植物的成花生理ppt課件-文庫(kù)吧資料
2025-01-20 22:48本頁(yè)面
【正文】 rs from the . Department of Agriculture, . Garner and . Allard, who found that neither the Maryland Mammoth variety of tobacco (Nicotiana tabacum) nor the Biloxi variety of soybean (Glycine max) would flower unless the day length was shorter than a critical number of hours. Garner and Allard called this phenomenon photoperiodism. Plants that flower only under certain daylength conditions are said to be photoperiodic. Photoperiodism is a biological response to a change in the proportions of light and dark in a 24 hour daily cycle. ? 在一天之中，白天和黑夜相對(duì)長(zhǎng)度的交替變化，稱為光周期 (photoperiod)。 GA以某種方式代替低溫的作用。 經(jīng)過(guò)低溫處理開(kāi)花結(jié)果 未經(jīng)低溫處理沒(méi)有花果 作用機(jī)理和應(yīng)用 ? ? 呼吸速率增強(qiáng)； ? 核酸代謝加速，在春化過(guò)程中核酸（特別是 RNA）含量增加，而且 RNA性質(zhì)有所變化； ? 蛋白質(zhì)代謝，可溶性 Pr及游離 AA含量（ Pro）增加。反過(guò)來(lái)，如把芹菜放在冰冷的室內(nèi)，而使莖生長(zhǎng)點(diǎn)處于高溫下，也不能開(kāi)花結(jié)實(shí)。曾將芹菜種植在高溫的溫室中，由于得不到花分化所需要的低溫，不能開(kāi)花結(jié)實(shí)。春化作用一旦完成，就非常穩(wěn)定，高溫處理就不起作用。一般說(shuō)來(lái)，冬性愈強(qiáng)，要求的春化溫度愈低，春化的天數(shù)也愈長(zhǎng)。根據(jù)原產(chǎn)地的不同，小麥可分為冬性、半冬性和春性類型。第一年秋季長(zhǎng)成蓮座型的營(yíng)養(yǎng)體，必須經(jīng)過(guò)冬季的低溫才能在夏季抽薹開(kāi)花。冬小麥經(jīng)低溫處理后，即使在春季播種也能在夏初抽穗開(kāi)花。在自然條件下，冬小麥等是在頭一年秋季萌發(fā)，以營(yíng)養(yǎng)體過(guò)冬，第二年夏初開(kāi)花和結(jié)實(shí)。 (vernalization) ? ： Cold may affect the flowering response. For example, if winter rye (Secale cereale) is planted in the autumn, it germinates during the winter and flowers the following summer, 7 weeks after growth resumes. If it is planted in the spring, it does not flower for 14 weeks. In 1915, the plant physiologist Gustav Gassner discovered that he could influence the flowering of winter rye and other cereal plants by controlling the temperature of the germinating seeds. He found that if the seeds of the winter strain are kept at nearfreezing (1 ℃ ) temperatures during germination, the winter rye, even when planted in late spring, will flower the same summer it is planted. This procedure, which came to be known as vernalization (from the Latin vernus, meaning spring), is now a mon practice in agriculture. ? 低溫誘導(dǎo)促使植物開(kāi)花的作用，稱為春化作用。成花啟動(dòng) (floral evocat
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