Zur Züchtung von Kartoffelsorten mit Kaltlagerfähigkeit unter Berücksichtigung genetischer Aspekte

Zusammenfassung

Knollen von 14 Populationen wurden sowohl im Sämlings- als auch Ramschstadium nach 12-wöchiger Lagerung bei 4°C auf Kaltlagerfähigkeit (sehr geringe Zuckerakkumulationsrate) und Chipseignung untersucht. Beide Merkmale wurden an jeweils 25 Genotypen pro Population ermittelt. Die Ergebnisse des Sämlings- und Ramschstadiums sind ebenso wie die zwischen Gehalt an reduzierenden Zuckern und Chipsfarbe signifikant miteinander korreliert. Auf ihrer Basis ist deshalb sowohl eine Selektion von Populationen als auch bedingt von Einzelsämlingen möglich.

Nachkommenschaftsanalysen an Kreuzungen von Eltern mit geringer, mittlerer und hoher Zuckerakkumulationsrate während der Kaltlagerung zeigten, dass der Heritabilitätskoeffizient des Merkmals kaltlagerfähigkeit nur mittel (0,6) ist, dass aber bei Beschränkung der Auswertung auf Kombinationen von Eltern mit niedriger bzw. mittlerer Zuckerakkumulationsrate die Heritabilität dieses Merkmals hoch (0,91) ist. Die Beschränkung wird aufgrund der erhaltenen logarithmischen Funktionen (Sättigungstendenz) als erlaubt angesehen. Aussagen zum Erbgang und Erbwert der eingesetzten Genotypen werden getroffen. Nach den Ergebnissen kann bei entsprechendem Ausgangsmaterial eine erfolgreiche Züchtung kältestabiler Sorten betrieben werden.

Summary

A series of 14 populations in seedling and first clone stage were studied to investigate their storability at low temperatures and their suitability for crisp/chip production. Cold storage stability refers to the quality of the potato to refrain from accumulating reducing sugars completely or to a large extent when stored at 4°C. Both characteristics were determined for 25 genotypes of each population after a 12-week storage period at 4°C. The populations were selected from parents showing a significant difference in their storability at low temperatures. Based on their different rates of sugar accumulation, these parents were placed into three categories.

The content of reducing sugars was colorimetrically quantified in alcoholic extracts after reaction to p-hydroxybenzoic acid hydrazide; the suitability for the production of crisps/chips was assessed in frying tests.

These methods are suitable for seedlings (greenhouse) as well as to the first clones (field) to assess the populations and the breeding value of parents (Table 1). Both tests are significantly correlated:r=0.98 (parents);r=0.88 (progeny); α=0.1%.

Deviations of reducing sugar content in absolute terms are caused by commonly known environmental influences. Variations caused by environmental influences can be characterized by the standard deviation of the reducing sugar content as determined for various parents. This standard deviation varied in most cases between 0.05–0.07.

An analysis of the parent progeny relation showed an intermediary inheritance (Table 1) for storability at low temperatures. The coefficients for heritability (for seedlingsh ²=0.586 and for first clonal generationsh ²=0.602) derived from parent to progeny regression are relatively low (Figs 1 and 2) as might be expected according to Table 1. A closer study reveals that with crosses of parents less suited for cold storage, the mean population value shows a shift towards the partner with a low or medium rate of sugar accumulation. According to the postulated intermediary heritability, this increase in reducing sugar content after cold storage is too low, a fact which is caused by physiological conditions (turgor, solubility). The logarithmic functions obtained (y=0.357lnx+0.698 for seedlings andy=0.362lnx+0.77 for first clonal generations) show as well that a saturation level has been reached. If the evaluation is limited to crosses of partners with good or medium storability at low temperatures, the coefficients for heritability are:h ²=0.922 for seedlings andh ²=0.892 for first clonal generations. This indicates good possibilities to improve this characteristic through breeding. On the base of the data obtained it can be assumed that storability at low temperatures most probably follows polygenic inheritance.