One basic prerequisite for the production of high-quality apples is the effective pollination of the blossoms. Apples are dependent chiefly upon cross-pollination. Controlled cross-pollination is carried out in order to determine suitable combinations of varieties. On the basis of data compiled also at the Laimburg Research Centre since 2002 by the “Varieties and Rootstocks” working group for apples and pears in the framework of EUFRIN (European Fruit Research Institutes Network), data on suitable pollen donors for new apple cultivars is being constantly collected (Table 1).
• • •
Suitable pollination combinations of new apple varieties
One basic prerequisite for the production of high-quality apples is the effective pollination of the blossoms. Apples are dependent chiefly upon cross-pollination. Controlled cross-pollination is carried out in order to determine suitable...
Read more
Controlled pollination
The blossoming branches of the female varieties are covered with cotton bags in the balloon stage in order to prevent cross-pollination. When full flowering is reached, the dried pollen of the male varieties is applied to the stigmas of the female plants (Fig. 1). The fruit set rate represents the ratio of developed fruits to pollinated flowers, and is used to determine the pollination success: A fruit set rate of 0 to 5.9% is classified as “poor,” of 6.0 to 9.9% as “moderate,” and of more than 10% as “good.” At least two test years are necessary in order to define the suitability of a pollen donor for a new variety.
Pollination results
In the case of 75% of the trials, a fruit set rate of almost 30% - which is characterized as “good” – was recorded (Fig. 1). Cross-pollinations with “poor” fruit set showed rates averaging less than 3% and produced significantly fewer seeds. In the case of “moderate” and “good” fruit set rates, the mean seed number (number of seeds per apple) was virtually identical (5.8 versus 5.9).
Using the results of the pollination combinations, suitable pollen donors were determined for several different apple varieties (see selected values in Table 2). The point in time of flowering was divided into five categories: “early,” “medium early,” “medium,” “medium late,” and “late.” Pollen donors and recipients should not differ from each other by more than two flowering time categories.
Conclusion The efficiency of a suitable pollen donor is dependent upon both the genetic disposition and the point in time of flowering of the pollen recipient. It must be taken into consideration that the quality of the flower bud, the activity of...
Conclusion
The efficiency of a suitable pollen donor is dependent upon both the genetic disposition and the point in time of flowering of the pollen recipient. It must be taken into consideration that the quality of the flower bud, the activity of the pollinating insects, and the weather conditions during flowering can impact the fruit set rate and the quality of the developing fruits. A low seed number as a consequence of a low pollination rate can increase the June fruit fall or result in asymmetrical fruits. In the case of larger areas planted with varieties unable to optimally pollinate each other, crabapples are often the first choice as pollen donors. Such decorative apples usually feature resistance to diseases, a slim tree structure, and abundant flowering. Crabapples often carry allele S26, which no cultivated apple possesses; this indicates good pollination performance.
Read more
