Our aim is to create high yielding and reliable varieties, suitable for all the areas where sugar beet are grown. The development of varieties is an ongoing task, and new varieties are released regularly. One of the major advances in variety development came at the end of the 1960's. Up until then all varieties were based on multigerm populations. In 1966, after almost 20 years of development, Hilleshög released the first, genetic monogerm hybrid variety in the world. Besides the improved stability and increased yield that the hybrid system provided, the real breakthrough was the reduction in working-hours that the monogerm varieties enabled. With monogerm seed - as each seed produces just one sugar beet plant - the grower is spared the laborious chore of singling plants in the field.

Monogermity

In 1948 in the USA, the Russian immigrant and sugar beet breeder V.F. Savitsky found some sugar beet plants with a unique character. At this time varieties were multigerm, meaning that each "seed" was in fact the result of a cluster of 3-5 united and not separable flowers. They in turn resulted in a similar seed cluster.   Savitsky discovered plants in some of his breeding material that had single flowers, which resulted in single seeds with only one germ. The gene source was distributed to the seed companies in both the US and Europe. Hilleshög realized very soon the possibilities of this character and crossed it into its breeding programme. In 1966, Hilleshög started selling Monohill, the first monogerm variety based on this character in Europe. Today, almost all European sugar beet growing is based on monogerm seed.

Hybrids

Even by the beginning of the 20th century, plant breeders had noticed that the yield from the progeny that resulted when two unrelated lines were crossed with each other was higher than the yield from any of the parent lines. However, one problem that faced the large-scale use of this hybrid vigour or heterosis was the plant breeders' ability to make a given crossing at a large enough scale for seed multiplication. Maize Maize, having male and female flowers separated on the plant, was the first major field crop in which hybrid vigour was used commercially. The seed multiplication of maize is still done in the same way, i.e. four rows of a line that constitute the "mother" in a crossing are planted alternating with one or two rows of another line being the "father" in the same crossing. When the plants have developed sufficiently in order to distinguish the male and female flowers on the female line, the male flowers at the top of the stalk are removed through manual or machine cutting. The row with "father" plants is left untouched and has consequently both male and female inflorescences intact. During flowering, pollen from the "father" line will pollinate the female flowers on the "mother" line, as it has no pollen itself, thereby resulting in hybrid seed. Seed is only harvested from the "mother" line. Sugar beet Hybrid varieties of sugar beet started to be produced later than those of maize. The production of hybrid seed of sugar beet is different from that of maize. One reason is that the male and female organs of the sugar beet are both placed in the same small flower. It is therefore not possible to remove unwanted male flowers on one of the two parent lines. However, in 1945 the American breeder F.V. Owen described for the first time a genetic system of the sugar beet plant that enabled male sterility (stamens not producing pollen). The system is based on a co-operation between genes in the nucleus and genes in the cytoplasm of the cell. By using this system, sugar beet hybrid seed could be produced principally in the same way as for maize. Some rows of male sterile plants from a mother line are planted alternating with one or two rows of male fertile (and female fertile) plants of the father line. The seed is then harvested only from the mother line. This seed is a pure hybrid seed and is used for commercial sugar beet growing. The plants from the father line are destroyed or removed before the harvest of the mother line.

As has been stated, it takes 10-12 years to develop a new variety. During the first stages of variety development, breeding is only done on a line level. When the most promising lines have been selected, they are crossed together to create hybrids and after that, all selections and trials are made on a hybrid level.
In the picture below, we describe broadly the time schedule for the different phases with crossings, inbreeding and field trials. You will get more detailed information about breeding on the following pages.

Crossings between selected parents

Every line that is developed is the result of carefully selected parents that are crossed together. The parents should have the characters that are required in the new variety. The cross is made by first removing all anthers from the flowers of one of the parents. The pollen from the other parent is placed on the stigma of the same flowers with the help of a brush. After 6-8 weeks the seeds of the new cross can be harvested.

Inbreeding

Inbreeding is the most important tool in the process of finding the best lines for future hybrids. In order to find the crossing progeny that combine the desired characters of the parents, the plants are forced into self-fertilisation. The easiest way to do this is to let the plant flower and set seed in small pollen-proof tents. Normally, inbreeding is made in the following 2-3 generations and is alternated with a selection process where the lines that do not consistently meet the requirements are discarded.

Selection on line level

The shape of the root and root analysis An important phase in the selection process is based around the form and smoothness of the root. At a number of trial locations the roots are lifted in the autumn and placed side by side, per line, in the field. The breeder then selects and saves the lines that combine a good root shape with healthy leaves and bolting tolerance. From the lines of interest, brei samples from the roots are analysed in order to establish the values of sugar content and amino-nitrogen. Lines that also show good results for these qualities are stored in cold chambers during the winter and proceed to renewed inbreeding or are crossed with other hybrids during the spring. Resistance characters The lines are placed in special disease trials, either in an area where the disease is naturally present, or in a greenhouse or field where the pathogen is artificially supplied. Biotechnology The more the sugar beet genome is mapped, the more help that can be obtained from molecular markers in its breeding. Much time and resources can be saved, as every unique character can be traced at an early stage by analysing the DNA-content of the sugar beet in the laboratory. In this way expensive, time-consuming and sometimes vulnerable field trials can be avoided.

Small-scaled hybrid selection

Promising lines are crossed to test hybrids. Mother lines, having a genetic make-up that makes them pollen sterile, are planted beside a father line that has normal pollen production. Seed from the mother line, resulting from a crossing between the two lines, is harvested for further testing. These crosses, or 'separations'as they are called, are placed at a certain distance from each other, which prevents pollen from spreading from one hybrid cross to another.

Yield trials

The new hybrids are placed in internal yield trials. In the first year selection is made at a limited number of trial locations. Gradually, as some hybrids are selected away, the extent of the testing and the number of locations is increased and can exceed 15 locations by year three. The locations are selected to represent a number of different growing conditions, such as degrees of water and temperature stress and different diseases. In this way, not only can the root yield and the sugar content be measured, but also the stability of the hybrids, as well as bolting and disease resistances.

Official trials

The most promising hybrids from our own trials are sent to official trials in different countries. Together with the varieties from other breeding companies, the varieties are tested by national competent authorities and by the sugar industry. Varieties are usually tested for three years. At the end of that time, in general, it will be those varieties that are as good or better than the better varieties already on the market, in one or more important characters, that will be approved. These are then included in the variety list of the sugar industry and can be used for growing.

Multiplication of basic seed lines

At the same time as the new hybrid varieties are tested in official trials, the hybrid components of the varieties - the so-called basic seed, is multiplied. This enables the rapid launch of a new variety, should it gain approval and be recommended for sales. When multiplying basic seed it is important that the genetic purity of the lines is maintained. The seed is multiplied in areas where no other sugar beet growing is present and where all cultivation of other beta species plants such as fodder beets, red beetroots and chard is controlled.