Breeding and Seed Production of Ornamental Crops (2+1)

Production of Open Pollinated varieties

Basic steps in the production of open pollinated varieties:
Site Selection

• Site selection is probably the most important factor in outdoor seed production.
• The production area should provide the required period of appropriate temperature, light and moisture condition for parent plants to develop and the seed to ripen fully.
• There should be a dry period at harvest time to allow field drying of seed
• Soil type is also an important factor in site selection. Some crops, e.g. pansy can tolerate heavy soils, while others, like nasturtium, only do well in well drained fields.
• Disease and pest pressures within the general production area are significant factors.

Isolation distance

• An open pollinated variety is one that is genetically stable and generally reproduced by self or cross pollination.
• In the open field, pollination is done by wind or insects, depending on the specific floral morphology and properties of the crop species. These natural means of pollen transfer are random in nature.
• To ensure varietal purity, care has to be taken that different seed crops of the same species are not grown closely together.
• The isolation distance requirements generally range from 200 to 1000 m or more, depending on whether the crop is mostly insect or wind pollinated.
• The topography of the production site, as well as the direction of prevalent winds should be considered when determining by how fair different varieties of the same species should be separated from each other.
• Some crops, like sweet pea, have flower structures that allow self pollination as the flowers develop and mature. Different varieties of these crops can be produced as close as 5m apart.
• Seed producers have to keep the required isolation distance in mind when they plan the placement of production fields.

Crop culture

• Agronomic practices used for flower seed production are generally similar between crops within a production area, but they vary greatly between different production areas. .
• The parent plants are usually grown in beds to facilitate irrigation, fertilizers application, and fungicide and insecticide sprays.
• The plants are checked for genetic uniformity when they begin to flower.
• Removal of off types in the population is an intensive activity. A few rounds of rouging are often necessary to ensure high genetic purity because not all plants begin to flower at the same time.
• Weeding is another labour intensive aspect of field production. There is an increasing use of plastic mulches in seed production fields for weed control and moisture conservation.
• Unpredictable weather condition, as well as pest and disease pressure requires day to day judgement on irrigation and pest management needs.
• Good seed yield and quantity occur when the environmental conditions are favourable.

Pollination

• Pollination management for open pollinated crops begins with selecting production locations naturally conducive to good seed set.
• Optimum climatic conditions must fit the crops temperature and light requirements for flowering, pollen production and stigma receptively.
• Insect pollinated crops are best placed in locations where populations of natural pollinators are high. In marginal cases, beehives can be placed in production fields to increase pollination activity.
• Honey bees are the most common pollinators. Other commercially available insect pollinators include bumble bees, leaf cutter bees and flies.
• Applications of fungicides and insecticides during the flowering period can negatively affect seed set. Some pesticides and fungicides cause damage to the stigma and interfere with pollen tube development. Insecticides commonly used for insect pest control also kill pollinating insects and reduce seed yield.