the spadix from September to October. In order to verify self-compatibility in A.sikokianum, pollen that was collected from several male plants and cryopreserved for a year was used to pollinate to the same plants when the sexual expression of the plants converted to female. Both self- and cross-pollinated spadices produced seeds, indicating that A.sikokianum is self-compatible. Dormancy of corms broke when corms were exposed to natural low temperature until middle December. Effective temperatures for breaking dormancy was 5℃. Vegetative corms exposed to low temperatures at 5℃ longer showed shorter days to sprout when grown at 20℃. Reproductive corms treated at 5℃ longer showed shorter days to flower. Potted A.sikokianum plants were grown under 28 … More , 14 and 4% of light intensity to full sunlight (100%) at an experimental field. Net CO_2 assimilation rate near saturating irradiance (A_<sat>) and chlorophyll fluorescence characteristics at predawn and daytime were measured for well-developed leaves. At the beginning of flowering, A_<sat> and electron transport rate (ETR) in midday were greater in female plants than those of male plants. Both in the male and the female plants at this period, A_<sat> and ETR increased, and light use efficiency (ΔF/Fm') in the midday decreased with the intensity of growing light. No midday depression of ETR in the male plants would be partly ascribed to greater non-photochemical quenching (NPQ), a successful dissipation of excess light energy. The decrease of ΔF/Fm' in the midday recovered until evening, suggesting that chronic photoinhibition can be avoided even in the male plants with smaller photosynthetic capacity. After the flowering, A_<sat> and ETR were decreased and ΔF/Fm' did not recover in the evening. However, at the low light levels (4 and 14%), similar photosynthetic characteristics were shown between the male and the female plants and/or light intensities. These results suggest that A.sikokianum plants growing in the low light have mechanisms to maintain photosynthetic productivity irrespective of sex expressions and light intensities. The productivity of female plants would be supported by greater photosynthetic capacity at the leaf level from the beginning of shoot expansion and flowering. Less