《植物的成花生理》ppt課件-預(yù)覽頁
【正文】 requires 16 hours or less of light, in Miami, San Francisco, and Chicago, it can flower as soon as it matures, but in Winnipeg(溫尼伯湖 [加拿大中南部 ]), the buds do not appear until early August, so late that the frost will probably kill the plants before the seed is set. 光周期反應(yīng)類型 ? 長日植物 (longday plant,LDP)：在 24h晝夜周期中，日照長度長于一定日數(shù)才能成花的植物。延長黑夜或縮短光照提早開花，延長日照推遲開花。 ? 長短日植物 (longshort day plant)：要求先長日后短日的雙重日照條件，如蘆薈、夜香樹等 ? 短長日植物 (shortlong day plant)：要求先短日后長日的雙重日照條件，如風(fēng)鈴草、鴨茅、瓦松、白三葉草等。 Representative shortday (a) and longday (b) plants, each grown under shortday (on left) and longday (on right) conditions. (a) Chrysanthemum(菊花 ). (b) Spinach(菠菜 ) (Spinada oleracea). Note that the plants exposed to long days have longer stems than those exposed to short days, regardless of whether or not they flower. (a) and (b) Natural 24hour light/dark cycles must have short nights any time the days are long (summer) and long nights when days are short (winter), so plants could detect season by measuring either day or night. When photoperiodism was first discovered, it was assumed that day length wag important, so all our terminology was based on that. (c) With electric lights, it is possible to create a long photoperiod36 hours long herewith both long days and long nights. Under these conditions, shomday (longnight) plants bloom, but longday (shortnight) plants do not. 臨界日長和臨界暗期 ? 根據(jù)各種短日植物和長日植物的臨界日長具體的數(shù)值，現(xiàn)在已知道原來以 12h作為短日植物和長日植物的臨界日長的假定是不正確的。因此，判斷一種植物是長日植物或短日植物，不能以日照長短為準(zhǔn)，必須以臨界日長來判斷。 ? 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(duì)應(yīng)的就有臨界暗期(critical dark period)。由此可見，臨界暗期比臨界日長對(duì)開花更為重要。短日植物菊花在秋季自然短日下開花，但在花開始誘導(dǎo)時(shí)，連續(xù)數(shù)周每天的午夜照光 1 h，就延遲開花。 對(duì)短日植物說，紅光使植株不開花，而遠(yuǎn)紅光使植株開花；對(duì)長日植物說，紅光使植株開花，遠(yuǎn)紅光使植株不開花。在暗誘導(dǎo)的后期，Pfr水平下降，誘導(dǎo)開花。遠(yuǎn)紅光的促花作用主要是降低 Pfr水平。同緯度地區(qū)的長日植物在日照較長的春季和夏季開花，短日植物在秋季開花。菊花為短日植物，原在秋季(10月 )開花，現(xiàn)經(jīng)人工處理 (遮光成短日照 )在六七月間就可開出鮮艷的花朵；如果延長光照或晚上閃光使暗間斷，則可使花期
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