Leaf water status, carbohydrate levels, net photosynthesis, stomatal conductance, ABA, dihydrozeatin riboside (DHZR), and trans-zeatin riboside (ZR) levels were determined in a greenhouse during rooting of stem cuttings of Acer rubrum L. `Red Sunset' taken on 3 Sept. 1987 and 28 May 1988. Leaf water status deteriorated before rooting and improved after root emergence. Leaf carbohydrate concentrations (glucose, sucrose, total soluble sugars, and total carbohydrates) increased until rooting and decreased after rooting, while changes in starch concentrations were trendless. ABA levels increased after insertion of cuttings into the rooting medium, but decreased before rooting. No correlation between timing of rooting and concentrations of the cytokinins ZR or DHZR was observed. Photosynthetic rates during rooting were higher for the Sept. 1987 cuttings and did not decrease to the compensation point as did those for May 1988 cuttings. Low photosynthetic rates and stomatal conductance of the cuttings during rooting were associated with water stress. The relationship between photosynthetic rates of such cuttings and cytokinin (CK) or ABA content was unclear. Chemical names used: [S-(Z,E]-5-(1-hydroxy-2,6,6-trimethyl-4-oxo-2-cyclohexen-1-yl)-3-methyl-2, 4-pentadienoic acid (abscisic acid, ABA); 2-methyl-4-(1H-purin-6-ylamino)-2-buten-1-ol (zeatin, Z).
Achillea millefolium `Summer Pastels' is a qualitative long-day plant with a critical photoperiod between 12 and 16 hours at 18C. Plants grown under a 16-hour photoperiod flowered after 27 days, while those under 8 hours remained vegetative. Shoot dry weight was not affected by photoperiod. Low temperature (10C) delayed the time of flower bud formation and anthesis by ≈20 days. Low irradiance (100 μmol·m–2·s–1) delayed flowering and resulted in lower shoot dry weight, while moderate shading (200 μmol·m–2·s–1) did not significantly affect flowering time and growth compared with high irradiance levels (300 μmol·m–2·s–1).
Buddleia davidii Franch. ‘Royal Red’ was grown in pine bark amended with 0.0, 2.4, 4.7 or 9.5 kg/m3 (0.0, 4.0, 8.0, or 16.0 lbs/yd3) dolomitic lime. Growth characteristics responded quadratically to dolomitic lime with those plants receiving 2.4 kg/m3 having the greatest shoot and root dry weights and inflorescence numbers. Plants grown in 4.7 kg/m3 had the greatest shoot lengths. Concentrations of Ca and Mg in leaves of plants grown in containers without dolomitic lime amendment were below that recommended for normal growth of B. davidii. Leaf concentrations of N, S and Mn showed quadratic responses to dolomitic lime additions. Media pH and concentrations of NO3, Al, B, Mn and P also showed quadratic responses. Media Zn concentrations showed a linear response. Although all dolomitic lime amendments tested improved growth of Buddleia davidii ‘Royal Red’, the incorporation of 2.4 kg/m3 produced maximum growth and inflorescence quantity.
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