植物的成花生理ppt課件(已改無錯字)
2023-02-14 22:48:34 本頁面
【正文】 ? 在自然條件下，晝夜總是在 24h的周期內(nèi)交替出現(xiàn)的，因此，和臨界日長相對應(yīng)的就有臨界暗期(critical dark period)。臨界暗期是指在晝夜周期中短日植物能夠開花所必需的最短暗期長度，或長日植物能夠開花所必需的最長暗期長度。植物開花究竟決定于日長還是夜長 ?例如短日植物開花是因日長縮短還是因暗期延長超過某一限度而引起的呢 ?有報道認為，以短日植物大豆為試驗材料，日長為 16h及 4h，暗期為 420h，結(jié)果表明，暗期在 10h以下無花芽分化，暗期長于 10h形成花芽，暗期 1314h花芽最多。又如長日植物天仙子，在12h日長和 12h暗期環(huán)境下不開花，但以 6h日長和6h暗期處理則開花。由此可見，臨界暗期比臨界日長對開花更為重要。短日植物實際是長夜植物(long night plant)，長日植物實際是短夜植物(short night plant)。 The soybean was cultivated under cycles of 10 h light and 8 62 h of darkness. Ordinate: Number of Flowers. The maxima are at 10 h light and 14 h darkness and at 10 h light and 30 h darkness (Periods of light are symbolized by light blue, periods of darkness by redviolet bars). On the abscissa are 6 h intervals marked. (K. C. HAMNER, 1960) Shortday plants flower only when the photoperiod is less than some critical value. The mon cocklebur (Xanthium strumafium), a shortday plant, requires less than 16 hours of light to flower. Longday plants flower only when the photoperiod is longer than some critical value. The longday plant henbane (Hyoscyamus niger) requires about 10 hours (depending on temperature) or more to flower. If the dark period is interrupted by a flash of light, Hyoscyamu will flower even when the daily light period is shorter than 10 hours. However, a pulse of light during the dark period has the opposite effect in a shortday plantit prevents flowering. The bars at the top indicate the duration of light and dark periods in a 24hour day. 光周期刺激的感受和傳遞 接受光周期的部位是葉 僅生長點照光不開花 僅莖照光不開花 If grafted together and given short days, both shortday plants and dayneutral plants flower. Apparently the floral stimulus that was induced le shortday plant has been transported to, is active in, the dayneutral plant` Under short days, shortday plants are induced to flower but dayneutral ones are n
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