Rose breeding

1. The Scientific Basis of Rose Breeding

• Genetic improvements of the rose (concerning the transmission of characters and hereditary) have definitely improved since the Mendel laws of 1875. Since then, the different kinds of roses grown in gardens in China, Persia, Mesopotamia, Japan, Greece, Italy etc. and acquired a great adaptability to the different environments through natural pollination and mutations.
• Every rose breeder has certain more or less definite ideals or objectives toward which his breeding efforts are directed. Some of these ideals are shared by all rosarians, while others express the individuality of the breeder and may or may not find popular acceptance. Apart from improved plant characteristics, for the grower or consumers benefit, the program also focuses on developing innovations to save energy. Breeders intend to improve and increase the following characteristics:
• 1) The range of colors and shades.
• 2) The shape of the bud and of the flower especially at the point of harvesting.
• 3) The elegance of the shape and color of the bud must be accompanied by an adequate and well-proportioned length of the stem.
• 4) The duration of the vase-life of the cut flower.
• 5) The presence of thorns, which customers dislike, is subject to a strict selection.
• 6) The development of new cultivars, preferably red in color.
• 7) The plants productivity and quality.
• 8) The leaf quality.
• 9) The length and strength of the stem is essential, especially with cultivars that have a large flower.
• 10) The adaptability to the different climatic environments around the world as well as different soils.

• Mechanics of Inheritance
• Biologists are agreed that the factors determining the characteristics of plants and animals are serially located in certain deeply staining bodies of the cell nucleus, called chromosomes. Each chromosome contains thousands of genes responsible for the revelation of all the morphological characteristics. With roses, these are, for example, the shape of the leaf, the size of the plant, quantity of thorns, shape of the flower, color and the physiological characteristics such as tolerance to low temperatures, diseases and re-blossoming.
• In the case of somatic cells of rose plants, can be 2n=14 chromosomes, 4n=28 chromosomes and so on. In male sexual cells (in the pollen granules of the anthers) and in the female ones (the oospheres in the ovules inside the ovary) such number is, always half.
• The 28 chromosomes correspond to 14 couples of chromosomes in the somatic cells

2. Conventional hybridization of cut-rose breeding system

• The mother plant select
• The creation of a new rose variety is the result of a breeding and selection process by the casual union of genetic and chromosome complement of the father and mother plant (parents). Initially the parent plants are carefully selected. These are grown, as all the other plants, with sufficient foliage being the green lung through bending to encourage good quality of stems and flowers. Thereafter, the photosynthetic mass or green lung also known as bent foliage is gradually reduced and eventually eliminated after the pollination (all the branches previously bent are cut away). The mother plant or seed-bearer is grown to produce 3-4 flowers per stem to increase the number of subjects (flowers) to pollinate.
• The process of artificial pollination
• During sexual fecundation or breeding, when the breeder (by brushing), puts the pollen of a variety on the stigma of another variety, the number of chromosomes will become double again in all the cells of the new plant. Through a reduction process or meiosis, such number will only be halved in the new sexual cells.