Rose petals of two varieties were used in this study: Golden Wave (Dr. Verhage), a short-lived variety (3-5 days of vase
life), and Lovita, a long-lived variety (8-12 days of vase life). Flowers grown in a greenhouse were allowed to develop and age on the plant. They were cut at two stages: (a) young stage, tight bud, half the sepals are released, about half a day before commercial harvest; (b) old stage, initial senescent phase, flowers fully open, showing first signs of color fading. Generally, Golden Wave flowers required 7 days to pass from the first to the second stage, while 8.5 days elapsed in the case of Lovita. From this initial senescent stage to petal drop, an additional period elapsed of 3 and 7 days in the Golden Wave and Lovita varieties, respectively. Petals were harvested, immediately frozen in liquid air, and lyophilized. Four grams dry weight of lyophilized petals were covered with 80% methanol and homogenized in a Waring Blendor. The homogenate was shaken for 14 hr at 4 C and filtered. The residue was shaken with methanol for an additional 1 hr and filtered. The combined filtrate was evaporated to the water phase under reduced pressure, adjusted to pH 2.5 with HC1, and extracted twice with petroleum-ether and then four times with ethyl acetate. (In preliminary experiments no cytokinin activity was detected in the petroleum-ether and the ethyl acetate fractions.) The aqueous fraction was adjusted to pH 3.3, 15 ml of 10% (w/v) AgNO3 was added, and the mixture was allowed to stand at 4 C for 12 hr. The precipitate was centrifuged, washed with cold AgNO3 solution, and shaken with 0.2 N HCI for 3 hr at 45 C. The supernatant was concentrated under reduced pressure and assayed by the soybean callus growth bioassay. Three tests were carried out with Golden Wave and one with Lovita(Table I). In all the tests each treatment included 10 to 15 replicates.
กลีบกุหลาบของสองสายพันธุ์ที่ใช้ในการศึกษานี้: คลื่นทอง (ดร. Verhage), หลายช่วงสั้น ๆ (3-5 วันของแจกันlife), and Lovita, a long-lived variety (8-12 days of vase life). Flowers grown in a greenhouse were allowed to develop and age on the plant. They were cut at two stages: (a) young stage, tight bud, half the sepals are released, about half a day before commercial harvest; (b) old stage, initial senescent phase, flowers fully open, showing first signs of color fading. Generally, Golden Wave flowers required 7 days to pass from the first to the second stage, while 8.5 days elapsed in the case of Lovita. From this initial senescent stage to petal drop, an additional period elapsed of 3 and 7 days in the Golden Wave and Lovita varieties, respectively. Petals were harvested, immediately frozen in liquid air, and lyophilized. Four grams dry weight of lyophilized petals were covered with 80% methanol and homogenized in a Waring Blendor. The homogenate was shaken for 14 hr at 4 C and filtered. The residue was shaken with methanol for an additional 1 hr and filtered. The combined filtrate was evaporated to the water phase under reduced pressure, adjusted to pH 2.5 with HC1, and extracted twice with petroleum-ether and then four times with ethyl acetate. (In preliminary experiments no cytokinin activity was detected in the petroleum-ether and the ethyl acetate fractions.) The aqueous fraction was adjusted to pH 3.3, 15 ml of 10% (w/v) AgNO3 was added, and the mixture was allowed to stand at 4 C for 12 hr. The precipitate was centrifuged, washed with cold AgNO3 solution, and shaken with 0.2 N HCI for 3 hr at 45 C. The supernatant was concentrated under reduced pressure and assayed by the soybean callus growth bioassay. Three tests were carried out with Golden Wave and one with Lovita(Table I). In all the tests each treatment included 10 to 15 replicates.
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