Search Results

You are looking at 1 - 10 of 47 items for

  • Author or Editor: Mark H. Brand x
Clear All Modify Search
Free access

Mark H. Brand

Nursery production of many ornamental grasses involves potting of established liners into 8.5-L containers. Direct potting of bare root divisions into 8.5-L containers may represent a more efficient production method. Large and small divisions (based on number of tillers and volume) of eight ornamental grasses were potted directly into 8.5-L containers. The potting medium used was a 3 aged pine bark: 2 peat moss: 1 sand nursery mix (by volume), amended with dolomitic lime at 3 kg/yard3, and top dressed with Sierra 17-6-10 plus minors at 40 g/container, 8 to 9 month fertilizer. Plants were grown outdoors in a container nursery from May through September. All grasses tested performed well using the direct potting method, with 100% survival. Large divisions of Miscanthus sinensis cultivars produced plants with greater fresh weight, dry weight and number of tillers than did small divisions. Division size did not affect Miscanthus foliage or flower height but did affect number of flowers for `Graziella' and `Purpurascens'. Large divisions of Calamagrostis `Karl Foerster', a grass grown primarily for flowering, produced twice as many flowers as small divisions. Panicum virgatum and Pennisetum alopecuriodes showed signs of nutrient stress when grown from large divisions. Although a greater number of tillers was produced by large divisions of Panicum and Pennisetum, fresh weight, dry weight, flower height, and foliage height were similar to or less than that observed on plants from small divisions.

Free access

Mark H. Brand

Information on fertility optimization for container-grown ornamental grasses is limited. For ornamental grasses, growers are concerned with the degree of flowering, number of tillers, and height and width of the plants as well as other growth or ornamental components. Pennisetum alopecuroides divisions potted into 8.5-L containers were grown outdoors in a container nursery from May through September. The potting medium used was a 3 aged pine bark: 2 peatmoss: 1 sand nursery mix (by volume), amended with dolomitic lime 3 kg/yard3. Sierra 17-6-10 plus minors, 8 to 9 month controlled-release fertilizer (CRF) was top dressed at 20, 30, 40, 50, or 60 g/container. Foliage height increased linearly with increasing CRF rate. Flower height increased to a maximum at 40 g of CRF per container and then decreased with higher levels of CRF. Basal plant width exhibited a quadratic response to CRF rate, reaching a maximum at 40 g of CRF per container. The greatest number of flowers and tillers were obtained using 50 g of CRF per container. Maximizing the number of flowers is important for marketing of Pennisetum, since this plant is grown primarily for its flowering.

Free access

Mark H. Brand

To introduce desirable trait genes into Kalmia latifolia, efficient adventitious shoot regeneration methods are needed. Silver Dollar (S$) callus induction and growth in the dark was compared on Woody Plant (WP) medium containing 2,4-dichlorophenoxyacetic acid (2,4-D) (1, 5, 10, 20 μM) or naphthaleneacetic acid (NAA) (1, 10, 20, 40 μM) with and without 5 μM isopentenyladenine (2iP). Both 2,4-D and NAA produced >450 mg of callus from leaf explants in 8 weeks. The addition of 2iP tripled growth for 2,4-D and doubled growth for NAA. Greatest callus growth was obtained on 20-40 μM NAA or 5-20 μM 2,4-D. Shoot regeneration on callus was achieved on WP medium containing 30 μM 2iP or 1 μM thidiazuron (TDZ), but a combination of the two was best, with 68% of dark-grown calli regenerating shoots in 4 weeks. 26% more dark-grown calli regenerated shoots than light-grown calli. The type of auxin (2,4-D or NAA) used to grow the calli did not affect shoot regeneration. For direct shoot regeneration, S$ leaf explants were tested on WP medium containing 5, 15, 30, 45 and 60 μM 2iP. The addition of 1 μM indole-3-butyric acid (IBA) doubled the percentage of leaves that regenerated shoots. 2iP concentrations between 15 and 45 μM supported excellent shoot regeneration, but optimal regeneration (95% of explants, 5.1 shoots/leaf) occurred on 30 μM 2iP+1 μM IBA. Leaf explants of six cultivars were grown on optimal medium with shoot regeneration ranging from 17% to 93% of leaves and 1.8 to 8.2 shoots per leaf, depending on the cultivar.

Free access

Mark H. Brand

Potting of bare-root spring divisions is a simplified approach to ornamental grass production. Large and small divisions of eight common ornamental grasses were directly potted into 7-L nursery containers and grown outdoors for 20 weeks to determine an appropriate division size for each grass. Response to division size was dependent on the grass species. Large divisions of Calamagrostis ×cutiflora `Karl Foerster' (Schräd.) produced twice as many inflorescences as small divisions. At harvest, large divisions of Miscanthus oligostachyus `Purpurascens' (Stapf.) had twice as many inflorescences and 1.5 times as many tillers as small divisions. However, new tiller production in large divisions was only 50% of that in small division plants. Large divisions of Miscanthus sinensis (Anderss.) cultivars produced more tillers and greater fresh and dry weights than did small divisions, but again, the differences were not proportional to the size difference between the initial divisions. Large divisions of Panicum virgatum (L.) produced 50 more tillers per plant than did small divisions, but plant weight, size, and number of inflorescences were not affected by division size. Plants from large divisions of Pennisetum alopecuroides (L.) Spreng. were 7 cm shorter than small divisions and produced 24% more inflorescences and 27% more tillers, but appeared nutrient and/or water stressed. For most grasses, smaller division size is recommended for direct spring potting.

Free access

Mark H. Brand

Although it is commonly recommended that shoot tip cultures be initiated from actively growing shoots, it has been demonstrated that shoot tips collected during the period of rapid shoot extension fail to produce shoot proliferating cultures. Shoot tips of Halesia Carolina and Malus `Golden Delicious' were collected at 2 week intervals from budbreak to summer dormancy and placed on medium containing 0, 4.5, 11.0, 22.5 and 44.5 uM benzyladenine (BA) to determine if elevated BA concentrations could overcome seasonal patterns of shoot proliferation potential (SPP). Both species reached maximum SPP 4 weeks post-budbreak (PBB), and exhibited a second window of high SPP during weeks 10 and 12. Elevated BA concentrations failed to overcome poor SPP exhibited by shoot tips harvested 6 to 8 weeks PBB. Shoot tips collected at 10 to 12 weeks PBB responded more favorably to higher exogenous BA concentrations than shoot tips collected at 2, 4, 6, or 8 weeks PBB. It appears as though seasonal fluctuations in SPP involve other endogenous factors in addition to cytokinins.

Free access

Mark H. Brand

Container production of recently-developed and popular Kalmia latifolia cultivars has not been fully optimized. A study was conducted using six cultivars grown in full sun, 40% shade or 60% shade. Under 60% shade, plant height was reduced slightly, but shading, at either 40% or 60%, had no significant effect on all other measured growth parameters. Plants were too young to set significant numbers of flower buds, so the study will be continued a second year to quantify the effects of shade on flower bud set. Foliage color was measured using a Minolta CR-200 Chroma Meter. As shading increased, hue angle increased and the chroma and value of the color decreased, indicating that shading produced greener (less yellow), darker and duller foliage colors. Foliar chlorophyll content increased with increasing shading. Higher foliar chlorophyll content correlates with greener leaves in shaded treatments and is likely contributing to the green color. Using moderate levels of shade over container-grown Kalmia could allow growers to produce greener, more marketable plants without sacrificing plant growth.

Free access

Mark H. Brand

The effect of shading during nursery production on the growth, foliage color, and foliar chlorophyll content of container-grown Kalmia latifolia cultivars was investigated. Five cultivars were grown under 40% shade, 60% shade, or full sunlight for a 2-year production cycle. During the first year of production, there were no significant differences in measured growth characteristics for most cultivars in response to light treatment. Shade improved foliar color by decreasing lightness (L*), decreasing chroma, and changing hue angle from a yellow-green to a darker green. Foliar chlorophyll concentration increased under shade. In the second year of the production cycle, the response of foliar color and chlorophyll concentration to shade was similar to that observed in year 1. Plant size, number of branches, leaf area, leaf dry mass, and stem dry mass decreased linearly with increasing shade in year 2. Although shading improves foliar color, it probably should not be employed for container production of Kalmia latifolia in cool, northern production areas due to reduced plant growth during year 2. Shade may be useful in the first year of production to enhance foliar color without reducing shoot growth.

Free access

Mark H. Brand and Richard Kiyomoto

Tissue proliferation (TP) of Rhododendron sp. is characterized by basal tumors that often develop into numerous dwarf shoots. Growers need to know if the TP condition will recur in plants grown from normal-appearing cuttings collected from plants with TP tumors. Stem cuttings of seven cultivars were collected from stock plants with TP [TP(+)] and without TP [TP(–)] and rooted. Plants were grown in containers outdoors for 2 years and were then evaluated for tumor formation and other TP-related morphological symptoms. Shoots of TP(+) plants were either similar in length to shoots of TP(–) plants, or were shorter, as was the case for `Boule de Neige', `Catawbiense Album', and `Montego'. Plants grown from TP(+) cuttings of all cultivars had more leaves per growth flush than did plants grown from TP(–) cuttings. `Holden', `Montego', and `Scintillation' TP(+) leaves were narrower than leaves from TP(–) shoots and had greater length: width ratios. Leaves of TP(+) `Montego' and `Scintillation' plants were shorter and smaller than leaves from their TP(–) counterparts. Tumors were not observed on any propagated plants, regardless of the TP status of cutting stock plants. To further test the influence of age and TP status of source plants used for cutting propagation, `Montego' plants were grown from cuttings collected from the following sources: 1) in vitro shoot cultures; 2) 3-year-old plants with TP; 3) 6-year-old plants with TP; and 4) TP(–) plants. Cuttings from TP(+) micropropagated plants less than 3 years old were more likely to develop tumors than were cuttings from older plants. Eighty-three percent of plants from microcuttings and 74% of plants from cuttings of 3-year-old TP(+) plants formed tumors, whereas no plants grown from 6-year-old TP(+) or TP(–) cuttings did so. Large tumors that surrounded half or more of the stem were more likely to develop on plants grown from microcuttings than on plants grown from the next youngest, 3-year-old TP(+), stock plants. Growers must be aware that cuttings from TP(+) plants may produce plants that exhibit morphological and growth abnormalities, possibly even including tumor redevelopment.

Free access

Yiqin Ruan and Mark H. Brand

Rhododendron `Montego' shoot cultures initiated from plants with and without tissue proliferation (TP and NTP) served as explant sources for all studies (Note: in vitro TP shoot cultures produce primarily dwarf shoots, some long shoots, and stem tumors). Calli induced from TP leaves and tumors and NTP leaves were cultured on woody plant (WP) medium containing NAA and 2-iP. During the first 4 weeks of culture, calli from NTP leaves had higher relative growth rates than calli from TP leaves or tumors. However, calli from TP leaves and tumors grew faster than calli from NTP leaves for all subculture periods that followed. Shoot tips (5 mm) were excised from TP dwarf shoots, TP long shoots, and NTP shoots and were cultured on WP medium with or without 15 μM 2-iP. Shoot tips from TP dwarf and long shoots multiplied on medium without 2-iP, averaging 18.4 and 1.7 shoots per shoot tip in 12 weeks, respectively. Shoot tips from NTP shoots only multiplied when maintained on 2-iP-containing medium. When placed on 2-iP-containing medium, both types of TP shoot tips produced clusters of callus-like nodules that gave rise to highly tumorized, short shoots or leafy meristems.