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  • Author or Editor: Michael S. Dosmann x
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Aconitum sinomontanum is a robust perennial monkshood native to China that shows promise as a cultivated ornamental. However, nothing has been reported about the germination requirements of the species, and little is known about the requirements of the genus as a whole. The objective of this study was to test the influence of stratification (moist prechilling) on germination of A. sinomontanum seeds. The seeds were from wild-collected plants of identical provenance growing at the Arnold Arboretum (Jamaica Plain, Mass.). After harvest and before stratification, seeds were stored dry at 38 °F (3.3 °C) and percentage germination was assessed after seeds were stratified, also at 38 °F, for 0, 21, 42, or 84 days. It is likely that stratification is required for seeds of this species to germinate, as unstratified seeds failed to germinate through the duration of the experiment (73 days). The highest level of germination (90.8%) was achieved after 84 days of stratification, and as length of stratification increased, so did percentage germination and indices of peak value and germination value. Days to maximum germination decreased with additional days of chilling. Growers wishing to germinate seed of this species should stratify seed for 3 months to achieve the highest level of germination.

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Germinability of two, half-sib seed sources of Cercidiphyllum japonicum Sieb. & Zucc. and one seed source of Cercidiphyllum magnificum (Nakai) Nakai was determined after not stratifying or stratifying seeds at 3.5 ± 0.5 °C (38.3 ± 0.9 °F) for 8 days followed by germination for 21 days at 25 °C (77 °F) in darkness or under a 15-hour photoperiod. Stratification was not required for germination, but increased germination percentage, peak value, and germination value for both species. Stratification increased germination of C. japonicum from 42% to 75%, and germination of C. magnificum from 12% to 24%. Light enhanced germination of nonstratified seeds of one source of C. japonicum and of C. magnificum from 34% to 52% and from 8% to 15%, respectively. Stratification improved germinability of both species and obviated any preexisting light requirements the seeds may have had.

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Double impatiens (Impatiens wallerana Hook.) `Blackberry Ice' (variegated-leaf) and `Purple Magic' (green-leaf) were grown on flood benches and irrigated with 50, 100, 200, or 300 mg·L-1 (ppm) N to study the effect of fertility on growth and development. Electrical conductivity (EC) levels at week 9 were similar for both cultivars at each fertilizer rate, except for the 100 mg·L-1 N where EC levels of `Blackberry Ice' were more than double those of `Purple Magic'. This indicated that the nutrient demands were less for `Blackberry Ice' and fertilization rates lower than 100 mg·L-1 N would be required. After nine weeks, plants grown with 100 mg·L-1 N had a 22% larger plant diameter than plants grown with either 50 or 200 mg·L-1 N. Fertilization rates of 50 mg·L-1 N resulted in plants which were covered with a higher percentage of blooms per unit of leaf area, but the plants were smaller. Plant tissue dry weight (leaf, bud, stem, and total) increased to the highest level at 100 mg·L-1 N, then decreased with further increases in fertilization rate. For maximum shoot growth with flood irrigation, growers should apply 100 mg·L-1 N when growing `Purple Magic' double impatiens and a fertilization rate between 50 and 100 mg·L-1 N for `Blackberry Ice'.

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