Thursday, May 14, 2009

Plant Genealogy

Some people think all new varieties are hybrids. This is not true. There are new flowers and vegetables introduced each year that are open pollinated (OP) varieties. To understand the difference between a hybrid and an open pollinated variety, think of plant genealogy. An open pollinated plant has one parent; a hybrid has two parents. In simplest terms, hybrid seed can be defined as the seed that results from the cross-pollination of two inbred parent plants. Open pollinated varieties, by contrast, have only one parent line.

Many seeds being offered for sale in packets, mail order and at nurseries are F1 hybrids but there are a number of classes where this method of hybridization does not work. New varieties are created by a plant breeder. When a breeder has uniform, genetically stable inbred plants, he or she can consider creating new hybrids. To produce hybrid seed, pollen is moved, often by hand, but possibly by insects or the wind, from the anthers of one inbred plant (male) and placed on the stigma of the second inbred plant (female). The seed that grows as a result of this pollination is 'hybrid seed'. Hybrids are often the preferred type of a variety for a number of reasons. The hybrid parents are chosen to complement each other and/or compensate for each other's flaws, creating a new variety that is better than the best qualities of each of the parents. Hybrids tend to be very uniform, have better seed quality, and they can be more vigorous plants. Many show other aspects of improved performance such as earlier or more sustained flowering, larger flowers, or in vegetables earlier or larger fruits.

Most large-scale production of F1 hybrid seed is produced in greenhouses or enclosed shade houses. The female flower plants are grown on greenhouse benches and workers place the selected pollen on the receptive female. This control of the cross-pollination is critical for hybrid seed production. The production structures are enclosed or sealed so that no bees or other pollen carrying insects enter the structure. In certain cases the creation of hybrid seed is not feasible for several reasons. First, the biology of the plant or the flower configuration are designed for self-pollination resulting in open pollinated plants.

In other cases the cost of creating a hybrid plant is prohibitive and the hybrids may not be notably superior. For example, Salvia splendens hybrids were created, offered by several companies, and are no longer sold because the hybrids were not noticeably improved over open pollinated plants.

Open pollinated flowers or vegetables are often easier and faster to breed and produce. Breeders create new varieties by selecting "parent" plants by repeatedly self-pollinating a particular plant and its resulting progeny over several generations. For instance, a plant breeder may find a plant with an interesting or unique characteristic, either growing in the greenhouse or perhaps even growing in the wild. The breeder would pollinate this plant and grow out large numbers of the second generation as this is where the most variations occur and good combinations of characteristics from the parents are sometimes found. Normally a number of selections are made in the greenhouse and outdoors. To make sure that the variety is true to type, the best individual plants are chosen, these are self-pollinated, and the whole process is repeated from as few as three to possibly eight or more times.

Production of OP varieties often takes place in acres of fields where thousands of plants are grown. Bees may be provided to enhance pollination, and seed may be harvested by hand or with specialized equipment. The only obstacle is that each variety or color must be produced at a location distant from other varieties or colors so that cross-pollination contamination does not occur.

Once the variety has been developed, named and introduced, the work has not ended. Some classes of OP flowers or vegetables need to be very closely watched as they can become quite variable for plant or flower type. Continuous stock seed maintenance is very important to maintain good quality.

When a promising line has been developed it is then tested under various climatic conditions. Outstanding varieties may be considered for entry in the All-America Selections or Fleuroselect (European) trials.

WHAT ARE ORGANIC SEEDS? We have received inquiries about organic seed. We offer this explanation. They are seeds harvested from plants that have been grown without the use of synthetic chemical fertilizers or pesticides. Also organic seeds are not treated with any fungicide or other synthetic chemical (after harvesting) prior to sale. Organic seed is sold through retail outlets and mail-order catalogs. Some organic seeds are sold as Certified Organic Seeds. Certified seed is seed that has been certified by an independent organization that says the seed meets specific organic standards established by the organization. There are many different certifying organizations in the U.S. and internationally including Oregon Tilth (www.tilth.org) and California Certified Organic Farmers (www.ccof.org).

Dave

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