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Armitage, A.M. 1990. New herbaceous ornamental crops research. p. 453-456. In: J. Janick and J.E. Simon (eds.), Advances in new crops. Timber Press, Portland, OR.

New Herbaceous Ornamental Crops Research

Allan M. Armitage

  1. INTRODUCTION
  2. UNIVERSITY OF GEORGIA SYSTEMS APPROACH TO NEW CROP EVALUATION
  3. SPECIFIC RESEARCH TOPICS
    1. Flowering Physiology
    2. Gas Exchange
    3. Growth Regulators
    4. Spacing
    5. Shading (Field Flowers)
    6. Postharvest
  4. CONCLUSIONS
  5. REFERENCES
  6. Table 1
  7. Fig. 1

INTRODUCTION

A great deal of interest in new floricultural crop research has occurred in recent years. The conferences in Davis, California, 1986 (Criley 1987) and Aarslev, Denmark. 1988 provided new and exciting avenues of study In general, three basic areas of research are presently being conducted in herbaceous ornamental crops around the world (Armitage 1987a). The first area consists of cultivar research in well-established ornamental species (type I species). For example, research evaluating new inflorescence shapes of Dendranthema grandiflora Tzvelev., new flower colors of Petunia xhybrida Vilm. or leaf varigation patterns of impatiens fall into this category. The second area deals with new uses for well known minor crop species (type II species). Examples include investigations into species of Aquilegia L., Armeria maritima Willd., Calendula officinalis L., and Capsicum annuum L., well known garden species, as potted plants. The third area of research involves development and evaluation of species about which little or no information concerning flowering physiology or performance under production conditions exists (type III species). The use of Melampodium paludosum L., Trachelium caeruleum L. or Cedrela sinensis Juss. as pot plants falls under this type of research as do investigations into Achillea x `Coronation Gold', Caryopteris incana Miq. or Oxypetalum caeruleum Decne. as field grown cut flower crops. The greatest amount of prior selection occurs with type I species, followed by type II while little, if any, selection has taken place in type III species. The grouping of species is dynamic and in a constant state of change. As type III species become accepted in the floriculture trade, they are relegated to type II or type I species. Examples of new crop species are listed in Table 1.

The potential for basic research is rich for type II and III species. Little is known concerning the control of flowering in these species and fruitful areas of investigation might include gas exchange, photoperiod manipulation, carbon partitioning, and factors affecting the onset of flowering. Information pertinent to commercial use, however, such as height control, irradiance levels, optimum temperatures and propagation techniques must also be understood before industry accepts a new species. In the case of cut flowers, the influence of spacing, shading, fertility and planting time on yield and shelf life may be exciting directions for research.

Little funding is available in the United States for new crop research in floriculture and scientists must balance fundamental studies on flowering physiology with applied applications to industry.

UNIVERSITY OF GEORGIA SYSTEMS APPROACH TO NEW CROP EVALUATION

The University of Georgia New Crops Program involves research on type II and type III species in two facets of floriculture: new pot plant crops for the greenhouse and new cut flower crops for the field. An enormous number of species exist with potential as new crops in one or both of these areas. The dilemma of the scientist is to not overlook potential successful species while at the same time ignoring or discarding those with little chance for acceptance. Therefore, a new crop program must have a system to choose species for research and to evaluate and develop information on those selected (Armitage, 1986). The most fundamental aspect of any system is that it be capable of quickly discarding species from the program. The systems approach used at Georgia has a number of places where the decision to terminate research on a species may be made (Fig. 1). The primary objective of our program is to develop information on crops with the following characteristics:

Potted plants must have at least 1 week shelf life without addition of extending sprays; cut flowers, 5 days without silver thiosulfate (STS). Floral preservatives are used in the case of cut flowers. If the shelf life is less than this standard, the decision may be made to terminate the species or to determine methods to extend shelf life.

The time from propagule (cutting or seed) to flower for pot plants must be less than 20 weeks. Many species occur for which rapidly flowering cultivars may one day be developed, however, there is little chance of commercial acceptance if greenhouse production time results in excessive cost of production. The program in Georgia is not in the position to spend the time necessary to breed and select new cultivars. The additional time required for slow flowering species detracts from other species to be investigated. If flowering time is felt to be too long, work on the species is terminated.

Exceptions may be made with species of outstanding potential such as Eustoma grandiflorum (Raf.) Shinn. In these cases, production partitioning within the industry will evolve. That is, propagation and growing occurs at one site while forcing into flower occurs at another. In this instance, it behooves the scientist to similarly partition his research on the species.

Species must be relatively tolerant of "normal" pests and diseases. Introducing species particularly attractive to whiteflies or highly susceptible to Botrytis should be avoided. If species being tested show weakness to diseases and pests, work may be terminated.

The new species should not have a deleterious effect on established commercial species. For example, our work with unproved cultivars of Primula obconica looked promising; however, the species contains primin and results in dermatitis in a small percentage of people. The adverse effects of primin could adversely affect sales of all primula species, particularly P. acaulis. Thus, the work was terminated.

Although the system provides objectivity, decisions to terminate are at the discretion of the scientist. Thus, the scientist in charge needs to work closely with industry.

SPECIFIC RESEARCH TOPICS

Flowering Physiology

Salvia leucantha. Plants are SD with a critical photoperiod of 12 hours for macrobud development and 10 hours for subsequent flower development. Approximately 14 cycles are necessary for initiation but 42 cycles are needed for normal anthesis and raceme elongation (Armitage and Laushman 1989).

Trachelium caeruleum. Plants are LD with a minimum of 14 hours for flower initiation but day neutral for subsequent flower development (Armitage 1988b).

Pentas lanceolata. Plants are quantitative LD, flowering 7-10 days earlier than SD (Armitage 1988a).

Oxypetalum caeruleum is day neutral for flowering but significant internode elongation occurs with LD (Armitage et al. 1990).

Gas Exchange

Trachelium caeruleum. Light compensation and light saturation are approximately 15 and 600 µmoles s-1 m-2 respectively at 25°C. At saturation, net photosynthesis is 10-12 mg CO2 dm-2 h-1 (Armitage, 1988b).

Oxypetalum caeruleum. Light compensation occurs at 25 µmoles s-1 m-2 and saturation at 700 (Armitage et al. 1990).

Growth Regulators

Height control—Height regulation studies with Melampodium paludosum, Pentas lanceolata (Armitage 1988a), Calendula officinalis (Armitage et al. 1987), and Trachelium caeruleum (Armitage 1988b) have indicated that these crops may be useful for commercial pot plant production.

Fruit ripening—Use of 150-300 ppm of 2-(chlorethyl) phosphonic acid resulted in accelerated ripening of fruit of Capsicum annuum under greenhouse conditions (Armitage 1989a). Concentrations of 75 ppm was less effective and 600 ppm resulted in phytotoxicity.

Spacing

Studies on spacing were conducted with Achillea x 'Coronation Gold', Physostegia virginiana Benth. and Salvia leucantha as field grown cut flowers. Yield per plant increased as spacing increased but yield per area decreased (Armitage 1987b).

Shading (Field Flowers)

Anemone coronaria L. Stem length increased significantly under 55% light reduction compared with ambient (Armitage and Laushman, 1990).

Echinops ritro L., Eryngium planum L. Reduction of ambient light resulted in increased stem lengths for both species. Yield of Eryngium decreased with 55% light reduction, however, yield of Echinops, increased significantly. Additional shade reduced yield of both species.

Postharvest

Species with increased shelf life from dips with sodium silver thiosulfate (STS) include Anemone coronaria, Physostegia virginiana and Salvia leucantha.

Optimum time of bulb planting was determined for Acidanthera bicolor Hochst., Anemone coronaria, Brodiaea laxa Engler, Allium sphaerocephalum L., Polianthes tuberosa L. and Liatris spicata Willd. Perenniality and yield response was determined over a 3-year-period (Armitage and Laushman, 1990).

CONCLUSIONS

New crops are the lifeblood of the floriculture industry. New cultivars of established crops have historically kept the industry strong but entirely new crops must be introduced continually to maintain consumer interest. Research on new crops is necessary to provide information to control flowering time, manipulate plant size, and provide repeatable schedules. However, far more potential species exist than can be evaluated and developed. A systems approach to new crop research is essential in order that limited resources are used efficiently.

REFERENCES

Table 1. Potential species for pot and cut flower culture for new crop research.

Type I. (Species well established as ornamental plants)

Type II Species (New uses for well known minor crops) Type III Species (little information available)

Fig. 1. Systems approach to crops research at University of Georgia New Crops Program (from Armitage 1986).

Last update September 4, 1997 by aw