Physiology of Pharbitis nil

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Physiology of flowering in Pharbitis nil 　　by Kiyotoshi Wada, Niigata University (2003)

Experiments on the physiology of flowering in Pharbitis nil

1. Seed planting 　Seeds should be treated with concentrated sulfuric acid to induce rapid and uniform germination. ＜Sulfuric acid treatment＞ 　Soak Pharbitis nil seeds in concentrated sulfuric acid in a glass beaker for 40 to 60 minutes. Occasionally stir with a glass rod. 　Pour sulfuric acid containing the seeds into a Buchner's funnel and wash under running tap water. Return the washed seeds into the beaker, and wash the seeds under running tap water for another hour. 　Keep the washed seeds in still water and place at 25℃ overnight to imbibe. ＜Seed placing＞ 　Place the swollen seeds on moist filter paper in a Petri dish and incubate at 25 ℃ under a 16-hour photoperiod (long-day condition, LD) for 1 day to germinate. ＜Planting onto agar medium＞ 　Plant the germinated seeds on 0.6 to 1 % plain agar medium in a plastic box, and grow at 25 ℃ under LD for 5 days. ＜Water culture＞ 　Transfer the 5-day-old seedlings to glass tubes (180 mm x 18 mm) containing mineral nutrient solution (composition is shown below). 2. Dark treatment 　Place the seedlings in an incubator (25℃、16-hour dark period) to give a single dark treatment. 　After the dark treatment, return the seedlings to an LD condition and grow them for 1 to 2 weeks. 3. Observation 　All the axil buds and the terminal bud of the seedlings should be dissected under a binocular microscope to determine whether they are floral buds or vegetative buds. 　The floral bud is a round structure attached with two equal-sized sharp bract leaves with short hairs. A vegetative bud consists of equal-shaped but different-sized leaf primordia with long hairs. 　The percentage of the treated plants with at least one flower bud is defined as % flowering. Estimate the average number of flower buds per plant. Both the % flowering and average number of flower buds per plant need to be presented as a measure of the flowering response. The total number of flower buds and vegetative buds per plant are used as a measure of the vegetative growth along with the average length of the main stem. At least twenty plants should be used for each treatment. 4. Composition of mineral nutrient solution for liquid culture of Pharbitis nil 　The following was originally reported by Nakayama and Hashimoto (1973) and partly modified. 　　　 　　　　　 　　　　　 Concentration( mg/L) Major components 　NH４NO３ 　　 　　　　　 　　　 250 　KNO３ 　　 　　　　　 　　　　　 250 　MgSO４･7H２O 　　 　　　　　 250 　Ca (H２PO４)２･H２O　 　　 　250 　KH２PO４ 　　 　　　　　 　　　 250 Minor components 　Fe(�V)-EDTA 　　 　　　　　 　　　6 　H３BO３ 　　 　　　　　 　　　　　 　2 　MnSO４･4H２O 　　 　　　　　 　　1 　ZnSO４･7H２O 　　 　　　　　 　　0.2 　Na２MoO４･2H２O 　　 　　　　　 0.2 　CuSO４･5H２O 　　 　　　　　 　　0.1

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