June 2008

Floriculture Research in full bloom By Mark Bridgen

Editors' Note: Last month's GPN featured the first in a five-part series of stories on Cornell University's Long Island Horticultural Research & Extension Center. The following articles will highlight the center's floriculture research and extension programs. Upcoming issues will feature Dan Gilrein (entomologist), Margery Daughtrey (plant pathologist) and Andrew Senesac (weed scientist).

The Long Island Horticultural Research & Extension Center's research program is driven by the needs of the horticulture industry, specifically floriculture. My interests are in the areas of new plant development and breeding, plant?environment interactions, plant cell and tissue culture, in vitro plant breeding, plant propagation, genetic modifications for plant improvement, and plant growth and development of ornamental plants.

A successful academic research program is only as good as the graduate students who provide assistance to the program. In the past 24 years, I have had the opportunity to advise many excellent graduate students who contributed greatly to the work that will be described.

Alstroemeria Breeding Efforts

The beginning of my breeding program with alstroemeria, the Lily-of-the-Inca or Inca Lily, was the result of a research grant funded by the American Floral Endowment (AFE) during my first year as a faculty member. One of the endowment's priorities was breeding Alstroemeria to produce American cultivars. Breeding alstroemeria created many exciting and diverse opportunities for me. The most wonderful has been my collection of wild alstroemeria species in Chile and Brazil. I have collected plants in Brazil only once but have been to Chile more than a dozen times.

My initial trips to Chile were with Adrianna Hoffmann, a well-respected botanist turned defender of Chile's environment. Her enthusiasm for Chilean plants was contagious and was responsible for my later breeding with other Chilean geophytes.

Breeding alstroemeria has been an integral part of my entire research career, beginning with traditional breeding of species that were collected. We quickly discovered that although seeds could be produced on interspecific hybrids — crosses between two different species — the seeds would abort before they reached maturity. This is when tissue culture techniques, specifically embryo culture, became important: We discovered that if we aseptically removed the embryos from the seeds on the mother plant early in their development and tissue cultured them on a sterile nutrient medium, the hybrids would often survive. Other in vitro techniques such as somaclonal variation, somatic embryogenesis and mutation induction have been developed over the years to produce new plants.

Alstroemeria Breeding Results

This exciting research led to the introduction of several novel, winter-hardy cultivars, including the first fragrant cultivar of alstroemeria on the market, 'Sweet Laura', and our patented 2007 introduction, 'Mauve Majesty'. Several of my students through the years have worked with alstroemeria: Betsy Kollman; Ockert Greyvenstein; Dr. Eduardo Olate, who still breeds this plant; Dr. Alessandr Chiari; Dr. Chunsheng Lu; Mark Smith; and Joe King.

Currently, our breeding objectives for alstroemeria are to develop varieties that are winter-hardy to USDA Zone 5, fragrant and suitable as potted plants. Hybrids from the recent work of Betsy Kollman and Maggie Saska are in their fourth year of trials and contain spectacular plants with peach-colored flowers, white flowers and a variety of color variations. There are varieties that are suitable for potted plant production and are short-day photoperiodic, which allows their flowering to be timed.

Other Breeding Projects

Since moving to Cornell University, I have been able to breed several other species of plants. Our breeding team has been focusing on some Chilean geophytes, particularly leucocoryne, conanthera, zephyra and rhodophiala. Breeding bulb crops is time consuming because often it takes three to four years from seed to flower. However, we are at a point now where we are testing some leucocoryne varieties that can be used as cut flower or garden varieties.

Our newest — and most exciting — project is with the genus plectranthus, sometimes known as the Swedish Ivy. Species from this genus are mostly soft, low-growing, semisucculent to succulent herbs. Some of them have unusually beautiful tubular flowers ranging in color from blue and violet to white and pink. Very little attention has been given to the beautiful flowers some of these plants produce or the potential that they have as garden plants. Two recent South African hybrid introductions of plectranthus, 'Mona-Lavender' and 'Cape Angel', have brought more attention to this group of plants. There is great potential for breeding and improvement of plectranthus, especially as a novel, shade-loving annual. These plants are normally fast growing, easy to root, and have ornamental foliage and beautiful flowers that make these plants very appealing. Ockert Greyvenstein is currently working on this project.

Season Extension of Field-Grown Cut Flowers

Since moving to Long Island, I have become more involved with the horticulture industry, which is extensive, diverse and, fortunately, geographically compact. The vegetable growers produce large numbers of field-grown cut flowers and look for new ways to increase their productivity, so we have developed programs specifically to extend the growing season of cut flowers.

Season-extension technologies, such as high tunnels, are used to extend the growing season in the spring and fall and protect the crops from the environment and pests. The production of cut flowers earlier or later in the season results in higher market prices. During 2007, several new cut flower varieties were grown early in the spring inside the high tunnels, including dianthus 'Sweet Purple'; stock (matthiola) 'Glory Pink', 'Glory Lavender', 'Glory Cherry', 'Glory Blue' and 'Glory White'; and snapdragon (Antirrhinum majus) cultivars 'Lavender', 'Pink', 'Plum Blossom', 'Rose', 'White' and 'Yellow'.

High tunnels allowed cut flower plants to flower earlier and obtain longer stem lengths than plants grown without protection. In many cases, there was also a reduction in the number of insect attacks within the tunnels.

This year, work with cut flowers and high tunnels will continue. We will be planting herbaceous perennial plants that are useful as field-grown cut flowers experiments both inside and outside of the high tunnels. Because our season on Long Island is long and markets are strong until Halloween, we are also planning to try field-grown cut mums under high tunnels and determine whether they are economically profitable.

LIHREC Trial Gardens

In 2005, a new research project — the long-term evaluation of herbaceous ornamental plants — began at Cornell's LIHREC because the perennial plant growers wanted a central, nonbiased location to grow and test the landscape performance of these plants under Long Island conditions. Thanks to the donation of more than 600 different plants from The Plantage, Glover Perennials, Talmage Farm and David Rose Perennials, the project had an excellent start on a 2-acre trial site. The project also allows new plants to be evaluated, promoting interest in the use of herbaceous plants in the landscape. Companies such as Proven Winners, Anthony Tesselaar International and Terra Nova have recently trialed their new plants at the LIHREC. Each year, these plants are evaluated from a professional landscaper's perspective: We record when the plants flower, their size and uniformity, winter hardiness and susceptibility to pests and diseases.

Since 2004, we have been conducting field trials of potted chrysanthemum varieties thanks to the support and generosity of the three major chrysanthemum breeders, Ball Horticulture, GroLink and Yoder Brothers. This project has grown in popularity, with guests from the United States, Canada and Europe visiting each year. We also conduct an educational program each fall and a Chrysanthemum Field Day where growers and other stakeholders can observe genetic differences in plant size and flower color of the various cultivars. During 2007, we evaluated 174 commercial chrysanthemum cultivars from the three breeders: Plants were potted into 9-inch pan pots and grown on landscape fabric, and we recorded the dates that the plants first showed color, when they reached full bloom and when they first turned to an unmarketable stage. Final height, shape and deformities such as splitting were also recorded.

During 2007, two major research projects were conducted at the LIHREC to evaluate the effect of controlled-release fertilizers (CRF) on the growth of field-grown potted chrysanthemums. Currently, most commercial growers of potted chrysanthemums fertilize their plants with soluble liquid fertilizers (LF) as daily applications in the irrigation water. LF has the potential to leach unused nitrates from the pots into the soil. CRFs can be used to decrease the amount of nitrates and other nutrients that are leached from pots. This research was conducted in cooperation with the Scotts Co. and SunGro Horticulture to determine whether their respective CRFs could be used as the exclusive or partial sources of fertilizer for outdoor potted chrysanthemums. The traditional procedure of using constant liquid feed of soluble fertilizers was compared to different formulations of CRFs.

The plants that received CRF alone grew into nice, marketable plants. The final size of the CRF plants was not as large as plants that received constant liquid feed, but the plants were still of high quality (Figure 1). A second study demonstrated that CRF plants can grow to a size and quality equal to an LF plant by supplying LF to the plants for only the first four to six weeks of its production. Next year, additional research will be conducted with different levels and application rates of CRF to determine if similar quality plants can be produced.