of U. kirkiana derived from marcots, grafts, and saplings; and 2) to determine whether allocation pattern and models of tree development differ among trees derived from different propagule types. Materials and Methods Site description. The study
Festus K. Akinnifesi, Simon A. Mng'omba, Gudeta Sileshi, Thomson G. Chilanga, Jarret Mhango, Oluyede C. Ajayi, Sebastian Chakeredza, Betserai I. Nyoka, and France M.T. Gondwe
Jessica D. Lubell and Mark H. Brand
Epimedium is a genus of shade tolerant herbaceous perennials and groundcovers that are slow growing and command high prices. This research examined the influence of division size and timing on propagation success and growth of E. pinnatum ssp. colchicum Boiss., E. × rubrum Morren, E. × versicolor `Sulphureum' Morren and E. × youngianum Fisch. To determine an appropriate division size for each species, small (single bud) and large (three bud) divisions were made in mid-June 2002 and 2003. For the timing study, uniform divisions (three to five buds for E. pinnatum ssp. colchicum and E. × versicolor `Sulphureum'; four to seven buds for E. ×rubrum and E. × youngianum) were made in March, late June and late August, when plants were dormant, had just completed foliage expansion, or were summer dormant. Half of the plants were destructively harvested in the fall and half were overwintered and forced in the greenhouse in early spring. By the end of the growing season, plants grown from large divisions were larger than those grown from small divisions and had produced more buds, however, plants from small divisions produced more buds per initial bud than plants from large divisions, demonstrating a faster increase in growing points. For each species, March divisions produced more vegetative growth, buds, buds per initial bud and potential propagules than June and August divisions, by the end of the growing season. However, by the following spring, both March and June divisions had produced plants of similar size and appearance, while plants grown from August divisions were smaller and of lower quality.
Kent E. Cushman and Muhammad Maqbool
Leaves of american mayapple (Podophyllum peltatum L.) contain podophyllotoxin, a compound of interest to the pharmaceutical industry. Cultural practices for establishment of mayapple in field plantings for commercial harvest have not been investigated. A factorial arrangement of three planting dates (Fall 2000, Spring 2001, or Summer 2001) and three propagule types (Nt+N1, Nt, or Nx; as described by Maqbool et al., 2004) were used to investigate strategies for establishing mayapple plantings. Rhizome segments were harvested from the wild and transplanted into plant beds in full sun in northern Mississippi. Plant emergence was recorded during March and April of each year from 2001 to 2004. Leaves within each plot were harvested as soon as they began to yellow, from the third week of April to the first week of June each year. Propagule type and planting time interacted to affect subsequent plant growth when measured on an area basis (per square meter of growing area). In 2004, spring-planted Nt+N1 produced more shoots with greater total leaf area and dry mass than spring-planted Nx or Nt. In contrast, Nt+N1 transplanted during fall or summer was equal in performance to that of Nx or Nt. Performance of summer-planted Nt was poor, producing far less leaf area and dry mass than any of the other treatment combinations. On a per plant basis, fall-planted propagules produced greater leaf area and dry mass in 2004 than spring- or summer-planted propagules, and Nt+N1 produced greater leaf area than Nx or Nt. The effect of year was not analyzed in this study due to complications of the experimental design. In conclusion, overall plant growth and performance of spring-planted Nt+N1 can be recommended as excellent and that of fall-planted Nt as poor. All other treatment combinations can be recommended as good. These results will assist growers of specialty crops in establishing mayapple plantings under field conditions in full sun.
Joe-Ann McCoy, Jeanine M. Davis, N. Dwight Camper, Ikhlas Khan, and Avula Bharathi
. Specific objectives were to 1) determine optimal rhizome propagule division size for successful regeneration, 2) quantify survival rates after 3 years of production, 3) compare triterpene glycoside concentrations between sites and rhizome propagule size
Lurline Marsh, Corrie Cotton, Elizabeth Philip, and Isoken Aighewi
Ginger(Zingiber officinalis) is a spice crop with a variety of medicinal uses. Potentially, it may be suitable for ethnic production following necessary studies to determine optimum cultural conditions. The propagation of ginger from rhizomes was investigated using three growth media, three media moisture levels, and two types of propagules. The media were poultry compost amended with peat and perlite in a volume ratio of 2:1:1, municipal yard waste compost, and the commercial mix Promix. The moisture levels of each medium were: no applied water, moderately watered (between wilting point and field capacity), and field capacity, which represented moisture tension levels of >–1.5, –0.08, and –0.03 MPa, respectively. Growth from single-node rhizome propagules and large pieces of 5.6 to 7.6 cm long with one or more nodes was determined over 90 days. The large propagules and the field capacity moisture regime produced the tallest shoots, and largest number of shoots and leaves per propagule, as well as the highest percentages of secondary rhizomes, root, and shoots per propagule. The yard waste and Promix were superior to poultry compost in the development of the propagules for all the traits measured. The large propagules produced earlier shoot emergence at field capacity than at the moderate moisture levels. Single-node propagules generally failed to emerge without applied moisture or when in poultry compost.
Dirk R. Vuylsteke and Rodomiro Ortiz
In vitro-propagated plants of plantain (Musa spp., AAB group) did not manifest consistently superior horticultural performance compared to conventional propagules. Tissue culture plants grew vigorously and taller than sucker-propagated plants, but higher yield was not obtained, probably because of severe disease and suboptimal husbandry input. Phenotypic variation was higher in tissue culture plants, although this increase was not always statistically significant. There were no other detrimental effects of in vitro propagation on field performance. Botanical seed set rates for the two types of propagules were similar. The advantages of tissue-culture-derived plants as improved planting material would be most relevant for establishing field nurseries for further clean, conventional propagation of newly bred or selected genotypes.
Mélanie Leclerc, Claude D. Caldwell, Rajasekaran R. Lada, and Jeffrey Norrie
Field experiments conducted in 2002 and 2003 evaluated the effects of timing of inflorescence removal on propagule formation, growth and development of Astilbe ×arendsii, Hemerocallis spp. and Hosta spp. Four timings of inflorescence removal were tested: 1) no removal (control), 2) removal at inflorescence emergence, 3) removal at preflower, and 4) Removal at full flower. Propagule formation in Astilbe was not enhanced by inflorescence removal. Hemerocallis plants with their inflorescences removed at emergence produced 25% more divisions than plants with their inflorescences removed at preflower. For Hosta, plants with inflorescences removed at pre- and full flower produced respectively 40% and 53% more divisions than control plants. These results have economic implications for commercial bare-root production, which need to be verified on a larger field scale.
Kent Cushman* and Muhammad Maqbool
The American mayapple (Podophyllum peltatum L.) is native to eastern North America and its leaves contain the pharmaceutical compound podophyllotoxin. Podophyllotoxin is used in the manufacture of several types of drugs used in the treatment of cancer, arthritis, and various skin conditions. With leaves being a renewable resource, the plant is a candidate for cultivation by growers of specialty crops. We are investigating strategies of establishing mayapple in field plantings. Rhizome segments were harvested from the wild and immediately transplanted to raised beds in northern Mississippi. There were three planting times, Fall 2000, Spring 2001, or Summer 2001, and three propagule types: (1) two-node rhizome segments with a terminal node and its adjacent one-year-old node, referred to as Nt+N1, (2) one-node segments with a single node, other than Nt, of unknown age, referred to as Nx, or (3) one-node segments with a single terminal node, referred to as Nt. Each spring, shoots emerged from the ground in March, grew during April, and senesced throughout May. Shoot emergence, leaf area, leaf dry mass, and shoot height were recorded each spring. Plant growth and performance can be ranked as follows. EXCELLENT: Spring-planted Nt+N1. GOOD: Fall- and summer-planted Nt+N1; fall-, spring-, and summer-planted Nx; and spring-planted Nt. FAIR: Fall-planted Nt. POOR: Summer-planted Nt. We can now recommend all three planting dates, but in the following order of preference: spring > fall > summer. We can also recommend two of the three propagule types, also in the following order of preference: Nt+N1 > Nx. The Nt propagules performed adequately when planted during fall or spring, but they did not perform well when planted during summer.
Mélanie Leclerc, Claude D. Caldwell, Rajasekaran R. Lada, and Jeffrey Norrie
Field experiments were conducted in 2002 and 2003 to evaluate the effects of selected plant growth regulators on propagule production in Hemerocallis `Happy Returns' and Hosta `Gold Standard'. Benzyladenine (BA), chlormequat chloride (Cycocel), ethephon (Ethrel), prohexadione calcium (Apogee), and an experimental preparation of commercial seaweed extract (Acadian Seaplants Limited Liquid Seaweed Concentrate) amended with BA and IBA were tested at two times of application and three rates of application. Results with Hemerocallis showed that the application of the seaweed/PGR mixture at 3000 mg·L–1, Cycocel at 3000 mg·L–1 or BA at 2500 mg·L–1 applied at flowering, increased the number of plants producing two divisions compared to control plants. In Hosta, no increase in divisions under any treatments was observed.
James W. Frisby and Schuyler D. Seeley
We determined whether the chilling process (endodormancy release) was similar in peach [Prunus persica (L.) Batch cv. Johnson Elberta] seeds, seedlings (near normal to physiologically dwarfed), and mature plants (cuttings) by comparing correlation coefficients of various growth measurements following similar chilling treatments. Seed germination (10 days after forcing at 20C) and seedling emergence (15 days after forcing in the greenhouse) correlated highly with leaf and shoot growth (56 days of growth) of seedlings and terminal shoot growth of cuttings (13 days after forcing). The correlations were higher for germination than for emergence. Initial (first season) seedling growth correlated poorly with germination, emergence, budbreak, and growth of seedlings (second season) and shoot growth of cuttings. Budbreak and growth of seedlings correlated highly with shoot growth of cuttings. The abnormal leaf problem, which can cause apex abortion (common with initial seedling growth), confounded correlations with initial seedling growth. Yet, the abnormal leaf problem did not hinder correlations with the second seasons growth. Good relationships between the chilling mechanisms that promoted germination, emergence, budbreak, and growth of seedlings and shoot growth of cuttings existed, but were dependent on what was measured and when the measurement was taken. Germination (forced at 20C) was the most accurate indicator of the seed chilling status for comparisons with the responses of the other propagules.